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Sample records for phytopathogen verticillium longisporum

  1. The Three Lineages of the Diploid Hybrid Verticillium longisporum Differ in Virulence and Pathogenicity.

    PubMed

    Novakazi, Fluturë; Inderbitzin, Patrik; Sandoya, German; Hayes, Ryan J; von Tiedemann, Andreas; Subbarao, Krishna V

    2015-05-01

    Verticillium longisporum is an economically important vascular pathogen of Brassicaceae crops in different parts of the world. V. longisporum is a diploid hybrid that consists of three different lineages, each of which originated from a separate hybridization event between two different sets of parental species. We used 20 isolates representing the three V. longisporum lineages and the relative V. dahliae, and performed pathogenicity tests on 11 different hosts, including artichoke, cabbage, cauliflower, cotton, eggplant, horseradish, lettuce, linseed, oilseed rape (canola), tomato, and watermelon. V. longisporum was overall more virulent on the Brassicaceae crops than V. dahliae, which was more virulent than V. longisporum across the non-Brassicaceae crops. There were differences in virulence between the three V. longisporum lineages. V. longisporum lineage A1/D1 was the most virulent lineage on oilseed rape, and V. longisporum lineage A1/D2 was the most virulent lineage on cabbage and horseradish. We also found that on the non-Brassicaceae hosts eggplant, tomato, lettuce, and watermelon, V. longisporum was more or equally virulent than V. dahliae. This suggests that V. longisporum may have a wider potential host range than currently appreciated. PMID:25585057

  2. Identification and Differentiation of Verticillium Species and V. longisporum Lineages by Simplex and Multiplex PCR Assays

    PubMed Central

    Inderbitzin, Patrik; Davis, R. Michael; Bostock, Richard M.; Subbarao, Krishna V.

    2013-01-01

    Accurate species identification is essential for effective plant disease management, but is challenging in fungi including Verticillium sensu stricto (Ascomycota, Sordariomycetes, Plectosphaerellaceae), a small genus of ten species that includes important plant pathogens. Here we present fifteen PCR assays for the identification of all recognized Verticillium species and the three lineages of the diploid hybrid V. longisporum. The assays were based on DNA sequence data from the ribosomal internal transcribed spacer region, and coding and non-coding regions of actin, elongation factor 1-alpha, glyceraldehyde-3-phosphate dehydrogenase and tryptophan synthase genes. The eleven single target (simplex) PCR assays resulted in amplicons of diagnostic size for V. alfalfae, V. albo-atrum, V. dahliae including V. longisporum lineage A1/D3, V. isaacii, V. klebahnii, V. nonalfalfae, V. nubilum, V. tricorpus, V. zaregamsianum, and Species A1 and Species D1, the two undescribed ancestors of V. longisporum. The four multiple target (multiplex) PCR assays simultaneously differentiated the species or lineages within the following four groups: Verticillium albo-atrum, V. alfalfae and V. nonalfalfae; Verticillium dahliae and V. longisporum lineages A1/D1, A1/D2 and A1/D3; Verticillium dahliae including V. longisporum lineage A1/D3, V. isaacii, V. klebahnii and V. tricorpus; Verticillium isaacii, V. klebahnii and V. tricorpus. Since V. dahliae is a parent of two of the three lineages of the diploid hybrid V. longisporum, no simplex PCR assay is able to differentiate V. dahliae from all V. longisporum lineages. PCR assays were tested with fungal DNA extracts from pure cultures, and were not evaluated for detection and quantification of Verticillium species from plant or soil samples. The DNA sequence alignments are provided and can be used for the design of additional primers. PMID:23823707

  3. The Ascomycete Verticillium longisporum Is a Hybrid and a Plant Pathogen with an Expanded Host Range

    PubMed Central

    Inderbitzin, Patrik; Davis, R. Michael; Bostock, Richard M.; Subbarao, Krishna V.

    2011-01-01

    Hybridization plays a central role in plant evolution, but its overall importance in fungi is unknown. New plant pathogens are thought to arise by hybridization between formerly separated fungal species. Evolution of hybrid plant pathogens from non-pathogenic ancestors in the fungal-like protist Phytophthora has been demonstrated, but in fungi, the most important group of plant pathogens, there are few well-characterized examples of hybrids. We focused our attention on the hybrid and plant pathogen Verticillium longisporum, the causal agent of the Verticillium wilt disease in crucifer crops. In order to address questions related to the evolutionary origin of V. longisporum, we used phylogenetic analyses of seven nuclear loci and a dataset of 203 isolates of V. longisporum, V. dahliae and related species. We confirmed that V. longisporum was diploid, and originated three different times, involving four different lineages and three different parental species. All hybrids shared a common parent, species A1, that hybridized respectively with species D1, V. dahliae lineage D2 and V. dahliae lineage D3, to give rise to three different lineages of V. longisporum. Species A1 and species D1 constituted as yet unknown taxa. Verticillium longisporum likely originated recently, as each V. longisporum lineage was genetically homogenous, and comprised species A1 alleles that were identical across lineages. PMID:21455321

  4. Comparative Verticillium genomics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genus Verticillium contains several phytopathogenic species, the most important being V. dahliae, V. albo-atrum, and V. longisporum. The soil-borne habitat of these species, and their capacity to infect a variety of crops, make them chronic economic problems in crop production. Verticillium wilt...

  5. ERECTA, salicylic acid, abscisic acid, and jasmonic acid modulate quantitative disease resistance of Arabidopsis thaliana to Verticillium longisporum

    PubMed Central

    2014-01-01

    Background Verticillium longisporum is a soil-borne vascular pathogen infecting cruciferous hosts such as oilseed rape. Quantitative disease resistance (QDR) is the major control means, but its molecular basis is poorly understood so far. Quantitative trait locus (QTL) mapping was performed using a new (Bur×Ler) recombinant inbred line (RIL) population of Arabidopsis thaliana. Phytohormone measurements and analyses in defined mutants and near-isogenic lines (NILs) were used to identify genes and signalling pathways that underlie different resistance QTL. Results QTL for resistance to V. longisporum-induced stunting, systemic colonization by the fungus and for V. longisporum-induced chlorosis were identified. Stunting resistance QTL were contributed by both parents. The strongest stunting resistance QTL was shown to be identical with Erecta. A functional Erecta pathway, which was present in Bur, conferred partial resistance to V. longisporum-induced stunting. Bur showed severe stunting susceptibility in winter. Three stunting resistance QTL of Ler origin, two co-localising with wall-associated kinase-like (Wakl)-genes, were detected in winter. Furthermore, Bur showed a much stronger induction of salicylic acid (SA) by V. longisporum than Ler. Systemic colonization was controlled independently of stunting. The vec1 QTL on chromosome 2 had the strongest effect on systemic colonization. The same chromosomal region controlled the level of abscisic acid (ABA) and jasmonic acid (JA) in response to V. longisporum: The level of ABA was higher in colonization-susceptible Ler than in colonization-resistant Bur after V. longisporum infection. JA was down-regulated in Bur after infection, but not in Ler. These differences were also demonstrated in NILs, varying only in the region containing vec1. All phytohormone responses were shown to be independent of Erecta. Conclusions Signalling systems with a hitherto unknown role in the QDR of A. thaliana against V. longisporum were

  6. Verticillium wilts and management with special emphasis on lettuce.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt causes billions of dollars in annual losses worldwide. The genus Verticillium contains several phytopathogenic species, the most important being V. dahliae, V. albo-atrum, and V. longisporum. The soilborne habitat of these species, and their capacity to infect a variety of crops, m...

  7. Verticillium longisporum infection affects the leaf apoplastic proteome, metabolome, and cell wall properties in Arabidopsis thaliana.

    PubMed

    Floerl, Saskia; Majcherczyk, Andrzej; Possienke, Mareike; Feussner, Kirstin; Tappe, Hella; Gatz, Christiane; Feussner, Ivo; Kües, Ursula; Polle, Andrea

    2012-01-01

    Verticillium longisporum (VL) is one of the most devastating diseases in important oil crops from the family of Brassicaceae. The fungus resides for much time of its life cycle in the extracellular fluid of the vascular system, where it cannot be controlled by conventional fungicides. To obtain insights into the biology of VL-plant interaction in the apoplast, the secretome consisting of the extracellular proteome and metabolome as well as cell wall properties were studied in the model Brassicaceae, Arabidopsis thaliana. VL infection resulted in increased production of cell wall material with an altered composition of carbohydrate polymers and increased lignification. The abundance of several hundred soluble metabolites changed in the apoplast of VL-infected plants including signalling and defence compounds such as glycosides of salicylic acid, lignans and dihydroxybenzoic acid as well as oxylipins. The extracellular proteome of healthy leaves was enriched in antifungal proteins. VL caused specific increases in six apoplast proteins (three peroxidases PRX52, PRX34, P37, serine carboxypeptidase SCPL20, α-galactosidase AGAL2 and a germin-like protein GLP3), which have functions in defence and cell wall modification. The abundance of a lectin-like, chitin-inducible protein (CILLP) was reduced. Since the transcript levels of most of the induced proteins were not elevated until late infection time points (>20 dpi), whereas those of CILLP and GLP3 were reduced at earlier time points, our results may suggest that VL enhances its virulence by rapid down-regulation and delay of induction of plant defence genes. PMID:22363647

  8. Verticillium longisporum Infection Affects the Leaf Apoplastic Proteome, Metabolome, and Cell Wall Properties in Arabidopsis thaliana

    PubMed Central

    Floerl, Saskia; Majcherczyk, Andrzej; Possienke, Mareike; Feussner, Kirstin; Tappe, Hella; Gatz, Christiane; Feussner, Ivo; Kües, Ursula; Polle, Andrea

    2012-01-01

    Verticillium longisporum (VL) is one of the most devastating diseases in important oil crops from the family of Brassicaceae. The fungus resides for much time of its life cycle in the extracellular fluid of the vascular system, where it cannot be controlled by conventional fungicides. To obtain insights into the biology of VL-plant interaction in the apoplast, the secretome consisting of the extracellular proteome and metabolome as well as cell wall properties were studied in the model Brassicaceae, Arabidopsis thaliana. VL infection resulted in increased production of cell wall material with an altered composition of carbohydrate polymers and increased lignification. The abundance of several hundred soluble metabolites changed in the apoplast of VL-infected plants including signalling and defence compounds such as glycosides of salicylic acid, lignans and dihydroxybenzoic acid as well as oxylipins. The extracellular proteome of healthy leaves was enriched in antifungal proteins. VL caused specific increases in six apoplast proteins (three peroxidases PRX52, PRX34, P37, serine carboxypeptidase SCPL20, α-galactosidase AGAL2 and a germin-like protein GLP3), which have functions in defence and cell wall modification. The abundance of a lectin-like, chitin-inducible protein (CILLP) was reduced. Since the transcript levels of most of the induced proteins were not elevated until late infection time points (>20 dpi), whereas those of CILLP and GLP3 were reduced at earlier time points, our results may suggest that VL enhances its virulence by rapid down-regulation and delay of induction of plant defence genes. PMID:22363647

  9. RabGAP22 Is Required for Defense to the Vascular Pathogen Verticillium longisporum and Contributes to Stomata Immunity

    PubMed Central

    Roos, Jonas; Bejai, Sarosh; Oide, Shinichi; Dixelius, Christina

    2014-01-01

    Verticillium longisporum is a soil-borne pathogen with a preference for plants within the family Brassicaceae. Following invasion of the roots, the fungus proliferates in the plant vascular system leading to stunted plant growth, chlorosis and premature senescence. RabGTPases have been demonstrated to play a crucial role in regulating multiple responses in plants. Here, we report on the identification and characterization of the Rab GTPase-activating protein RabGAP22 gene from Arabidopsis, as an activator of multiple components in the immune responses to V. longisporum. RabGAP22Pro:GUS transgenic lines showed GUS expression predominantly in root meristems, vascular tissues and stomata, whereas the RabGAP22 protein localized in the nucleus. Reduced RabGAP22 transcript levels in mutants of the brassinolide (BL) signaling gene BRI1-ASSOCIATED RECEPTOR KINASE 1, together with a reduction of fungal proliferation following BL pretreatment, suggested RabGAP22 to be involved in BL-mediated responses. Pull-down assays revealed SERINE:GLYOXYLATE AMINOTRANSFERASE (AGT1) as an interacting partner during V. longisporum infection and bimolecular fluorescence complementation (BiFC) showed the RabGAP22-AGT1 protein complex to be localized in the peroxisomes. Further, fungal-induced RabGAP22 expression was found to be associated with elevated endogenous levels of the plant hormones jasmonic acid (JA) and abscisic acid (ABA). An inadequate ABA response in rabgap22-1 mutants, coupled with a stomata-localized expression of RabGAP22 and impairment of guard cell closure in response to V. longisporum and Pseudomonas syringae, suggest that RabGAP22 has multiple roles in innate immunity. PMID:24505423

  10. Defence reactions in the apoplastic proteome of oilseed rape (Brassica napus var. napus) attenuate Verticillium longisporum growth but not disease symptoms

    PubMed Central

    Floerl, Saskia; Druebert, Christine; Majcherczyk, Andrzej; Karlovsky, Petr; Kües, Ursula; Polle, Andrea

    2008-01-01

    Background Verticillium longisporum is one of the most important pathogens of Brassicaceae that remains strictly in the xylem during most stages of its development. It has been suggested that disease symptoms are associated with clogging of xylem vessels. The aim of our study was to investigate extracellular defence reactions induced by V. longisporum in the xylem sap and leaf apoplast of Brassica napus var. napus in relation to the development of disease symptoms, photosynthesis and nutrient status. Results V. longisporum (strain VL43) did not overcome the hypocotyl barrier until 3 weeks after infection although the plants showed massive stunting of the stem and mild leaf chlorosis. During this initial infection phase photosynthetic carbon assimilation, transpiration rate and nutrient elements in leaves were not affected in VL43-infected compared to non-infected plants. Proteome analysis of the leaf apoplast revealed 170 spots after 2-D-protein separation, of which 12 were significantly enhanced in response to VL43-infection. LS-MS/MS analysis and data base searches revealed matches of VL43-responsive proteins to an endochitinase, a peroxidase, a PR-4 protein and a β-1,3-glucanase. In xylem sap three up-regulated proteins were found of which two were identified as PR-4 and β-1,3-glucanase. Xylem sap of infected plants inhibited the growth of V. longisporum. Conclusion V. longisporum infection did not result in drought stress or nutrient limitations. Stunting and mild chlorosis were, therefore, not consequences of insufficient water and nutrient supply due to VL43-caused xylem obstruction. A distinct array of extracellular PR-proteins was activated that might have limited Verticillium spreading above the hypocotyl. In silico analysis suggested that ethylene was involved in up-regulating VL43-responsive proteins. PMID:19094241

  11. Identification and characterization of microRNAs in oilseed rape (Brassica napus) responsive to infection with the pathogenic fungus Verticillium longisporum using Brassica AA (Brassica rapa) and CC (Brassica oleracea) as reference genomes.

    PubMed

    Shen, Dan; Suhrkamp, Ina; Wang, Yu; Liu, Shenyi; Menkhaus, Jan; Verreet, Joseph-Alexander; Fan, Longjiang; Cai, Daguang

    2014-11-01

    Verticillium longisporum, a soil-borne pathogenic fungus, causes vascular disease in oilseed rape (Brassica napus). We proposed that plant microRNAs (miRNAs) are involved in the plant-V. longisporum interaction. To identify oilseed rape miRNAs, we deep-sequenced two small RNA libraries made from V. longisporum infected/noninfected roots and employed Brassica rapa and Brassica oleracea genomes as references for miRNA prediction and characterization. We identified 893 B. napus miRNAs representing 360 conserved and 533 novel miRNAs, and mapped 429 and 464 miRNAs to the AA and CC genomes, respectively. Microsynteny analysis with the conserved miRNAs and their flanking protein coding sequences revealed 137 AA-CC genome syntenic miRNA pairs and 61 AA and 42 CC genome-unique miRNAs. Sixty-two miRNAs were responsive to the V. longisporum infection. We present data for specific interactions and simultaneously reciprocal changes in the expression levels of the miRNAs and their targets in the infected roots. We demonstrate that miRNAs are involved in the plant-fungus interaction and that miRNA168-Argonaute 1 (AGO1) expression modulation might act as a key regulatory module in a compatible plant-V. longisporum interaction. Our results suggest that V. longisporum may have evolved a virulence mechanism by interference with plant miRNAs to reprogram plant gene expression and achieve infection. PMID:25132374

  12. Transposable elements in phytopathogenic Verticillium spp.: insights into genome evolution and inter- and intra-specific diversification

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae (Vd) and Verticillium albo-atrum (Va) are cosmopolitan soil fungi causing very disruptive vascular diseases on a wide range of crop plants. To date, no sexual stage has been identified in either microorganism suggesting that somatic mutation is a major force in generating geneti...

  13. Diversity, Pathogenicity And Control of Verticillium Species.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genus Verticillium is a cosmopolitan group of ascomycetous fungi, encompassing phytopathogenic species that cause vascular wilts of plants. Two of these species, V. dahliae and V. albo-atrum, cause billions of dollars in annual crop losses worldwide. The soil habitat of these species, the exte...

  14. Verticillium Suppression Is Associated with the Glucosinolate Composition of Arabidopsis thaliana Leaves

    PubMed Central

    Witzel, Katja; Hanschen, Franziska S.; Schreiner, Monika; Krumbein, Angelika; Ruppel, Silke; Grosch, Rita

    2013-01-01

    The soil-borne fungal pathogen Verticillium longisporum is able to penetrate the root of a number of plant species and spread systemically via the xylem. Fumigation of Verticillium contaminated soil with Brassica green manure is used as an environmentally friendly method for crop protection. Here we present a study focused on the potential role of glucosinolates and their breakdown products of the model plant Arabidopsis thaliana in suppressing growth of V. longisporum. For this purpose we analysed the glucosinolate composition of the leaves and roots of a set of 19 key accessions of A. thaliana. The effect of volatile glucosinolate hydrolysis products on the in vitro growth of the pathogen was tested by exposing the fungus to hydrated lyophilized plant tissue. Volatiles released from leaf tissue were more effective than from root tissue in suppressing mycelial growth of V. longisporum. The accessions varied in their efficacy, with the most effective suppressing mycelial growth by 90%. An analysis of glucosinolate profiles and their enzymatic degradation products revealed a correlation between fungal growth inhibition and the concentration of alkenyl glucosinolates, particularly 2-propenyl (2Prop) glucosinolate, respectively its hydrolysis products. Exposure of the fungus to purified 2Prop glucosinolate revealed that its suppressive activity was correlated with its concentration. Spiking of 2Prop glucosinolate to leaf material of one of the least effective A. thaliana accessions led to fungal growth suppression. It is suggested that much of the inhibitory effect observed for the tested accessions can be explained by the accumulation of 2Prop glucosinolate. PMID:24039726

  15. Genetic and environmental control of the Verticillium syndrome in Arabidopsis thaliana

    PubMed Central

    2010-01-01

    Background Verticillium spp. are major pathogens of dicotyledonous plants such as cotton, tomato, olive or oilseed rape. Verticillium symptoms are often ambiguous and influenced by development and environment. The aim of the present study was to define disease and resistance traits of the complex Verticillium longisporum syndrome in Arabidopsis thaliana (L.) Heynh. A genetic approach was used to determine genetic, developmental and environmental factors controlling specific disease and resistance traits and to study their interrelations. Results A segregating F2/F3 population originating from ecotypes 'Burren' (Bur) and 'Landsberg erecta' (Ler) was established. Plants were root-dip inoculated and tested under greenhouse conditions. The Verticillium syndrome was dissected into components like systemic spread, stunting, development time and axillary branching. Systemic spread of V. longisporum via colonisation of the shoot was extensive in Ler; Bur showed a high degree of resistance against systemic spread. Fungal colonisation of the shoot apex was determined by (a) determining the percentage of plants from which the fungus could be re-isolated and (b) measuring fungal DNA content with quantitative real-time PCR (qPCR). Four quantitative trait loci (QTL) controlling systemic spread were identified for the percentage of plants showing fungal outgrowth, two of these QTL were confirmed with qPCR data. The degree of colonisation by V. longisporum was negatively correlated with development time. QTL controlling development time showed some overlap with QTL for resistance to systemic spread. Stunting depended on host genotype, development time and seasonal effects. Five QTL controlling this trait were identified which did not co-localize with QTL controlling systemic spread. V. longisporum induced increased axillary branching in Bur; two QTL controlling this reaction were found. Conclusions Systemic spread of V. longisporum in the host as well as resistance to this major

  16. Verticillium infection triggers VASCULAR-RELATED NAC DOMAIN7-dependent de novo xylem formation and enhances drought tolerance in Arabidopsis.

    PubMed

    Reusche, Michael; Thole, Karin; Janz, Dennis; Truskina, Jekaterina; Rindfleisch, Sören; Drübert, Christine; Polle, Andrea; Lipka, Volker; Teichmann, Thomas

    2012-09-01

    The soilborne fungal plant pathogen Verticillium longisporum invades the roots of its Brassicaceae hosts and proliferates in the plant vascular system. Typical aboveground symptoms of Verticillium infection on Brassica napus and Arabidopsis thaliana are stunted growth, vein clearing, and leaf chloroses. Here, we provide evidence that vein clearing is caused by pathogen-induced transdifferentiation of chloroplast-containing bundle sheath cells to functional xylem elements. In addition, our findings suggest that reinitiation of cambial activity and transdifferentiation of xylem parenchyma cells results in xylem hyperplasia within the vasculature of Arabidopsis leaves, hypocotyls, and roots. The observed de novo xylem formation correlates with Verticillium-induced expression of the VASCULAR-RELATED NAC DOMAIN (VND) transcription factor gene VND7. Transgenic Arabidopsis plants expressing the chimeric repressor VND7-SRDX under control of a Verticillium infection-responsive promoter exhibit reduced de novo xylem formation. Interestingly, infected Arabidopsis wild-type plants show higher drought stress tolerance compared with noninfected plants, whereas this effect is attenuated by suppression of VND7 activity. Together, our results suggest that V. longisporum triggers a tissue-specific developmental plant program that compensates for compromised water transport and enhances the water storage capacity of infected Brassicaceae host plants. In conclusion, we provide evidence that this natural plant-fungus pathosystem has conditionally mutualistic features. PMID:23023171

  17. Verticillium Infection Triggers VASCULAR-RELATED NAC DOMAIN7–Dependent de Novo Xylem Formation and Enhances Drought Tolerance in Arabidopsis[W

    PubMed Central

    Reusche, Michael; Thole, Karin; Janz, Dennis; Truskina, Jekaterina; Rindfleisch, Sören; Drübert, Christine; Polle, Andrea; Lipka, Volker; Teichmann, Thomas

    2012-01-01

    The soilborne fungal plant pathogen Verticillium longisporum invades the roots of its Brassicaceae hosts and proliferates in the plant vascular system. Typical aboveground symptoms of Verticillium infection on Brassica napus and Arabidopsis thaliana are stunted growth, vein clearing, and leaf chloroses. Here, we provide evidence that vein clearing is caused by pathogen-induced transdifferentiation of chloroplast-containing bundle sheath cells to functional xylem elements. In addition, our findings suggest that reinitiation of cambial activity and transdifferentiation of xylem parenchyma cells results in xylem hyperplasia within the vasculature of Arabidopsis leaves, hypocotyls, and roots. The observed de novo xylem formation correlates with Verticillium-induced expression of the VASCULAR-RELATED NAC DOMAIN (VND) transcription factor gene VND7. Transgenic Arabidopsis plants expressing the chimeric repressor VND7-SRDX under control of a Verticillium infection-responsive promoter exhibit reduced de novo xylem formation. Interestingly, infected Arabidopsis wild-type plants show higher drought stress tolerance compared with noninfected plants, whereas this effect is attenuated by suppression of VND7 activity. Together, our results suggest that V. longisporum triggers a tissue-specific developmental plant program that compensates for compromised water transport and enhances the water storage capacity of infected Brassicaceae host plants. In conclusion, we provide evidence that this natural plant–fungus pathosystem has conditionally mutualistic features. PMID:23023171

  18. An aversion to Verticillium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt is a one of the most serious diseases affecting field production of ornamental trees and shrubs. The disease is caused by the soilborne fungus, Verticillium dahliae. The pathogen is very common in agricultural fields and infects hundreds of economically important plant species incl...

  19. Analysis of a MULE-cyanide hydratase gene fusion in Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genome of the phytopathogenic fungus Verticillium dahliae encodes numerous Class II “cut-and-paste” transposable elements, including those of a small group of MULE transposons. We have previously identified a fusion event between a MULE transposon sequence and sequence encoding a cyanide hydrata...

  20. Interfamily Transfer of Tomato Ve1 Mediates Verticillium Resistance in Arabidopsis1[C][W][OA

    PubMed Central

    Fradin, Emilie F.; Abd-El-Haliem, Ahmed; Masini, Laura; van den Berg, Grardy C.M.; Joosten, Matthieu H.A.J.; Thomma, Bart P.H.J.

    2011-01-01

    Vascular wilts caused by soil-borne fungal species of the Verticillium genus are devastating plant diseases. The most common species, Verticillium dahliae and Verticillium albo-atrum, have broad host ranges and are notoriously difficult to control. Therefore, genetic resistance is the preferred method for disease control. Only from tomato (Solanum lycopersicum) has a Verticillium resistance locus been cloned, comprising the Ve1 gene that encodes a receptor-like protein-type cell surface receptor. Due to lack of a suitable model for receptor-like protein (RLP)-mediated resistance signaling in Arabidopsis (Arabidopsis thaliana), so far relatively little is known about RLP signaling in pathogen resistance. Here, we show that Ve1 remains fully functional after interfamily transfer to Arabidopsis and that Ve1-transgenic Arabidopsis is resistant to race 1 but not to race 2 strains of V. dahliae and V. albo-atrum, nor to the Brassicaceae-specific pathogen Verticillium longisporum. Furthermore, we show that signaling components utilized by Ve1 in Arabidopsis to establish Verticillium resistance overlap with those required in tomato and include SERK3/BAK1, EDS1, and NDR1, which strongly suggests that critical components for resistance signaling are conserved. We subsequently investigated the requirement of SERK family members for Ve1 resistance in Arabidopsis, revealing that SERK1 is required in addition to SERK3/BAK1. Using virus-induced gene silencing, the requirement of SERK1 for Ve1-mediated resistance was confirmed in tomato. Moreover, we show the requirement of SERK1 for resistance against the foliar fungal pathogen Cladosporium fulvum mediated by the RLP Cf-4. Our results demonstrate that Arabidopsis can be used as model to unravel the genetics of Ve1-mediated resistance. PMID:21617027

  1. Role of anionic isoforms of peroxidase during phytopathogenic infection of plants from the family Malvaceae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An increase of the activity and the appearance of new isoforms (high- and low-molecular-weight) in the isospectrum of peroxidase were noted after the action of the phytopathogen Verticillium dahliae on plants from the family Malvaceae. The temperature was shown to have an effect on the resistance to...

  2. Phylogenetics and Taxonomy of the Fungal Vascular Wilt Pathogen Verticillium, with the Descriptions of Five New Species

    PubMed Central

    Inderbitzin, Patrik; Bostock, Richard M.; Davis, R. Michael; Usami, Toshiyuki; Platt, Harold W.; Subbarao, Krishna V.

    2011-01-01

    Knowledge of pathogen biology and genetic diversity is a cornerstone of effective disease management, and accurate identification of the pathogen is a foundation of pathogen biology. Species names provide an ideal framework for storage and retrieval of relevant information, a system that is contingent on a clear understanding of species boundaries and consistent species identification. Verticillium, a genus of ascomycete fungi, contains important plant pathogens whose species boundaries have been ill defined. Using phylogenetic analyses, morphological investigations and comparisons to herbarium material and the literature, we established a taxonomic framework for Verticillium comprising ten species, five of which are new to science. We used a collection of 74 isolates representing much of the diversity of Verticillium, and phylogenetic analyses based on the ribosomal internal transcribed spacer region (ITS), partial sequences of the protein coding genes actin (ACT), elongation factor 1-alpha (EF), glyceraldehyde-3-phosphate dehydrogenase (GPD) and tryptophan synthase (TS). Combined analyses of the ACT, EF, GPD and TS datasets recognized two major groups within Verticillium, Clade Flavexudans and Clade Flavnonexudans, reflecting the respective production and absence of yellow hyphal pigments. Clade Flavexudans comprised V. albo-atrum and V. tricorpus as well as the new species V. zaregamsianum, V. isaacii and V. klebahnii, of which the latter two were morphologically indistinguishable from V. tricorpus but may differ in pathogenicity. Clade Flavnonexudans comprised V. nubilum, V. dahliae and V. longisporum, as well as the two new species V. alfalfae and V. nonalfalfae, which resembled the distantly related V. albo-atrum in morphology. Apart from the diploid hybrid V. longisporum, each of the ten species corresponded to a single clade in the phylogenetic tree comprising just one ex-type strain, thereby establishing a direct link to a name tied to a herbarium specimen

  3. Dynamics of verticillium species microsclerotia in field soils in response to fumigation, cropping patterns, and flooding.

    PubMed

    Short, Dylan P G; Sandoya, German; Vallad, Gary E; Koike, Steven T; Xiao, Chang-Lin; Wu, Bo-Ming; Gurung, Suraj; Hayes, Ryan J; Subbarao, Krishna V

    2015-05-01

    Verticillium dahliae is a soilborne, economically significant fungal plant pathogen that persists in the soil for up to 14 years as melanized microsclerotia (ms). Similarly, V. longisporum is a very significant production constraint on members of the family Brassicaceae. Management of Verticillium wilt has relied on methods that reduce ms below crop-specific thresholds at which little or no disease develops. Methyl bromide, a broad-spectrum biocide, has been used as a preplant soil fumigant for over 50 years to reduce V. dahliae ms. However, reductions in the number of ms in the vertical and horizontal soil profiles and the rate at which soil recolonization occurs has not been studied. The dynamics of ms in soil before and after methyl bromide+chloropicrin fumigation were followed over 3 years in six 8-by-8-m sites in two fields. In separate fields, the dynamics of ms in the 60-cm-deep vertical soil profile pre- and postfumigation with methyl bromide+chloropicrin followed by various cropping patterns were studied over 4 years. Finally, ms densities were assessed in six 8-by-8-m sites in a separate field prior to and following a natural 6-week flood. Methyl bromide+chloripicrin significantly reduced but did not eliminate V. dahliae ms in either the vertical or horizontal soil profiles. In field studies, increases in ms were highly dependent upon the crop rotation pattern followed postfumigation. In the vertical soil profile, densities of ms were highest in the top 5 to 20 cm of soil but were consistently detected at 60-cm depths. Six weeks of natural flooding significantly reduced (on average, approximately 65% in the total viable counts of ms) but did not eliminate viable ms of V. longisporum. PMID:25626074

  4. New outbreaks of verticillium wilt on Hop in Oregon caused by nonlethal verticillium albo-atrum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2006 and 2007, new outbreaks of Verticillium wilt on hop were detected on two farms in Oregon. Verticillium pathogens vary in their virulence to hop; some strains cause minor damage but others can kill susceptible cultivars. Studies were conducted to determine the identity of the Verticillium sp...

  5. Genetic Dissection of Verticillium Wilt Resistance Mediated by Tomato Ve11[C][W][OA

    PubMed Central

    Fradin, Emilie F.; Zhang, Zhao; Juarez Ayala, Juan C.; Castroverde, Christian D.M.; Nazar, Ross N.; Robb, Jane; Liu, Chun-Ming; Thomma, Bart P.H.J.

    2009-01-01

    Vascular wilt diseases caused by soil-borne pathogens are among the most devastating plant diseases worldwide. The Verticillium genus includes vascular wilt pathogens with a wide host range. Although V. longisporum infects various hosts belonging to the Cruciferaceae, V. dahliae and V. albo-atrum cause vascular wilt diseases in over 200 dicotyledonous species, including economically important crops. A locus responsible for resistance against race 1 strains of V. dahliae and V. albo-atrum has been cloned from tomato (Solanum lycopersicum) only. This locus, known as Ve, comprises two closely linked inversely oriented genes, Ve1 and Ve2, that encode cell surface receptor proteins of the extracellular leucine-rich repeat receptor-like protein class of disease resistance proteins. Here, we show that Ve1, but not Ve2, provides resistance in tomato against race 1 strains of V. dahliae and V. albo-atrum and not against race 2 strains. Using virus-induced gene silencing in tomato, the signaling cascade downstream of Ve1 is shown to require both EDS1 and NDR1. In addition, NRC1, ACIF, MEK2, and SERK3/BAK1 also act as positive regulators of Ve1 in tomato. In conclusion, Ve1-mediated resistance signaling only partially overlaps with signaling mediated by Cf proteins, type members of the receptor-like protein class of resistance proteins. PMID:19321708

  6. Autophagy in plants and phytopathogens.

    PubMed

    Yoshimoto, Kohki; Takano, Yoshitaka; Sakai, Yasuyoshi

    2010-04-01

    Plants and plant-associated microorganisms including phytopathogens have to adapt to drastic changes in environmental conditions. Because of their immobility, plants must cope with various types of environmental stresses such as starvation, oxidative stress, drought stress, and invasion by phytopathogens during their differentiation, development, and aging processes. Here we briefly describe the early studies of plant autophagy, summarize recent studies on the molecular functions of ATG genes, and speculate on the role of autophagy in plants and phytopathogens. Autophagy regulates senescence and pathogen-induced cell death in plants, and autophagy and pexophagy play critical roles in differentiation and the invasion of host cells by phytopathogenic fungi. PMID:20079356

  7. Verticillium wilt in the Pacific Northwest

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt is a serious disease of many economically important agricultural and horticultural crops in the Pacific Northwest (PNW). The disease affects herbaceous annuals and perennials as well as woody trees and shrubs. Plants affected by Verticillium wilt exhibit chlorosis, wilting, defolia...

  8. Progress toward breeding for Verticillium wilt resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt is a persistent and serious problem in potato production. Host plant resistance offers an attractive long-term control method. Breeding progress depends on access to germplasm carrying resistance genes. This study was carried out to identify sources of Verticillium wilt resistan...

  9. Progress Toward Breeding for Verticillium Wilt Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt is a persistent and serious problem in potato production. Host plant resistance offers an attractive long-term control method. Breeding progress depends on access to germplasm carrying resistance genes. This study was carried out to identify sources of Verticillium wilt resistan...

  10. A novel method for rapidly isolating microbes that suppress soil-borne phytopathogens

    NASA Astrophysics Data System (ADS)

    Cooper, Sarah; Agnew, Linda; Pereg, Lily

    2016-04-01

    Seedling establishment faces a large number of challenges related to soil physical properties as well as to fungal root diseases. It is extremely difficult to eliminate fungal pathogens from soils where their populations are established due to the persistent nature of their spores and since fumigation of resident fungi is very ineffective in clay-containing soils. Therefore it is necessary to find ways to overcome disease in areas where the soils are infected with fungal phytopathogens. The phenomenon of disease suppressive soils, where the pathogen is present but no disease observed, suggests that microbial antagonism in the soil may lead to the suppression of the growth of fungal pathogens. There are also cases in the literature where soil microorganisms were isolated that suppress the growth of phytopathogens. Antibiosis is one of the most important mechanisms responsible for fungal antagonism, with some significant antifungal compounds involved including antibiotics, volatile organic compounds, hydrogen cyanide and lytic enzymes. Isolation of pathogen-suppressive microorganisms from the soil is time consuming and tedious. We established a simple method for direct isolation of soil microbes (bacteria and fungi) that suppress fungal phytopathogens as well as procedures for confirmation of disease suppression. We will discuss such methods, which were so far tested with the cotton fungal pathogens Thielaviopsis basicola, Verticillium dahliae and Fusarium oxysporum and Verticillium fungicola. We have isolated a diversity of T. basicola-suppressive fungi and bacteria from two vastly different soil types. Identification of the antagonistic isolates revealed that they are a diverse lot, some belong to groups known to be suppressive of a wide range of fungal pathogens, endorsing the power of this technique to rapidly and directly isolate soil-borne microbes antagonistic to a wide variety of fungal pathogens.

  11. Isolation, partial characterization, and cloning of an extracellular chitinase from the entomopathogenic fungus Verticillium lecanii.

    PubMed

    Yu, G; Xie, L Q; Li, J T; Sun, X H; Zhang, H; Du, Q; Li, Q Y; Zhang, S H; Pan, H Y

    2015-01-01

    The entomopathogenic fungus Verticillium lecanii is a well-known biocontrol agent of fungal phytopathogens, as well as insect pests. A 42-kDa chitinase belonging to family 18 of the glycosyl hydrolases was isolated and partially characterized. Chitinase was purified using successive column chromatography on phenyl-sepharose, DEAE-sepharose, and CM-sepharose. The enzyme showed the highest activity at 40°C and pH 4.6. Enzyme activity was strongly activated in the presence of Mg(2+). The purified enzyme showed inhibitory activity of spore germination against several plant pathogens, particularly Fusarium moniliforme. The genomic DNA and cDNA sequences were resolved by polymerase chain reaction amplification and sequencing. Protein modeling and comparative investigation of different chitinase amino acids showed that chitinases are conserved in parasitic fungi. PMID:25867374

  12. Expression of BvGLP-1 encoding a germin-like protein from sugar beet in Arabidopsis thaliana leads to resistance against phytopathogenic fungi.

    PubMed

    Knecht, Katrin; Seyffarth, Monique; Desel, Christine; Thurau, Tim; Sherameti, Irena; Lou, Binggan; Oelmüller, Ralf; Cai, Daguang

    2010-04-01

    Nematode (Heterodera schachtii) resistance in sugar beet (Beta vulgaris) is controlled by a single dominant resistance gene, Hs1(pro-1). BvGLP-1 was cloned from resistant sugar beet. The BvGLP-1 messenger (m)RNA is highly upregulated in the resistant plants after nematode infection, suggesting its role in the Hs1(pro-1) mediated resistance. BvGLP-1 exhibits sequence homology to a set of plant germin-like proteins (GLP), from which several have proved to be functional in plant basal or defense resistance against fungal pathogens. To test whether BvGLP-1 is also involved in the plant-fungus interaction, we transferred BvGLP-1 into Arabidopsis and challenged the transgenic plants with the pathogenic fungi Verticillium longisporum and Rhizoctonia solani as well as with the beneficial endophytic fungus Piriformospora indica. The expression of BvGLP-1 in Arabidopsis elevated the H(2)O(2) content and conferred significant resistance to V. longisporum and R. solani but did not affect the beneficial interaction with P. indica in seedlings. Microscopic observations revealed a dramatic reduction in the amount of hyphae of the pathogenic fungi on the root surface as well as of fungal mycelium developed inside the roots of transgenic Arabidopsis compared with wild-type plants. Molecular analysis demonstrated that the BvGLP-1 expression in Arabidopsis constitutively activates the expression of a subset of plant defense-related proteins such as PR-1 to PR-4 and PDF1.2 but not PDF2.1 and PDF2.3. In contrast, the PDF2.1 mRNA level was downregulated. These data suggest an important role of BvGLP-1 in establishment of plant defense responses, which follow specific signaling routes that diverge from those induced by the beneficial fungus. PMID:20192832

  13. Data on morphological features of mycosis induced by Colletotrichum nymphaeae and Lecanicillium longisporum on citrus orthezia scale.

    PubMed

    Mascarin, Gabriel Moura; Guarín-Molina, Juan Humberto; Arthurs, Steven Paul; Humber, Richard Alan; de Andrade Moral, Rafael; Demétrio, Clarice Garcia Borges; Delalibera, Ítalo

    2016-09-01

    We describe symptoms of mycosis induced by two native fungal entomopathogens of the citrus orthezia scale, Praelongorthezia praelonga (Hemiptera: Ortheziidae), an important pest of citrus orchards. The data presented in this article are related to the article entitled "Seasonal prevalence of the insect pathogenic fungus Colletotrichum nymphaeae in Brazilian citrus groves under different chemical pesticide regimes" [1]. The endemic fungal pathogen, C. nymphaeae, emerges through the thin cuticular intersegmental regions of the citrus orthezia scale body revealing orange salmon-pigmented conidiophores bearing conidial masses, as well as producing rhizoid-like hyphae that extend over the citrus leaf. By contrast, nymphs or adult females of this scale insect infected with Lecanicillium longisporum exhibit profuse outgrowth of bright white-pigmented conidiophores with clusters of conidia emerging from the insect intersegmental membranes, and mycosed cadavers are commonly observed attached to the leaf surface by hyphal extensions. These morphological differences are important features to discriminate these fungal entomopathogens in citrus orthezia scales. PMID:27274531

  14. Host Range Specificity in Verticillium dahliae.

    PubMed

    Bhat, R G; Subbarao, K V

    1999-12-01

    ABSTRACT Verticillium dahliae isolates from artichoke, bell pepper, cabbage, cauliflower, chili pepper, cotton, eggplant, lettuce, mint, potato, strawberry, tomato, and watermelon and V. albo-atrum from alfalfa were evaluated for their pathogenicity on all 14 hosts. One-month-old seedlings were inoculated with a spore suspension of about 10(7) conidia per ml using a root-dip technique and incubated in the greenhouse. Disease incidence and severity, plant height, and root and shoot dry weights were recorded 6 weeks after inoculation. Bell pepper, cabbage, cauliflower, cotton, eggplant, and mint isolates exhibited host specificity and differential pathogenicity on other hosts, whereas isolates from artichoke, lettuce, potato, strawberry, tomato, and watermelon did not. Bell pepper was resistant to all Verticillium isolates except isolates from bell pepper and eggplant. Thus, host specificity exists in some isolates of V. dahliae. The same isolates were characterized for vegetative compatibility groups (VCGs) through complementation of nitrate nonutilizing (nit) mutants. Cabbage and cauliflower isolates did not produce nit mutants. The isolate from cotton belonged to VCG 1; isolates from bell pepper, eggplant, potato, and tomato, to VCG 4; and the remaining isolates, to VCG 2. These isolates were also analyzed using the random amplified polymorphic DNA (RAPD) method. Forty random primers were screened, and eighteen of them amplified DNA from Verticillium. Based on RAPD banding patterns, cabbage and cauliflower isolates formed a unique group, distinct from other V. dahliae and V. albo-atrum groups. Minor genetic variations were observed among V. dahliae isolates from other hosts, regardless of whether they were host specific or not. There was no correlation among pathogenicity, VCGs, and RAPD banding patterns. Even though the isolates belonged to different VCGs, they shared similar RAPD profiles. These results suggest that management of Verticillium wilt in some crops

  15. MADS-Box Transcription Factor VdMcm1 Regulates Conidiation, Microsclerotia Formation, Pathogenicity, and Secondary Metabolism of Verticillium dahliae

    PubMed Central

    Xiong, Dianguang; Wang, Yonglin; Tian, Longyan; Tian, Chengming

    2016-01-01

    Verticillium dahliae, a notorious phytopathogenic fungus, causes vascular wilt diseases in many plant species resulting in devastating yield losses worldwide. Due to its ability to colonize plant xylem and form microsclerotia, V. dahliae is highly persistent and difficult to control. In this study, we show that the MADS-box transcription factor VdMcm1 is a key regulator of conidiation, microsclerotia formation, virulence, and secondary metabolism of V. dahliae. In addition, our findings suggest that VdMcm1 is involved in cell wall integrity. Finally, comparative RNA-Seq analysis reveals 823 significantly downregulated genes in the VdMcm1 deletion mutant, with diverse biological functions in transcriptional regulation, plant infection, cell adhesion, secondary metabolism, transmembrane transport activity, and cell secretion. When taken together, these data suggest that VdMcm1 performs pleiotropic functions in V. dahliae. PMID:27536281

  16. MADS-Box Transcription Factor VdMcm1 Regulates Conidiation, Microsclerotia Formation, Pathogenicity, and Secondary Metabolism of Verticillium dahliae.

    PubMed

    Xiong, Dianguang; Wang, Yonglin; Tian, Longyan; Tian, Chengming

    2016-01-01

    Verticillium dahliae, a notorious phytopathogenic fungus, causes vascular wilt diseases in many plant species resulting in devastating yield losses worldwide. Due to its ability to colonize plant xylem and form microsclerotia, V. dahliae is highly persistent and difficult to control. In this study, we show that the MADS-box transcription factor VdMcm1 is a key regulator of conidiation, microsclerotia formation, virulence, and secondary metabolism of V. dahliae. In addition, our findings suggest that VdMcm1 is involved in cell wall integrity. Finally, comparative RNA-Seq analysis reveals 823 significantly downregulated genes in the VdMcm1 deletion mutant, with diverse biological functions in transcriptional regulation, plant infection, cell adhesion, secondary metabolism, transmembrane transport activity, and cell secretion. When taken together, these data suggest that VdMcm1 performs pleiotropic functions in V. dahliae. PMID:27536281

  17. Verticillium comparative genomics--understanding pathogenicity and diversity.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is the primary causal agent of Verticillium wilt that causes billions of dollars in annual losses worldwide. This soil-borne fungal pathogen exhibits extraordinary genetic plasticity, capable of colonizing a broad range of hosts in diverse ecological niches. Moreover, V. dahlia...

  18. Verticillium Wilt in Potato: Host-Pathogen Interactions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW) is a widespread disease that causes consistent yield losses in many potato growing regions worldwide. In the U.S., it is mainly caused by the soil-borne fungal pathogen Verticillium dahliae. Microsclerotia can survive in the soil for many years. When they germinate and infec...

  19. Verticillium Wilt Resistance Evaluation of Wisconsin Breeding Clones

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt is one of the most widespread and persistent problems encountered by potato producers. In Wisconsin, it is caused in large part by the fungal pathogen Verticillium dahliae. Soil fumigation is currently the only consistently effective control measure. However, host plant resistan...

  20. A soilless Verticillium wilt assay using an early flowering lettuce

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A soilless growth chamber assay was evaluated for rapid assessment of Verticillium wilt symptoms on lettuce. Seedlings of the early flowering plant introduction (PI) 251246 were inoculated in tubes with conidial suspensions of Verticillium spp. isolates from lettuce or cauliflower. PI 251246 devel...

  1. Microbial antagonists of Verticillium dahliae colonize cotton root system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt remains one of the most severe diseases affecting cotton production in Uzbekistan. We are investigating microbial antagonist to control this pathogen. To this end, we have identified several antagonists of Verticillium dahliae (Bacillus sp. 234, Bacillus sp. 3, Streptomyces roseofl...

  2. Host range of Verticillium isaacii and Verticillium klebahnii from artichoke, spinach, and lettuce

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium is a genus that includes major vascular wilt pathogens. The recent multilocus phylogenetic analyses of the genus identified 5 new species including V. isaacii and V. klebahnii, both of which occur in agricultural soils in coastal California, and have been isolated from asymptomatic and ...

  3. Complete mitochondrial genome of the Verticillium-wilt causing plant pathogen Verticillium nonalfalfae

    PubMed Central

    Jelen, Vid; de Jonge, Ronnie; Van de Peer, Yves; Javornik, Branka; Jakše, Jernej

    2016-01-01

    Verticillium nonalfalfae is a fungal plant pathogen that causes wilt disease by colonizing the vascular tissues of host plants. The disease induced by hop isolates of V. nonalfalfae manifests in two different forms, ranging from mild symptoms to complete plant dieback, caused by mild and lethal pathotypes, respectively. Pathogenicity variations between the causal strains have been attributed to differences in genomic sequences and perhaps also to differences in their mitochondrial genomes. We used data from our recent Illumina NGS-based project of genome sequencing V. nonalfalfae to study the mitochondrial genomes of its different strains. The aim of the research was to prepare a V. nonalfalfae reference mitochondrial genome and to determine its phylogenetic placement in the fungal kingdom. The resulting 26,139 bp circular DNA molecule contains a full complement of the 14 "standard" fungal mitochondrial protein-coding genes of the electron transport chain and ATP synthase subunits, together with a small rRNA subunit, a large rRNA subunit, which contains ribosomal protein S3 encoded within a type IA-intron and 26 tRNAs. Phylogenetic analysis of this mitochondrial genome placed it in the Verticillium spp. lineage in the Glomerellales group, which is also supported by previous phylogenetic studies based on nuclear markers. The clustering with the closely related Verticillium dahliae mitochondrial genome showed a very conserved synteny and a high sequence similarity. Two distinguishing mitochondrial genome features were also found—a potential long non-coding RNA (orf414) contained only in the Verticillium spp. of the fungal kingdom, and a specific fragment length polymorphism observed only in V. dahliae and V. nubilum of all the Verticillium spp., thus showing potential as a species specific biomarker. PMID:26839950

  4. Complete mitochondrial genome of the Verticillium-wilt causing plant pathogen Verticillium nonalfalfae.

    PubMed

    Jelen, Vid; de Jonge, Ronnie; Van de Peer, Yves; Javornik, Branka; Jakše, Jernej

    2016-01-01

    Verticillium nonalfalfae is a fungal plant pathogen that causes wilt disease by colonizing the vascular tissues of host plants. The disease induced by hop isolates of V. nonalfalfae manifests in two different forms, ranging from mild symptoms to complete plant dieback, caused by mild and lethal pathotypes, respectively. Pathogenicity variations between the causal strains have been attributed to differences in genomic sequences and perhaps also to differences in their mitochondrial genomes. We used data from our recent Illumina NGS-based project of genome sequencing V. nonalfalfae to study the mitochondrial genomes of its different strains. The aim of the research was to prepare a V. nonalfalfae reference mitochondrial genome and to determine its phylogenetic placement in the fungal kingdom. The resulting 26,139 bp circular DNA molecule contains a full complement of the 14 "standard" fungal mitochondrial protein-coding genes of the electron transport chain and ATP synthase subunits, together with a small rRNA subunit, a large rRNA subunit, which contains ribosomal protein S3 encoded within a type IA-intron and 26 tRNAs. Phylogenetic analysis of this mitochondrial genome placed it in the Verticillium spp. lineage in the Glomerellales group, which is also supported by previous phylogenetic studies based on nuclear markers. The clustering with the closely related Verticillium dahliae mitochondrial genome showed a very conserved synteny and a high sequence similarity. Two distinguishing mitochondrial genome features were also found-a potential long non-coding RNA (orf414) contained only in the Verticillium spp. of the fungal kingdom, and a specific fragment length polymorphism observed only in V. dahliae and V. nubilum of all the Verticillium spp., thus showing potential as a species specific biomarker. PMID:26839950

  5. Distribution of phytopathogenic bacteria in infested seeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Populations of phytopathogenic bacteria representing five host-pathogen combinations were assessed to determine if there was a mathematical relationship common across seedborne bacterial diseases. Bacterial populations were estimated from naturally-infested seeds of cowpea (Vigna unguiculata), peppe...

  6. Identification and characterization of a pathogenicity-related gene VdCYP1 from Verticillium dahliae

    PubMed Central

    Zhang, Dan-Dan; Wang, Xin-Yan; Chen, Jie-Yin; Kong, Zhi-Qiang; Gui, Yue-Jing; Li, Nan-Yang; Bao, Yu-Ming; Dai, Xiao-Feng

    2016-01-01

    Verticillium dahliae is a phytopathogenic fungus that causes vascular wilt disease in a wide variety of crop plants, thereby causing extensive economic loss. In present study, one V. dahliae T-DNA mutant M01C06 showed the pathogenicity loss on cotton, and the expression of a flanking gene encoding cytochrome P450 monooxygenase (P450, VdCYP1) was strongly repressed. P450s of fungi could affect the fungal pathogenicity by involving in the synthesis of secondary metabolites. However, there was no report about the pathogenic function of P450s in V. dahliae. VdCYP1 gene deletion and complementation experiments confirmed that VdCYP1 was the pathogenicity-related gene in V. dahliae. A comparison of culture supernatants of the VdCYP1 deletion mutants and wild-type strains indicates that at least 14 kinds of secondary metabolites syntheses were affected due to VdCYP1 gene deletion. One of these compounds, sulfacetamide, had the ability to induce the necrosis and wilting symptoms in cotton. Above results indicate that VdCYP1 could participate in pathogenesis by involving the secondary metabolism in V. dahliae, such as the compound sulfacetamide. In conclusion, VdCYP1 acts as an important pathogenicity-related factor to involve in secondary metabolism that likely contributes to the pathogenic process in V. dahliae. PMID:27329129

  7. Identification and characterization of a pathogenicity-related gene VdCYP1 from Verticillium dahliae.

    PubMed

    Zhang, Dan-Dan; Wang, Xin-Yan; Chen, Jie-Yin; Kong, Zhi-Qiang; Gui, Yue-Jing; Li, Nan-Yang; Bao, Yu-Ming; Dai, Xiao-Feng

    2016-01-01

    Verticillium dahliae is a phytopathogenic fungus that causes vascular wilt disease in a wide variety of crop plants, thereby causing extensive economic loss. In present study, one V. dahliae T-DNA mutant M01C06 showed the pathogenicity loss on cotton, and the expression of a flanking gene encoding cytochrome P450 monooxygenase (P450, VdCYP1) was strongly repressed. P450s of fungi could affect the fungal pathogenicity by involving in the synthesis of secondary metabolites. However, there was no report about the pathogenic function of P450s in V. dahliae. VdCYP1 gene deletion and complementation experiments confirmed that VdCYP1 was the pathogenicity-related gene in V. dahliae. A comparison of culture supernatants of the VdCYP1 deletion mutants and wild-type strains indicates that at least 14 kinds of secondary metabolites syntheses were affected due to VdCYP1 gene deletion. One of these compounds, sulfacetamide, had the ability to induce the necrosis and wilting symptoms in cotton. Above results indicate that VdCYP1 could participate in pathogenesis by involving the secondary metabolism in V. dahliae, such as the compound sulfacetamide. In conclusion, VdCYP1 acts as an important pathogenicity-related factor to involve in secondary metabolism that likely contributes to the pathogenic process in V. dahliae. PMID:27329129

  8. Identification of fungal phytopathogens using Fourier transform infrared-attenuated total reflection spectroscopy and advanced statistical methods

    NASA Astrophysics Data System (ADS)

    Salman, Ahmad; Lapidot, Itshak; Pomerantz, Ami; Tsror, Leah; Shufan, Elad; Moreh, Raymond; Mordechai, Shaul; Huleihel, Mahmoud

    2012-01-01

    The early diagnosis of phytopathogens is of a great importance; it could save large economical losses due to crops damaged by fungal diseases, and prevent unnecessary soil fumigation or the use of fungicides and bactericides and thus prevent considerable environmental pollution. In this study, 18 isolates of three different fungi genera were investigated; six isolates of Colletotrichum coccodes, six isolates of Verticillium dahliae and six isolates of Fusarium oxysporum. Our main goal was to differentiate these fungi samples on the level of isolates, based on their infrared absorption spectra obtained using the Fourier transform infrared-attenuated total reflection (FTIR-ATR) sampling technique. Advanced statistical and mathematical methods: principal component analysis (PCA), linear discriminant analysis (LDA), and k-means were applied to the spectra after manipulation. Our results showed significant spectral differences between the various fungi genera examined. The use of k-means enabled classification between the genera with a 94.5% accuracy, whereas the use of PCA [3 principal components (PCs)] and LDA has achieved a 99.7% success rate. However, on the level of isolates, the best differentiation results were obtained using PCA (9 PCs) and LDA for the lower wavenumber region (800-1775 cm-1), with identification success rates of 87%, 85.5%, and 94.5% for Colletotrichum, Fusarium, and Verticillium strains, respectively.

  9. Breeding and genetics of lettuce against race 2 of Verticillium wilt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt, caused by the soil-borne fungus Verticillium dahliae, is a destructive disease of lettuce in California. Verticillium resistance 1 (Vr1) confers resistance to race 1 isolates but is defeated by race 2 isolates, which are predicted to increase in prevalence. Three Plant Introductio...

  10. Development of a qPCR assay for quantification of verticillium dahliae in spinach seed.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt, caused by the soilborne fungus Verticillium dahliae, is an important disease of lettuce and other specialty crops in the Salinas Valley of California. Although spinach is not affected by Verticillium wilt in commercial production, spinach seed infected with V. dahliae from locatio...

  11. RNA-seq analyses of gene expression in the microsclerotia of Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The soilborne fungus, Verticillium dahliae, causes Verticillium wilt disease in plants. Verticillium wilt is difficult to control since V. dahliae is capable of persisting in the soil for 10 to15 years as melanized microsclerotia, rendering crop rotation strategies for disease control ineffective. ...

  12. Molecular research and genetic engineering of resistance to Verticillium wilt in cotton: A review

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae, a soil-borne pathogen, causes Verticillium wilt, one of the most serious diseases in cotton, deleteriously influencing the crop’s production and quality. Verticillium wilt has become a major obstacle in cotton production since Helicoverpa armigera, the cotton bollworm, became e...

  13. A qPCR assay for detection and quantification of Verticillium dahliae in spinach seed.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Verticillium dahliae is the causal agent of Verticillium wilt of lettuce and other specialty crops in the Salinas Valley of California. Spinach, another major specialty crop in California, is not affected by Verticillium wilt in commercial production. However, spinach seed infected with ...

  14. [Antagonistic interactions between saprotrophic fungi and geohelminths. 1. Saprotrophic fungi in the biological control of phytopathogenic geohelminths].

    PubMed

    Mazurkiewicz-Zapałowicz, Kinga; Kołodziejczyk, Lidia

    2009-01-01

    The state of knowledge on the possible antagonism between soil saprotrophic fungi and phytopathogenic nematodes of the genera Meloidogyne, Heterodera, and Globodera is reviewed basing on the literature and our own research. Mycelial colonisation of various developmental stages of these geohelminths is the most common factor thought to reduce their populations in nature. The following parasitic fungi can be found on the cysts, eggs, as well as the larvae of the nematodes: Paecilomyces lilacinus, Verticillium chlamydosporium, Cylindrocarpon destructans, Pochonia chlamydosporia, Fusarium spp., and Penicillium spp. The fungi invade the nematodes, such as Heterodera, Globodera, or Meloidogyne, "passively" penetrating through the natural orifices of the cysts, eggs, and larvae of the host. Equally frequent, however, is a biochemical action of the fungi prior to colonisation, which is linked with production of mycotoxirls or hydrolytic enzymes. Such an active way of fungal penetration of various stages of the phytopathogenic nematodes has been observed in Pochonia chlamydosporia, Penicillium verrucosum var. cyclopium, P. frequentans, Sclerotinia rolfsii, Rhizoctonia solani, and Fusarium spp. Triacylglycerols (TAG), phenols, as well as trichothecene, T-2, have been found in the metabolites extracted from mycelia of these species. Predation by fungi is also a factor that may reduce a population of phytopathogenic nematodes. This form of antagonism is characteristic for nematicidal fungi of the genera Arthrobotrys and Dactylella. These fungi form shrinking rings and hooks in their mycelia by which the fungus entangles and paralyses a migrating form of nematode. Despite the fact that the antagonism between fungi and nematodes is a commonly occurring phenomenon observed in the soil, the nematicidal and nematotoxic properties of fungi have not a wide application in biological plant protection. Up till now, only the bionematicides based on Arthrobotrys robusta (Royal 300 and

  15. Insects as alternative hosts for phytopathogenic bacteria.

    PubMed

    Nadarasah, Geetanchaly; Stavrinides, John

    2011-05-01

    Phytopathogens have evolved specialized pathogenicity determinants that enable them to colonize their specific plant hosts and cause disease, but their intimate associations with plants also predispose them to frequent encounters with herbivorous insects, providing these phytopathogens with ample opportunity to colonize and eventually evolve alternative associations with insects. Decades of research have revealed that these associations have resulted in the formation of bacterial-vector relationships, in which the insect mediates dissemination of the plant pathogen. Emerging research, however, has highlighted the ability of plant pathogenic bacteria to use insects as alternative hosts, exploiting them as they would their primary plant host. The identification of specific bacterial genetic determinants that mediate the interaction between bacterium and insect suggests that these interactions are not incidental, but have likely arisen following the repeated association of microorganisms with particular insects over evolutionary time. This review will address the biology and ecology of phytopathogenic bacteria that interact with insects, including the traditional role of insects as vectors, as well as the newly emerging paradigm of insects serving as alternative primary hosts. Also discussed is one case where an insect serves as both host and vector, which may represent a transitionary stage in the evolution of insect-phytopathogen associations. PMID:21251027

  16. A synthetic antimicrobial peptide BTD-S expressed in Arabidopsis thaliana confers enhanced resistance to Verticillium dahliae.

    PubMed

    Li, Feng; Shen, Hao; Wang, Ming; Fan, Kai; Bibi, Noreen; Ni, Mi; Yuan, Shuna; Wang, Xuede

    2016-08-01

    BTD-S is a synthetic non-cyclic θ-defensin derivative which was previously designed in our laboratory based on baboon θ-defensins (BTDs). It shows robust antimicrobial activity against economically important phytopathogen, Verticillium dahliae. Here, we deduced the coding nucleotide sequence of BTD-S and introduced the gene into wild-type (ecotype Columbia-0) Arabidopsis thaliana plants. Results demonstrated that BTD-S-transgenic lines displayed in bioassays inhibitory effects on the growth of V. dahliae in vivo and in vitro. Based on symptom severity, enhanced resistance was found in a survey of BTD-S-transgenic lines. Besides, crude protein extracts from root tissues of BTD-S-transformed plants significantly restricted the growth of fungal hyphae and the germination of conidia. Also, fungal biomass over time determined by real-time PCR demonstrated the overgrowth of V. dahliae in wild-type plants 2-3 weeks after inoculation, while almost no fungal DNA was detected in aerial tissues of their transgenic progenitors. The result suggested that fungus failed to invade and progress acropetally up to establish a systemic infection in BTD-S-transgenic plants. Moreover, the assessment of basal defense responses was performed in the leaves of WT and BTD-S-transgenic plants. The mitigated oxidative stress and low antioxidase level in BTD-S-transgenic plants revealed that BTD-S acts via permeabilizing target microbial membranes, which is in a category different from hypersensitive response-dependent defense. Taken together, our results demonstrate that BTD-S is a promising gene to be explored for transgenic engineering for plant protection against Verticillium wilt. PMID:27138919

  17. Phytopathogen emergence in the genomics era.

    PubMed

    Thynne, Elisha; McDonald, Megan C; Solomon, Peter S

    2015-04-01

    Phytopathogens are a global threat to plant agriculture and biodiversity. The genomics era has lead to an exponential rise in comparative gene and genome studies of both economically significant and insignificant microorganisms. In this review we highlight some recent comparisons and discuss how they identify shared genes or genomic regions associated with host virulence. The two major mechanisms of rapid genome adaptation - horizontal gene transfer and hybridisation - are reviewed and we consider how intra-specific pan-genome sequences encode alternative host specificity. We also discuss the power that access to expansive gene databases provides in aiding the study of phytopathogen emergence. These databases can rapidly enable the identification of an unknown pathogen and its origin, as well as genomic adaptations required for emergence. PMID:25682011

  18. Peroxidase activity in cotton cell culture infected with Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In our studies with cotton, we have shown that the plant’s induced anionic peroxidases bind to chitin, which is a component of the cell wall of the plant pathogenic fungus Verticillium dahliae. In binding to the cell wall surface, they disrupt the integrity of the pathogen’s cell wall. Thus, these...

  19. MANAGEMENT OF SCLEROTINIA BLIGHT AND VERTICILLIUM WILT IN PEANUTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Some of the objectives of this research are to study the biology of economically important peanut pathogens including Tomato Spotted Wilt Virus (TSWV), and to determine the role of disease resistance in managing soil-borne peanut pathogens, particularly Sclerotinia blight, Verticillium wilt, and Sou...

  20. Breeding for Verticillium Wilt Resistance: Prospects and Challenges

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt is a serious yield-limiting factor for potato production worldwide. The disease is caused mainly by the soil-borne fungus V. dahliae. Cultural practices provide limited control of the disease. Fumigation is effective but costly. Host plant resistance, however, offers an attractive ...

  1. Repetitive elements, architects of genomic variation in Verticillium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vascular wilt pathogens in the genus Verticillium show considerable variation with respect to their host ranges, genomic organization, and the variety and number of transposable elements (TEs) that they carry. These families of TE sequences were first documented in the wide host range, plant pathog...

  2. Verticillium Wilt Resistance in U.S. Potato Breeding Programs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW), caused mainly by the soil-borne fungus V. dahliae, is a persistent and serious problem in potato production. Host-plant resistance offers an attractive control strategy, but major cultivars are susceptible to VW. Resistance to VW was evaluated in 14 advanced clones from U.S...

  3. Selection for resistance to Verticillium wilt caused by race 2 isolates of Verticillium dahliae in accessions of lettuce (Lactuca sativa L.).

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt of lettuce caused by Verticillium dahliae can cause severe economic damage to lettuce producers. The pathogen exists as two races (races 1 and 2) in lettuce, and complete resistance to race 1 is known. Resistance to race 2 isolates has not been reported, and production of race 1 re...

  4. The inheritance of resistance to Verticillium wilt caused by race 1 isolates of Verticillium dahliae in the lettuce cultivar La Brillante.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt of lettuce caused by Verticillium dahliae can cause severe economic damage to lettuce producers. Complete resistance to race 1 isolates is available in L. sativa cultivar (cv) La Brillante and understanding the inheritance of resistance will aid development of new resistant cultiva...

  5. Iceberg lettuce breeding lines with resistance to Verticillium wilt caused by race 1 isolates of Verticillium dahliae.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Agricultural Research Service, United States Department of Agriculture and the University of California, Davis, announce the release of two breeding lines of lettuce (Lactuca sativa L.). Lines RH08-0472 and RH08-0475 are F9 iceberg type lettuce breeding lines with resistance to Verticillium wil...

  6. Resistance to Verticillium dahliae (Kleb.) in the strawberry breeding lines.

    PubMed

    Zebrowska, J; Hortyński, J; Cholewa, T; Honcz, K

    2006-01-01

    Verticillium species are soil-borne fungi with worldwide distribution, causing vascular disease that results in severe yield and quality losses in fruit and nut crops, legumes, vegetables, forest trees, and woody and herbaceous ornamentals. Most crop diseases are caused by the two species Verticillium dahliae Klebahn and V. albo-atrum Reinke and Berthier, which differ in morphology, host range, and growth characteristics. The control of Verticillium spp. is especially difficult because they can survive in the soil as resting structures for several years. Cultivation of resistant plant material is the most effective method of the disease elimination. Resistance to Verticillium dahliae Kleb. was examined in the four strawberry breeding lines i.e.'Kent S1', 'Kent o.p.', 'Plena S1', 'Plena o.p'. The strawberry isolate of cv. 'Elsanta' no.1093 of Verticillium dahliae from Pathogen Gene Bank (Poland-Poznań) was used throughout this study. Seedlings of strawberry breeding lines were used for in vitro inoculation at stage of 4 leaves. Their roots were dipped for approximately 1 min in conidial suspensions (inoculum concentration--60 spores at 100x magnification in the microscopic field). Observations of disease symptoms were performed at 15, 30, 45, 60 and 75 days post inoculation. Extent of leaf chlorosis was rated on a scale of 0-4 in which: 0 no symptom. 1 up to 25% chlorotic leaves. 2 up to 50% chlorotic leaves. 3 up to 75% chlorotic leaves. 4 up to 100% chlorotic leaves. Plant response to in vitro inoculation of V. dahliae was different and depended on the breeding line. The most susceptible breeding line was 'Plena S1' and the most resistant was the line 'Kent o.p'. The line 'Kent S1' was more susceptible than the last one, but much more resistant than the line 'Plena o.p'. Seedlings without disease symptoms were observed in all examined lines at 15 and 30 days post inoculation At 45 days post inoculation no plant without disease symptoms was observed. Disease

  7. Caffeine fostering of mycoparasitic fungi against phytopathogens.

    PubMed

    Sugiyama, Akifumi; Sano, Cecile M; Yazaki, Kazufumi; Sano, Hiroshi

    2016-01-01

    Caffeine (1,3,7-trimethixanthine) is a typical purine alkaloid produced in more than 80 plant species. Its biological role is considered to strengthen plant's defense capabilities, directly as a toxicant to biotic attackers (allelopathy) and indirectly as an activator of defense system (priming). Caffeine is actively secreted into rhizosphere through primary root, and possibly affects the structure of microbe community nearby. The fungal community in coffee plant rhizosphere is enriched with particular species, including Trichoderma family, a mycoparasite that attacks and kills phytopathogens by coiling and destroying their hyphae. In the present study, the caffeine response of 8 filamentous fungi, 4 mycoparasitic Trichoderma, and 4 prey phytopathogens, was examined. Results showed that allelopathic effect of caffeine on fungal growth and development was differential, being stronger on pathogens than on Trichoderma species. Upon confronting, the prey immediately ceased the growth, whereas the predator continued to grow, indicating active mycoparasitism to have occurred. Caffeine enhanced mycoparasitism up to 1.7-fold. Caffeine thus functions in a double-track manner against fungal pathogens: first by direct suppression of growth and development, and second by assisting their natural enemy. These observations suggest that caffeine is a powerful weapon in the arms race between plants and pathogens by fostering enemy's enemy, and we propose the idea of "caffeine fostering" as the third role of caffeine. PMID:26529400

  8. Caffeine fostering of mycoparasitic fungi against phytopathogens

    PubMed Central

    Sugiyama, Akifumi; Sano, Cecile M.; Yazaki, Kazufumi; Sano, Hiroshi

    2016-01-01

    Caffeine (1,3,7-trimethixanthine) is a typical purine alkaloid produced in more than 80 plant species. Its biological role is considered to strengthen plant's defense capabilities, directly as a toxicant to biotic attackers (allelopathy) and indirectly as an activator of defense system (priming). Caffeine is actively secreted into rhizosphere through primary root, and possibly affects the structure of microbe community nearby. The fungal community in coffee plant rhizosphere is enriched with particular species, including Trichoderma family, a mycoparasite that attacks and kills phytopathogens by coiling and destroying their hyphae. In the present study, the caffeine response of 8 filamentous fungi, 4 mycoparasitic Trichoderma, and 4 prey phytopathogens, was examined. Results showed that allelopathic effect of caffeine on fungal growth and development was differential, being stronger on pathogens than on Trichoderma species. Upon confronting, the prey immediately ceased the growth, whereas the predator continued to grow, indicating active mycoparasitism to have occurred. Caffeine enhanced mycoparasitism up to 1.7-fold. Caffeine thus functions in a double-track manner against fungal pathogens: first by direct suppression of growth and development, and second by assisting their natural enemy. These observations suggest that caffeine is a powerful weapon in the arms race between plants and pathogens by fostering enemy's enemy, and we propose the idea of "caffeine fostering" as the third role of caffeine. PMID:26529400

  9. Verticillium Wilt in Potato: Host-Pathogen Interactions and Breeding for Resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW) is a widespread disease that causes consistent yield losses in many potato growing regions worldwide. In the U.S., it is mainly caused by the soil-borne fungal pathogen Verticillium dahliae. Microsclerotia can survive in the soil for many years. When they germinate and infe...

  10. Screening of wild and cultivated Capsicum germplasm reveals new sources of Verticillium wilt resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt caused by Verticillium dahliae is an important soilborne disease of pepper (Capsicum species) worldwide. Most commercial pepper cultivars lack resistance to this pathogen. Our objective was to identify resistance to multiple V. dahliae isolates in wild and cultivated Capsicum acces...

  11. Using comparative genomics to develop a new model of understanding Verticillium wilt resistance in potato

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW) is a persistent and costly disease affecting potato production. VW is caused by the soilborne fungi Verticillium dahliae and V. albo-atrum. Because of the difficulty in dealing with this disease, host resistance offers a low input, effective method of control. Most potato cult...

  12. Molecular variation among isolates of verticillium dahliae and PCR-based differentiation of races.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is a soilborne fungal pathogen that causes Verticillium wilt on a variety of economically important crops worldwide. Although race 1-specific resistance has been identified in both tomato and lettuce, no such resistance is available against race 2 of the pathogen. Knowledge of t...

  13. COMPARISON OF CROP ROTATION FOR VERTICILLIUM WILT MANAGEMENT IN CONVENTIONAL AND ORGANIC STRAWBERRY PRODUCTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wilt caused by Verticillium dahliae is a major disease in non-fumigated and organic strawberry production systems in California. A comparative study of the effects of broccoli and lettuce rotations on strawberry growth, Verticillium wilt, and yield were evaluated in conventional and organic producti...

  14. Verticillium comparative genomics yields insights into niche adaptation by plant vascular wilt pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The vascular wilt fungi Verticillium dahliae and V. albo-atrum infect over 200 plant species worldwide, causing recurring crop losses estimated in the billions of dollars annually. Plant pathogenic Verticillium species are soilborne, and produce dormant structures that enable survival for years in ...

  15. Pathogenicity, vegetative compatibility, and genetic diversity in verticillium dahliae from sugar beet and historical strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt of sugar beet is a disease problem that has received very little attention in the literature, but has been reported to reduce sucrose production and purity. To improve our understanding of Verticillium wilt, a survey of sugar beet plants with wilt symptoms (leaves with yellow or n...

  16. Development of a Molecular Marker Associated with Verticillium Wilt Resistance in Diploid Interspecific Potato Hybrids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW) is a widespread and serious potato (Solanum tuberosum) disease caused by the soilborne fungi Verticillium dahliae and V. albo-atrum. Breeding for VW resistance in potato is challenging due to ambiguous symptom expression, a lack of high throughput screening techniques, and va...

  17. Decreased defense gene expression in tolerance versus resistance to Verticillium dahliae in potato

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae Kleb. is a soil-borne fungi that colonizes vascular tissues and induces early senescence in potato in a disease called Verticillium wilt. A diploid potato clone, 07506-01, was infected at high levels with V. dahliae but did not develop symptoms, indicating tolerance to the patho...

  18. Population biology of Verticillium dahliae isolates from lettuce in the Sallinas Valley of Californis.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is a soil borne fungus and the primary causal agent of Verticillium wilt, which affects many crops worldwide. Many crops grown in the Salinas Valley (SV) of California, including strawberry and lettuce (Lactuca sativa), are susceptible to V. dahliae and severe outbreaks are comm...

  19. Molecular variation among isolates of verticillium dahliae and PCR-based differentiation of races.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is a soilborne fungal pathogen that causes Verticillium wilt on a variety of economically important crops worldwide. Although race 1-specific resistance has been identified in both tomato and lettuce, no such resistance is available against race 2 of the pathogen. Knowledge of ...

  20. Evaluation of Verticillium Wilt Resistance in Russet Norkotah and Six Strain Selections

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Strain selections of Russet Norkotah have been selected for enhanced vigor and high yield. In addition, they exhibit less severe expression of disease symptoms on the presence of Verticillium dahliae, a soil-borne fungal pathogen that causes Verticillium wilt. However, this apparent resistance may b...

  1. Field evaluation of mint mutant and hybrid lines for resistance to Verticillium wilt and yield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Severity of Verticillium wilt varied significantly among mint lines and cultivars in the inoculated and non-inoculated sub-plots in two field trials. Verticillium wilt was significantly less severe for mutant lines 87M0109-1, 84M0107-7, and M90-11 than for Black Mitcham in 2002 and 2003. Verticilli...

  2. Development of an assay for rapid detection and quantification of Verticillium dahliae in soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is responsible for Verticillium wilt on a wide range of hosts including strawberry, on which low inoculum densities can cause significant crop loss. Determination of inoculum density is currently done by soil plating, but this can take 6-8 weeks to complete and delay the grower...

  3. The potential for early generation selection to identify potato clones with resistance to Verticillium wilt.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW) of potato, caused primarily by the fungus Verticillium dahliae, results in yield loss and is therefore an important soil-borne disease. Resistance to VW exists in potato germplasm and is used by breeders during cultivar development. Breeders could make more rapid progress tow...

  4. Variability associated with screening for common scab and verticillium wilt in potato

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Common Scab (CS) and Verticillium Wilt (VW) are caused by the soilborne bacteria Streptomyces scabies, and fungi, Verticillium dahliae and V. albo-atrum, respectively, in potato (Solanum tuberosum). Both diseases result in biological and/or marketable yield loss and are tested in fields with high di...

  5. Two CAPS markers predict Verticillium wilt resistance in wild Solanum species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt of potato is a persistent problem across several production areas of the United States. The disease, which is caused primarily by the fungus Verticillium dahliae is difficult to manage, causes yield losses and contaminates the soils for subsequent plantings. Control strategies base...

  6. Development of rapid pathogenicity assay for Verticillium dahliae using early flowering lettuce.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conventional assays of Verticillium wilt on lettuce require approximately three months from the time of seeding. A reduction in time required for analyses of symptom development would be useful in studies of the Verticillium dahliae-lettuce interaction. In this study, a growth chamber assay was ev...

  7. Bidirectional promoter trapping T-DNA for insertional mutagenesis in Verticillium dahliae.

    PubMed

    Deng, Sheng; Wang, Cai-yue; Zhang, Xin; Lin, Ling

    2014-07-01

    Transfer DNA (T-DNA)-based random insertional mutagenesis is a universal forward genetic approach for gene identification and cloning in many phytopathogenic fungi. In a large number of randomly selected transformants, screening for mutants with a specific phenotype is laborious, especially for pathogenicity-defective mutants. To accelerate mutant screening and gene identification, a bidirectional promoter-trapping Ti binary vector, 1300-bisGFP-hyg, was constructed and deployed in this study. More than 6000 Verticillium dahliae transformants were obtained by the mediation of Agrobacterium tumefaciens carrying the vector. One thousand randomly selected transformants were cultured on Czapek-Dox and on Czapek-Dox plus cotton root extract media plates. The cultured transformants with green fluorescent protein (GFP) expression or changes in phenotype were selected and used in virulence or promoter-trapping assays. Based on the virulence assay of 60 transformants, the pathogenicity of 17 of these mutants was compromised. Ten pathogenicity-defective mutants were found with GFP expression, and 6 with expression in Czapek-Dox plus cotton root extract media specifically. Using TAIL-PCR (thermal asymmetric interlaced polymerase chain reaction), the T-DNA insertion sites were identified in 8 GFP-expressing transformants, including 5 pathogenicity-defective mutants and 3 unaffected transformants. Promoters of 6 genes were successfully trapped using the T-DNA method in this study. The nonpathogenic transformant 24C9 was the subject of additional investigation. It displayed strong GFP expression on water agar medium supplemented with cotton root extracts and on cotton seedling stems. The results obtained by Southern blot and quantitative real-time PCR confirmed that the transcription level of VdUGPU (encoding UTP-glucose-1-phosphate uridylyltransferase) was significantly reduced owing to T-DNA insertion in the gene promoter region. These results indicate that the bidirectional

  8. VdNUC-2, the Key Regulator of Phosphate Responsive Signaling Pathway, Is Required for Verticillium dahliae Infection

    PubMed Central

    Deng, Sheng; Wang, Cai-yue; Zhang, Xin; Wang, Qing; Lin, Ling

    2015-01-01

    In fungal cells, a phosphate (Pi) responsive signaling and metabolism (PHO) pathway regulates Pi-homeostasis. NUC-2/PHO81 and its homologs are one of the most important components in the regulation pathway. In soil-borne phytopathogenic fungus Verticillium dahliae, we identified a Neurospora crassa nuc-2 homolog gene VdNUC-2. VdNUC-2 is composed of 1,018 amino acids, and is highly conserved in tested filamentous fungi. Under conditions of Pi-starvation, compared with the wild-type strain and ectopic complementation strains, the VdNUC-2 knocked out mutants exhibited reduced radial growth, decreased production of conidia and microsclerotia, and were more sensitive to hydrogen peroxide stress. The virulence of VdNUC-2 defective mutants was significantly compromised, and that was unable to be restored by exogenous application of extra Pi. Additionally, the deletion mutants of VdNUC-1, a key transcription factor gene positively controlled by VdNUC-2 in the PHO pathway, showed the similar cultural phenotypes as VdNUC-2 mutants when both of them grew in Pi-limited conditions. However, the virulence of VdNUC-1 mutants was comparable to the wild-type strain. These evidences indicated that the virulence reduction in VdNUC-2 mutants is not due to the interruptions in the PHO pathway or the disturbance of Pi-homeostasis in V. dahliae cytoplasm. VdNUC-2 is not only a crucial gene in the PHO pathway in V. dahliae, but also is required for the full virulence during host-infection. PMID:26670613

  9. VdNUC-2, the Key Regulator of Phosphate Responsive Signaling Pathway, Is Required for Verticillium dahliae Infection.

    PubMed

    Deng, Sheng; Wang, Cai-yue; Zhang, Xin; Wang, Qing; Lin, Ling

    2015-01-01

    In fungal cells, a phosphate (Pi) responsive signaling and metabolism (PHO) pathway regulates Pi-homeostasis. NUC-2/PHO81 and its homologs are one of the most important components in the regulation pathway. In soil-borne phytopathogenic fungus Verticillium dahliae, we identified a Neurospora crassa nuc-2 homolog gene VdNUC-2. VdNUC-2 is composed of 1,018 amino acids, and is highly conserved in tested filamentous fungi. Under conditions of Pi-starvation, compared with the wild-type strain and ectopic complementation strains, the VdNUC-2 knocked out mutants exhibited reduced radial growth, decreased production of conidia and microsclerotia, and were more sensitive to hydrogen peroxide stress. The virulence of VdNUC-2 defective mutants was significantly compromised, and that was unable to be restored by exogenous application of extra Pi. Additionally, the deletion mutants of VdNUC-1, a key transcription factor gene positively controlled by VdNUC-2 in the PHO pathway, showed the similar cultural phenotypes as VdNUC-2 mutants when both of them grew in Pi-limited conditions. However, the virulence of VdNUC-1 mutants was comparable to the wild-type strain. These evidences indicated that the virulence reduction in VdNUC-2 mutants is not due to the interruptions in the PHO pathway or the disturbance of Pi-homeostasis in V. dahliae cytoplasm. VdNUC-2 is not only a crucial gene in the PHO pathway in V. dahliae, but also is required for the full virulence during host-infection. PMID:26670613

  10. Production of extracellular enzymes in the entomopathogenic fungus Verticillium lecanii.

    PubMed

    Hasan, Saba; Ahmad, Anis; Purwar, Abhinav; Khan, Nausheen; Kundan, Rishi; Gupta, Garima

    2013-01-01

    This study investigates the mechanisms as well as strategies for purification and characterization of potential enzymes involved in pathogenesis of entomopathogenic fungi. The test strain of Verticillium lecanii that was screened, during the present investigation, proved to be an efficient producer of protein and polysaccharide degrading enzymes (amylase, protease, and lipase), hence indicating versatility in biochemical mechanisms. Halo zones produced colony growth of V. lecanii on agar confirmed activity of protease, amylase and lipase enzyme by the V. lecanii isolate. Enzymatic Index (EI) observed were: Protease - 2.195, Amylase- 2.196, Lipase- 2.147. Spectrophotometric analysis of enzymatic activity of V.lecanii at five different pH - 3, 5, 7, 9, 11 revealed that highest proteolytic activity of the V. lecanii isolate was reported at pH 7 and 9 whereas proteolytic activity was minimum at acidic pH 3. Maximum amylolytic activity of V. lecanii on the 7(th) day of inoculation was at pH 3 i.e. in an acidic environment in contrast to neutral pH 7. Maximum lipolytic activity of V. lecanii was found at pH 7. Since enzyme production in entomopathogenic fungi is specific and forms an important criterion for successful development as well as improvement of mycoinsecticides, hence a significant conclusion from the present analysis is the degree of variation in secretion of enzymes in test strain of Verticillium lecanii. PMID:23515428

  11. Systematics of key phytopathogenic fusaria: Current status and future challenges

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This brief review is intended to provide plant pathologists and other scientists, especially ones in Japan, with a current overview of the most important fusarial phytopathogens and mycotoxin producers. Knowledge of Fusarium species diversity and their evolutionary relationships has increased dramat...

  12. Use of the phytopathogenic effect for studies of Burkholderia virulence.

    PubMed

    Molchanova, E V; Ageeva, N P

    2015-02-01

    The phytopathogenic effect of the pseudomallei group Burkholderia is demonstrated on the Peireskia aculeata model. A method for evaluation of the effect is suggested. The effect correlates with the levels of Burkholderia pseudomallei, Burkholderia mallei, and Burkholderia thailandensis virulence for laboratory animals. P. aculeata can be used as a model for preliminary studies of the virulence of the above species. PMID:25705037

  13. Phytopathogenicity of Serratia marcescens strains in different plant host species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Strains of Seriatia marcescens (Sm), cause of cucurbit yellow vine disease (CYVD), colonize many niches (water, soil, humans, animals, insects, plants). To assess whether phytopathogenicity is strain-specific, tobacco leaves were needle-inoculated with various Sm strains. A HR-like response was ob...

  14. A study of interaction between Verticillium wilt Verticillium dahliae and root-knot nematode Meloidogyne javanica in olive cultivars.

    PubMed

    Saeedizadeh, Ayatollah; Kheiri, Ahmad; Zad, Javad; Etebarian, Hasan Reza; Bandani, Ali Reza; Nasiri, Mohammad Bagher

    2009-01-01

    Second stage juvenile (J2) of root-knot nematode, Meloidogyne javanica, and microsclerotia of verticillium wilt, Verticillium dahliae, were used as the source of inoculum for nematode and fungus respectively. One-year-old seedlings of olive cultivars, Zard, Roghani, Koroneiki and Manzanilla, were transplanted to pots containing 2000g of sterilized sandy loam soil. Experiment was conducted in completely randomized design with 32 treatments and five replications. Treatments were as follows: control, nematode alone, fungus alone and fungus + nematode. Pots were inoculated with (0, 2000, 3000, 4000) J2 of nematode and/or (10 no/g soil) microsclerotia of fungus according to the treatments. Experiment was terminated after 10 months and fallowing parameters were determined i.e., fresh weight of root and stem, number of galls and egg masses per root system, and percentage of incidence of symptom on aerial parts, browning of vascular tissue, decrease of seedling height and stem/root tissue colonization by fungus. Results showed that presence of nematode caused reduction on colonization of the fungus in the root and stem and vice versa i.e. presence of fungus caused reduction on number of galls and egg masses produced by the nematode. Severe fungus wilt on aerial parts of Manzanilla cultivar was observed when both pathogens were inoculated and mild fungus wilt was observed in fungus alone treatments of Koroneiki cultivar. Galling and egg mass production in root system were reduced in cvs Manzanilla, Zard, Roghani and Koroneiki, respectively (p < or = 0/05). Based on the results obtained in this study, verticilliosis symptoms and galling of nematode in olive seedlings were be less on cvs Koroneiki, Roghani, Zard and Manzanilla, respectively (p < or = 0/05). PMID:20222619

  15. Fifteen years of verticillium wilt of lettuce in america’s salad bowl: a tale of immigration, subjugation and abatement.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lettuce is a popular leafy vegetable that is globally cultivated. The US ranks second in production, with coastal California producing half of the US supply. In 1995, Verticillium wilt caused by the soil borne fungus Verticillium dahliae was identified as a disease of lettuce in coastal California, ...

  16. Frequency of Verticillium species in commercial spinach fields and transmission of V. dahliae from spinach to subsequent lettuce crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt, caused by Verticillium dahlia,e is a devastating disease of lettuce in California. The disease on lettuce is currently restricted to a small geographic area in the central coastal California, even though cropping patterns in other coastal lettuce production regions in the state ar...

  17. Quantitative trait locus analysis of Verticillium wilt resistance in an introgressed recombinant inbred population of Upland cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW) of Upland cotton (Gossypium hirsutum L.) is caused by the soil-borne fungal pathogen Verticillium dahlia Kleb. The availability of VW-resistant cultivars is vital for control of this economically important disease, but there is a paucity of Upland cotton breeding lines and cul...

  18. Non-defoliating and defoliating strains from cotton correlate with races 1 and 2 of Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt caused by Verticillium dahliae is an important disease of cotton worldwide. Isolates of V. dahliae can be characterized as race 1 or race 2 based on the responses of differential cultivars of tomato and lettuce or as defoliating or non-defoliating based on symptom expression in cot...

  19. Identification of molecular markers associated with verticillium wilt resistance in alfalfa (medicago sativa l.) using high-resolution melting

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW), caused by the soilborne fungus, Verticillium alfalfae, is one of the most serious diseases of alfalfa (Medicago sativa L.) worldwide. To identify loci associated with resistance to VW, an association study was conducted using autotetraploid alfalfa populations composed of 352...

  20. Identification of lettuce genes differentially expressed in a Verticillium dahliae-lettuce interaction by suppression subtractive hybridization

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt, caused by the fungus Verticillium dahliae, is an emerging threat to the U.S. lettuce industry. Lettuce germplasm with resistance to race 1of V. dahliae is available for breeding programs, although germplasm with resistance to race 2 of the pathogen has not been identified. The obj...

  1. Colonization of spinach by Verticillium dahliae and effects of pathogen localization on the efficacy of seed treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt is caused by the soilborne fungus V. dahliae on spinach (Spinacia oleracea L.) but the disease is a serious problem only in seed production fields. Spinach crops are harvested well before symptom expression, and thus, Verticillium wilt is not a significant threat in fresh and proc...

  2. Segregation of unknown signaling components in potato complicates marker-assisted selection for Ve-mediated Verticillium resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW), caused primarily by soil-borne fungi Verticillium dahliae Kleb and V. albo-atrum Reinke and Berthold is characterized by unilateral wilting of leaves, chlorosis, and premature senescence. VW is mainly controlled by fumigating fields with metam sodium, which has negative econo...

  3. Identification of Molecular Markers Associated with Verticillium Wilt Resistance in Alfalfa (Medicago Sativa L.) Using High-Resolution Melting

    PubMed Central

    Zhang, Tiejun; Yu, Long-Xi; McCord, Per; Miller, David; Bhamidimarri, Suresh; Johnson, David; Monteros, Maria J.; Ho, Julie; Reisen, Peter; Samac, Deborah A.

    2014-01-01

    Verticillium wilt, caused by the soilborne fungus, Verticillium alfalfae, is one of the most serious diseases of alfalfa (Medicago sativa L.) worldwide. To identify loci associated with resistance to Verticillium wilt, a bulk segregant analysis was conducted in susceptible or resistant pools constructed from 13 synthetic alfalfa populations, followed by association mapping in two F1 populations consisted of 352 individuals. Simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) markers were used for genotyping. Phenotyping was done by manual inoculation of the pathogen to replicated cloned plants of each individual and disease severity was scored using a standard scale. Marker-trait association was analyzed by TASSEL. Seventeen SNP markers significantly associated with Verticillium wilt resistance were identified and they were located on chromosomes 1, 2, 4, 7 and 8. SNP markers identified on chromosomes 2, 4 and 7 co-locate with regions of Verticillium wilt resistance loci reported in M. truncatula. Additional markers identified on chromosomes 1 and 8 located the regions where no Verticillium resistance locus has been reported. This study highlights the value of SNP genotyping by high resolution melting to identify the disease resistance loci in tetraploid alfalfa. With further validation, the markers identified in this study could be used for improving resistance to Verticillium wilt in alfalfa breeding programs. PMID:25536106

  4. [Secretion of proteolytic enzymes by three phytopathogenic microorganisms].

    PubMed

    2013-01-01

    Serine proteinases from three phytopathogenic microorganisms that belong to different fungal families and cause diseases in potatoes were studied and characterized. The oomycete Phytophthora infestans (Mont.) de Bary and the fungi Rhizoctonia solani and Fusarium culmorum were shown to secrete serine proteinases. An analysis of the substrate specificity of these enzymes and their sensitivity to synthetic and protein inhibitors allowed us to refer them to trypsin- and subtilisin-like proteinases. The correlation between the trypsin- and subtilisin-like proteinases depended on the composition of the culture medium, particularly on the form of the nitrogen source. A phylogenetic analysis was carried out. In contrast to basidiomycetes R. solani, ascomycetes F. culmorum and oomycetes P. infestans produced a similar set of exoproteinases, although they had more distant phylogenetic positions. This indicated that the secretion of serine proteinases by various phytopathogenic microorganisms also depended on their phylogenetic position. These results allowed us to suggest that exoproteinases from phytopathogenic fungi play a different role in pathogenesis. They may promote the adaptation of fungi if the range of hosts is enlarged. On the other hand, they may play an important role in the survival of microorganisms in hostile environements outside their hosts. PMID:25508654

  5. [Secretion of proteolytic enzymes by three phytopathogenic microorganisms].

    PubMed

    Kudriavtseva, N N; Sof'in, A V; Revina, T A; Gvozdeva, E L; Ievleva, E V; Valueva, T A

    2013-01-01

    Serine proteinases from three phytopathogenic microorganisms that belong to different fungal families and cause diseases in potatoes were studied and characterized. The oomycete Phytophthora infestans (Mont.) de Bary and the fungi Rhizoctonia solani and Fusarium culmorum were shown to secrete serine proteinases. An analysis of the substrate specificity of these enzymes and their sensitivity to synthetic and protein inhibitors allowed us to refer them to trypsin- and subtilisin-like proteinases. The correlation between the trypsin- and subtilisin-like proteinases depended on the composition of the culture medium, particularly on the form of the nitrogen source. A phylogenetic analysis was carried out. In contrast to basidiomycetes R. solani, ascomycetes F. culmorum and oomycetes P. infestans produced a similar set of exoproteinases, although they had more distant phylogenetic positions. This indicated that the secretion of serine proteinases by various phytopathogenic microorganisms also depended on their phylogenetic position. These results allowed us to suggest that exoproteinases from phytopathogenic fungi play a different role in pathogenesis. They may promote the adaptation of fungi if the range of hosts is enlarged. On the other hand, they may play an important role in the survival of microorganisms in hostile environements outside their hosts. PMID:25474875

  6. Verticillium dahliae Infects, Alters Plant Biomass, and Produces Inoculum on Rotation Crops.

    PubMed

    Wheeler, D L; Johnson, D A

    2016-06-01

    Verticillium wilt, caused by Verticillium dahliae, reduces yields of potato and mint. Crop rotation is a potential management tactic for Verticillium wilt; however, the wide host range of V. dahliae may limit the effectiveness of this tactic. The hypothesis that rotation crops are infected by V. dahliae inoculum originating from potato and mint was tested by inoculation of mustards, grasses, and Austrian winter pea with eight isolates of V. dahliae. Inoculum density was estimated from plants and soil. Typical wilt symptoms were not observed in any rotation crop but plant biomass of some crops was reduced, not affected, or increased by infection of specific isolates. Each isolate was host-specific and infected a subset of the rotation crops tested but microsclerotia from at least one isolate were observed on each rotation crop. Some isolates were host-adapted and differentially altered plant biomass or produced differential amounts of inoculum on rotation crops like arugula and Austrian winter pea, which supported more inoculum of specific isolates than potato. Evidence of asymptomatic and symptomatic infection and differential inoculum formation of V. dahliae on rotation crops presented here will be useful in designing rotations for management of Verticillium wilt. PMID:26828231

  7. Development of a potato seedling assay to screen for resistance to Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A seedling assay was developed for Verticillium wilt (VW) resistance in potato (Solanum tuberosum) in order to provide efficient and rapid screening to identify resistant clones in segregating populations. The method provides uniform inoculum to avoid false negatives and reduces the confusion of sy...

  8. VARIATION FOR RESISTANCE TO VERTICILLIUM WILT IN LETTUCE (LACTUCA SATIVA L.).

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Host resistance offers the most cost-effective control method of Verticillium wilt of lettuce, caused by V. dahliae. One hundred and seven lettuce cultivars were screened in infested fields for resistance and disease progress on resistant and susceptible cultivars was determined. Subsequent greenhou...

  9. Verticillium wilt in transgenic sugar beet cultivars in Cassia County, ID, 2006

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Twenty-three transgenic (resistant to glyphosate) and six commercial sugar beet cultivars were evaluated for their susceptibility to Verticillium dahliae in Heyburn, ID during the 2006 growing season. The cultivars were planted in a commercial sugar beet field and exposed to natural levels of V. da...

  10. Selection for Verticillium Wilt Resistance in Potato Breeding Populations Derived from Four Cross Types

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt is one of the important yield-limiting diseases for potato production. To develop resistant clones, the potential for early generation selection was studied using three basic selection methods, individual, family, and within family selection, for two clonal generations. A total o...

  11. Verticillium comparative genomics yields insights into niche adaptation by plant vascular wilt pathogens.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The vascular wilt fungi Verticillium dahliae and V. albo-atrum infect over 200 plant species, causing billions of dollars in annual losses. The characteristic vascular wilt symptoms are a result of colonization and proliferation of the pathogens in the xylem vessels. To gain insights into the mechan...

  12. Colonization of spinach (Spinacia oleracea L.) by GFP-tagged verticillium dahliae.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The soilborne fungus, Verticillium dahliae, causes wilt in a wide range of hosts, including spinach (Spinacia oleracea L.). The interaction between a green fluorescent protein (GFP)-tagged V. dahliae strain and spinach was studied by confocal laser scanning microscopy. The roots of spinach seedlings...

  13. The effect of tillage on decomposing mulch, Verticillium, the microbial community, soil nutrients, and soil aggregation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In assessing the underlying reasons for the apparent effect of no tillage on causing lower levels of Verticillium symptoms on pistachio trees, we assessed the effects of tillage practices on predominant rhizosphere bacteria. Predominant bacteria were deemed as such when they occurred on the outer pe...

  14. Analysis of returns above variable costs for management of Verticillium wilt in cotton.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A large plot study located in Halfway, TX, was conducted from 2007 to 2013 in an irrigated field infested with Verticillium wilt. Management options (crop rotation, irrigation amount, variety election) and combinations of options that can reduce this disease were compared using returns above variabl...

  15. Dynamics of Verticillium species microsclerotia in field soils in response to fumigation, cropping patterns, and flooding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many soil-inhabiting fungi are capable of surviving the dynamic soil microenvironment through the formation of resilient resting structures, such as thick-walled spores, melanized hyphae, and sclerotia. Verticillium dahliae is a soil-inhabiting, economically significant plant pathogenic fungus that ...

  16. Sources of resistance to a new strain of Verticillium dahliae on sunflower in North America-2006

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2004, a new strain of Verticillium dahliae was identified in North Dakota and Minnesota and was designated NA-V2, which overcomes the V1 resistance gene in current sunflower hybrids. Greenhouse trials were conducted in 2004 and field trials were conducted in 2005 and 2006 to evaluate sunflower ge...

  17. Verticillium dahliae Causes Wilt on Sugar Beet Following Potato in Eastern North Dakota

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wilt is a serious disease on sugar beet that decreases content and purity of sugar, but does not significantly decrease root yield. The disease is typically reported as caused by the microorganism Verticillium albo-atrum. The disease has not been previously reported on sugar beet in the Red River ...

  18. SSH reveals a linkage between a senescence-associated protease and Verticillium wilt symptom development in lettuce (Lactuca sativa)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Suppression subtractive hybridization (SSH) was employed to identify lettuce (Lactuca sativa) genes that are differentially expressed in symptomatic leaves infected with Verticillium dahliae. Genes expressed only in symptomatic leaves included those with homology to pathogenesis-related (PR) protei...

  19. Characterization of Two ABC Transporters from Biocontrol and Phytopathogenic Fusarium oxysporus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ABC transporter genes from four strains of Fusarium oxysporum [two biocontrol and two phytopathogenic (f. sp. lycopersici Race 1) isolates] indicated that this gene is well conserved. However, sequences of promoter regions of FoABC1 differed between 8 phytopathogenic and 11 biocontrol strains of F....

  20. Mapping QTL associated with Verticillium dahliae resistance in the cultivated strawberry (Fragaria × ananassa)

    PubMed Central

    Antanaviciute, L; Šurbanovski, N; Harrison, N; McLeary, K J; Simpson, D W; Wilson, F; Sargent, D J; Harrison, R J

    2015-01-01

    A biparental cross of octoploid strawberry segregating for resistance to Verticillium dahliae, the causative agent of Verticillium wilt, was screened under field conditions for three seasons. Average wilt scores were significantly associated with multiple QTL, which were mostly significant across all years. Markers significantly associated with the traits were used to screen material with known wilt resistance and susceptibility phenotypes. A clear and statistically significant relationship was observed between resistant, tolerant and susceptible material and the total number of markers present in the different resistance classes. In field situations resistance QTL appear to behave in an additive manner. These markers are abundant in the cultivated strawberry germplasm indicating that, despite the large number of markers, clear genetic gain is possible through marker-assisted breeding. PMID:26504565

  1. Mapping QTL associated with Verticillium dahliae resistance in the cultivated strawberry (Fragaria × ananassa).

    PubMed

    Antanaviciute, L; Šurbanovski, N; Harrison, N; McLeary, K J; Simpson, D W; Wilson, F; Sargent, D J; Harrison, R J

    2015-01-01

    A biparental cross of octoploid strawberry segregating for resistance to Verticillium dahliae, the causative agent of Verticillium wilt, was screened under field conditions for three seasons. Average wilt scores were significantly associated with multiple QTL, which were mostly significant across all years. Markers significantly associated with the traits were used to screen material with known wilt resistance and susceptibility phenotypes. A clear and statistically significant relationship was observed between resistant, tolerant and susceptible material and the total number of markers present in the different resistance classes. In field situations resistance QTL appear to behave in an additive manner. These markers are abundant in the cultivated strawberry germplasm indicating that, despite the large number of markers, clear genetic gain is possible through marker-assisted breeding. PMID:26504565

  2. [THE SENSITIVITY OF PHYTOPATHOGENIC BACTERIA TO STREPTOMYCIN UNDER THE INFLUENCE OF PESTICIDES].

    PubMed

    Buletsa, N M; Butsenko, L M; Pasichnyk, L A; Patyka, V P

    2015-01-01

    The results of the streptomycin sensitivity changes of phytopathogenic Pseudomonas syringae and Xanthomonas translucens bacteria under the action of pesticides are pre- sented. It is demonstrated that phytopathogenic strains show greater changes of strepto- mycin sensitivity compared to epiphytic Pantoea agglomerans strain under the pesticides influence. Granstar herbicide, Tviks and Alpha Super insecticides increase the number of streptomycin resistant cells of Xanthomonas translucens 3164, P syringae pv. syringae YKM B-1027 and P syringae pv. atrofaciens YKM B-1011. This fact indicates mutagenic action of these pesticides against researched phytopathogenic bacteria. PMID:26829841

  3. Plant-Dependent Genotypic and Phenotypic Diversity of Antagonistic Rhizobacteria Isolated from Different Verticillium Host Plants

    PubMed Central

    Berg, Gabriele; Roskot, Nicolle; Steidle, Anette; Eberl, Leo; Zock, Angela; Smalla, Kornelia

    2002-01-01

    To study the effect of plant species on the abundance and diversity of bacterial antagonists, the abundance, the phenotypic diversity, and the genotypic diversity of rhizobacteria isolated from potato, oilseed rape, and strawberry and from bulk soil which showed antagonistic activity towards the soilborne pathogen Verticillium dahliae Kleb. were analyzed. Rhizosphere and soil samples were taken five times over two growing seasons in 1998 and 1999 from a randomized field trial. Bacterial isolates were obtained after plating on R2A (Difco, Detroit, Mich.) or enrichment in microtiter plates containing high-molecular-weight substrates followed by plating on R2A. A total of 5,854 bacteria isolated from the rhizosphere of strawberry, potato, or oilseed rape or bulk soil from fallow were screened by dual testing for in vitro antagonism towards Verticillium. The proportion of isolates with antagonistic activity was highest for strawberry rhizosphere (9.5%), followed by oilseed rape (6.3%), potato (3.7%), and soil (3.3%). The 331 Verticillium antagonists were identified by their fatty acid methyl ester profiles. They were characterized by testing their in vitro antagonism against other pathogenic fungi; their glucanolytic, chitinolytic, and proteolytic activities; and their BOX-PCR fingerprints. The abundance and composition of Verticillium antagonists was plant species dependent. A rather high proportion of antagonists from the strawberry rhizosphere was identified as Pseudomonas putida B (69%), while antagonists belonging to the Enterobacteriaceae (Serratia spp., Pantoea agglomerans) were mainly isolated from the rhizosphere of oilseed rape. For P. putida A and B plant-specific genotypes were observed, suggesting that these bacteria were specifically enriched in each rhizosphere. PMID:12089011

  4. Plant-dependent genotypic and phenotypic diversity of antagonistic rhizobacteria isolated from different Verticillium host plants.

    PubMed

    Berg, Gabriele; Roskot, Nicolle; Steidle, Anette; Eberl, Leo; Zock, Angela; Smalla, Kornelia

    2002-07-01

    To study the effect of plant species on the abundance and diversity of bacterial antagonists, the abundance, the phenotypic diversity, and the genotypic diversity of rhizobacteria isolated from potato, oilseed rape, and strawberry and from bulk soil which showed antagonistic activity towards the soilborne pathogen Verticillium dahliae Kleb. were analyzed. Rhizosphere and soil samples were taken five times over two growing seasons in 1998 and 1999 from a randomized field trial. Bacterial isolates were obtained after plating on R2A (Difco, Detroit, Mich.) or enrichment in microtiter plates containing high-molecular-weight substrates followed by plating on R2A. A total of 5,854 bacteria isolated from the rhizosphere of strawberry, potato, or oilseed rape or bulk soil from fallow were screened by dual testing for in vitro antagonism towards VERTICILLIUM: The proportion of isolates with antagonistic activity was highest for strawberry rhizosphere (9.5%), followed by oilseed rape (6.3%), potato (3.7%), and soil (3.3%). The 331 Verticillium antagonists were identified by their fatty acid methyl ester profiles. They were characterized by testing their in vitro antagonism against other pathogenic fungi; their glucanolytic, chitinolytic, and proteolytic activities; and their BOX-PCR fingerprints. The abundance and composition of Verticillium antagonists was plant species dependent. A rather high proportion of antagonists from the strawberry rhizosphere was identified as Pseudomonas putida B (69%), while antagonists belonging to the Enterobacteriaceae (Serratia spp., Pantoea agglomerans) were mainly isolated from the rhizosphere of oilseed rape. For P. putida A and B plant-specific genotypes were observed, suggesting that these bacteria were specifically enriched in each rhizosphere. PMID:12089011

  5. Successful strategy for the selection of new strawberry-associated rhizobacteria antagonistic to Verticillium wilt.

    PubMed

    Berg, G; Kurze, S; Buchner, A; Wellington, E M; Smalla, K

    2000-12-01

    In order to isolate and characterize new strawberry-associated bacteria antagonistic to the soil-borne pathogenic fungus Verticillium dahliae Kleb., rhizobacterial populations from two different strawberry species, Greenish Strawberry (Fragaria viridis) and Garden Strawberry (F. x ananassa) obtained after plating onto King's B and glycerol-arginine agar, were screened for in vitro antagonism toward V. dahliae. The proportion of isolates with antifungal activity determined in in vitro assay against V. dahliae was higher for the Garden Strawberry than for the Greenish Strawberry. From 300 isolates, 20 isolates with strong antifungal activity were selected characterized by physiological profiling and molecular fingerprinting methods. Diversity among the isolates was characterized with molecular fingerprints using amplified ribosomal DNA restriction analysis (ARDRA) and the more discriminating BOX-PCR fingerprint method. The physiological profiles were well correlated with molecular fingerprinting pattern analysis. Significant reduction of Verticillium wilt by bacterial dipping bath treatment was shown in the greenhouse and in fields naturally infested by V. dahliae. The relative increase of yield ranged from 117% (Streptomyces albidoflavus S1) to 344% (Pseudomonas fluorescens P10) in greenhouse trials, and 113% (Streptomyces albidoflavus S1) to 247% (Pseudomonas fluorescens P6) in field trials. Evaluation resulted in the selection of three effective biocontrol agents (Pseudomonas fluorescens P6, P10, and Streptomyces diastatochromogenes S9) antagonistic to the Verticillium wilt pathogen. PMID:11142403

  6. Impact of Plant Species and Site on Rhizosphere-Associated Fungi Antagonistic to Verticillium dahliae Kleb.

    PubMed Central

    Berg, Gabriele; Zachow, Christin; Lottmann, Jana; Götz, Monika; Costa, Rodrigo; Smalla, Kornelia

    2005-01-01

    Fungi with antagonistic activity toward plant pathogens play an essential role in plant growth and health. To analyze the effects of the plant species and the site on the abundance and composition of fungi with antagonistic activity toward Verticillium dahliae, fungi were isolated from oilseed rape and strawberry rhizosphere and bulk soil from three different locations in Germany over two growing seasons. A total of 4,320 microfungi screened for in vitro antagonism toward Verticillium resulted in 911 active isolates. This high proportion of fungi antagonistic toward the pathogen V. dahliae was found for bulk and rhizosphere soil at all sites. A plant- and site-dependent specificity of the composition of antagonistic morphotypes and their genotypic diversity was found. The strawberry rhizosphere was characterized by preferential occurrence of Penicillium and Paecilomyces isolates and low numbers of morphotypes (n = 31) and species (n = 13), while Monographella isolates were most frequently obtained from the rhizosphere of oilseed rape, for which higher numbers of morphotypes (n = 41) and species (n = 17) were found. Trichoderma strains displayed high diversity in all soils, but a high degree of plant specificity was shown by BOX-PCR fingerprints. The diversity of rhizosphere-associated antagonists was lower than that of antagonists in bulk soil, suggesting that some fungi were specifically enriched in each rhizosphere. A broad spectrum of new Verticillium antagonists was identified, and the implications of the data for biocontrol applications are discussed. PMID:16085804

  7. Impact of plant species and site on rhizosphere-associated fungi antagonistic to Verticillium dahliae kleb.

    PubMed

    Berg, Gabriele; Zachow, Christin; Lottmann, Jana; Götz, Monika; Costa, Rodrigo; Smalla, Kornelia

    2005-08-01

    Fungi with antagonistic activity toward plant pathogens play an essential role in plant growth and health. To analyze the effects of the plant species and the site on the abundance and composition of fungi with antagonistic activity toward Verticillium dahliae, fungi were isolated from oilseed rape and strawberry rhizosphere and bulk soil from three different locations in Germany over two growing seasons. A total of 4,320 microfungi screened for in vitro antagonism toward Verticillium resulted in 911 active isolates. This high proportion of fungi antagonistic toward the pathogen V. dahliae was found for bulk and rhizosphere soil at all sites. A plant- and site-dependent specificity of the composition of antagonistic morphotypes and their genotypic diversity was found. The strawberry rhizosphere was characterized by preferential occurrence of Penicillium and Paecilomyces isolates and low numbers of morphotypes (n = 31) and species (n = 13), while Monographella isolates were most frequently obtained from the rhizosphere of oilseed rape, for which higher numbers of morphotypes (n = 41) and species (n = 17) were found. Trichoderma strains displayed high diversity in all soils, but a high degree of plant specificity was shown by BOX-PCR fingerprints. The diversity of rhizosphere-associated antagonists was lower than that of antagonists in bulk soil, suggesting that some fungi were specifically enriched in each rhizosphere. A broad spectrum of new Verticillium antagonists was identified, and the implications of the data for biocontrol applications are discussed. PMID:16085804

  8. Analysis of molecular variability among the isolated of Verticillium dahliae from diverse host species based on florescene-based amplified fragment length polymorphism.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is a soil borne fungus and the primary causal agent of Verticillium wilt, which affects many crops worldwide. Many crops grown in the Salinas Valley (SV) of California, including strawberry and lettuce (Lactuca sativa), are susceptible to V. dahliae and severe outbreaks are comm...

  9. Quantitative trait locus mapping for Verticillium wilt resistance in a backcross inbred line population of cotton (Gossypium hirsutum × Gossypium barbadense) based on RGA-AFLP analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium wilt (VW), caused by Verticillium dahliae, is one of the most important diseases in cotton. Development and growing of VW resistant cultivars is the most effective and economic strategy in controlling the disease. However, little is currently known on the genetic basis of VW resistanc...

  10. VdCYC8, encoding CYC8 glucose repression mediator protein, is required for microsclerotia formation and full virulence in Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is the primary causal agent for Verticillium wilt disease on a diverse array of economically important crops, including cotton. In previous research, we screened a T-DNA insertional mutant library of the highly virulent isolate Vd080 derived from cotton. In this study, the targ...

  11. Overexpression of GbRLK, a putative receptor-like kinase gene, improved cotton tolerance to Verticillium wilt

    PubMed Central

    Jun, Zhao; Zhang, Zhiyuan; Gao, Yulong; Zhou, Lei; Fang, Lei; Chen, Xiangdong; Ning, Zhiyuan; Chen, Tianzi; Guo, Wangzhen; Zhang, Tianzhen

    2015-01-01

    Verticillium dahliae is a causative fungal pathogen and only a few genes have been identified that exhibit critical roles in disease resistance and few has shown positive effects on the resistance to Verticillium wilt in transgenic cotton. We cloned a receptor-like kinase gene (GbRLK) induced by Verticillium dahliae (VD) in the disease-resistant cotton Gossypium barbadense cv. Hai7124. Northern blotting revealed that the GbRLK was induced by VD at 96 h after inoculation. The functional GbRLK is from D subgenome since a single base deletion results in a frameshift or dysfunctional homologue in the A subgenome in tetraploid cotton. To verify the function of GbRLK, we developed the overexpression transgenic GbRLK cotton and Arabidopsis lines, and found that they all showed the higher resistance to Verticillium in the greenhouse and field trial. The results of the expression profile using transgenic and non-transgenic Arabidopsis thaliana revealed that the GbRLK regulated expressions of a series genes associated with biotic and abiotic stresses. Therefore, we propose that the increased resistance to Verticillium dahliae infection in transgnic plants could result from reduction in the damage of water loss and regulation of defense gene expression. PMID:26446555

  12. Hyphopodium-Specific VdNoxB/VdPls1-Dependent ROS-Ca2+ Signaling Is Required for Plant Infection by Verticillium dahliae.

    PubMed

    Zhao, Yun-Long; Zhou, Ting-Ting; Guo, Hui-Shan

    2016-07-01

    Verticillium dahliae is a phytopathogenic fungus obligate in root infection. A few hyphopodia differentiate from large numbers of hyphae after conidia germination on the root surface for further infection. However, the molecular features and role of hyphopodia in the pathogenicity of V. dahliae remain elusive. In this study, we found that the VdPls1, a tetraspanin, and the VdNoxB, a catalytic subunit of membrane-bound NADPH oxidases for reactive oxygen species (ROS) production, were specifically expressed in hyphopodia. VdPls1 and VdNoxB highly co-localize with the plasma membrane at the base of hyphopodia, where ROS and penetration pegs are generated. Mutant strains, VdΔnoxb and VdΔpls1, in which VdPls1 and VdNoxB were deleted, respectively, developed defective hyphpodia incapable of producing ROS and penetration pegs. Defective plasma membrane localization of VdNoxB in VdΔpls1 demonstrates that VdPls1 functions as an adaptor protein for the recruitment and activation of the VdNoxB. Furthermore, in VdΔnoxb and VdΔpls1, tip-high Ca2+ accumulation was impaired in hyphopodia, but not in vegetative hyphal tips. Moreover, nuclear targeting of VdCrz1 and activation of calcineurin-Crz1 signaling upon hyphopodium induction in wild-type V. dahliae was impaired in both knockout mutants, indicating that VdPls1/VdNoxB-dependent ROS was specifically required for tip-high Ca2+ elevation in hyphopodia to activate the transcription factor VdCrz1 in the regulation of penetration peg formation. Together with the loss of virulence of VdΔnoxb and VdΔpls1, which are unable to initiate colonization in cotton plants, our data demonstrate that VdNoxB/VdPls1-mediated ROS production activates VdCrz1 signaling through Ca2+ elevation in hyphopodia, infectious structures of V. dahliae, to regulate penetration peg formation during the initial colonization of cotton roots. PMID:27463643

  13. Hyphopodium-Specific VdNoxB/VdPls1-Dependent ROS-Ca2+ Signaling Is Required for Plant Infection by Verticillium dahliae

    PubMed Central

    Zhao, Yun-Long; Zhou, Ting-Ting; Guo, Hui-Shan

    2016-01-01

    Verticillium dahliae is a phytopathogenic fungus obligate in root infection. A few hyphopodia differentiate from large numbers of hyphae after conidia germination on the root surface for further infection. However, the molecular features and role of hyphopodia in the pathogenicity of V. dahliae remain elusive. In this study, we found that the VdPls1, a tetraspanin, and the VdNoxB, a catalytic subunit of membrane-bound NADPH oxidases for reactive oxygen species (ROS) production, were specifically expressed in hyphopodia. VdPls1 and VdNoxB highly co-localize with the plasma membrane at the base of hyphopodia, where ROS and penetration pegs are generated. Mutant strains, VdΔnoxb and VdΔpls1, in which VdPls1 and VdNoxB were deleted, respectively, developed defective hyphpodia incapable of producing ROS and penetration pegs. Defective plasma membrane localization of VdNoxB in VdΔpls1 demonstrates that VdPls1 functions as an adaptor protein for the recruitment and activation of the VdNoxB. Furthermore, in VdΔnoxb and VdΔpls1, tip-high Ca2+ accumulation was impaired in hyphopodia, but not in vegetative hyphal tips. Moreover, nuclear targeting of VdCrz1 and activation of calcineurin-Crz1 signaling upon hyphopodium induction in wild-type V. dahliae was impaired in both knockout mutants, indicating that VdPls1/VdNoxB-dependent ROS was specifically required for tip-high Ca2+ elevation in hyphopodia to activate the transcription factor VdCrz1 in the regulation of penetration peg formation. Together with the loss of virulence of VdΔnoxb and VdΔpls1, which are unable to initiate colonization in cotton plants, our data demonstrate that VdNoxB/VdPls1-mediated ROS production activates VdCrz1 signaling through Ca2+ elevation in hyphopodia, infectious structures of V. dahliae, to regulate penetration peg formation during the initial colonization of cotton roots. PMID:27463643

  14. Temperature Modulates the Secretome of the Phytopathogenic Fungus Lasiodiplodia theobromae

    PubMed Central

    Félix, Carina; Duarte, Ana S.; Vitorino, Rui; Guerreiro, Ana C. L.; Domingues, Pedro; Correia, António C. M.; Alves, Artur; Esteves, Ana C.

    2016-01-01

    Environmental alterations modulate host–microorganism interactions. Little is known about how climate changes can trigger pathogenic features on symbiont or mutualistic microorganisms. Current climate models predict increased environmental temperatures. The exposing of phytopathogens to these changing conditions can have particularly relevant consequences for economically important species and for humans. The impact on pathogen/host interaction and the shift on their biogeographical range can induce different levels of virulence in new hosts, allowing massive losses in agricultural and health fields. Lasiodiplodia theobromae is a phytopathogenic fungus responsible for a number of diseases in various plants. It has also been described as an opportunist pathogen in humans, causing infections with different levels of severity. L. theobromae has a high capacity of adaptation to different environments, such as woody plants, moist argillaceous soils, or even humans, being able to grow and infect hosts in a wide range of temperatures (9–39°C). Nonetheless, the effect of an increase of temperature, as predicted in climate change models, on L. theobromae is unknown. Here we explore the effect of temperature on two strains of L. theobromae – an environmental strain, CAA019, and a clinical strain, CBS339.90. We show that both strains are cytotoxic to mammalian cells but while the environmental strain is cytotoxic mainly at 25°C, the clinical strain is cytotoxic mainly at 30 and 37°C. Extracellular gelatinolytic, xylanolytic, amylolytic, and cellulolytic activities at 25 and 37°C were characterized by zymography and the secretome of both strains grown at 25, 30, and 37°C were characterized by electrophoresis and by Orbitrap LC-MS/MS. More than 75% of the proteins were identified, mostly enzymes (glycosyl hydrolases and proteases). The strains showed different protein profiles, which were affected by growth temperature. Also, strain specific proteins were identified

  15. Temperature Modulates the Secretome of the Phytopathogenic Fungus Lasiodiplodia theobromae.

    PubMed

    Félix, Carina; Duarte, Ana S; Vitorino, Rui; Guerreiro, Ana C L; Domingues, Pedro; Correia, António C M; Alves, Artur; Esteves, Ana C

    2016-01-01

    Environmental alterations modulate host-microorganism interactions. Little is known about how climate changes can trigger pathogenic features on symbiont or mutualistic microorganisms. Current climate models predict increased environmental temperatures. The exposing of phytopathogens to these changing conditions can have particularly relevant consequences for economically important species and for humans. The impact on pathogen/host interaction and the shift on their biogeographical range can induce different levels of virulence in new hosts, allowing massive losses in agricultural and health fields. Lasiodiplodia theobromae is a phytopathogenic fungus responsible for a number of diseases in various plants. It has also been described as an opportunist pathogen in humans, causing infections with different levels of severity. L. theobromae has a high capacity of adaptation to different environments, such as woody plants, moist argillaceous soils, or even humans, being able to grow and infect hosts in a wide range of temperatures (9-39°C). Nonetheless, the effect of an increase of temperature, as predicted in climate change models, on L. theobromae is unknown. Here we explore the effect of temperature on two strains of L. theobromae - an environmental strain, CAA019, and a clinical strain, CBS339.90. We show that both strains are cytotoxic to mammalian cells but while the environmental strain is cytotoxic mainly at 25°C, the clinical strain is cytotoxic mainly at 30 and 37°C. Extracellular gelatinolytic, xylanolytic, amylolytic, and cellulolytic activities at 25 and 37°C were characterized by zymography and the secretome of both strains grown at 25, 30, and 37°C were characterized by electrophoresis and by Orbitrap LC-MS/MS. More than 75% of the proteins were identified, mostly enzymes (glycosyl hydrolases and proteases). The strains showed different protein profiles, which were affected by growth temperature. Also, strain specific proteins were identified, such

  16. Companion cropping with potato onion enhances the disease resistance of tomato against Verticillium dahliae

    PubMed Central

    Fu, Xuepeng; Wu, Xia; Zhou, Xingang; Liu, Shouwei; Shen, Yanhui; Wu, Fengzhi

    2015-01-01

    Intercropping could alleviate soil-borne diseases, however, few studies focused on the immunity of the host plant induced by the interspecific interactions. To test whether or not intercropping could enhance the disease resistance of host plant, we investigated the effect of companion cropping with potato onion on tomato Verticillium wilt caused by Verticillium dahliae (V. dahliae). To investigate the mechanisms, the root exudates were collected from tomato and potato onion which were grown together or separately, and were used to examine the antifungal activities against V. dahliae in vitro, respectively. Furthermore, RNA-seq was used to examine the expression pattern of genes related to disease resistance in tomato companied with potato onion compared to that in tomato grown alone, under the condition of infection with V. dahliae. The results showed that companion cropping with potato onion could alleviate the incidence and severity of tomato Verticillium wilt. The further studies revealed that the root exudates from tomato companied with potato onion significantly inhibited the mycelia growth and spore germination of V. dahliae. However, there were no significant effects on these two measurements for the root exudates from potato onion grown alone or from potato onion grown with tomato. RNA-seq data analysis showed the disease defense genes associated with pathogenesis-related proteins, biosynthesis of lignin, hormone metabolism and signal transduction were expressed much higher in the tomato companied with potato onion than those in the tomato grown alone, which indicated that these defense genes play important roles in tomato against V. dahliae infection, and meant that the disease resistance of tomato against V. dahliae was enhanced in the companion copping with potato onion. We proposed that companion cropping with potato onion could enhance the disease resistance of tomato against V. dahliae by regulating the expression of genes related to disease

  17. RNA-seq analyses of gene expression in the microsclerotia of Verticillium dahliae

    PubMed Central

    2013-01-01

    Background The soilborne fungus, Verticillium dahliae, causes Verticillium wilt disease in plants. Verticillium wilt is difficult to control since V. dahliae is capable of persisting in the soil for 10 to 15 years as melanized microsclerotia, rendering crop rotation strategies for disease control ineffective. Microsclerotia of V. dahliae overwinter and germinate to produce infectious hyphae that give rise to primary infections. Consequently, microsclerotia formation, maintenance, and germination are critically important processes in the disease cycle of V. dahliae. Results To shed additional light on the molecular processes that contribute to microsclerotia biogenesis and melanin synthesis in V. dahliae, three replicate RNA-seq libraries were prepared from 10 day-old microsclerotia (MS)-producing cultures of V. dahliae, strain VdLs.17 (average = 52.23 million reads), and those not producing microsclerotia (NoMS, average = 50.58 million reads). Analyses of these libraries for differential gene expression revealed over 200 differentially expressed genes, including up-regulation of melanogenesis-associated genes tetrahydroxynaphthalene reductase (344-fold increase) and scytalone dehydratase (231-fold increase), and additional genes located in a 48.8 kilobase melanin biosynthetic gene cluster of strain VdLs.17. Nearly 50% of the genes identified as differentially expressed in the MS library encode hypothetical proteins. Additional comparative analyses of gene expression in V. dahliae, under growth conditions that promote or preclude microsclerotial development, were conducted using a microarray approach with RNA derived from V. dahliae strain Dvd-T5, and from the amicrosclerotial vdh1 strain. Differential expression of selected genes observed by RNA-seq or microarray analysis was confirmed using RT-qPCR or Northern hybridizations. Conclusion Collectively, the data acquired from these investigations provide additional insight into gene expression and molecular

  18. Overexpression of potato miR482e enhanced plant sensitivity to Verticillium dahliae infection.

    PubMed

    Yang, Liu; Mu, Xiaoying; Liu, Chao; Cai, Jinghui; Shi, Ke; Zhu, Wenjiao; Yang, Qing

    2015-12-01

    Verticillium wilt of potato is caused by the fungus pathogen Verticillium dahliae. Present sRNA sequencing data revealed that miR482 was in response to V. dahliae infection, but the function in potato is elusive. Here, we characterized potato miR482 family and its putative role resistance to Verticillium wilt. Members of the potato miR482 superfamily are variable in sequence, but all variants target a class of disease-resistance proteins with nucleotide binding site (NBS) and leucine-rich repeat (LRR) motifs. When potato plantlets were infected with V. dahliae, the expression level of miR482e was downregulated, and that of several NBS-LRR targets of miR482e were upregulated. Transgenic potato plantlets overexpressing miR482e showed hypersensitivity to V. dahliae infection. Using sRNA and degradome datasets, we validated that miR482e targets mRNAs of NBS-LRR disease-resistance proteins and triggers the production of trans-acting (ta)-siRNAs, most of which target mRNAs of defense-related proteins. Thus, the hypersensitivity of transgenic potato could be explained by enhanced miR482e and miR482e-derived ta-siRNA-mediated silencing on NBS-LRR-disease-resistance proteins. It is speculated that a miR482-mediated silencing cascade mechanism is involved in regulating potato resistance against V. dahliae infection and could be a counter defense action of plant in response to pathogen infection. PMID:25735453

  19. Polyamine Metabolism in Fungi with Emphasis on Phytopathogenic Species

    PubMed Central

    Valdés-Santiago, Laura; Cervantes-Chávez, José Antonio; León-Ramírez, Claudia Geraldine; Ruiz-Herrera, José

    2012-01-01

    Polyamines are essential metabolites present in all living organisms, and this subject has attracted the attention of researchers worldwide interested in defining their mode of action in the variable cell functions in which they are involved, from growth to development and differentiation. Although the mechanism of polyamine synthesis is almost universal, different biological groups show interesting differences in this aspect that require to be further analyzed. For these studies, fungi represent interesting models because of their characteristics and facility of analysis. During the last decades fungi have contributed to the understanding of polyamine metabolism. The use of specific inhibitors and the isolation of mutants have allowed the manipulation of the pathway providing information on its regulation. During host-fungus interaction polyamine metabolism suffers striking changes in response to infection, which requires examination. Additionally the role of polyamine transporter is getting importance because of its role in polyamine regulation. In this paper we analyze the metabolism of polyamines in fungi, and the difference of this process with other biological groups. Of particular importance is the difference of polyamine biosynthesis between fungi and plants, which makes this process an attractive target for the control of phytopathogenic fungi. PMID:22957208

  20. Streptomycetes and micromycetes as perspective antagonists of fungal phytopathogens.

    PubMed

    Postolaky, O; Syrbu, T; Poiras, N; Baltsat, K; Maslobrod, S; Boortseva, S

    2012-01-01

    Among natural factors that permanently influence on the plants, the soil microorganisms play a special role for the growing of plants as habitants of their rhizosphere. Mainly they are the representatives of actinomycetes genus Streptomyces and fungal genus Penicillium and their metabolic products stimulate plant growth and inhibit the growth of pathogenic fungi and bacteria. The aim of our study was to determine the antagonism of actinomycetes and micromycetes isolated from soils of R. Moldova against the fungal pathogens of agricultural plants. The strains were isolated from 5 types of chernozem (black soil) from central zone of R. Moldova, with different concentration of humus. Most of micromycetes and streptomycetes were isolated from soil sample 1 (monoculture of maize) and soil sample 2 (Poltava road border) with similar humus content (2.4-2.6%). The antifungal activity of micromycetes strains was occurring mostly against Fusarium solani and Thelaviopsis basicola, at streptomycetes against Alternaria alternata and Botrytis cinerea. It was revealed the strains completely inhibit the growth of Alt. alternata (streptomycetes strains 23, 33, 37), B. cinerea (Streptomyces sp. 17), and F. solani (Penicillium sp. 104). Our results allow to consider the actinomycetes Streptomyces sp.9, Streptomyces sp. 12, Streptomyces sp. 17, Streptomyces sp. 37 Streptomyces sp. 66 and micromycetes Penicillium sp. 5, Penicillium sp. 65, Penicillium sp. 104 isolated from soils of R. Moldova, as prospective strains-antagonists against the phytopathogenic fungus, the causative agents of agricultural plants deseasis. PMID:23878981

  1. Guanacastane-type diterpenoids from the insect-associated fungus Verticillium dahliae.

    PubMed

    Wu, Fa-Biao; Li, Tian-Xiao; Yang, Ming-Hua; Kong, Ling-Yi

    2016-01-01

    Four new guanacastane-type diterpenoids, namely dahlianes A (1), B (2), C (3), and D (4), were isolated from cultures of Verticillium dahliae. Their structures were elucidated on the basis of extensive spectroscopic data analysis. Their absolute configurations were determined by a combination of Mo2(OAc)4-induced electronic circular dichroism experiment and Mosher ester method. In cytotoxicity evaluation against human tumor cell lines, compounds 2 and 3 exhibited significant cytotoxicities against MCF-7 cell lines with IC50 values of 3.35 and 4.72 μM, respectively. PMID:26221875

  2. Soil Temperature Determines the Reaction of Olive Cultivars to Verticillium dahliae Pathotypes

    PubMed Central

    Calderón, Rocío; Lucena, Carlos; Trapero-Casas, José L.; Zarco-Tejada, Pablo J.; Navas-Cortés, Juan A.

    2014-01-01

    Background Development of Verticillium wilt in olive, caused by the soil-borne fungus Verticillium dahliae, can be influenced by biotic and environmental factors. In this study we modeled i) the combined effects of biotic factors (i.e., pathotype virulence and cultivar susceptibility) and abiotic factors (i.e., soil temperature) on disease development and ii) the relationship between disease severity and several remote sensing parameters and plant stress indicators. Methodology Plants of Arbequina and Picual olive cultivars inoculated with isolates of defoliating and non-defoliating V. dahliae pathotypes were grown in soil tanks with a range of soil temperatures from 16 to 32°C. Disease progression was correlated with plant stress parameters (i.e., leaf temperature, steady-state chlorophyll fluorescence, photochemical reflectance index, chlorophyll content, and ethylene production) and plant growth-related parameters (i.e., canopy length and dry weight). Findings Disease development in plants infected with the defoliating pathotype was faster and more severe in Picual. Models estimated that infection with the defoliating pathotype was promoted by soil temperatures in a range of 16 to 24°C in cv. Picual and of 20 to 24°C in cv. Arbequina. In the non-defoliating pathotype, soil temperatures ranging from 16 to 20°C were estimated to be most favorable for infection. The relationship between stress-related parameters and disease severity determined by multinomial logistic regression and classification trees was able to detect the effects of V. dahliae infection and colonization on water flow that eventually cause water stress. Conclusions Chlorophyll content, steady-state chlorophyll fluorescence, and leaf temperature were the best indicators for Verticillium wilt detection at early stages of disease development, while ethylene production and photochemical reflectance index were indicators for disease detection at advanced stages. These results provide a better

  3. Constitutive expression of a novel antimicrobial protein, Hcm1, confers resistance to both Verticillium and Fusarium wilts in cotton.

    PubMed

    Zhang, Zhiyuan; Zhao, Jun; Ding, Lingyun; Zou, Lifang; Li, Yurong; Chen, Gongyou; Zhang, Tianzhen

    2016-01-01

    Fusarium and Verticillium wilts, two of the most important diseases in cotton, pose serious threats to cotton production. Here we introduced a novel antimicrobial protein Hcm1, which comprised harpin protein from Xanthomonas oryzae pv. oryzicola (Xoc), and the chimeric protein, cecropin A-melittin, into cotton. The transgenic cotton lines with stable Hcm1 expression showed a higher resistance to Verticillium and Fusarium wilts both in greenhouse and field trials compared to controls. Hcm1 enabled the transgenic cotton to produced a microscopic hypersensitive response (micro-HR), reactive oxygen species (ROS) burst, and caused the activation of pathogenesis-related (PR) genes in response to biotic stress, indicating that the transgenic cotton was in a primed state and ready to protect the host from pathogenic infection. Simultaneously, Hcm1 protein inhibited the growth of Verticillium dahliae (V. dahliae) and Fusarium oxysporum (F. oxysporum) in vitro. The spread of fungal biomass was also inhibited in vivo since the V. dahliae biomass was decreased dramatically in transgenic cotton plants after inoculation with V. dahliae. Together, these results demonstrate that Hcm1 could activate innate immunity and inhibit the growth of V. dahliae and F. oxysporum to protect cotton against Verticillium and Fusarium wilts. PMID:26856318

  4. The genome of the saprophytic fungus Verticillium tricorpus reveals a complex effector repertoire largely resembling its pathogenic relatives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Vascular wilts belong to the most destructive plant diseases, affecting hundreds of economically and ecologically important plant species. The fungal genus Verticillium presently comprises ten species, of which only few are causal agents of vascular wilt diseases. Of these, V. dahliae is the most no...

  5. Multiplex real-time quantitative PCR methodology to assist in the breeding of potato lines with resistance to Verticillium wilt

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potato early dying (PED), caused by Verticillium dahliae, is a seasonal yield-limiting disease of potato worldwide and PED-resistant cultivars currently represent only a small percentage of potato production. In this study we developed a real-time quantitative PCR (Q-PCR) approach to detect and quan...

  6. Management of Verticillium wilt of potato with disease-suppressive green manures and as affected by previous cropping history

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of potential disease-suppressive rotation crops to reduce potato disease problems and increase crop productivity in a field severely infested with Verticillium wilt was evaluated over three field seasons in Maine. Disease-suppressive rotation treatments consisted of 1) a high glucosinola...

  7. Constitutive expression of a novel antimicrobial protein, Hcm1, confers resistance to both Verticillium and Fusarium wilts in cotton

    PubMed Central

    Zhang, Zhiyuan; Zhao, Jun; Ding, Lingyun; Zou, Lifang; Li, Yurong; Chen, Gongyou; Zhang, Tianzhen

    2016-01-01

    Fusarium and Verticillium wilts, two of the most important diseases in cotton, pose serious threats to cotton production. Here we introduced a novel antimicrobial protein Hcm1, which comprised harpin protein from Xanthomonas oryzae pv. oryzicola (Xoc), and the chimeric protein, cecropin A-melittin, into cotton. The transgenic cotton lines with stable Hcm1 expression showed a higher resistance to Verticillium and Fusarium wilts both in greenhouse and field trials compared to controls. Hcm1 enabled the transgenic cotton to produced a microscopic hypersensitive response (micro-HR), reactive oxygen species (ROS) burst, and caused the activation of pathogenesis-related (PR) genes in response to biotic stress, indicating that the transgenic cotton was in a primed state and ready to protect the host from pathogenic infection. Simultaneously, Hcm1 protein inhibited the growth of Verticillium dahliae (V. dahliae) and Fusarium oxysporum (F. oxysporum) in vitro. The spread of fungal biomass was also inhibited in vivo since the V. dahliae biomass was decreased dramatically in transgenic cotton plants after inoculation with V. dahliae. Together, these results demonstrate that Hcm1 could activate innate immunity and inhibit the growth of V. dahliae and F. oxysporum to protect cotton against Verticillium and Fusarium wilts. PMID:26856318

  8. Natural diversity in the model legume Medicago truncatula allows identifying distinct genetic mechanisms conferring partial resistance to Verticillium wilt

    PubMed Central

    Gentzbittel, Laurent

    2013-01-01

    Verticillium wilt is a major threat to alfalfa (Medicago sativa) and many other crops. The model legume Medicago truncatula was used as a host for studying resistance and susceptibility to Verticillium albo-atrum. In addition to presenting well-established genetic resources, this wild plant species enables to investigate biodiversity of the response to the pathogen and putative crosstalk between disease and symbiosis. Symptom scoring after root inoculation and modelling of disease curves allowed assessing susceptibility levels in recombinant lines of three crosses between susceptible and resistant lines, in a core collection of 32 lines, and in mutants affected in symbiosis with rhizobia. A GFP-expressing V. albo-atrum strain was used to study colonization of susceptible plants. Symptoms and colonization pattern in infected M. truncatula plants were typical of Verticillium wilt. Three distinct major quantitative trait loci were identified using a multicross, multisite design, suggesting that simple genetic mechanisms appear to control Verticillium wilt resistance in M. truncatula lines A17 and DZA45.5. The disease functional parameters varied largely in lines of the core collection. This biodiversity with regard to disease response encourages the development of association genetics and ecological approaches. Several mutants of the resistant line, impaired in different steps of rhizobial symbiosis, were affected in their response to V. albo-atrum, which suggests that mechanisms involved in the establishment of symbiosis or disease might have some common regulatory control points. PMID:23213135

  9. Analysis of upland cotton (Gossypium hirsutum) response to Verticillium dahliae inoculation by transcriptome sequencing.

    PubMed

    Shao, B X; Zhao, Y L; Chen, W; Wang, H M; Guo, Z J; Gong, H Y; Sang, X H; Cui, Y L; Wang, C H

    2015-01-01

    Verticillium wilt is one of the main diseases in cotton (Gossypium hirsutum), severely reduces yield and fiber quality, and is difficult to be con-trolled effectively. At present, the molecular mechanism that confers resistance to this disease is unclear. Transcriptome sequencing is an important method to detect resistance genes, explore metabolic pathways, and study resistance mechanisms. In this study, the transcriptome of a disease-resistant inbred cot-ton line inoculated with Verticillium dahliae was sequenced. A total of 126,402 unigenes were obtained using de novo assembly and data analysis, 99,712 (78.88%) of which were annotated into the Nr, Nt, Swiss-Prot, KEGG, COG, and GO databases. The expression patterns of 16 candidate disease-resis-tance genes showed that some genes were upregulated soon after V. dahliae inoculation and others were upregulated later, which may indicate instanta-neous basal defense and lagged specific defense, respectively. We conducted a preliminary analysis of the transcriptome database, which will contribute to further research regarding the cloning of disease-resistance genes. PMID:26535625

  10. Comparative Proteomic Analysis of Gossypium thurberi in Response to Verticillium dahliae Inoculation

    PubMed Central

    Fang, Weiping; Xie, Deyi; Zhu, Heqin; Li, Wu; Xu, Zhenzhen; Yang, Lirong; Li, Zhifang; Sun, Li; Wang, Jinxia; Nie, Lihong; Tang, Zhongjie; Lv, Shuping; Zhao, Fu’an; Sun, Yao; Zhao, Yuanming; Hou, Jianan; Yang, Xiaojie

    2015-01-01

    Verticillium wilt is threatening cotton productivity globally. This disease is caused by soil-borne Verticillium dahliae which directly infects cotton roots, and exclusively colonizes and occludes xylem vessels, finally resulting in necrosis, defoliation, and most severely, plant death. For the first time, iTRAQ (isobaric tags for relative and absolute quantification) was applied to screen the differentially expressed proteins of Gossypium thurberi inoculated with V. dahliae. A total of 6533 proteins were identified from the roots of G. thurberi after inoculation with V. dahliae, and 396 showed up- and 279 down-regulated in comparison to a mock-inoculated roots. Of these identified proteins, the main functional groups were those involved in cell wall organization and reinforcement, disease-resistant chemicals of secondary metabolism, phytohormone signaling, pathogenesis-related proteins, and disease-resistant proteins. Physiological and biochemical analysis showed that peroxidase activity, which promotes the biosynthesis and accumulation of lignin, was induced early in the hypocotyl after inoculation with V. dahliae. Similarly, salicylic acid also accumulated significantly in hypocotyl of the seedlings after inoculation. These findings provide an important knowledge of the molecular events and regulatory networks occurring during G. thurberi-V. dahliae interaction, which may provide a foundation for breeding disease-resistance in cotton. PMID:26506344

  11. Comparative Proteomic Analysis of Gossypium thurberi in Response to Verticillium dahliae Inoculation.

    PubMed

    Fang, Weiping; Xie, Deyi; Zhu, Heqin; Li, Wu; Xu, Zhenzhen; Yang, Lirong; Li, Zhifang; Sun, Li; Wang, Jinxia; Nie, Lihong; Tang, Zhongjie; Lv, Shuping; Zhao, Fu'an; Sun, Yao; Zhao, Yuanming; Hou, Jianan; Yang, Xiaojie

    2015-01-01

    Verticillium wilt is threatening cotton productivity globally. This disease is caused by soil-borne Verticillium dahliae which directly infects cotton roots, and exclusively colonizes and occludes xylem vessels, finally resulting in necrosis, defoliation, and most severely, plant death. For the first time, iTRAQ (isobaric tags for relative and absolute quantification) was applied to screen the differentially expressed proteins of Gossypium thurberi inoculated with V. dahliae. A total of 6533 proteins were identified from the roots of G. thurberi after inoculation with V. dahliae, and 396 showed up- and 279 down-regulated in comparison to a mock-inoculated roots. Of these identified proteins, the main functional groups were those involved in cell wall organization and reinforcement, disease-resistant chemicals of secondary metabolism, phytohormone signaling, pathogenesis-related proteins, and disease-resistant proteins. Physiological and biochemical analysis showed that peroxidase activity, which promotes the biosynthesis and accumulation of lignin, was induced early in the hypocotyl after inoculation with V. dahliae. Similarly, salicylic acid also accumulated significantly in hypocotyl of the seedlings after inoculation. These findings provide an important knowledge of the molecular events and regulatory networks occurring during G. thurberi-V. dahliae interaction, which may provide a foundation for breeding disease-resistance in cotton. PMID:26506344

  12. A Ve homologous gene from Gossypium barbadense, Gbvdr3, enhances the defense response against Verticillium dahliae.

    PubMed

    Chen, Tianzi; Kan, Jialiang; Yang, Yuwen; Ling, Xitie; Chang, Youhong; Zhang, Baolong

    2016-01-01

    The tomato Ve1 gene and several Ve1 homologues are involved in the resistance to Verticillium dahliae. Here, we report on another Ve homologous gene, Gbvdr3, from a Verticillium wilt-resistant cotton cultivar, Gossypium barbadense Hai7124, which has a 3207-bp region that encodes a predicted receptor-like protein. Transient expression analyses indicated that Gbvdr3 is localized in the plasma membrane, and virus-induced gene silencing of Gbvdr3 compromised the resistance of Hai7124 cotton to a defoliating strain of V. dahliae, V991, but not to a non-defoliating strain, BP2. This resistance pattern was further confirmed by over-expression of Gbvdr3 in transgenic Arabidopsis, which significantly elevated the expression of the ethylene-regulated gene GST2, the ethylene- and jasmonic acid-regulated defense-related genes PR3 and PDF1.2, and the salicylic acid-regulated genes PR1 and PR5, but not the PR2 gene. It also triggered the accumulation of hydrogen peroxide and callose at early time points during infection by the V991 defoliating strain. In contrast, elevated accumulation of hydrogen peroxide or callose in Gbvdr3-expressed Arabidopsis leaves was not apparent under infection by the non-defoliating strain, BP2. These results suggested that Gbvdr3 is involved in the resistance to a unique spectrum of defoliating V. dahliae strains. PMID:26686282

  13. Generation of transcriptome profiling and gene functional analysis in Gossypium hirsutum upon Verticillium dahliae infection.

    PubMed

    Zhang, Wenwei; Zhang, Huachong; Qi, Fangjun; Jian, Guiliang

    2016-05-13

    Verticillium wilt caused by the soil-borne fungus Verticillium dahliae, is a devastating disease in cotton. To get more candidate genes related to wilt resistance, a normalized, full-length cDNA library was used to generate the transcriptome profile from a wilt-resistant Gossypium hirsutum variety (Zhongzhimian KV3) upon V. dahliae strain V991 infection. Total 3486 high-quality ESTs were focused from randomly selected 4000 clones, which included 3065 singletons and 421 contigs. To categorize these unigenes, they were compared to functional domain databases. Total 106 unigenes were found to be homologous to known defense-related genes. Among them, PR genes were the major group. Furthermore, knockdown of GhWRKY22, GhWRKY33, GhChitinase, GhCML, and GhDirigent resulted in increased susceptibility of resistant cotton to V. dahliae infection. The results of transcriptome profiles and virus induced gene silencing (VIGS) analysis laid a good foundation for further investigation of cotton resistance to wilt disease. PMID:27038549

  14. Comparative proteomic profiling in compatible and incompatible interactions between hop roots and Verticillium albo-atrum.

    PubMed

    Mandelc, Stanislav; Timperman, Isaak; Radišek, Sebastjan; Devreese, Bart; Samyn, Bart; Javornik, Branka

    2013-07-01

    Verticillium wilt, caused by the soil borne fungal pathogen Verticillium albo-atrum, is a serious threat to hop (Humulus lupulus L.) production in several hop-growing regions. A proteomic approach was applied to analyse the response of root tissue in compatible and incompatible interactions between hop and V. albo-atrum at 10, 20 and 30 days after inoculation, using two-dimensional difference gel electrophoresis (2D-DIGE) coupled with de novo sequencing of derivatized peptides. Approximately 1200 reproducible spots were detected on the gels, of which 102 were identified. In the compatible interaction, 252 spots showed infection-specific changes in spot abundance and an accumulation of defence-related proteins, such as chitinase, β-glucanase, thaumatin-like protein, peroxidase and germin-like protein, was observed. However, no significant infection-specific changes were detected in the incompatible interaction. The results indicate that resistance in this pathosystem may be conferred by constitutive rather than induced defence mechanisms. The identification and high abundance of two mannose/glucose-specific lectin isoforms present only in the roots of the resistant cultivar suggests function of lectins in hop resistance against V. albo-atrum. PMID:23619241

  15. Rootstock Effects on Pistachio Trees Grown in Verticillium dahliae-Infested Soil.

    PubMed

    Epstein, L; Beede, R; Kaur, S; Ferguson, L

    2004-04-01

    ABSTRACT In a field trial in soil infested with Verticillium dahliae, we compared the yield, growth, incidence of symptoms of Verticillium wilt, and mortality of two interspecific hybrid pistachio tree rootstocks (UCBI and PGII) with the standard rootstocks: the V. dahliae-resistant and susceptible Pistacia integerrima and P. atlantica, respectively. After 10 years, the trees were destructively sampled for V. dahliae in the xylem at the graft union. The results indicate that trees on the (P. atlantica 'KAC' x P. integerrima) hybrid UCBI rootstock grew and yielded as well as those on P. integerrima. Trees on the hybrid PGII yielded the least. Analysis of variance and log-linear models indicate that in soil infested with V. dahliae, three associations significantly affect pistachio nut yield. Rootstock affects scion vigor and extent of infection. Third, the extent of infection and scion vigor are inversely associated. Although trees on the P. integerrima rootstock had the highest ratings in a visual assessment of vigor, 65% were infected with V. dahliae in the trunk in the graft region compared with 73% in P. atlantica and 25% in UCBI. Thus, P. integerrima and UCBI have at least one different mechanism for resistance to V. dahliae. PMID:18944115

  16. Growth Regulator Changes in Cotton Associated with Defoliation Caused by Verticillium albo-atrum.

    PubMed

    Wiese, M V; Devay, J E

    1970-03-01

    Cotton plants, variety Acala 4-42 family 77 (Gossypium hirsutum L.,), were stem puncture-inoculated with either a defoliating isolate (T9) or a nondefoliating isolate (SS4) of Verticillium albo-atrum (Reinke and Berth.). As symptoms developed, growth regulators were assayed in diseased plants to discern their importance in the disease syndrome.An Avena coleoptile straight growth bioassay demonstrated the presence of several growth-regulatory compounds in cotton tissue extracts. Indoleacetic acid was among the compounds whose effects on coleoptile growth were influenced by disease development. Coleoptile growth due to indoleacetic acid was greater in extracts of diseased stems and leaves than in extracts of comparable healthy tissues. During the defoliation period the T9 and SS4 isolates appeared equally effective in increasing indoleacetic acid and reducing indoleacetic acid decarboxylation. Preceding defoliation, however, in plants showing equivalent symptoms the degradation of auxin was reduced more by infection with T9, the defoliating isolate. The reduced auxin degradation appeared to be releated to concomitant increases in caffeic acid and other indoleacetic acid-oxidase inhibitors in the affected tissues.Abscisic acid in tissue extracts strongly inhibited coleoptile growth. During the defoliation period gas-liquid chromatographic and ultraviolet absorption measurements revealed that abscisic acid levels were approximately doubled in T9-infected leaves but were relatively unaffected in leaves infected with the nondefoliating isolate and in stems infected with either isolate.The onset of epinasty and especially defoliation was also accompanied by increased ethylene production in diseased plants. Ethylene in gas samples taken from jars confining plants infected with SS4 or T9, respectively, was increased 2- and 5-fold over uninoculated controls. Ethylene supplied exogenously to healthy plants in concentrations as low as 0.2 microliter per liter induced both the

  17. Growth Regulator Changes in Cotton Associated with Defoliation Caused by Verticillium albo-atrum1

    PubMed Central

    Wiese, M. V.; Devay, J. E.

    1970-01-01

    Cotton plants, variety Acala 4-42 family 77 (Gossypium hirsutum L.,), were stem puncture-inoculated with either a defoliating isolate (T9) or a nondefoliating isolate (SS4) of Verticillium albo-atrum (Reinke and Berth.). As symptoms developed, growth regulators were assayed in diseased plants to discern their importance in the disease syndrome. An Avena coleoptile straight growth bioassay demonstrated the presence of several growth-regulatory compounds in cotton tissue extracts. Indoleacetic acid was among the compounds whose effects on coleoptile growth were influenced by disease development. Coleoptile growth due to indoleacetic acid was greater in extracts of diseased stems and leaves than in extracts of comparable healthy tissues. During the defoliation period the T9 and SS4 isolates appeared equally effective in increasing indoleacetic acid and reducing indoleacetic acid decarboxylation. Preceding defoliation, however, in plants showing equivalent symptoms the degradation of auxin was reduced more by infection with T9, the defoliating isolate. The reduced auxin degradation appeared to be releated to concomitant increases in caffeic acid and other indoleacetic acid-oxidase inhibitors in the affected tissues. Abscisic acid in tissue extracts strongly inhibited coleoptile growth. During the defoliation period gas-liquid chromatographic and ultraviolet absorption measurements revealed that abscisic acid levels were approximately doubled in T9-infected leaves but were relatively unaffected in leaves infected with the nondefoliating isolate and in stems infected with either isolate. The onset of epinasty and especially defoliation was also accompanied by increased ethylene production in diseased plants. Ethylene in gas samples taken from jars confining plants infected with SS4 or T9, respectively, was increased 2- and 5-fold over uninoculated controls. Ethylene supplied exogenously to healthy plants in concentrations as low as 0.2 microliter per liter induced both

  18. Understanding Interactions between Phytopathogenic Phytophthora Effector IpiO and the Host Resistance Protein RB

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Species of phytopathogenic Phytophthora are well known for their ability to cause disease on economically important crops, with almost 100 recognized species targeting close to 300 different hosts. The host resistance protein RB, isolated from wild potato, specifically recognizes the P. infestans Ip...

  19. Transcriptional profile of P. syringae pv. phaseolicola NPS3121 at low temperature: Physiology of phytopathogenic bacteria

    PubMed Central

    2013-01-01

    Background Low temperatures play key roles in the development of most plant diseases, mainly because of their influence on the expression of various virulence factors in phytopathogenic bacteria. Thus far, studies regarding this environmental parameter have focused on specific themes and little is known about phytopathogenic bacteria physiology under these conditions. To obtain a global view regarding phytopathogenic bacteria strategies in response to physiologically relevant temperature changes, we used DNA microarray technology to compare the gene expression profile of the model bacterial pathogen P. syringae pv. phaseolicola NPS3121 grown at 18°C and 28°C. Results A total of 236 differentially regulated genes were identified, of which 133 were up-regulated and 103 were down-regulated at 18°C compared to 28°C. The majority of these genes are involved in pathogenicity and virulence processes. In general, the results of this study suggest that the expression profile obtained may be related to the fact that low temperatures induce oxidative stress in bacterial cells, which in turn influences the expression of iron metabolism genes. The expression also appears to be correlated with the profile expression obtained in genes related to motility, biofilm production, and the type III secretion system. Conclusions From the data obtained in this study, we can begin to understand the strategies used by this phytopathogen during low temperature growth, which can occur in host interactions and disease development. PMID:23587016

  20. "Light-tagged" bacteriophage as a diagnostic tool for the detection of phytopathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Detection of the phytopathogen Pseudomonas cannabina pv. alisalensis, the causeal agent of bacterial blight of crucifers is essential for managing this disease. A phage-based diagnostic assay was developed that detected and identify P. cannabina pv. alisalensis from cultures and diseased plant spec...

  1. Effect of Ditylenchus dipsaci and Pratylenchus penetrans on Verticillium Wilt of Alfalfa.

    PubMed

    Vrain, T C

    1987-07-01

    Verticillium albo-atrum wilt symptoms appeared faster and were significantly more severe in the presence of Ditylenchus dipsaci in Vernal, a wilt-susceptible cultivar, than in Marls Kabul, a wilt-resistant cultivar. Winter kill in the field was not affected by the nematode during the first winter, but 50% of plants were killed in the second winter. Forage yield from nematode-infected plants was significantly reduced the second year. Interaction with V. albo-atrum did not significantly reduce forage yields below that of D. dipsaci alone. Pratylenchus penetrans did not increase the severity of wilt symptoms in the presence of V. albo-atrum, nor did it affect forage yield in the greenhouse. It did, however, reduce alfalfa yields in presence of V. albo-atrum under field conditions. D. dipsaci and P. penetrans reproduced faster in Vernal than in Maris Kabul when the fungus was present. PMID:19290158

  2. Effect of Ditylenchus dipsaci and Pratylenchus penetrans on Verticillium Wilt of Alfalfa

    PubMed Central

    Vrain, T. C.

    1987-01-01

    Verticillium albo-atrum wilt symptoms appeared faster and were significantly more severe in the presence of Ditylenchus dipsaci in Vernal, a wilt-susceptible cultivar, than in Marls Kabul, a wilt-resistant cultivar. Winter kill in the field was not affected by the nematode during the first winter, but 50% of plants were killed in the second winter. Forage yield from nematode-infected plants was significantly reduced the second year. Interaction with V. albo-atrum did not significantly reduce forage yields below that of D. dipsaci alone. Pratylenchus penetrans did not increase the severity of wilt symptoms in the presence of V. albo-atrum, nor did it affect forage yield in the greenhouse. It did, however, reduce alfalfa yields in presence of V. albo-atrum under field conditions. D. dipsaci and P. penetrans reproduced faster in Vernal than in Maris Kabul when the fungus was present. PMID:19290158

  3. Isolation and characterization of a chitinase gene from entomopathogenic fungus Verticillium lecanii

    PubMed Central

    Zhu, Yanping; Pan, Jieru; Qiu, Junzhi; Guan, Xiong

    2008-01-01

    Entomopathogenic fungus Verticillium lecanii is a promising whitefly and aphid control agent. Chitinases secreted by this insect pathogen have considerable importance in the biological control of some insect pests. An endochitinase gene Vlchit1 from the fungus was cloned and overexpressed in Escherichia coli. The Vlchit1 gene not only contains an open reading frame (ORF) which encodes a protein of 423 amino acids (aa), but also is interrupted by three short introns. Vlchit1 protein showed that the chitinase Vlchit1 has a (a/b)8 TIM barrel structure. Overexpression test and Enzymatic activity assay indicated that the Vlchit1 is a functional enzyme that can hydrolyze the chitin substrate, so the Vlchit1 gene can service as a useful gene source for genetic manipulation leading to strain improvement of entomopathogenic fungi or constructing new transgenic plants with resistance to various fungal and insects pests. PMID:24031223

  4. Development of an assay for rapid detection and quantification of Verticillium dahliae in soil.

    PubMed

    Bilodeau, Guillaume J; Koike, Steven T; Uribe, Pedro; Martin, Frank N

    2012-03-01

    ABSTRACT Verticillium dahliae is responsible for Verticillium wilt on a wide range of hosts, including strawberry, on which low soil inoculum densities can cause significant crop loss. Determination of inoculum density is currently done by soil plating but this can take 6 to 8 weeks to complete and delay the grower's ability to make planting decisions. To provide a faster means for estimating pathogen populations in the soil, a multiplexed TaqMan real-time polymerase chain reaction (PCR) assay based on the ribosomal DNA (rDNA) intergenic spacer (IGS) was developed for V. dahliae. The assay was specific for V. dahliae and included an internal control for evaluation of inhibition due to the presence of PCR inhibitors in DNA extracted from soil samples. An excellent correlation was observed in regression analysis (R(2) = 0.96) between real-time PCR results and inoculum densities determined by soil plating in a range of field soils with pathogen densities as low as 1 to 2 microsclerotia/g of soil. Variation in copy number of the rDNA was also evaluated among isolates by SYBR Green real-time PCR amplification of the V. dahliae-specific amplicon compared with amplification of several single-copy genes and was estimated to range from ≈24 to 73 copies per haploid genome, which translated into possible differences in results among isolates of ≈1.8 cycle thresholds. Analysis of the variation in results of V. dahliae quantification among extractions of the same soil sample indicated that assaying four replicate DNA extractions for each field sample would provide accurate results. A TaqMan assay also was developed to help identify colonies of V. tricorpus on soil plates. PMID:22066673

  5. Whole Genome Wide Expression Profiles on Germination of Verticillium dahliae Microsclerotia

    PubMed Central

    Tao, Fei; Cui, Qian; Xu, Xiangming; Shang, Wenjing; Hu, Xiaoping

    2014-01-01

    Verticillium dahliae is a fungal pathogen causing Verticillium wilt on a range of economically important crops. Microsclerotia are its main survival and dormancy structures and serve as the primary inoculum on many hosts. Studies were conducted to determine the effect of temperature (5 to 50°C), pH (2 to 12) and nutrient regimes on microsclerotia germination. The optimal condition for microsclerotium germination was 20°C with pH 8.0 whereas nutrient regimes had no significant effect on its germination. The whole genome wide expression profiles during microsclerotium germination were characterized using the Illumina sequencing technology. Approximately 7.4 million of 21-nt cDNA tags were sequenced in the cDNA libraries derived from germinated and non-germinated microsclerotia. About 3.9% and 2.3% of the unique tags were up-regulated and down-regulated at least five-fold, respectively, in the germinated microsclerotia compared with the non-germinated microsclerotia. A total of 1654 genes showing differential expression were identified. Genes that are likely to have played important roles in microsclerotium germination include those encoding G-protein coupled receptor, lipase/esterase, cyclopentanone 1,2-monooxygenase, H(+)/hexose cotransporter 1, fungal Zn(2)-Cys(6) binuclear cluster domain, thymus-specific serine protease, glucan 1,3-beta-glucosidase, and alcohol dehydrogenase. These genes were mainly up-regulated or down-regulated only in germinated microsclerotia, compared with non-germinated microsclerotia. The differential expression of genes was confirmed by qRT-PCR analysis of 20 randomly selected genes from the 40 most differentially expressed genes. PMID:24927478

  6. Analysis of sea-island cotton and upland cotton in response to Verticillium dahliae infection by RNA sequencing

    PubMed Central

    2013-01-01

    Background Cotton Verticillium wilt is a serious soil-borne vascular disease that causes great economic loss each year. However, due to the lack of resistant varieties of upland cotton, the molecular mechanisms of resistance to this disease, especially to the pathogen Verticillium dahliae, remain unclear. Results We used the RNA-seq method to research the molecular mechanisms of cotton defence responses to different races of Verticillium dahliae by comparing infected sea-island cotton and upland cotton. A total of 77,212 unigenes were obtained, and the unigenes were subjected to BLAST searching and annotated using the GO and KO databases. Six sets of digital gene expression data were mapped to the reference transcriptome. The gene expression profiles of cotton infected with Verticillium dahliae were compared to those of uninfected cotton; 44 differentially expressed genes were identified. Regarding genes involved in the phenylalanine metabolism pathway, the hydroxycinnamoyl transferase gene (HCT) was upregulated in upland cotton whereas PAL, 4CL, CAD, CCoAOMT, and COMT were upregulated in sea-island cotton. Almost no differentially expressed genes in this pathway were identified in sea-island cotton and upland cotton when they were infected with V. dahliae V991 and V. dahliae D07038, respectively. Conclusions Our comprehensive gene expression data at the transcription level will help elucidate the molecular mechanisms of the cotton defence response to V. dahliae. By identifying the genes involved in the defence response of each type of cotton to V. dahliae, our data not only provide novel molecular information for researchers, but also help accelerate research on genes involved in defences in cotton. PMID:24314117

  7. The rhizosphere effect on bacteria antagonistic towards the pathogenic fungus Verticillium differs depending on plant species and site.

    PubMed

    Berg, Gabriele; Opelt, Katja; Zachow, Christin; Lottmann, Jana; Götz, Monika; Costa, Rodrigo; Smalla, Kornelia

    2006-05-01

    Rhizobacteria with antagonistic activity towards plant pathogens play an essential role in root growth and plant health and are influenced by plant species in their abundance and composition. To determine the extent of the effect of the plant species and of the site on the abundance and composition of bacteria with antagonistic activity towards Verticillium dahliae, bacteria isolated from the rhizosphere of two Verticillium host plants, oilseed rape and strawberry, and from bulk soil were analysed at three different locations in Germany over two growing seasons. A total of 6732 bacterial isolates screened for in vitro antagonism towards Verticillium resulted in 560 active isolates, among which Pseudomonas (77%) and Serratia (6%) were the most dominant genera. The rhizosphere effect on the antagonistic bacterial community was shown by an enhanced proportion of antagonistic isolates, by enrichment of specific amplified ribosomal DNA restriction analysis types, species and genotypes, and by a reduced diversity in the rhizosphere in comparison to bulk soil. Such an effect was influenced by the plant species and by the site of its cultivation. Altogether, 16S rRNA gene sequencing of 66 isolates resulted in the identification of 22 different species. Antagonists of the genus Serratia were preferentially isolated from oilseed rape rhizosphere, with the exception of one site. For isolates of Pseudomonas and Serratia, plant-specific and site-specific genotypes were found. PMID:16629754

  8. Genome Sequence of the Endophytic Bacterium Bacillus thuringiensis Strain KB1, a Potential Biocontrol Agent against Phytopathogens.

    PubMed

    Jeong, Haeyoung; Jo, Sung Hee; Hong, Chi Eun; Park, Jeong Mee

    2016-01-01

    ITALIC! Bacillus thuringiensisis the most widely known microbial pesticide used in agricultural applications. Herein, we report a draft genome sequence of the endophytic bacterium ITALIC! Bacillus thuringiensisstrain KB1, which exhibits antagonism against phytopathogens. PMID:27103716

  9. Genome Sequence of the Endophytic Bacterium Bacillus thuringiensis Strain KB1, a Potential Biocontrol Agent against Phytopathogens

    PubMed Central

    Jo, Sung Hee; Hong, Chi Eun

    2016-01-01

    Bacillus thuringiensis is the most widely known microbial pesticide used in agricultural applications. Herein, we report a draft genome sequence of the endophytic bacterium Bacillus thuringiensis strain KB1, which exhibits antagonism against phytopathogens. PMID:27103716

  10. Biological preparation of chitosan nanoparticles and its in vitro antifungal efficacy against some phytopathogenic fungi.

    PubMed

    Sathiyabama, M; Parthasarathy, R

    2016-10-20

    The aim of the present study was to prepare Chitosan nanoparticles through biological method with high antifungal activities. Chitosan nanoparticles were prepared by the addition of anionic proteins isolated from Penicillium oxalicum culture to chitosan solutions. The formation of chitosan nanoparticles was preliminary confirmed by UV-vis spectrophotometric analysis. The physico-chemical properties of the chitosan nanoparticles were determined by size and zeta potential analysis, FTIR analysis, HRTEM and XRD pattern. The chitosan nanoparticles were evaluated for its potential to inhibit the growth of phytopathogens viz., Pyricularia grisea, Alternaria solani, Fusarium oxysporum. It is evident from our results that chitosan nanoparticles inhibit the growth of phytopathogens tested. Chitosan nanoparticle treated chickpea seeds showed positive morphological effects such as enhanced germination%, seed vigor index and vegetative biomass of seedlings. All these results indicate that chitosan nanoparticle can be used further under field condition to protect various crops from the devastating fungal pathogens as well as growth promoters. PMID:27474573

  11. Chemical Composition and Antibacterial Activity of Essential Oils of Two Species of Lamiaceae against Phytopathogenic Bacteria.

    PubMed

    Gormez, Arzu; Bozari, Sedat; Yanmis, Derya; Gulluce, Medine; Sahin, Fikrettin; Agar, Guleray

    2015-01-01

    In this study, we aimed to determine chemical composition and antibacterial activities of Satureja hortensis and Calamintha nepeta against to 20 phytopathogenic bacteria causing serious crop loss. The essential oils of S. hortensis and C. nepeta were isolated by the hydrodistillation method and the chemical composition of the essential oils were analyzed by GC-MS. The antibacterial properties of the essential oils were evaluated against 20 phytopathogenic bacteria through Disc diffusion assay and micro dilution assay. The results revealed that the essential oils of S. hortensis and C. nepeta have significant antibacterial activity. Furthermore, the findings of the study are valuable for future investigations focusing on the alternative natural compounds to control plant diseases. PMID:26373171

  12. Investigation of mycoviruses in endophytic and phytopathogenic strains of Colletotrichum from different hosts.

    PubMed

    Rosseto, P; Costa, A T; Polonio, J C; da Silva, A A; Pamphile, J A; Azevedo, J L

    2016-01-01

    Fungi belonging to the Colletotrichum genus can be categorized as endophytic or phytopathogenic. These fungi can be infected by viruses, termed mycoviruses, which are know to promote hypovirulence in infected fungi. However, there are few studies that have described mycoviral infections of endophytes. The production of secondary metabolites by endophytes with antimicrobial potential in inhibiting numerous pathogens has gained increasing attention. The aim of the current study was to investigate the presence of mycoviruses in endophytic and phytopathogenic fungi of the Colletotrichum genus, as well as to analyze the antimicrobial activity of crude extracts obtained from these samples. To detect the presence of mycoviruses in the samples, dsRNA was extracted, treated with enzymes, and analyzed following electrophoresis in agarose gel. Furthermore, isometric mycoviral particles were observed by transmission electron microscopy. Serial microdilution methodology was used to test crude extracts of Colletotrichum spp for antibacterial activity against Escherichia coli and Staphylococcus aureus, and antifungal activity against Fusarium solani. The results of the molecular and microscopic analyses indicated that a phytopathogenic strain presented infection by mycovirus. The antibacterial activity analysis revealed that the minimum inhibitory concentrations and minimum bactericidal concentrations were low for the fungal extracts of the two endophytes, indicating that these extracts were effective antibacterial agents. However, their antifungal activity against F. solani was not statistically different compared to that of the negative control. PMID:26985921

  13. [Screening probiotic endophytic bacteria from medicinal plant flex cornuta and the phytopathogen-inhibiting effect].

    PubMed

    Zhao, Long-fei; Xu, Ya-jun; Lai, Xin-he; Kou, Tian-chao; Yan, Jun-li; Zhou, Pei-pei; Fan, Shan-shan; Yan, Yong-feng

    2015-05-01

    Culturable endophytic bacteria were isolated from medicinal plant Ilex cornuta by plate-spreading method, strains with strong inhibitory effect on phytopathogen were screened by confrontation culture and fermentation filtrate culture methods, and the morphological changes of phytopathogen hyphae treated with endophytic bacteria were examined by microscopy and micrograph. Their phylogenetic relationships were determined by homology analysis of the 16S rDNA sequences of PCR products and the taxonomic status of the selected strains was determined based on their morphology, physiology, biochemical test results and 16S rDNA sequence analysis. A total of 85 endophytic bacteria were isolated from the healthy roots, stems, leaves and fruits of I. cornuta, and 10 strains of them showed strong inhibitory effect on Alternaria alternata, Magnaporthe grisea, Fusarium oxysporum, and were preliminarily identified belonging to four genera and seven species. Three strains with the strongest inhibitory effect, GG78 (60.3%), GG31 (48.1%) and GG13 (61.0%) belonged to Enterobacter cloacae, Enterobacter ludwigii and Bacillus cereus, respectively. Microscopic analyses showed that the inhibited phytopathogen hyphae became deformed, distorted, and partially expanded forming plasma concentration and hair-like branch on the hyphae base. These morphological changes could be caused by the extracellular metabolic substances secreted by the endophytic bacteria, such as antibiotics, hydrolytic enzymes, alkaloids and so on. PMID:26571677

  14. Evaluation of Fungicides on Growth and Conidial Germination of Verticillium theobromae Isolated from Plantain

    NASA Astrophysics Data System (ADS)

    Igeleke, C. L.; Ayanru, D. K. G.

    An evaluation of three fungicides, namely, benomyl [methyl l-(butyl-carbamoyl)-2-benzimidazole carbamate], calixin (tridomorph) and dithane M-45 (mancozeb), was carried out for their inhibitory effects on Verticillium theobromae, the causal organism of cigar-end rot disease of plantain (Musa paradisiaca). The LD50 of calixin, benomyl and dithane M-45 in inhibiting mycelial growth, were 0.14, 0.98 and 535.17 µg mL-1, respectively. Calixin was also the most effective in conidial germination inhibition with an LD50 of 21.78 µg mL-1, as compared with dithane M-45 86.39 µg mL-1 and benomyl 275.50 µg mL-1. Germ tubes of the test organism were distorted by the fungicides at varying concentrations. Calixin had greater distortion effect at a lower concentration of 10 µg mL-1, dithane M-45 (100 µg mL-1) and benomyl (1000 µg mL-1). The relevance of these results in relation to the control and management of cigar-end rot disease of plantain is discussed.

  15. Interlaboratory Comparison of Methods To Quantify Microsclerotia of Verticillium dahliae in Soil

    PubMed Central

    Termorshuizen, A. J.; Davis, J. R.; Gort, G.; Harris, D. C.; Huisman, O. C.; Lazarovits, G.; Locke, T.; Melero Vara, J. M.; Mol, L.; Paplomatas, E. J.; Platt, H. W.; Powelson, M.; Rouse, D. I.; Rowe, R. C.; Tsror, L.

    1998-01-01

    In a comparison of different methods for estimating Verticillium dahliae in soil, 14 soil samples were analyzed in a blinded fashion by 13 research groups in seven countries, using their preferred methods. One group analyzed only four samples. Twelve soil samples were naturally infested, and two had known numbers of microsclerotia of V. dahliae added to them. In addition, a control was included to determine whether transport had an effect on the results. Results differed considerably among the research groups. There was a 118-fold difference between the groups with the lowest and highest mean estimates. Results of the other groups were evenly distributed between these extremes. In general, methods based on plating dry soil samples gave higher numbers of V. dahliae than did plating of an aqueous soil suspension. Recovery of V. dahliae from samples with added microsclerotia varied from 0 to 59%. Most of the variability within each analysis was at the petri dish level. The results indicate the necessity to check the performance of detection assays regularly by comparing recoveries with other laboratories, using a common set of soil samples. We conclude that wet plating assays are less accurate than dry plating assays. PMID:9758809

  16. [Research of influence factors on spectral recognition for cotton leaf infected by Verticillium wilt].

    PubMed

    Chen, Bing; Wang, Fang-Yong; Han, Huan-Yong; Liu, Zheng; Xiao, Chun-Hua; Zou, Nan

    2014-03-01

    Through carrying out spectral test experiment, the influence factors of spectrum test were analyzed, the influence degree of various factors in spectral recognition was explicated and the method of spectra test was optimized for cotton leaf infected by verticillium wilt. The results indicated that under different severity levels, the shape and value of reflectance of disease symptoms part were Significantly higher than healthy part on cotton leaf, compared with the black board as baseboard, the spectral values of disease leaves were slightly higher in visible light wavebands and significantly higher in others wavebands than healthy leaves on white baseboard. Different position of leaf on cotton plant has different effect degree to the recognition of disease, the effect of stem leaf was more obvious than that of else leaf, the identical leaf position was less influenced by disease than band. Test time and cotton varieties had less influence on recognizing disease by spectra, and the effect of the same condition was acceptable. Test site had no effect on disease recognition by spectra. The effect of each factor was different for recognizing disease leaf by spectra, and this study will provide reference for the researchers of crop disease diagnosis by spectra. PMID:25208415

  17. Verticillium wilt of olive branches in Iran and its control managements with soil solarization method.

    PubMed

    Saremi, H; Amarlou, A; Okhovvat, S M

    2006-01-01

    Wilting of mostly one branch in nurseries and newly established orchards of olive was studied in eastern north of Iran including Zanjan, Golestan and Khorassan provinces during 2002-2004. Different infected plants were visited and samples showing symptoms including wilting or death of branches collected from various areas and transferred to laboratory. Samples were cultured in common media (PDA) and different fungi were identified. The most frequently isolated pathogen was Verticillium dahliae which caused wilting of mostly one branch of olive seedling or trees in studied areas. Results showed that the disease caused main losses where olive cuttings were cultured in infected soils, previously cropped to susceptible plants. In fact, the population density of V. dahliae was high in the garden soil, previously produced susceptible crop cultivar to the fungus especially cotton or potatoes. Soil disinfestations by soil solarization method was carried in Taroam as the warmer climate in studied areas to control the pathogen. Application of this method reduced population density of the pathogen from 1700 CFU g/soil to 1000 after 4 weeks. This method was simple, effective, non negative side and economic which can be used in nearly warm areas. PMID:17390877

  18. Verticillium dahliae alters Pseudomonas spp. populations and HCN gene expression in the rhizosphere of strawberry.

    PubMed

    DeCoste, Nadine J; Gadkar, Vijay J; Filion, Martin

    2010-11-01

    The production of hydrogen cyanide (HCN) by beneficial root-associated bacteria is an important mechanism for the biological control of plant pathogens. However, little is known about the biotic factors affecting HCN gene expression in the rhizosphere of plants. In this study, real-time reverse transcription PCR (qRT-PCR) assays were developed to investigate the effect of the plant pathogen Verticillium dahliae on hcnC (encoding for HCN biosynthesis) gene expression in Pseudomonas sp. LBUM300. Strawberry plants were inoculated with Pseudomonas sp. LBUM300 and (or) V. dahliae and grown in pots filled with nonsterilized field soil. RNA was extracted from rhizosphere soil sampled at 0, 15, 30, and 45 days following inoculation with V. dahliae and used for qRT-PCR analyses. Populations of V. dahliae and Pseudomonas sp. LBUM300 were also monitored using a culture-independent qPCR approach. hcnC expression was detected at all sampling dates. The presence of V. dahliae had a significant stimulation effect on hcnC gene expression and also increased the population of Pseudomonas sp. LBUM300. However, the V. dahliae population was not altered by the presence of Pseudomonas sp. LBUM300. To our knowledge, this study is the first to evaluate the effect of a plant pathogen on HCN gene expression in the rhizosphere soil. PMID:21076481

  19. Characterization of dusts collected from swine confinement buildings. [Verticillium sp. ; Actinomycetes

    SciTech Connect

    Donham, K.J.; Scallon, L.J.; Popendorf, W.; Treauhaft, M.W.; Roberts, R.D.

    1986-07-01

    The air in 21 different swine confinement buildings was sampled with 37 mm cassette filters with and without cyclone preselectors and with cascade impactors. Filter results yielded a mean total aerosol of 6.3 mg/m/sup 3/, a mean respirable aerosol of 0.5 mg/m/sup 3/; the geometric mean diameter was 2.9 microns. Cascade impactor measurements revealed a mean total aerosol of 7.6 mg/m/sup 3/, a respirable aerosol of 2.5 mg/m/sup 3/ and a mass median diameter of 9.6 microns. The two major constituents in these aerosols were grain particles and dried fecal matter. The grain particles were larger than fecal particles and proportionately more abundant in finishing buildings where 50 kg-100 kg animals are housed. Therefore the respirable fraction was less in finishing buildings than in farrowing and nursery buildings. Culturing of settled dusts yielded six different mold species, with the highest counts for Verticillium sp. (5 x 10/sup 2/ cfu/mg dry dust) grown at 37/sup 0/C. Thermophilic Actinomycetes and both gram negative and gram positive bacteria were isolated.

  20. Identification of Novel Virulence-Associated Proteins Secreted to Xylem by Verticillium nonalfalfae During Colonization of Hop Plants.

    PubMed

    Flajsman, Marko; Mandelc, Stanislav; Radisek, Sebastjan; Stajner, Natasa; Jakse, Jernej; Kosmelj, Katarina; Javornik, Branka

    2016-05-01

    Plant pathogens employ various secreted proteins to suppress host immunity for their successful host colonization. Identification and characterization of pathogen-secreted proteins can contribute to an understanding of the pathogenicity mechanism and help in disease control. We used proteomics to search for proteins secreted to xylem by the vascular pathogen Verticillium nonalfalfae during colonization of hop plants. Three highly abundant fungal proteins were identified: two enzymes, α-N-arabinofuranosidase (VnaAbf4.216) and peroxidase (VnaPRX1.1277), and one small secreted hypothetical protein (VnaSSP4.2). These are the first secreted proteins so far identified in xylem sap following infection with Verticillium spp. VnaPRX1.1277, classified as a heme-containing peroxidase from Class II, similar to other Verticillium spp. lignin-degrading peroxidases, and VnaSSP4.2, a 14-kDa cysteine-containing protein with unknown function and with a close homolog in related V. alfalfae strains, were further examined. The in planta expression of VnaPRX1.1277 and VnaSSP4.2 genes increased with the progression of colonization, implicating their role in fungal virulence. Indeed, V. nonalfalfae deletion mutants of both genes exhibited attenuated virulence on hop plants, which returned to the level of the wild-type pathogenicity in the knockout complementation lines, supporting VnaPRX1.1277 and VnaSSP4.2 as virulence factors required to promote V. nonalfalfae colonization of hop plants. PMID:26883488

  1. Evolution of the metabolic and regulatory networks associated with oxygen availability in two phytopathogenic enterobacteria

    PubMed Central

    2012-01-01

    Background Dickeya dadantii and Pectobacterium atrosepticum are phytopathogenic enterobacteria capable of facultative anaerobic growth in a wide range of O2 concentrations found in plant and natural environments. The transcriptional response to O2 remains under-explored for these and other phytopathogenic enterobacteria although it has been well characterized for animal-associated genera including Escherichia coli and Salmonella enterica. Knowledge of the extent of conservation of the transcriptional response across orthologous genes in more distantly related species is useful to identify rates and patterns of regulon evolution. Evolutionary events such as loss and acquisition of genes by lateral transfer events along each evolutionary branch results in lineage-specific genes, some of which may have been subsequently incorporated into the O2-responsive stimulon. Here we present a comparison of transcriptional profiles measured using densely tiled oligonucleotide arrays for two phytopathogens, Dickeya dadantii 3937 and Pectobacterium atrosepticum SCRI1043, grown to mid-log phase in MOPS minimal medium (0.1% glucose) with and without O2. Results More than 7% of the genes of each phytopathogen are differentially expressed with greater than 3-fold changes under anaerobic conditions. In addition to anaerobic metabolism genes, the O2 responsive stimulon includes a variety of virulence and pathogenicity-genes. Few of these genes overlap with orthologous genes in the anaerobic stimulon of E. coli. We define these as the conserved core, in which the transcriptional pattern as well as genetic architecture are well preserved. This conserved core includes previously described anaerobic metabolic pathways such as fermentation. Other components of the anaerobic stimulon show variation in genetic content, genome architecture and regulation. Notably formate metabolism, nitrate/nitrite metabolism, and fermentative butanediol production, differ between E. coli and the phytopathogens

  2. Characterization of 22 highly polymorphic microsatellite loci in the cosmopolitan fungal plant pathogen Verticillium dahliae. Permanent Genetic Resources added to Molecular Ecology Resources

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Twenty-two microsatellite loci were characterized in the soilborne plant pathogenic fungus Verticillium dahliae by analysis of the genome sequence. All loci were polymorphic in at least two of three populations of V. dahliae tested and collected from lettuce, spinach and tomato. These loci were us...

  3. Colonization dynamics and spatial progression of Verticillium dahliae in individual stems of two potato cultivars with differing responses to potato early dying

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potato early dying (PED), caused by Verticillium dahliae, is a chronic yield-limiting disease of potato (Solanum tuberosum). In this study, we describe the population dynamics of V. dahliae in two potato cultivars with varying responses to PED. We utilized a quantitative real-time PCR (Q-PCR) assay ...

  4. Inheritance and variability of tolerance to Verticillium dahliae Kleb amoung geographically remote F1-F2 hybrids of Gossypium hirsutum L.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    One of the most important problems for cotton breeding in Uzbekistan is development of Verticillium dahliae tolerant varieties. One approach is to utilize ecologically remote intraspecific and interspecific hybridization with local commercial cultivars. To this end, we have conducted genetically b...

  5. Characterization of a Novel Cotton Subtilase Gene GbSBT1 in Response to Extracellular Stimulations and Its Role in Verticillium Resistance.

    PubMed

    Duan, Xingpeng; Zhang, Zhidong; Wang, Jin; Zuo, Kaijing

    2016-01-01

    Verticillium wilt is a disastrous vascular disease in plants caused by Verticillium dahliae. Verticillium pathogens secrete various disease-causing effectors in cotton. This study identified a subtilase gene GbSBT1 from Gossypium babardense and investigated the roles against V. dahliae infection. GbSBT1 gene expression is responsive to V. dahliae defense signals, jasmonic acid, and ethylene treatments. Moreover, the GbSBT1 protein is mainly localized in the cell membrane and moves into the cytoplasm following jasmonic acid and ethylene treatments. Silencing GbSBT1 gene expression through virus-induced GbSBT1 gene silencing reduced the tolerance of Pima-90 (resistant genotype), but not facilitated the infection process of V. dahliae in Coker-312 (sensitive genotype). Moreover, the ectopically expressed GbSBT1 gene enhanced the resistance of Arabidopsis to Fusarium oxysporum and V. dahliae infection and activated the expression levels of defense-related genes. Furthermore, pull-down, yeast two-hybrid assay, and BiFC analysis revealed that GbSBT1 interacts with a prohibitin (PHB)-like protein expressed in V. dahliae pathogens during infection. In summary, GbSBT1 recognizes the effector PHB protein secreted from V. dahliae and is involved in Verticillium-induced resistance in cotton. PMID:27088499

  6. Characterization of a Novel Cotton Subtilase Gene GbSBT1 in Response to Extracellular Stimulations and Its Role in Verticillium Resistance

    PubMed Central

    Duan, Xingpeng; Zhang, Zhidong; Wang, Jin; Zuo, Kaijing

    2016-01-01

    Verticillium wilt is a disastrous vascular disease in plants caused by Verticillium dahliae. Verticillium pathogens secrete various disease-causing effectors in cotton. This study identified a subtilase gene GbSBT1 from Gossypium babardense and investigated the roles against V. dahliae infection. GbSBT1 gene expression is responsive to V. dahliae defense signals, jasmonic acid, and ethylene treatments. Moreover, the GbSBT1 protein is mainly localized in the cell membrane and moves into the cytoplasm following jasmonic acid and ethylene treatments. Silencing GbSBT1 gene expression through virus-induced GbSBT1 gene silencing reduced the tolerance of Pima-90 (resistant genotype), but not facilitated the infection process of V. dahliae in Coker-312 (sensitive genotype). Moreover, the ectopically expressed GbSBT1 gene enhanced the resistance of Arabidopsis to Fusarium oxysporum and V. dahliae infection and activated the expression levels of defense-related genes. Furthermore, pull-down, yeast two-hybrid assay, and BiFC analysis revealed that GbSBT1 interacts with a prohibitin (PHB)-like protein expressed in V. dahliae pathogens during infection. In summary, GbSBT1 recognizes the effector PHB protein secreted from V. dahliae and is involved in Verticillium-induced resistance in cotton. PMID:27088499

  7. The mitogen-activated protein kinase gene, VdHog1, regulates osmotic stress response, microsclerotia formation and virulence in Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungus Verticillium dahliae has gained worldwide notoriety as a destructive plant pathogen, causing vascular wilt diseases on diverse plant species. The fungus produces melanized resting bodies, known as microsclerotia that can survive for 15 years in the soil, and are thus critically important ...

  8. Deep mRNA sequencing reveals stage-specific transcriptome alterations during microsclerotia development in the smoke tree vascular wilt pathogen, Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Verticillium dahliae is a soil-borne fungus that causes vascular wilt diseases in a wide range of plant hosts. V. dahliae produces multicelled, melanized resting bodies, also known as microsclerotia (MS) that can survive for years in the soil. Thus, MS formation marks an important event in the disea...

  9. A Novel and Effective Streptomyces sp. N2 Against Various Phytopathogenic Fungi.

    PubMed

    Xu, Bo; Chen, Wei; Wu, Zhi-ming; Long, Yue; Li, Kun-tai

    2015-11-01

    Phytopathogenic fungi would induce a variety of plant diseases, resulting in a severe reduction of agricultural output. However, the current plant disease control is mainly dependent on the environmentally and healthily hazardous chemical fungicides. Thus, the present work aimed to isolate an effective antagonistic microorganism against various soilborne phytopathogenic fungi. By dual culture with Rhizoctonia solani, a novel Streptomyces specie, Streptomyces sp. N2, was screened out from a total of 167 isolated actinomycetes, which displayed a strong inhibitory effect on R. solani (26.85 ± 1.35 mm of inhibition zone diameter). By means of macroporous resin and silica gel column chromatography coupled with preparative HPLC, an antifungal metabolite (3-methyl-3,5-amino-4-vinyl-2-pyrone, C6H7O2N) was isolated and purified from Streptomyces sp. N2. The bioassay results showed that the purified antifungal metabolite could not only possess a broad-spectrum inhibitory effect on a range of plant pathogenic fungi in vitro (e.g., R. solani, Pyricularia grisea, Fusarium oxysporum f. sp. niveum, F. oxysporum f. sp. vasinfectum, Penicillium italicum, and Colletotrichum gloeosporioides), but also had a significantly effective in vivo biocontrol efficacy on grape fruits anthracnose caused by C. gloeosporioides. Microscopic observation indicated that the antifungal metabolite from Streptomyces sp. N2 would exert its antimicrobial activity by disorganizing the cytoplasmic organelles of phytopathogenic fungi. The above results suggested that Streptomyces sp. N2 was one of promising fungicide for biocontrol of fungal plant diseases, especially due to its broad-spectrum and effective antagonist on various plant pathogens. PMID:26306529

  10. Transcriptome profiling of Gossypium barbadense inoculated with Verticillium dahliae provides a resource for cotton improvement

    PubMed Central

    2013-01-01

    Background Verticillium wilt, caused by the fungal pathogen Verticillium dahliae, is the most severe disease in cotton (Gossypium spp.), causing great lint losses worldwide. Disease management could be achieved in the field if genetically improved, resistant plants were used. However, the interaction between V. dahliae and cotton is a complicated process, and its molecular mechanism remains obscure. To understand better the defense response to this pathogen as a means for obtaining more tolerant cultivars, we monitored the transcriptome profiles of roots from resistant plants of G. barbadense cv. Pima90-53 that were challenged with V. dahliae. Results In all, 46,192 high-quality expressed sequence tags (ESTs) were generated from a full-length cDNA library of G. barbadense. They were clustered and assembled into 23126 unigenes that comprised 2661 contigs and 20465 singletons. Those unigenes were assigned Gene Ontology terms and mapped to 289 KEGG pathways. A total of 3027 unigenes were found to be homologous to known defense-related genes in other plants. They were assigned to the functional classification of plant–pathogen interactions, including disease defenses and signal transduction. The branch of "SA→NPR1→TGA→PR-1→Disease resistance" was first discovered in the interaction of cotton–V. dahliae, indicating that this wilt process includes both biotrophic and necrotrophic stages. In all, 4936 genes coding for putative transcription factors (TF) were identified in our library. The most abundant TF family was the NAC group (527), followed by G2-like (440), MYB (372), BHLH (331), bZIP (271) ERF, C3H, and WRKY. We also analyzed the expression of genes involved in pathogen-associated molecular pattern (PAMP) recognition, the activation of effector-triggered immunity, TFs, and hormone biosynthesis, as well as genes that are pathogenesis-related, or have roles in signaling/regulatory functions and cell wall modification. Their differential expression

  11. Monosubstituted Benzene Derivatives from Fruits of Ficus hirta and Their Antifungal Activity against Phytopathogen Penicillium italicum.

    PubMed

    Wan, Chunpeng; Han, Jianxin; Chen, Chuying; Yao, Liangliang; Chen, Jinyin; Yuan, Tao

    2016-07-20

    Ficus hirta, a widely consumed food by Hakka people, has been reported to show potent antifungal activity against phytopathogen Penicillium italicum. However, there is no report of chemical constituents responsible for the antifungal activity. In the current study, nine monosubstituted benzene derivatives, including three new derivatives (1-3), were isolated from the fruits of F. hirta. The structures of these isolates were elucidated on the basis of the analysis of spectroscopic data (mass spectrometry and nuclear magnetic resonance). All of the isolates were evaluated for antifungal activities against P. italicum. At an equivalent concentration, compound 1 exhibited stronger antifungal activity than that of the ethanol extract of F. hirta fruits. PMID:27381890

  12. Spatial Pattern of Verticillium dahliae Microsclerotia and Cotton Plants with Wilt Symptoms in Commercial Plantations

    PubMed Central

    Yang, Jiarong; Hu, Xiaoping; Xu, Xiangming

    2015-01-01

    Spatial patterns of pathogen inoculum in field soils and the resulting patterns of disease may reflect the underlying mechanisms of pathogen dispersal. This knowledge can be used to design more efficient sampling schemes for assessing diseases. Spatial patterns of Verticillium dahliae microsclerotia were characterized in commercial cotton fields through quadrat and point sampling in 1994 and 2013, respectively. Furthermore, cotton plants with wilt symptoms, caused by V. dahliae, were assessed in six commercial cotton fields in 2013. Soil samples were assayed for the density of microsclerotia (expressed as CFU g-1 of soil) using a wet-sieving plating method and a real-time quantitative PCR method for the 1994 and 2013 study, respectively. The estimated inoculum threshold for causing wilt development on individual plants varied with the three fields: ca. 1.6 CFU g-1 of soil for one field, and 7.2 CFU g-1 of soil for the other two. Both quadrat and point sampling spatial analyses showed that aggregation of V. dahliae inoculum in soils was usually not detected beyond 1.0 m. Similarly, the spatial patterns of wilted cotton plants indicated that spatial aggregation of diseased plants were only observed below the scale of 1.0 m in six commercial cotton plantations. Therefore, spatial aggregation of both V. dahliae inoculum and cotton plants with wilt symptoms is not likely to be detected above the scale of 1.0 m for most commercial cotton plantations. When designing schemes for assessing wilt inoculum and wilt development, this scale needs to be taken into consideration. PMID:26167868

  13. Cloning and characterization of a Verticillium wilt resistance gene from Gossypium barbadense and functional analysis in Arabidopsis thaliana.

    PubMed

    Zhang, Yan; Wang, Xingfen; Yang, Shuo; Chi, Jina; Zhang, Guiyin; Ma, Zhiying

    2011-11-01

    Verticillium wilt causes enormous loss to yield or quality in many crops. In an effort to help controlling this disease through genetic engineering, we first cloned and characterized a Verticillium wilt resistance gene (GbVe) from cotton (Gossypium barbadense) and analyzed its function in Arabidopsis thaliana. Its nucleotide sequence is 3,819 bp long, with an open reading frame of 3,387 bp, and encoding an 1,128-aa protein precursor. Sequence analysis shows that GbVe produces a leucine-rich repeat receptor-like protein. It shares identities of 55.9% and 57.4% with tomato Ve1 and Ve2, respectively. Quantitative real-time PCR indicated that the Ve gene expression pattern was different between the resistant and susceptible cultivars. In the resistant Pima90-53, GbVe was quickly induced and reached to a peak at 2 h after inoculation, two-fold higher than that of control. We localized the GbVe-GFP fusion protein to the cytomembrane in onion epidermal cells. By inserting GbVe into Arabidopsis via Agrobacterium-mediated transformation, T(3) transgenic lines were obtained. Compared with the wild-type control, GbVe-overexpressing plants had greater levels of resistance to V. dahliae. This suggests that GbVe is a useful gene for improving the plant resistance against fungal diseases. PMID:21739145

  14. Systemic responses in a tolerant olive (Olea europaea L.) cultivar upon root colonization by the vascular pathogen Verticillium dahliae

    PubMed Central

    Gómez-Lama Cabanás, Carmen; Schilirò, Elisabetta; Valverde-Corredor, Antonio; Mercado-Blanco, Jesús

    2015-01-01

    Verticillium wilt of olive (VWO) is caused by the vascular pathogen Verticillium dahliae. One of the best VWO management measures is the use of tolerant cultivars; however, our knowledge on VWO tolerance/resistance genetics is very limited. A transcriptomic analysis was conducted to (i) identify systemic defense responses induced/repressed in aerial tissues of the tolerant cultivar Frantoio upon root colonization by V. dahliae, and (ii) determine the expression pattern of selected defense genes in olive cultivars showing differential susceptibility to VWO. Two suppression subtractive hybridization cDNA libraries, enriched in up-regulated (FU) and down-regulated (FD) genes respectively, were generated from “Frantoio” aerial tissues. Results showed that broad systemic transcriptomic changes are taking place during V. dahliae-“Frantoio” interaction. A total of 585 FU and 381 FD unigenes were identified, many of them involved in defense response to (a)biotic stresses. Selected genes were then used to validate libraries and evaluate their temporal expression pattern in “Frantoio.” Four defense genes were analyzed in cultivars Changlot Real (tolerant) and Picual (susceptible). An association between GRAS1 and DRR2 gene expression patterns and susceptibility to VWO was observed, suggesting that these transcripts could be further evaluated as markers of the tolerance level of olive cultivars to V. dahliae. PMID:26441865

  15. Identification of quantitative trait loci for resistance to Verticillium wilt and yield parameters in hop (Humulus lupulus L.).

    PubMed

    Jakse, Jernej; Cerenak, Andreja; Radisek, Sebastjan; Satovic, Zlatko; Luthar, Zlata; Javornik, Branka

    2013-06-01

    Verticillium wilt (VW) can cause substantial yield loss in hop particularly with the outbreaks of the lethal strain of Verticillium albo-atrum. To elucidate genetic control of VW resistance in hop, an F1 mapping population derived from a cross of cultivar Wye Target, with the predicted genetic basis of resistance, and susceptible male breeding line BL2/1 was developed to assess wilting symptoms and to perform QTL mapping. The genetic linkage map, constructed with 203 markers of various types using a pseudo-testcross strategy, formed ten major linkage groups (LG) of the maternal and paternal maps, covering 552.98 and 441.1 cM, respectively. A significant QTL for VW resistance was detected at LOD 7 on a single chromosomal region on LG03 of both parental maps, accounting for 24.2-26.0 % of the phenotypic variance. QTL analysis for alpha-acid content and yield parameters was also performed on this map. QTLs for these traits were also detected and confirmed our previously detected QTLs in a different pedigree and environment. The work provides the basis for exploration of QTL flanking markers for possible use in marker-assisted selection. PMID:23423654

  16. Field resistance to Fusarium oxysporum and Verticillium dahliae in transgenic cotton expressing the plant defensin NaD1

    PubMed Central

    Anderson, Marilyn A.

    2014-01-01

    The plant defensin NaD1, from Nicotiana alata, has potent antifungal activity against a range of filamentous fungi including the two important cotton pathogens, Fusarium oxysporum f. sp. vasinfectum (Fov) and Verticillium dahliae. Transgenic cotton plants expressing NaD1 were produced and plants from three events were selected for further characterization. Homozygous plants were assessed in greenhouse bioassays for resistance to Fov. One line (D1) was selected for field trial testing over three growing seasons in soils naturally infested with Fov and over two seasons in soils naturally infested with V. dahliae. In the field trials with Fov-infested soil, line D1 had 2–3-times the survival rate, a higher tolerance to Fov (higher disease rank), and a 2–4-fold increase in lint yield compared to the non-transgenic Coker control. When transgenic line D1 was planted in V. dahliae-infested soil, plants had a higher tolerance to Verticillium wilt and up to a 2-fold increase in lint yield compared to the non-transgenic Coker control. Line D1 did not exhibit any detrimental agronomic features compared to the parent Coker control when plants were grown in non-diseased soil. This study demonstrated that the expression of NaD1 in transgenic cotton plants can provide substantial resistance to two economically important fungal pathogens. PMID:24502957

  17. Synthesis and antifungal activity of ethers, alcohols, and iodohydrin derivatives of sclareol against phytopathogenic fungi in vitro.

    PubMed

    Ma, Miaofeng; Feng, Jili; Li, Ruoxin; Chen, Shu-Wei; Xu, Hui

    2015-07-15

    This study synthesized 20 sclareol derivatives. The antifungal activities of these derivatives were evaluated in vitro against five phytopathogenic fungi using the mycelium growth rate method. Among all the tested compounds, compound 16 with one iodine atom and three hydroxyl groups displayed higher fungicidal activities against all the tested phytopathogenic fungi than precursor sclareol. Compound 16 also showed more pronounced antifungal activities against Curvularia lunata (IC50=12.09 μg/mL) and Alternaria brassicae (IC50=14.47 μg/mL) than the positive control, a commercial agricultural fungicide thiabendazole. PMID:26013848

  18. Gene silencing and gene expression in phytopathogenic fungi using a plant virus vector

    PubMed Central

    Mascia, Tiziana; Nigro, Franco; Abdallah, Alì; Ferrara, Massimo; De Stradis, Angelo; Faedda, Roberto; Palukaitis, Peter; Gallitelli, Donato

    2014-01-01

    RNA interference (RNAi) is a powerful approach for elucidating gene functions in a variety of organisms, including phytopathogenic fungi. In such fungi, RNAi has been induced by expressing hairpin RNAs delivered through plasmids, sequences integrated in fungal or plant genomes, or by RNAi generated in planta by a plant virus infection. All these approaches have some drawbacks ranging from instability of hairpin constructs in fungal cells to difficulties in preparing and handling transgenic plants to silence homologous sequences in fungi grown on these plants. Here we show that RNAi can be expressed in the phytopathogenic fungus Colletotrichum acutatum (strain C71) by virus-induced gene silencing (VIGS) without a plant intermediate, but by using the direct infection of a recombinant virus vector based on the plant virus, tobacco mosaic virus (TMV). We provide evidence that a wild-type isolate of TMV is able to enter C71 cells grown in liquid medium, replicate, and persist therein. With a similar approach, a recombinant TMV vector carrying a gene for the ectopic expression of the green fluorescent protein (GFP) induced the stable silencing of the GFP in the C. acutatum transformant line 10 expressing GFP derived from C71. The TMV-based vector also enabled C. acutatum to transiently express exogenous GFP up to six subcultures and for at least 2 mo after infection, without the need to develop transformation technology. With these characteristics, we anticipate this approach will find wider application as a tool in functional genomics of filamentous fungi. PMID:24594602

  19. Interkingdom Gene Transfer May Contribute to the Evolution of Phytopathogenicity in Botrytis Cinerea

    PubMed Central

    Zhu, Bo; Zhou, Qing; Xie, Guanlin; Zhang, Guoqing; Zhang, Xiaowei; Wang, Yanli; Sun, Gunchang; Li, Bin; Jin, Gulei

    2012-01-01

    The ascomycete Botrytis cinerea is a phytopathogenic fungus infecting and causing significant yield losses in a number of crops. The genome of B. cinerea has been fully sequenced while the importance of horizontal gene transfer (HGT) to extend the host range in plant pathogenic fungi has been recently appreciated. However, recent data confirm that the B. cinerea fungus shares conserved virulence factors with other fungal plant pathogens with narrow host range. Therefore, interkingdom HGT may contribute to the evolution of phytopathogenicity in B. cinerea. In this study, a stringent genome comparison pipeline was used to identify potential genes that have been obtained by B. cinerea but not by other fungi through interkingdom HGT. This search led to the identification of four genes: a UDP-glucosyltransferase (UGT), a lipoprotein and two alpha/beta hydrolase fold proteins. Phylogenetic analysis of the four genes suggests that B. cinerea acquired UGT from plants and the other 3 genes from bacteria. Based on the known gene functions and literature searching, a correlation between gene acquision and the evolution of pathogenicity in B. cinerea can be postulated. PMID:22346340

  20. A phytopathogenic cysteine peptidase from latex of wild rubber vine Cryptostegia grandiflora.

    PubMed

    Ramos, M V; Souza, D P; Gomes, M T R; Freitas, C D T; Carvalho, C P S; Júnior, P A V R; Salas, C E

    2014-04-01

    A 24,118 Da (MALDI-TOF) cysteine peptidase (EC 3.4.22.16) was purified from the latex extract of Cryptostegia grandiflora by two chromatographic steps involving ion exchange and Reverse-phase HPLC. The purified protein (Cg24-I) exhibits a single band profile following reduced SDS-PAGE and a unique amino terminal sequence, 1VPASIDWREKGTVL14, that is similar to other plant cysteine peptidases. Cg24-I displayed optimal proteolytic activity at pH 8.0 with 25 mM phosphate buffer. The proteolytic activity was inhibited with 0.2 mM E-64 and 1 mM iodoacetamide and was stimulated with 1 mM DTT. Cg24-I fully inhibited spore germination of phytopathogenic fungi Fusarium solani at a dose of 28.1 μg/mL. Its toxicity involves the membrane permeabilization of spores as probed by propidium iodide uptake. These results show that latex peptidases are part of the plant's defensive strategy against phytopathogens and that they most likely act synergistically with other recognized defensive proteins. PMID:24596120

  1. Lipopeptides as main ingredients for inhibition of fungal phytopathogens by Bacillus subtilis/amyloliquefaciens.

    PubMed

    Cawoy, Hélène; Debois, Delphine; Franzil, Laurent; De Pauw, Edwin; Thonart, Philippe; Ongena, Marc

    2015-03-01

    Some isolates of the Bacillus subtilis/amyloliquefaciens species are known for their plant protective activity against fungal phytopathogens. It is notably due to their genetic potential to form an impressive array of antibiotics including non-ribosomal lipopeptides (LPs). In the work presented here, we wanted to gain further insights into the relative role of these LPs in the global antifungal activity of B. subtilis/amyloliquefaciens. To that end, a comparative study was conducted involving multiple strains that were tested against four different phytopathogens. We combined various approaches to further exemplify that secretion of those LPs is a crucial trait in direct pathogen ward off and this can actually be generalized to all members of these species. Our data illustrate that for each LP family, the fungitoxic activity varies in function of the target species and that the production of iturins and fengycins is modulated by the presence of pathogens. Our data on the relative involvement of these LPs in the biocontrol activity and modulation of their production are discussed in the context of natural conditions in the rhizosphere. PMID:25529983

  2. Responses of Cultured Parsley Cells to Elicitors from Phytopathogenic Fungi 1

    PubMed Central

    Kombrink, Erich; Hahlbrock, Klaus

    1986-01-01

    Cultured parsley cells (Petroselinum crispum) responded to treatment with heat-released soluble cell-wall fragments (elicitors) from several different phytopathogenic fungi by forming coumarin derivatives (phytoalexins). This response was preceded in all cases by large but transient increases in the activities of two enzymes of general phenylpropanoid metabolism, phenylalanine ammonia-lyase (PAL) and 4-coumarate:CoA ligase (4CL). The activities of two hydrolytic enzymes, chitinase and 1,3-β-glucanase, also increased strongly in elicitor-treated cells, whereas the activities of three enzymes participating in primary metabolism were affected differently by the elicitor treatment. Glucose-6-phosphate dehydrogenase increased, phosphofructokinase remained almost constant, and pyrophosphate:fructose-6-phosphate phosphotransferase declined sharply in activity. Different amounts of cell-wall preparations from various phytopathogenic fungi were required for maximum elicitor activity. While three oomycetes (Phytophthora spp.) yielded the most active elicitors studied (maximum coumarin accumulation at concentrations of about 10 microgram per milliliter), cell-wall preparations from an ascomycete and three deuteromycetes gave comparable results only at 10 to 100 times higher concentrations. Optimal induction of PAL, 4CL, and chitinase with Phytophthora elicitor required only about 1 microgram per milliliter, whereas 1,3-β-glucanase induction showed a dose dependence similar to that observed for coumarins. The elicitor concentration had pronounced effects not only on the extent, but also on the timing of all induced reactions. Images Fig. 2 Fig. 3 PMID:16664778

  3. Diversity of bacterial endosymbionts associated with Macrosteles leafhoppers vectoring phytopathogenic phytoplasmas.

    PubMed

    Ishii, Yoshiko; Matsuura, Yu; Kakizawa, Shigeyuki; Nikoh, Naruo; Fukatsu, Takema

    2013-08-01

    Here, we investigate the endosymbiotic microbiota of the Macrosteles leafhoppers M. striifrons and M. sexnotatus, known as vectors of phytopathogenic phytoplasmas. PCR, cloning, sequencing, and phylogenetic analyses of bacterial 16S rRNA genes identified two obligate endosymbionts, "Candidatus Sulcia muelleri" and "Candidatus Nasuia deltocephalinicola," and five facultative endosymbionts, Wolbachia, Rickettsia, Burkholderia, Diplorickettsia, and a novel bacterium belonging to the Rickettsiaceae, from the leafhoppers. "Ca. Sulcia muelleri" and "Ca. Nasuia deltocephalinicola" exhibited 100% infection frequencies in the host species and populations and were separately harbored within different bacteriocytes that constituted a pair of coherent bacteriomes in the abdomen of the host insects, as in other deltocephaline leafhoppers. Wolbachia, Rickettsia, Burkholderia, Diplorickettsia, and the novel Rickettsiaceae bacterium exhibited infection frequencies at 7%, 31%, 12%, 0%, and 24% in M. striifrons and at 20%, 0%, 0%, 20%, and 0% in M. sexnotatus, respectively. Although undetected in the above analyses, phytoplasma infections were detected in 16% of M. striifrons and 60% of M. sexnotatus insects by nested PCR of 16S rRNA genes. Two genetically distinct phytoplasmas, namely, "Candidatus Phytoplasma asteris," associated with aster yellows and related plant diseases, and "Candidatus Phytoplasma oryzae," associated with rice yellow dwarf disease, were identified from the leafhoppers. These results highlight strikingly complex endosymbiotic microbiota of the Macrosteles leafhoppers and suggest ecological interactions between the obligate endosymbionts, the facultative endosymbionts, and the phytopathogenic phytoplasmas within the same host insects, which may affect vector competence of the leafhoppers. PMID:23770905

  4. [Expression of cecropin P1 gene increases resistance of Camelina sativa (L.) plants to microbial phytopathogenes].

    PubMed

    Zakharchenko, N S; Kaliaeva, M A; Bur'ianov, Ia I

    2013-05-01

    Transgenic plants of camelina (Camelina sativa (L.) Crantz) with the synthetic gene of antimicrobial peptide cecropin P1 (cecP1) were obtained. Agrobacterium-mediated transformation is performed using the binary vector pGA482::cecP1 by vacuum infiltration of flower buds. The presence of the cecP1 gene in the genome of plants was confirmed by PCR. cecP1 gene expression in transgenic plants was shown by Western blot analysis and by antimicrobial activity of plant extracts against the bacterial phytopathogene Erwinia carotovora. The plants of F0 and F1 generations had the normal phenotype and retained the ability to form viable seeds in self-pollination. cecP1 plants exhibit enhanced resistance to bacterial and fungal phytopathogens: Erwinia carotovora and Fusarium sporotrichioides. The increased sustainability of cecropin P1-expressing plants against salt stress is shown. The possibility of the integration of the cecP1 gene into the overall protective system of plants against biotic and abiotic stresses is discussed. PMID:24159802

  5. Multiple effects of Bacillus amyloliquefaciens volatile compounds: plant growth promotion and growth inhibition of phytopathogens.

    PubMed

    Asari, Shashidar; Matzén, Staffan; Petersen, Mikael Agerlin; Bejai, Sarosh; Meijer, Johan

    2016-06-01

    Biotic interactions through volatile organic compounds (VOC) are frequent in nature. This investigation aimed to study the role of ITALIC! BacillusVOC for the beneficial effects on plants observed as improved growth and pathogen control. Four ITALIC! Bacillus amyloliquefacienssubsp. ITALIC! plantarumstrains were screened for VOC effects on ITALIC! Arabidopsis thalianaCol-0 seedlings and ITALIC! Brassicafungal phytopathogens. VOC from all four ITALIC! Bacillusstrains could promote growth of ITALIC! Arabidopsisplants resulting in increased shoot biomass but the effects were dependent on the growth medium. Dose response studies with UCMB5113 on MS agar with or without root exudates showed significant plant growth promotion even at low levels of bacteria. ITALIC! BacillusVOC antagonized growth of several fungal pathogens ITALIC! in vitro However, the plant growth promotion efficacy and fungal inhibition potency varied among the ITALIC! Bacillusstrains. VOC inhibition of several phytopathogens indicated efficient microbial antagonism supporting high rhizosphere competence of the ITALIC! Bacillusstrains. GC-MS analysis identified several VOC structures where the profiles differed depending on the growth medium. The ability of ITALIC! Bacillusstrains to produce both volatile and soluble compounds for plant growth promotion and disease biocontrol provides examples of rhizosphere microbes as an important ecosystem service with high potential to support sustainable crop production. PMID:27053756

  6. Phytopathogenic bacteria phenotype conversion as a result of their lysogenisation by coliphage P1.

    PubMed

    Faidiuk, I V; Tovkach, E I

    2014-01-01

    A set of lysogenic strains of phytopathogenic bacteria Erwinia "horticola" and Erwinia amylovora associated with woody plants was obtained using bacteriophage P1 Cmc1ts100. The phenotype conversion from Cm(S) to Cm(R) was shown to be connected with introducing of authentic prophage DNA of 94.8 kb as a single-copy plasmid into the cells. Prophage state is unstable: P1 plasmid is spontaneously lost with high frequency by the cells. In lysogenic cells the prophage genes of type III restriction-modification complex EcoP1I are actively expressed. The system formed by E. "horticola" 450 and 60 as well as their lysogenic derivatives and specific bacteriophages provides an opportunity to divide the latter into three groups according to the level of restriction in the course of their interaction with the enzyme EcoP1I. The difference in phage responses to the endonuclease presence in a lysogenized host presumably correlates with the number of enzyme recognition sequences and the adsorption sites availability. After the prophage plasmid DNA curing the characteristic value of phage sensitivity of cells is changed. The lysogenic strains obtained in this work allow for the exploration of EcoP1I restriction-modification gene complex interaction with polyvalent phages able to grow not only on E. coli, but also on such phytopathogens as E. "horticola" and E. amylovora. PMID:25000732

  7. Lipopeptides as main ingredients for inhibition of fungal phytopathogens by Bacillus subtilis/amyloliquefaciens

    PubMed Central

    Cawoy, Hélène; Debois, Delphine; Franzil, Laurent; De Pauw, Edwin; Thonart, Philippe; Ongena, Marc

    2015-01-01

    Some isolates of the Bacillus subtilis/amyloliquefaciens species are known for their plant protective activity against fungal phytopathogens. It is notably due to their genetic potential to form an impressive array of antibiotics including non-ribosomal lipopeptides (LPs). In the work presented here, we wanted to gain further insights into the relative role of these LPs in the global antifungal activity of B. subtilis/amyloliquefaciens. To that end, a comparative study was conducted involving multiple strains that were tested against four different phytopathogens. We combined various approaches to further exemplify that secretion of those LPs is a crucial trait in direct pathogen ward off and this can actually be generalized to all members of these species. Our data illustrate that for each LP family, the fungitoxic activity varies in function of the target species and that the production of iturins and fengycins is modulated by the presence of pathogens. Our data on the relative involvement of these LPs in the biocontrol activity and modulation of their production are discussed in the context of natural conditions in the rhizosphere. PMID:25529983

  8. Effect of anaerobic soil disinfestation and vermicompost on soilborne phytopathogenic agents under tree-crop nursery conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic soil disinfestation (ASD) is a fumigation-independent management strategy for controlling soilborne pathogens. Walnut nurseries currently employ preplant fumigation to control soilborne phytopathogens and weeds, and may be amenable to use ASD instead. We investigated the potential of ASD a...

  9. Antimicrobial activity of essential oils of Thymus vulgaris and Origanum vulgare on phytopathogenic strains isolated from soybean.

    PubMed

    Oliva, M de las M; Carezzano, M E; Giuliano, M; Daghero, J; Zygadlo, J; Bogino, P; Giordano, W; Demo, M

    2015-05-01

    The aim of this work was to study the antimicrobial activity of essential oils obtained from Thymus vulgaris (thyme) and Origanum vulgare (oregano) on phytopathogenic Pseudomonas species isolated from soybean. Strains with characteristics of P. syringae were isolated from leaves of soybean plants with blight symptoms. Ten of these could be identified in Group Ia of LOPAT as P. syringae. Six of these were confirmed as P. syringae using 16S rRNA, indicating the presence of these phytopathogenic bacteria in east and central Argentina. All the phytopathogenic bacteria were re-isolated and identified from the infected plants. MIC values for thyme were 11.5 and 5.7 mg·ml(-1) on P. syringae strains, while oregano showed variability in the inhibitory activity. Both essential oils inhibited all P. syringae strains, with better inhibitory activity than the antibiotic streptomycin. The oils were not bactericidal for all pseudomonads. Both oils contained high carvacrol (29.5% and 19.7%, respectively) and low thymol (1.5%). Natural products obtained from aromatic plants represent potential sources of molecules with biological activity that could be used as new alternatives for the treatment of phytopathogenic bacteria infections. PMID:25359697

  10. Clonal Expansion and Migration of a Highly Virulent, Defoliating Lineage of Verticillium dahliae.

    PubMed

    Milgroom, Michael G; Del Mar Jiménez-Gasco, María; Olivares-García, Concepción; Jiménez-Díaz, Rafael M

    2016-09-01

    We used a population genomics approach to test the hypothesis of clonal expansion of a highly fit genotype in populations of Verticillium dahliae. This fungal pathogen has a broad host range and can be dispersed in contaminated seed or other plant material. It has a highly clonal population structure, with several lineages having nearly worldwide distributions in agricultural crops. Isolates in lineage 1A are highly virulent and cause defoliation in cotton, okra, and olive (denoted 1A/D), whereas those in other lineages cause wilting but not defoliation (ND). We tested whether the highly virulent lineage 1A/D could have spread from the southwestern United States to the Mediterranean basin, as predicted from historical records. We found 187 single-nucleotide polymorphisms (SNPs), determined by genotyping by sequencing, among 91 isolates of lineage 1A/D and 5 isolates in the closely related lineage 1B/ND. Neighbor-joining and maximum-likelihood analyses on the 187 SNPs showed a clear divergence between 1A/D and 1B/ND haplotypes. Data for only 77 SNPs were obtained for all 96 isolates (no missing data); lineages 1A/D and 1B/ND differed by 27 of these 77 SNPs, confirming a clear divergence between the two lineages. No evidence of recombination was detected within or between these two lineages. Phylogenetic and genealogical analyses resulted in five distinct subclades of 1A/D isolates that correlated closely with geographic origins in the Mediterranean basin, consistent with the hypothesis that the D pathotype was introduced at least five times in independent founder events into this region from a relatively diverse source population. The inferred ancestral haplotype was found in two isolates sampled before 1983 from the southwestern United States, which is consistent with historical records that 1A/D originated in North America. The five subclades coalesce with the ancestral haplotype at the same time, consistent with a hypothesis of rapid population expansion in the

  11. Effect of foliar application of antibiotics and gibberellic acid on the rhizosphre microflora of pea, infected with Verticillium dahliae.

    PubMed

    Ramarao, P; Isaac, I

    1980-01-01

    A study was made of the effects of foliar spray of bacitracin, chloramphenicol and gibberellic acid on the rhizosphere microflora of pea seedlings (Pisum sativum L.) infected with Verticillium dahliae. The antibiotics increased fungus and actinomycete counts and reduced the bacterial populations in the rhizosphere. Gibberellic acid at 10 ppm concentration reduced all three groups of microorganisms while at 100 ppm fungi and actinomycetes increased slightly. Invariably the rhizosphere effect was as follows: bacteria leads to fungi leads to actinomycetes. Foliar sprays also affected percentage occurrence of particular genera of fungi in the rhizosphere; for example, Trichoderma spp. were stimulated by all the treatments, the maximum being with 10 ppm gibberellic acid, even though the total fungus count was reduced. The disease severity was markedly reduced by foliar sprays. PMID:7191387

  12. Streptomyces lividans inhibits the proliferation of the fungus Verticillium dahliae on seeds and roots of Arabidopsis thaliana

    PubMed Central

    Meschke, Holger; Schrempf, Hildgund

    2010-01-01

    Summary Verticillium wilt, a vascular disease in more than 200 dicotyledonous plants, is due to the ascomycete fungus Verticillium dahliae. As documented by video‐microscopy, the soil bacterium Streptomyces lividans strongly reduces the germination of V. dahliae conidia, and the subsequent growth of hyphae. Quantification by the use of DNA‐intercalating dyes and Calcofluor‐staining revealed that during prolonged co‐cultivation, bacterial hyphae proliferate to a dense network, provoke a poor development of V. dahliae vegetative hyphae and lead to an enormous reduction of conidia and microsclerotia. Upon individual application to seeds of the model plant Arabidopsis thaliana, either the bacterial spores or the fungal conidia germinate at or within the mucilage, including its volcano‐shaped structures. The extension of hyphae from each individual strain correlates with the reduction of the pectin‐containing mucilage‐layer. Proliferating hyphae then spread to roots of the emerging seedlings. Plants, which arise in the presence of V. dahliae within agar or soil, have damaged root cells, an atrophied stem and root, as well as poorly developed leaves with chlorosis symptoms. In contrast, S. lividans hyphae settle in bunches preferentially at the outer layer near tips and alongside roots. Resulting plants have a healthy appearance including an intact root system. Arabidopsis thaliana seeds, which are co‐inoculated with V. dahliae and S. lividans, have preferentially proliferating bacterial hyphae within the mucilage, and at roots of the outgrowing seedlings. As a result, plants have considerably reduced disease symptoms. As spores of the beneficial S. lividans strain are obtainable in large quantity, its application is highly attractive. PMID:21255341

  13. Anthelmintic Efficacy of Gold Nanoparticles Derived from a Phytopathogenic Fungus, Nigrospora oryzae

    PubMed Central

    Kar, Pradip Kumar; Murmu, Sanatan; Saha, Saswati; Tandon, Veena; Acharya, Krishnendu

    2014-01-01

    Exploring a green chemistry approach, this study brings to the fore, the anthelmintic efficacy of gold nanoparticles, highlighting the plausible usage of myconanotechnology. Gold nanoparticles of ∼6 to ∼18 nm diameter were synthesized by treating the mycelia-free culture filtrate of the phytopathogenic fungus with gold chloride. Their size and morphology were confirmed by UV-Vis spectroscopy, DLS data, AFM and TEM images. The XRD studies reveal a crystalline nature of the nanoparticles, which are in cubic phase. The FTIR spectroscopic studies before and after the formation of nanoparticles show the presence of possible functional groups responsible for the bio-reduction and capping of the synthesized gold nanoparticles. The latter were tested as vermifugal agents against a model cestode Raillietina sp., an intestinal parasite of domestic fowl. Further, ultrastructural and biochemical parameters were used to corroborate the efficacy study. PMID:24465424

  14. "Light-tagged" bacteriophage as a diagnostic tool for the detection of phytopathogens.

    PubMed

    Schofield, David; Bull, Carolee T; Rubio, Isael; Wechter, W Patrick; Westwater, Caroline; Molineux, Ian J

    2013-01-01

    Detection of the phytopathogen Pseudomonas cannabina pv alisalensis, the causal agent of bacterial blight of crucifers is essential for managing this disease. A phage-based diagnostic assay was developed that detects and identifies P. cannabina pv alisalensis from cultures and diseased plant specimens. A recombinant "light-tagged" reporter phage was generated by integrating the luxAB genes into the P. cannabina pv alisalensis phage PBSPCA1 genome. PBSPCA1::luxAB is viable, stable and detects P. cannabina pv alisalensis within minutes and with high sensitivity by conferring a bioluminescent signal. Detection is dependent on cell viability since cells treated with a bactericidal disinfectant are unable to elicit a signal. Importantly, the reporter phage detects P. cannabina pv alisalensis from diseased plant specimens indicating the potential of the diagnostic for disease identification. The reporter phage displays promise for the rapid and specific diagnostic detection of cultivated isolates, and infected plant specimens. PMID:22990589

  15. Antifungal Activity of Narceine Methyl Ester and Narceine Isolated from Corydalis longipes Against Some Phytopathogenic Fungi

    PubMed Central

    Chowdhury, Dibyendu; Maurya, S.; Pandey, M. B.; Pandey, V. B.; Sarma, B. K.

    2005-01-01

    Narceine methyl ester and narceine are potent alkaloids which were isolated from Corydalis longipes were found effective in vitro at very low concentration, i.e., 100~500 ppm against spore germination of some test plant pathogenic fungi (Alternaria solani, A. tagetica, Cercospora abelmoschi, Curvularia maculans, Erysiphe cichoracearum, E. pisi, Fusarium udum, Helminthosporium oryzae, H. penniseti, Ustilago cynodontis). Among the test, phytopathogens the spores of F. udum, C. maculans and H. penniseti were highly sensitive at 200 ppm. However, spores of E. pisi, A. solani and A. tagetica were less sensitive at low concentration followed by other test fungi. Most of the fungi showed zero or nearly zero percent spore germination at 400 and 500 ppm. PMID:24049502

  16. In vitro inhibition activity of essential oils from some Lamiaceae species against phytopathogenic fungi.

    PubMed

    Kumar, Vinod; Mathela, C S; Tewari, A K; Bisht, K S

    2014-09-01

    Natural products have been in focus as alternative, effective and safe materials against the phytopathogens. Investigations show Nepeta oils as effective in controlling the food crops decay. The inhibitory effects of essential oils derived from Nepeta leucophylla, Nepeta ciliaris, Nepeta clarkei and Calamintha umbrosa against five phytopthogenic fungi have been determined. In vitro antifungal activity varied with their constituents and target species. More active being the oils containing oxygenated terpenoids. Helminthosporium maydis was sensitive to the all oils, IC50 values have 43.6-109.3 μg mL(-1). The N. leucophylla oil possessing oxygenated iridoids was more effective against H. maydis (IC50 value of 43.6 μg mL(-1)) while N. ciliaris was more active against Fusarium oxysporum (IC50 value of 219.2 μg mL(-1)). The oils were effective against the spore germination of all the tested plant pathogens. PMID:25175652

  17. Plant lectin-like antibacterial proteins from phytopathogens Pseudomonas syringae and Xanthomonas citri.

    PubMed

    Ghequire, Maarten G K; Li, Wen; Proost, Paul; Loris, Remy; De Mot, René

    2012-08-01

    The genomes of Pseudomonas syringae pv. syringae 642 and Xanthomonas citri pv. malvacearum LMG 761 each carry a putative homologue of the plant lectin-like bacteriocin (llpA) genes previously identified in the rhizosphere isolate Pseudomonas putida BW11M1 and the biocontrol strain Pseudomonas fluorescens Pf-5. The respective purified recombinant proteins, LlpAPss642 and LlpAXcm761 , display genus-specific antibacterial activity across species boundaries. The inhibitory spectrum of the P. syringae bacteriocin overlaps partially with those of the P. putida and P. fluorescens LlpAs. Notably, Xanthomonas axonopodis pv. citri str. 306 secretes a protein identical to LlpAXcm761 . The functional characterization of LlpA proteins from two different phytopathogenic γ-proteobacterial species expands the lectin-like bacteriocin family beyond the Pseudomonas genus and suggests its involvement in competition among closely related plant-associated bacteria with different lifestyles. PMID:23760822

  18. Effects of pH and ionic strength on precipitation of phytopathogenic viruses by polyethylene glycol.

    PubMed

    Pastorek, J; Marcinka, K

    1989-01-01

    The effects of ionic strength of the solution (changed by varying NaCl concentrations or buffer molarity) on the precipitation with polyethylene glycol (PEG) 6000 were studied on phytopathogenic viruses of different morphology: the isometric red clover mottle virus (RCMV), rod-shaped tobacco mosaic virus, flexuous potato virus X (PVX) and bacilliform alfalfa mosaic virus. With increasing NaCl concentration or buffer molarity up to a certain level (0.1 mol/l), the efficiency of PEG precipitation increased. This relationship did not apply to PVX. The effects of pH on PEG precipitation were studied on RCMV. The efficiency of precipitation increased with decreasing difference between pH of the solution and pI of the virus. PMID:2565676

  19. Genome sequence of a novel endornavirus from the phytopathogenic fungus Alternaria brassicicola.

    PubMed

    Shang, Hong-Hong; Zhong, Jie; Zhang, Ru-Jia; Chen, Chuan-Yuan; Gao, Bi-Da; Zhu, Hong-Jian

    2015-07-01

    In an effort to discover new mycoviruses from phytopathogenic fungi, a dsRNA molecule of 10,290 nt, resembling those associated with the viruses belonging to the family Endornaviridae, was isolated from Alternaria brassicicola, one of the causal agents of rapeseed black spot disease. Genome analysis revealed the presence of a single open reading frame coding for a polyprotein of 3400 aa containing conserved viral methyltransferase (MTR), viral RNA helicase 1 (Hel-1), and RNA-dependent RNA polymerase (RdRp) domains. In addition, a cysteine-rich region (CRR) with conserved CXCC motifs, shared among several endornaviruses, was also identified between the MTR and Hel-1 domains. Phylogenetic analysis based on the RdRp sequence strongly suggested that the virus infecting A. brassicicola should be considered a representative of a novel endornavirus species, and this virus was designated as Alternaria brassicicola endornavirus 1 (AbEV1). PMID:25951967

  20. Diversity of Bacterial Endosymbionts Associated with Macrosteles Leafhoppers Vectoring Phytopathogenic Phytoplasmas

    PubMed Central

    Ishii, Yoshiko; Matsuura, Yu; Kakizawa, Shigeyuki; Nikoh, Naruo

    2013-01-01

    Here, we investigate the endosymbiotic microbiota of the Macrosteles leafhoppers M. striifrons and M. sexnotatus, known as vectors of phytopathogenic phytoplasmas. PCR, cloning, sequencing, and phylogenetic analyses of bacterial 16S rRNA genes identified two obligate endosymbionts, “Candidatus Sulcia muelleri” and “Candidatus Nasuia deltocephalinicola,” and five facultative endosymbionts, Wolbachia, Rickettsia, Burkholderia, Diplorickettsia, and a novel bacterium belonging to the Rickettsiaceae, from the leafhoppers. “Ca. Sulcia muelleri” and “Ca. Nasuia deltocephalinicola” exhibited 100% infection frequencies in the host species and populations and were separately harbored within different bacteriocytes that constituted a pair of coherent bacteriomes in the abdomen of the host insects, as in other deltocephaline leafhoppers. Wolbachia, Rickettsia, Burkholderia, Diplorickettsia, and the novel Rickettsiaceae bacterium exhibited infection frequencies at 7%, 31%, 12%, 0%, and 24% in M. striifrons and at 20%, 0%, 0%, 20%, and 0% in M. sexnotatus, respectively. Although undetected in the above analyses, phytoplasma infections were detected in 16% of M. striifrons and 60% of M. sexnotatus insects by nested PCR of 16S rRNA genes. Two genetically distinct phytoplasmas, namely, “Candidatus Phytoplasma asteris,” associated with aster yellows and related plant diseases, and “Candidatus Phytoplasma oryzae,” associated with rice yellow dwarf disease, were identified from the leafhoppers. These results highlight strikingly complex endosymbiotic microbiota of the Macrosteles leafhoppers and suggest ecological interactions between the obligate endosymbionts, the facultative endosymbionts, and the phytopathogenic phytoplasmas within the same host insects, which may affect vector competence of the leafhoppers. PMID:23770905

  1. Effects of acivicin on growth, mycotoxin production and virulence of phytopathogenic fungi.

    PubMed

    Maeda, K; Nakajima, Y; Motoyama, T; Kitou, Y; Kosaki, T; Saito, T; Nishiuchi, T; Kanamaru, K; Osada, H; Kobayashi, T; Kimura, M

    2014-10-01

    Acivicin is an inhibitor of γ-glutamyl transpeptidase and glutamine amidotransferase. When grown on a synthetic minimal agar medium, acivicin strongly inhibited the growth of Magnaporthe oryzae and Alternaria brassicicola, and to a lesser extent, Botrytis cinerea. However, only partial or marginal growth inhibition was observed with regard to Fusarium sporotrichioides and Fusarium graminearum. The growth retardation caused by acivicin was significantly alleviated by cultivating the fungus on a nutrient-rich medium. The inhibition of M. oryzae growth caused by 1 μmol l(-1) of acivicin on minimal agar medium was subdued by the addition of specific single amino acids, including His, a branched-chain amino acid (Leu, Ile or Val), an aromatic amino acid (Trp, Tyr or Phe), Met or Gln, at a concentration of 0·4 mmol l(-1). Trichothecene production by F. graminearum in trichothecene-inducing liquid medium was reduced significantly in the presence of acivicin despite its inability to inhibit growth in the trichothecene-inducing liquid medium. Foliar application of conidia in the presence of acivicin reduced the severity of rice blast disease caused by M. oryzae. These results suggest the usefulness of this modified amino acid natural product to mitigate agricultural problems caused by some phytopathogenic fungi. Significance and impact of the study: Fusarium head blight or scab disease and rice blast, caused by Fusarium graminearum and Magnaporthe oryzae, respectively, are major diseases of cereal crops that cause a significant loss of yield and deterioration in the quality of the grain. The present study investigated the effects of acivicin, a glutamine amino acid analog, on the physiology of various phytopathogenic fungi. Application of acivicin to a fungal culture and conidial suspension reduced mycotoxin production by the wheat scab fungus and the severity of rice blast, respectively. These results suggest the possibility that acivicin may serve as a lead compound to

  2. In vitro photodynamic inactivation of conidia of the phytopathogenic fungus Colletotrichum graminicola with cationic porphyrins.

    PubMed

    Vandresen, Camila Chevonica; Gonçalves, Alan Guilherme; Ducatti, Diogo Ricardo Bazan; Murakami, Fabio Seigi; Noseda, Miguel Daniel; Duarte, Maria Eugenia Rabello; Barreira, Sandra Mara Woranovicz

    2016-05-11

    Photodynamic inactivation (PDI) is an efficient approach for the elimination of a series of microorganisms; however, PDI involving phytopathogenic filamentous fungi is scarce in the literature. In the present study, we have demonstrated the photoinactivating properties of five cationic meso-(1-methyl-4-pyridinio)porphyrins on conidia of the phytopathogen Colletotrichum graminicola. For this purpose, photophysical properties (photostability and (1)O2 singlet production) of the porphyrins under study were first evaluated. PDI assays were then performed with a fluence of 30, 60, 90 and 120 J cm(-2) and varying the porphyrin concentration from 1 to 25 μmol L(-1). Considering the lowest concentration that enabled the best photoinactivation, with the respective lowest effective irradiation time, the meso-(1-methyl-4-pyridinio)porphyrins herein studied could be ranked as follows: triple-charged 4 (1 μmol L(-1) with a fluence of 30 J cm(-2)) > double-charged-trans2 (1 μmol L(-1) with 60 J cm(-2)) > tetra-charged 5 (15 μmol L(-1) with 90 J cm(-2)) > mono-charged 1 (25 μmol L(-1) with 120 J cm(-2)). Double-charged-cis-porphyrin 3 inactivated C. graminicola conidia in the absence of light. Evaluation of the porphyrin binding to the conidia and fluorescence microscopic analysis were also performed, which were in agreement with the PDI results. In conclusion, the cationic porphyrins herein studied were considered efficient photosensitizers to inactivate C. graminicola conidia. The amount and position of positive charges are related to the compounds' amphiphilicity and therefore to their photodynamic activity. PMID:27109559

  3. Structure Analysis Uncovers a Highly Diverse but Structurally Conserved Effector Family in Phytopathogenic Fungi

    PubMed Central

    Gracy, Jérome; Fournier, Elisabeth; Kroj, Thomas; Padilla, André

    2015-01-01

    Phytopathogenic ascomycete fungi possess huge effector repertoires that are dominated by hundreds of sequence-unrelated small secreted proteins. The molecular function of these effectors and the evolutionary mechanisms that generate this tremendous number of singleton genes are largely unknown. To get a deeper understanding of fungal effectors, we determined by NMR spectroscopy the 3-dimensional structures of the Magnaporthe oryzae effectors AVR1-CO39 and AVR-Pia. Despite a lack of sequence similarity, both proteins have very similar 6 β-sandwich structures that are stabilized in both cases by a disulfide bridge between 2 conserved cysteins located in similar positions of the proteins. Structural similarity searches revealed that AvrPiz-t, another effector from M. oryzae, and ToxB, an effector of the wheat tan spot pathogen Pyrenophora tritici-repentis have the same structures suggesting the existence of a family of sequence-unrelated but structurally conserved fungal effectors that we named MAX-effectors (Magnaporthe Avrs and ToxB like). Structure-informed pattern searches strengthened this hypothesis by identifying MAX-effector candidates in a broad range of ascomycete phytopathogens. Strong expansion of the MAX-effector family was detected in M. oryzae and M. grisea where they seem to be particularly important since they account for 5–10% of the effector repertoire and 50% of the cloned avirulence effectors. Expression analysis indicated that the majority of M. oryzae MAX-effectors are expressed specifically during early infection suggesting important functions during biotrophic host colonization. We hypothesize that the scenario observed for MAX-effectors can serve as a paradigm for ascomycete effector diversity and that the enormous number of sequence-unrelated ascomycete effectors may in fact belong to a restricted set of structurally conserved effector families. PMID:26506000

  4. Graphene oxide exhibits broad-spectrum antimicrobial activity against bacterial phytopathogens and fungal conidia by intertwining and membrane perturbation

    NASA Astrophysics Data System (ADS)

    Chen, Juanni; Peng, Hui; Wang, Xiuping; Shao, Feng; Yuan, Zhaodong; Han, Heyou

    2014-01-01

    To understand the interaction mechanism between graphene oxide (GO) and typical phytopathogens, a particular investigation was conducted about the antimicrobial activity of GO against two bacterial pathogens (P. syringae and X. campestris pv. undulosa) and two fungal pathogens (F. graminearum and F. oxysporum). The results showed that GO had a powerful effect on the reproduction of all four pathogens (killed nearly 90% of the bacteria and repressed 80% macroconidia germination along with partial cell swelling and lysis at 500 μg mL-1). A mutual mechanism is proposed in this work that GO intertwinds the bacteria and fungal spores with a wide range of aggregated graphene oxide sheets, resulting in the local perturbation of their cell membrane and inducing the decrease of the bacterial membrane potential and the leakage of electrolytes of fungal spores. It is likely that GO interacts with the pathogens by mechanically wrapping and locally damaging the cell membrane and finally causing cell lysis, which may be one of the major toxicity actions of GO against phytopathogens. The antibacterial mode proposed in this study suggests that the GO may possess antibacterial activity against more multi-resistant bacterial and fungal phytopathogens, and provides useful information about the application of GO in resisting crop diseases.To understand the interaction mechanism between graphene oxide (GO) and typical phytopathogens, a particular investigation was conducted about the antimicrobial activity of GO against two bacterial pathogens (P. syringae and X. campestris pv. undulosa) and two fungal pathogens (F. graminearum and F. oxysporum). The results showed that GO had a powerful effect on the reproduction of all four pathogens (killed nearly 90% of the bacteria and repressed 80% macroconidia germination along with partial cell swelling and lysis at 500 μg mL-1). A mutual mechanism is proposed in this work that GO intertwinds the bacteria and fungal spores with a wide range

  5. Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7.

    PubMed

    Maldonado-González, M Mercedes; Bakker, Peter A H M; Prieto, Pilar; Mercado-Blanco, Jesús

    2015-01-01

    The effective management of Verticillium wilts (VW), diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control VW of olive caused by the highly virulent, defoliating (D) pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V. dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i) olive D and non-defoliating V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii) strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii) strain PICF7 controls VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. A. thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7. PMID:25904904

  6. Arabidopsis thaliana as a tool to identify traits involved in Verticillium dahliae biocontrol by the olive root endophyte Pseudomonas fluorescens PICF7

    PubMed Central

    Maldonado-González, M. Mercedes; Bakker, Peter A. H. M.; Prieto, Pilar; Mercado-Blanco, Jesús

    2015-01-01

    The effective management of Verticillium wilts (VW), diseases affecting many crops and caused by some species of the soil-borne fungus Verticillium, is problematic. The use of microbial antagonists to control these pathologies fits modern sustainable agriculture criteria. Pseudomonas fluorescens PICF7 is an endophytic bacterium isolated from olive roots with demonstrated ability to control VW of olive caused by the highly virulent, defoliating (D) pathotype of Verticillium dahliae Kleb. However, the study of the PICF7-V. dahliae-olive tripartite interaction poses difficulties because of the inherent characteristics of woody, long-living plants. To overcome these problems we explored the use of the model plant Arabidopsis thaliana. Results obtained in this study showed that: (i) olive D and non-defoliating V. dahliae pathotypes produce differential disease severity in A. thaliana plants; (ii) strain PICF7 is able to colonize and persist in the A. thaliana rhizosphere but is not endophytic in Arabidopsis; and (iii) strain PICF7 controls VW in Arabidopsis. Additionally, as previously observed in olive, neither swimming motility nor siderophore production by PICF7 are required for VW control in A. thaliana, whilst cysteine auxotrophy decreased the effectiveness of PICF7. Moreover, when applied to the roots PICF7 controlled Botrytis cinerea infection in the leaves of Arabidopsis, suggesting that this strain is able to induce systemic resistance. A. thaliana is therefore a suitable alternative to olive bioassays to unravel biocontrol traits involved in biological control of V. dahliae by P. fluorescens PICF7. PMID:25904904

  7. An Improved Single-Step Cloning Strategy Simplifies the Agrobacterium tumefaciens-Mediated Transformation (ATMT)-Based Gene-Disruption Method for Verticillium dahliae.

    PubMed

    Wang, Sheng; Xing, Haiying; Hua, Chenlei; Guo, Hui-Shan; Zhang, Jie

    2016-06-01

    The soilborne fungal pathogen Verticillium dahliae infects a broad range of plant species to cause severe diseases. The availability of Verticillium genome sequences has provided opportunities for large-scale investigations of individual gene function in Verticillium strains using Agrobacterium tumefaciens-mediated transformation (ATMT)-based gene-disruption strategies. Traditional ATMT vectors require multiple cloning steps and elaborate characterization procedures to achieve successful gene replacement; thus, these vectors are not suitable for high-throughput ATMT-based gene deletion. Several advancements have been made that either involve simplification of the steps required for gene-deletion vector construction or increase the efficiency of the technique for rapid recombinant characterization. However, an ATMT binary vector that is both simple and efficient is still lacking. Here, we generated a USER-ATMT dual-selection (DS) binary vector, which combines both the advantages of the USER single-step cloning technique and the efficiency of the herpes simplex virus thymidine kinase negative-selection marker. Highly efficient deletion of three different genes in V. dahliae using the USER-ATMT-DS vector enabled verification that this newly-generated vector not only facilitates the cloning process but also simplifies the subsequent identification of fungal homologous recombinants. The results suggest that the USER-ATMT-DS vector is applicable for efficient gene deletion and suitable for large-scale gene deletion in V. dahliae. PMID:26780432

  8. Cytoplasmic- and extracellular-proteome analysis of Diplodia seriata: a phytopathogenic fungus involved in grapevine decline

    PubMed Central

    2010-01-01

    Background The phytopathogenic fungus Diplodia seriata, whose genome remains unsequenced, produces severe infections in fruit trees (fruit blight) and grapevines. In this crop is recognized as one of the most prominent pathogens involved in grapevine trunk disease (or grapevine decline). This pathology can result in the death of adult plants and therefore it produces severe economical losses all around the world. To date no genes or proteins have been characterized in D. seriata that are involved in the pathogenicity process. In an effort to help identify potential gene products associated with pathogenicity and to gain a better understanding of the biology of D. seriata, we initiated a proteome-level study of the fungal mycelia and secretome. Results Intracellular and secreted proteins from D. seriata collected from liquid cultures were separated using two-dimensional gel electrophoresis. About 550 cytoplasmic proteins were reproducibly present in 3 independent extractions, being 53 identified by peptide mass fingerprinting and tandem mass spectrometry. The secretome analysis showed 75 secreted proteins reproducibly present in 3 biological replicates, being 16 identified. Several of the proteins had been previously identified as virulence factors in other fungal strains, although their contribution to pathogenicity in D. seriata remained to be analyzed. When D. seriata was grown in a medium supplemented with carboxymethylcellulose, 3 proteins were up-regulated and 30 down-regulated. Within the up-regulated proteins, two were identified as alcohol dehydrogenase and mitochondrial peroxyrredoxin-1, suggesting that they could play a significant role in the pathogenicity process. As for the 30 down-regulated proteins, 9 were identified being several of them involved in carbohydrate metabolism. Conclusions This study is the first report on proteomics on D. seriata. The proteomic data obtained will be important to understand the pathogenicity process. In fact, several of

  9. Detection of Verticillium wilt of olive trees and downy mildew of opium poppy using hyperspectral and thermal UAV imagery

    NASA Astrophysics Data System (ADS)

    Calderón Madrid, Rocío; Navas Cortés, Juan Antonio; Montes Borrego, Miguel; Landa del Castillo, Blanca Beatriz; Lucena León, Carlos; Jesús Zarco Tejada, Pablo

    2014-05-01

    The present study explored the use of high-resolution thermal, multispectral and hyperspectral imagery as indicators of the infections caused by Verticillium wilt (VW) in olive trees and downy mildew (DM) in opium poppy fields. VW, caused by the soil-borne fungus Verticillium dahliae, and DM, caused by the biotrophic obligate oomycete Peronospora arborescens, are the most economically limiting diseases of olive trees and opium poppy, respectively, worldwide. V. dahliae infects the plant by the roots and colonizes its vascular system, blocking water flow and eventually inducing water stress. P. arborescens colonizes the mesophyll, appearing the first symptoms as small chlorotic leaf lesions, which can evolve to curled and thickened tissues and systemic infections that become deformed and necrotic as the disease develops. The work conducted to detect VW and DM infection consisted on the acquisition of time series of airborne thermal, multispectral and hyperspectral imagery using 2-m and 5-m wingspan electric Unmanned Aerial Vehicles (UAVs) in spring and summer of three consecutive years (2009 to 2011) for VW detection and on three dates in spring of 2009 for DM detection. Two 7-ha commercial olive orchards naturally infected with V. dahliae and two opium poppy field plots artificially infected by P. arborescens were flown. Concurrently to the airborne campaigns, olive orchards and opium poppy fields were assessed "in situ" to assess actual VW severity and DM incidence. Furthermore, field measurements were conducted at leaf and crown level. The field results related to VW detection showed a significant increase in crown temperature (Tc) minus air temperature (Ta) and a decrease in leaf stomatal conductance (G) as VW severity increased. This reduction in G was associated with a significant increase in the Photochemical Reflectance Index (PRI570) and a decrease in chlorophyll fluorescence. DM asymptomatic leaves showed significantly higher NDVI and lower green/red index

  10. Molecular and functional characterization of an endoglucanase in the phytopathogenic fungus Pyrenochaeta lycopersici.

    PubMed

    Valente, Maria Teresa; Infantino, Alessandro; Aragona, Maria

    2011-08-01

    Many fungal plant pathogens secrete an array of cell wall degrading enzymes mainly involved in the pathogenesis. In this work, a cDNA clone encoding an extracellular endo-1,4-β-glucanase (named PlEGL1) from the causal agent of the Corky Root Rot of tomato, Pyrenochaeta lycopersici, was isolated and characterized, in order to understand its putative role in the pathogenesis and its mechanism of action. Multiple alignment of the deduced amino acidic sequence shows a high homology with other endoglucanases from different phytopathogenic fungi and detects a well-defined conserved domain of the Glycosyl Hydrolase family 61 (GH61). In vitro, Plegl1 gene transcription is correlated to a cellulolytic activity of the fungus, regulated, in its turn, by the presence of sugar and/or cellulose in the culture medium. In the infected plants, expression level of Plegl1 is positively correlated to the development of the disease. PlEGL1 was heterologously expressed in Escherichia coli and the recombinant protein was purified and tested for its cellulolytic ability, showing a very weak activity, in agreement with all the endoglucanases belonging to GH61 family. The finding in this paper will provide the basis for further determination of biochemical properties of the PlEGL1 protein and its possible involvement in the host-pathogen interaction. PMID:21544619

  11. Possibilities of the use of vinasses in the control of fungi phytopathogens.

    PubMed

    Santos, M; Diánez, F; de Cara, M; Tello, J C

    2008-12-01

    The purpose of this research was to study the biocide effect of three agroindustrial subproducts, concretely sugar beet, sugar cane and wine vinasse. Results from in vitro testing determined that wine vinasse is what shows a 100% capacity to suppress fungal growth with concentrations between 5% and 7% for Fusarium oxysporum f.sp. melonis race 0 and 1, Sclerotinia sclerotiorum, Pythium aphanidermatum and Phytophthora parasitica and 10-15% for F. oxysporum f.sp. radicis-cucumerinum. On the other hand, sugar cane vinasse produced an increase at high concentrations and sugar beet vinasse showed an approximate 100% suppressor effect on fungal growth for only some of the phytopathogens tested: S. sclerotiorum (15%), P. aphanidermatum (7%), P. parasitica (15%) and F. oxysporum f.sp. radicis-cucumerinum (15%). In the soil samples analyzed none of the three vinasse extracts decreased fusaric microbiota, producing an increase in the three samples tested. This would implicitly convey an improvement in soil quality by producing a potential increase in bacterial and fungal microbiota. PMID:18519163

  12. Differential Response of Extracellular Proteases of Trichoderma Harzianum Against Fungal Phytopathogens.

    PubMed

    Sharma, Vivek; Salwan, Richa; Sharma, Prem N

    2016-09-01

    In the present study, production of extracellular proteases by Trichoderma harzianum was evaluated based on the relative gene expression and spectrophotometric assay. The fungal isolates were grown in Czapek Dox Broth medium supplemented with deactivated mycelium of plant fungal pathogens such as Fusarium oxysporum, Colletotrichum capsici, Gloeocercospora sorghi, and Colletotrichum truncatum. The maximum protease activity was detected after 48 h of incubation against Colletotrichum spp. Similarly in qRT-PCR, the relative gene expression of four proteases varied from 48 to 96 h against host pathogens in a time-independent manner. Among proteases, statistically significant upregulation of asp, asp, and srp was observed against Colletotrichum spp., followed by F. oxysporum. But in the case of pepM22, maximum upregulation was observed against F. oxysporum. The variation in enzyme assay and qRT-PCR of proteases at different time intervals against various fungal phytopathogens could be due to the limitation of using casein as a substrate for all types of proteases or protease-encoding transcripts selected for qRT-PCR, which may not be true representative of total protease activity. PMID:27278806

  13. Screening for Antimicrobial Activity of Wood Rotting Higher Basidiomycetes Mushrooms from Uruguay against Phytopathogens.

    PubMed

    Barneche, Stephanie; Jorcin, Gabriela; Cecchetto, Gianna; Cerdeiras, María Pía; Vázquez, Alvaro; Alborés, Silvana

    2016-01-01

    In this work, the antimicrobial activity of extracts of wood rotting higher Basidiomycetes mushrooms isolated from Eucalyptus plantations in Uruguay was studied using bacterial and fungal phytopathogens as targets. Fifty-one extracts from mycelia and growth broth were prepared from higher Basidiomycetes mushrooms, from which eight extracts (from Ganoderma resinaceum, Laetiporus sulphureus, Dictyopanus pusillus, and Bjerkandera adusta) showed antimicrobial activity against Xanthomonas vesicatoria, Aspergillus oryzae, Penicillium expansum, Botrytis cinerea, and Rhizopus stolonifer as assayed in the qualitative test. The minimum inhibitory concentration (MIC) for those fungal extracts was determined and the results showed that L. sulphureus deserved further study, with low MIC values against X. vesicatoria. The antimicrobial activity of L. sulphureus culture broth extracts grown under different culture conditions was evaluated against X. vesicatoria. From the results of these assays, larger-scale cultures for the production of the compound(s) with antimicrobial activity should be performed using malt extract broth, at pH 5, at 20°C and static culture conditions. PMID:27481160

  14. Proteomic response of the phytopathogen Phyllosticta citricarpa to antimicrobial volatile organic compounds from Saccharomyces cerevisiae.

    PubMed

    Fialho, Mauricio Batista; de Andrade, Alexander; Bonatto, José Matheus Camargo; Salvato, Fernanda; Labate, Carlos Alberto; Pascholati, Sérgio Florentino

    2016-02-01

    Volatile organic compounds (VOCs) released by Saccharomyces cerevisiae inhibit plant pathogens, including the filamentous fungus Phyllosticta citricarpa, causal agent of citrus black spot. VOCs mediate relevant interactions between organisms in nature, and antimicrobial VOCs are promising, environmentally safer fumigants to control phytopathogens. As the mechanisms by which VOCs inhibit microorganisms are not well characterized, we evaluated the proteomic response in P. citricarpa after exposure for 12h to a reconstituted mixture of VOCs (alcohols and esters) originally identified in S. cerevisiae. Total protein was extracted and separated by 2D-PAGE, and differentially expressed proteins were identified by LC-MS/MS. About 600 proteins were detected, of which 29 were downregulated and 11 were upregulated. These proteins are involved in metabolism, genetic information processing, cellular processes, and transport. Enzymes related to energy-generating pathways, particularly glycolysis and the tricarboxylic acid cycle, were the most strongly affected. Thus, the data indicate that antimicrobial VOCs interfere with essential metabolic pathways in P. citricarpa to prevent fungal growth. PMID:26805613

  15. Potential application of Northern Argentine propolis to control some phytopathogenic bacteria.

    PubMed

    Ordóñez, R M; Zampini, I C; Moreno, M I Nieva; Isla, M I

    2011-10-20

    The antimicrobial activity of samples of Northern Argentine propolis (Tucumán, Santiago del Estero and Chaco) against phytopathogenic bacteria was assessed and the most active samples were identified. Minimal inhibitory concentration (MIC) values were determined by agar macrodilution and broth microdilution assays. Strong antibacterial activity was detected against Erwinia carotovora spp carotovora CECT 225, Pseudomonas syringae pvar tomato CECT 126, Pseudomonas corrugata CECT 124 and Xanthomonas campestris pvar vesicatoria CECT 792. The most active propolis extract (Tucumán, T1) was selected to bioguide isolation and identified for antimicrobial compound (2',4'-dihydroxychalcone). The antibacterial chalcone was more active than the propolis ethanolic extract (MIC values of 0.5-1 μg ml(-1) and 9.5-15 μg ml(-1), respectively). Phytotoxicity assays were realized and the propolis extracts did not retard germination of lettuce seeds or the growth of onion roots. Propolis solutions applied as sprays on tomato fruits infected with P. syringae reduced the severity of disease. Application of the Argentine propolis extracts diluted with water may be promising for the management of post harvest diseases of fruits. PMID:21237629

  16. Isolation of bacteria with antifungal activity against the phytopathogenic fungi Stenocarpella maydis and Stenocarpella macrospora.

    PubMed

    Petatán-Sagahón, Iván; Anducho-Reyes, Miguel Angel; Silva-Rojas, Hilda Victoria; Arana-Cuenca, Ainhoa; Tellez-Jurado, Alejandro; Cárdenas-Álvarez, Isabel Oyuki; Mercado-Flores, Yuridia

    2011-01-01

    Stenocarpella maydis and Stenocarpella macrospora are the causal agents of ear rot in corn, which is one of the most destructive diseases in this crop worldwide. These fungi are important mycotoxin producers that cause different pathologies in farmed animals and represent an important risk for humans. In this work, 160 strains were isolated from soil of corn crops of which 10 showed antifungal activity against these phytopathogens, which, were identified as: Bacillus subtilis, Pseudomonas spp., Pseudomonas fluorescens, and Pantoea agglomerans by sequencing of 16S rRNA gene and the phylogenetic analysis. From cultures of each strain, extracellular filtrates were obtained and assayed to determine antifungal activity. The best filtrates were obtained in the stationary phase of B. subtilis cultures that were stable to the temperature and extreme pH values; in addition they did not show a cytotoxicity effect against brine shrimp and inhibited germination of conidia. The bacteria described in this work have the potential to be used in the control of white ear rot disease. PMID:22016606

  17. Trichoderma species mediated differential tolerance against biotic stress of phytopathogens in Cicer arietinum L.

    PubMed

    Saxena, Amrita; Raghuwanshi, Richa; Singh, Harikesh Bahadur

    2015-02-01

    Trichoderma spp. have been reported to aid in imparting biotic as well as abiotic tolerance to plants. However, there are only few reports unfolding the differential ability of separate species of Trichoderma genera generally exploited for their biocontrol potential in this framework. A study was undertaken to evaluate the biocontrol potential of different Trichoderma species namely T. harzianum, T. asperellum, T. koningiopsis, T. longibrachiatum, and T. aureoviride as identified in the group of indigenous isolates from the agricultural soils of Eastern Uttar Pradesh, India. Their biocontrol potential against three major soilborne phytopathogens, i.e., Sclerotium rolfsii, Sclerotinia sclerotiorum, and Colletotrichum capsici was confirmed by dual culture plate technique. Efficient mycoparasitic ability was further assessed in all the isolates in relation to chitinase, β-1,3 glucanase, pectinase, lipase, amylase, and cellulase production while equally consistent results were obtained for their probable phosphate solubilization and indole acetic acid (IAA) production abilities. The selected isolates were further subjected to test their ability to promote plant growth, to reduce disease incidence and to tolerate biotic stress in terms of lignification pattern against S. rolfsii in chickpea plants. Among the identified Trichoderma species, excellent results were observed for T. harzianum and T. koningiopsis indicating better biocontrol potential of these species in the group and thus exhibiting perspective for their commercial exploitation. PMID:25205162

  18. Genome sequence of a novel mitovirus identified in the phytopathogenic fungus Alternaria arborescens.

    PubMed

    Komatsu, Ken; Katayama, Yukie; Omatsu, Tsutomu; Mizutani, Tetsuya; Fukuhara, Toshiyuki; Kodama, Motoichiro; Arie, Tsutomu; Teraoka, Tohru; Moriyama, Hiromitsu

    2016-09-01

    The phytopathogenic fungus Alternaria spp. contains a variety of double-stranded RNA (dsRNA) elements of different sizes. Detailed analysis of next-generation sequencing data obtained using dsRNA purified from Alternaria arborescens, from which we had previously found Alternaria arborescens victorivirus 1, revealed the presence of another mycoviral-like dsRNA of approximately 2.5 kbp in length. When using the fungal mitochondrial genetic code, this dsRNA has a single open reading frame that potentially encodes an RNA-dependent RNA polymerase (RdRp) with significant to sequence similarity to those of viruses of the genus Mitovirus. Moreover, both the 5'- and 3'-untranslated regions have the potential to fold into stable stem-loop structures, which is characteristic of mitoviruses. Pairwise comparisons and phylogenetic analysis of the deduced amino acid sequences of RdRp indicated that the virus we identified in A. arborescens is a distinct member of the genus Mitovirus in the family Narnaviridae, designated as "Alternaria arborescens mitovirus 1" (AaMV1). PMID:27368994

  19. In Vitro Antifungal Activity of Burkholderia gladioli pv. agaricicola against Some Phytopathogenic Fungi

    PubMed Central

    Elshafie, Hazem S.; Camele, Ippolito; Racioppi, Rocco; Scrano, Laura; Iacobellis, Nicola S.; Bufo, Sabino A.

    2012-01-01

    The trend to search novel microbial natural biocides has recently been increasing in order to avoid the environmental pollution from use of synthetic pesticides. Among these novel natural biocides are the bioactive secondary metabolites of Burkholderia gladioli pv. agaricicola (Bga). The aim of this study is to determine antifungal activity of Bga strains against some phytopathogenic fungi. The fungicidal tests were carried out using cultures and cell-free culture filtrates against Botrytis cinerea, Aspergillus flavus, Aspergillus niger, Penicillium digitatum, Penicillium expansum, Sclerotinia sclerotiorum and Phytophthora cactorum. Results demonstrated that all tested strains exert antifungal activity against all studied fungi by producing diffusible metabolites which are correlated with their ability to produce extracellular hydrolytic enzymes. All strains significantly reduced the growth of studied fungi and the bacterial cells were more bioactive than bacterial filtrates. All tested Bulkholderia strains produced volatile organic compounds (VOCs), which inhibited the fungal growth and reduced the growth rate of Fusarium oxysporum and Rhizoctonia solani. GC/MS analysis of VOCs emitted by strain Bga 11096 indicated the presence of a compound that was identified as 1-methyl-4-(1-methylethenyl)-cyclohexene, a liquid hydrocarbon classified as cyclic terpene. This compound could be responsible for the antifungal activity, which is also in agreement with the work of other authors. PMID:23208371

  20. Differences in stability of seed-associated microbial assemblages in response to invasion by phytopathogenic microorganisms

    PubMed Central

    Rezki, Samir; Campion, Claire; Iacomi-Vasilescu, Beatrice; Preveaux, Anne; Toualbia, Youness; Bonneau, Sophie; Briand, Martial; Laurent, Emmanuelle; Hunault, Gilles; Simoneau, Philippe; Jacques, Marie-Agnès

    2016-01-01

    Seeds are involved in the vertical transmission of microorganisms from one plant generation to another and consequently act as reservoirs for the plant microbiota. However, little is known about the structure of seed-associated microbial assemblages and the regulators of assemblage structure. In this work, we have assessed the response of seed-associated microbial assemblages of Raphanus sativus to invading phytopathogenic agents, the bacterial strain Xanthomonas campestris pv. campestris (Xcc) 8004 and the fungal strain Alternaria brassicicola Abra43. According to the indicators of bacterial (16S rRNA gene and gyrB sequences) and fungal (ITS1) diversity employed in this study, seed transmission of the bacterial strain Xcc 8004 did not change the overall composition of resident microbial assemblages. In contrast seed transmission of Abra43 strongly modified the richness and structure of fungal assemblages without affecting bacterial assemblages. The sensitivity of seed-associated fungal assemblage to Abra43 is mostly related to changes in relative abundance of closely related fungal species that belong to the Alternaria genus. Variation in stability of the seed microbiota in response to Xcc and Abra43 invasions could be explained by differences in seed transmission pathways employed by these micro-organisms, which ultimately results in divergence in spatio-temporal colonization of the seed habitat. PMID:27077013

  1. Differences in stability of seed-associated microbial assemblages in response to invasion by phytopathogenic microorganisms.

    PubMed

    Rezki, Samir; Campion, Claire; Iacomi-Vasilescu, Beatrice; Preveaux, Anne; Toualbia, Youness; Bonneau, Sophie; Briand, Martial; Laurent, Emmanuelle; Hunault, Gilles; Simoneau, Philippe; Jacques, Marie-Agnès; Barret, Matthieu

    2016-01-01

    Seeds are involved in the vertical transmission of microorganisms from one plant generation to another and consequently act as reservoirs for the plant microbiota. However, little is known about the structure of seed-associated microbial assemblages and the regulators of assemblage structure. In this work, we have assessed the response of seed-associated microbial assemblages of Raphanus sativus to invading phytopathogenic agents, the bacterial strain Xanthomonas campestris pv. campestris (Xcc) 8004 and the fungal strain Alternaria brassicicola Abra43. According to the indicators of bacterial (16S rRNA gene and gyrB sequences) and fungal (ITS1) diversity employed in this study, seed transmission of the bacterial strain Xcc 8004 did not change the overall composition of resident microbial assemblages. In contrast seed transmission of Abra43 strongly modified the richness and structure of fungal assemblages without affecting bacterial assemblages. The sensitivity of seed-associated fungal assemblage to Abra43 is mostly related to changes in relative abundance of closely related fungal species that belong to the Alternaria genus. Variation in stability of the seed microbiota in response to Xcc and Abra43 invasions could be explained by differences in seed transmission pathways employed by these micro-organisms, which ultimately results in divergence in spatio-temporal colonization of the seed habitat. PMID:27077013

  2. Lactic acid bacteria from fresh fruit and vegetables as biocontrol agents of phytopathogenic bacteria and fungi.

    PubMed

    Trias, Rosalia; Bañeras, Lluís; Montesinos, Emilio; Badosa, Esther

    2008-12-01

    This study evaluated the efficacy of lactic acid bacteria (LAB) isolated from fresh fruits and vegetables as biocontrol agents against the phytopathogenic and spoilage bacteria and fungi, Xanthomonas campestris, Erwinia carotovora, Penicillium expansum, Monilinia laxa, and Botrytis cinerea. The antagonistic activity of 496 LAB strains was tested in vitro and all tested microorganisms except P. expansum were inhibited by at least one isolate. The 496 isolates were also analyzed for the inhibition of P. expansum infection in wounds of Golden Delicious apples. Four strains (TC97, AC318, TM319, and FF441) reduced the fungal rot diameter of the apples by 20%; only Weissella cibaria strain TM128 decreased infection levels by 50%. Cell-free supernatants of selected antagonistic bacteria were studied to determine the nature of the antimicrobial compounds produced. Organic acids were the preferred mediators of inhibition but hydrogen peroxide was also detected when strains BC48, TM128, PM141 and FF441 were tested against E. carotovora. While previous reports of antifungal activity by LAB are scarce, our results support the potential of LAB as biocontrol agents against postharvest rot. PMID:19204894

  3. Synthesis of chitosan based nanoparticles and their in vitro evaluation against phytopathogenic fungi.

    PubMed

    Saharan, Vinod; Mehrotra, Akanksha; Khatik, Rajesh; Rawal, Pokhar; Sharma, S S; Pal, Ajay

    2013-11-01

    The main aim of present study was to prepare chitosan, chitosan-saponin and Cu-chitosan nanoparticles to evaluate their in vitro antifungal activities. Various nanoparticles were prepared using ionic gelation method by interaction of chitosan, sodium tripolyphosphate, saponin and Cu ions. Their particle size, polydispersity index, zeta potential and structures were confirmed by DLS, FTIR, TEM and SEM. The antifungal properties of nanoparticles against phytopathogenic fungi namely Alternaria alternata, Macrophomina phaseolina and Rhizoctonia solani were investigated at various concentrations ranging from 0.001 to 0.1%. Among the various formulations of nanoparticles, Cu-chitosan nanoparticles were found most effective at 0.1% concentration and showed 89.5, 63.0 and 60.1% growth inhibition of A. alternata, M. phaseolina and R. solani, respectively in in vitro model. At the same concentration, Cu-chitosan nanoparticles also showed maximum of 87.4% inhibition rate of spore germination of A. alternata. Chitosan nanoparticles showed the maximum growth inhibitory effects (87.6%) on in vitro mycelial growth of M. phaseolina at 0.1% concentration. From our study it is evident that chitosan based nanoparticles particularly chitosan and Cu-chitosan nanoparticles have tremendous potential for further field screening towards crop protection. PMID:24141067

  4. The effects of some polyamine biosynthetic inhibitors on growth and morphology of phytopathogenic fungi

    NASA Technical Reports Server (NTRS)

    Rajam, M. V.; Galston, A. W.

    1985-01-01

    We have studied the effects of two polyamine biosynthetic inhibitors, alpha-difluoromethylornithine (DFMO) and alpha-difluoromethylarginine (DFMA), and of polyamines (PAs), alone and in combination, on mycelial growth and morphology of four phytopathogenic fungi: Botrytis sp, B. cinerea, Rhizoctonia solani and Monilinia fructicola. The inhibitors were added to a Czapek agar medium to get final concentrations of 0.1, 0.5 and 1.0 mM. DFMO and DFMA, suicide inhibitors of ornithine decarboxylase (ODC) and arginine decarboxylase (ADC) respectively, inhibited mycelial growth strongly; the effect was generally more pronounced with DFMA than with DFMO, but each fungus had its own response pattern. The addition of the PAs putrescine (Put) and spermidine (Spd) to the culture medium resulted in a promotion of growth. In Botrytis sp and Monilinia fructicola exposed to inhibitors plus PAs, mycelial growth was actually increased above control values. Mycelial morphology was altered and cell size dramatically reduced in plates containing inhibitors alone, whereas with PAs alone, or in combination with inhibitors, morphology was normal, but cell length and diameters increased considerably. These results suggest that PAs are essential for growth in fungal mycelia. The inhibition caused by DFMA may be due to its arginase-mediated conversion to DFMO.

  5. Isolation of Bacteria with Antifungal Activity against the Phytopathogenic Fungi Stenocarpella maydis and Stenocarpella macrospora

    PubMed Central

    Petatán-Sagahón, Iván; Anducho-Reyes, Miguel Angel; Silva-Rojas, Hilda Victoria; Arana-Cuenca, Ainhoa; Tellez-Jurado, Alejandro; Cárdenas-Álvarez, Isabel Oyuki; Mercado-Flores, Yuridia

    2011-01-01

    Stenocarpella maydis and Stenocarpella macrospora are the causal agents of ear rot in corn, which is one of the most destructive diseases in this crop worldwide. These fungi are important mycotoxin producers that cause different pathologies in farmed animals and represent an important risk for humans. In this work, 160 strains were isolated from soil of corn crops of which 10 showed antifungal activity against these phytopathogens, which, were identified as: Bacillus subtilis, Pseudomonas spp., Pseudomonas fluorescens, and Pantoea agglomerans by sequencing of 16S rRNA gene and the phylogenetic analysis. From cultures of each strain, extracellular filtrates were obtained and assayed to determine antifungal activity. The best filtrates were obtained in the stationary phase of B. subtilis cultures that were stable to the temperature and extreme pH values; in addition they did not show a cytotoxicity effect against brine shrimp and inhibited germination of conidia. The bacteria described in this work have the potential to be used in the control of white ear rot disease. PMID:22016606

  6. Antifungal screening of endophytic fungi from Ginkgo biloba for discovery of potent anti-phytopathogenic fungicides.

    PubMed

    Xiao, Yu; Li, Hong-Xia; Li, Cong; Wang, Jian-Xin; Li, Jun; Wang, Ming-Hua; Ye, Yong-Hao

    2013-02-01

    Many endophytic fungi have been found to synthesize bioactive compounds to defend host plants against pathogenic organisms. Here we performed anti-fungal bioassay of 80 endophytic fungi isolated from Ginkgo biloba. Fifteen endophytes were active against at least one of the selected fungi, Fusarium graminearum, Sclerotinia sclerotiorum and Phytophthora capsici, using the agar diffusion method. The most bioactive strain CDW7 was identified as Chaetomium globosum by microscopic examination and ITS rRNA gene sequence data. Culture broth of CDW7 diluted 3-fold completely inhibited the mycelial growth and conidia germination of F. graminearum in vitro. Therefore, Fusarium head blight, a common disease in wheat and barley associated with Fusarium spp., was used to test the anti-phytopathogenic activity in vivo. The fermentation broth of CDW7 resulted in a protective efficacy of 54.9% and curative efficacy of 48.8%. Followed by a bioassay-guided approach, 1,2-benzenedicarboxaldehyde-3,4,5-trihydroxy-6-methyl (flavipin) was isolated and demonstrated to significantly inhibit the growth of several plant-pathogenic fungi, especially F. graminearum with an EC(50) value of 0.73 μg mL(-1) comparable to the commonly used fungicide carbendazim, indicating that it could be used as a fungicide or as a lead compound of new fungicides. PMID:23240805

  7. Production of lipopeptides among Bacillus strains showing growth inhibition of phytopathogenic fungi.

    PubMed

    Velho, R V; Medina, L F C; Segalin, J; Brandelli, A

    2011-07-01

    The biological activity and the presence of genes sfp and ituD (surfactin and iturin A) among Bacillus strains isolated from the Amazon basin were determined. Bacillus spp. were tested for hemolytic activity and inhibition of fungal growth by agar plate assays in parallel with PCR for identification of sfp and ituD genes. All strains tested produced surface-active compounds, giving evidence by lysis of erythrocytes and emulsifying activity on mineral oil and soybean oil. These strains of Bacillus caused growth inhibition of several phytopathogenic fungi, including Fusarium spp., Aspergillus spp., and Bipolaris sorokiniana. The presence of genes ituD and sfp was confirmed by PCR and sequence analysis. The only exception was Bacillus sp. P34 that lacks sfp gene. Lipopeptides were isolated from culture supernatants and analyzed by mass spectrometry. Characteristic m/z peaks for surfactin and iturin were observed, and some strains also produced fengycin and bacillomycin. The remarkable antifungal activity showed by the strains could be associated with the co-production of three or more lipopeptide antibiotics. Screening for novel bacteria producing useful biosurfactants or biocontrol agents for agriculture is a topic of greatest importance to eliminate chemical pollutants. PMID:21818610

  8. Genome sequence of a novel victorivirus identified in the phytopathogenic fungus Alternaria arborescens.

    PubMed

    Komatsu, Ken; Katayama, Yukie; Omatsu, Tsutomu; Mizutani, Tetsuya; Fukuhara, Toshiyuki; Kodama, Motoichiro; Arie, Tsutomu; Teraoka, Tohru; Moriyama, Hiromitsu

    2016-06-01

    Strains of the phytopathogenic fungus Alternaria spp. have been found to contain a variety of double-stranded RNA (dsRNA) elements indicative of mycovirus infection. Here, we report the molecular characterization of a novel dsRNA mycovirus, Alternaria arborescens victorivirus 1 (AaVV1), from A. arborescens, the tomato pathotype of A. alternata. Using next-generation sequencing of dsRNA purified from an A. arborescens strain from the United States of America, we found that the AaVV1 genome is 5203 bp in length and contains two open reading frames (ORF1 and 2) that overlap at the tetranucleotide AUGA. Proteins encoded by ORF1 and ORF2 showed significant similarities to the coat protein (CP) and the RNA-dependent RNA polymerase (RdRp), respectively, of dsRNA mycoviruses of the genus Victorivirus. Pairwise comparisons and phylogenetic analysis of the deduced amino acid sequences of both CP and RdRp indicated that AaVV1 is a member of a distinct species of the genus Victorivirus in the family Totiviridae. PMID:26923927

  9. Zoosporicidal activity of polyflavonoid tannin identified in Lannea coromandelica stem bark against phytopathogenic oomycete Aphanomyces cochlioides.

    PubMed

    Islam, Md Tofazzal; Ito, Toshiaki; Sakasai, Mitsuyoshi; Tahara, Satoshi

    2002-11-01

    In a survey of nonhost plant secondary metabolites regulating motility and viability of zoospores of the Aphanomyces cochlioides, we found that stem bark extracts of Lannea coromandelica remarkably inhibited motility of zoospores followed by lysis. Bioassay-guided fractionation and chemical characterization of Lannea extracts by MALDI-TOF-MS revealed that the active constituents were angular type polyflavonoid tannins. Commercial polyflavonoid tannins, Quebracho and Mimosa, also showed identical zoosporicidal activity. Against zoospores, the motility-inhibiting and lytic activities were more pronounced in Lannea extracts (MIC 0.1 microg/mL) than in Quebracho (MIC 0.5 microg/mL) and Mimosa (MIC 0.5 microg/mL). Scanning electron microscopic observation visualized that both Lannea and commercial tannins caused lysis of cell membrane followed by fragmentation of cellular materials. Naturally occurring polyflavonoid tannin merits further study as potential zoospore regulating agent or as lead compound. To the best of our knowledge, this is the first report of zoosporicidal activity of natural polyflavonoid tannins against an oomycete phytopathogen. PMID:12405764

  10. Perturbations in the Primary Metabolism of Tomato and Arabidopsis thaliana Plants Infected with the Soil-Borne Fungus Verticillium dahliae.

    PubMed

    Buhtz, Anja; Witzel, Katja; Strehmel, Nadine; Ziegler, Jörg; Abel, Steffen; Grosch, Rita

    2015-01-01

    The hemibiotrophic soil-borne fungus Verticillium dahliae is a major pathogen of a number of economically important crop species. Here, the metabolic response of both tomato and Arabidopsis thaliana to V. dahliae infection was analysed by first using non-targeted GC-MS profiling. The leaf content of both major cell wall components glucuronic acid and xylose was reduced in the presence of the pathogen in tomato but enhanced in A. thaliana. The leaf content of the two tricarboxylic acid cycle intermediates fumaric acid and succinic acid was increased in the leaf of both species, reflecting a likely higher demand for reducing equivalents required for defence responses. A prominent group of affected compounds was amino acids and based on the targeted analysis in the root, it was shown that the level of 12 and four free amino acids was enhanced by the infection in, respectively, tomato and A. thaliana, with leucine and histidine being represented in both host species. The leaf content of six free amino acids was reduced in the leaf tissue of diseased A. thaliana plants, while that of two free amino acids was raised in the tomato plants. This study emphasizes the role of primary plant metabolites in adaptive responses when the fungus has colonized the plant. PMID:26381754

  11. The G protein β subunit controls virulence and multiple growth- and development-related traits in Verticillium dahliae.

    PubMed

    Tzima, Aliki K; Paplomatas, Epaminondas J; Tsitsigiannis, Dimitrios I; Kang, Seogchan

    2012-04-01

    To gain insight into the role of G protein-mediated signaling in virulence and development of the soilborne, wilt causing fungus Verticillium dahliae, the G protein β subunit gene (named as VGB) was disrupted in tomato race 1 strain of V. dahliae. A resulting mutant strain, 70ΔGb15, displayed drastic reduction in virulence, increased microsclerotia formation and conidiation, and decreased ethylene production compared to the corresponding wild type (wt) strain 70wt-r1. Moreover, 70ΔGb15 exhibited an elongated rather than radial growth pattern on agar media. A transformant of 70ΔGb15 (named as 70ΔGbPKAC1) that carries an extra copy of VdPKAC1, a V. dahliae gene encoding the catalytic subunit of the cAMP-dependent protein kinase A, exhibited wt growth pattern and conidiation, was unable to form microsclerotia, produced high amounts of ethylene, and exhibited virulence between that of 70ΔGb15 and 70wt-r1 on tomato plants. Phenotypical changes observed in 70ΔGb15 and 70ΔGbPKAC1 correlated with transcriptional changes in several genes involved in signaling (MAP kinase VMK1) and development (hydrophobin VDH1 and ACC synthase ACS1) of V. dahliae. Results from the present work suggest a linkage between VGB and VdPKAC1 signaling pathways in regulating virulence, hormone production and development in V. dahliae. PMID:22387367

  12. Isolation and functional analysis of the pathogenicity-related gene VdPR3 from Verticillium dahliae on cotton.

    PubMed

    Zhang, Ya-Lin; Li, Zhi-Fang; Feng, Zi-Li; Feng, Hong-Jie; Zhao, Li-Hong; Shi, Yong-Qiang; Hu, Xiao-Ping; Zhu, He-Qin

    2015-11-01

    The fungal plant pathogen Verticillium dahliae is the causal agent of vascular wilt, a disease that can seriously diminish cotton fiber yield. The pathogenicity mechanism and the identity of the genes that interact with cotton during the infection process still remain unclear. In this study, we investigated the low-pathogenic, non-microsclerotium-producing mutant vdpr3 obtained in a previous study from the screening of a T-DNA insertional library of the highly virulent isolate Vd080; the pathogenicity-related gene (VdPR3) in wild-type strain Vd080 was cloned. Knockout mutants (ΔVdPR3) showed lower mycelium growth and obvious reduction in sporulation ability without microsclerotium formation. An evaluation of carbon utilization in mutants and wild-type isolate Vd080 demonstrated that mutants-lacking VdPR3 exhibited decreased cellulase and amylase activities, which was restored in the complementary mutants (ΔVdPR3-C) to levels similar to those of Vd080. ΔVdPR3 postponed infectious events in cotton and showed a significant reduction in pathogenicity. Reintroduction of a functional VdPR3 copy into ΔVdPR3-C restored the ability to infect cotton plants. These results suggest that VdPR3 is a multifunctional gene involved in growth development, extracellular enzyme activity, and virulence of V. dahliae on cotton. PMID:25652159

  13. The Innate Immune Signaling System as a Regulator of Disease Resistance and Induced Systemic Resistance Activity Against Verticillium dahliae.

    PubMed

    Gkizi, Danai; Lehmann, Silke; L'Haridon, Floriane; Serrano, Mario; Paplomatas, Epaminondas J; Métraux, Jean-Pierre; Tjamos, Sotirios E

    2016-04-01

    In the last decades, the plant innate immune responses against pathogens have been extensively studied, while biocontrol interactions between soilborne fungal pathogens and their hosts have received much less attention. Treatment of Arabidopsis thaliana with the nonpathogenic bacterium Paenibacillus alvei K165 was shown previously to protect against Verticillium dahliae by triggering induced systemic resistance (ISR). In the present study, we evaluated the involvement of the innate immune response in the K165-mediated protection of Arabidopsis against V. dahliae. Tests with Arabidopsis mutants impaired in several regulators of the early steps of the innate immune responses, including fls2, efr-1, bak1-4, mpk3, mpk6, wrky22, and wrky29 showed that FLS2 and WRKY22 have a central role in the K165-triggered ISR, while EFR1, MPK3, and MPK6 are possible susceptibility factors for V. dahliae and bak1 shows a tolerance phenomenon. The resistance induced by strain K165 is dependent on both salicylate and jasmonate-dependent defense pathways, as evidenced by an increased transient accumulation of PR1 and PDF1.2 transcripts in the aerial parts of infected plants treated with strain K165. PMID:26780421

  14. Effects of a Mutant Strain and a Wild Type Strain of Verticillium lecanii on Heterodera glycines Populations in the Greenhouse

    PubMed Central

    Meyer, Susan L. F.; Meyer, Robert J.

    1995-01-01

    A wild type strain ofVerticillium lecanii and a mutant strain with increased tolerance to the fungicide benomyl were evaluated in greenhouse experiments for effects on Heterodera glycines populations. Nematodes were applied at 300 eggs and juveniles per 4,550-cm³ pot (two soybean plants in 4,990 g loamy sand per pot) and at both 300 and 10,000 eggs and juveniles per 1,720-cm³ pot (one soybean plant in 2,060 g sand per pot). With 300 nematodes added per pot, both V. lecanii strains significantly reduced nematode populations in loamy sand (fungus applied at 0.02% dry weight per dry weight loamy sand) and sand (0.006% and 0.06% fungus application rates). The mutant strain applied at 0.002% to sand also significantly reduced cyst numbers. When 10,000 nematodes were added per pot, only the mutant strain at 0.06% significantly decreased population. Various media were tested for isolation of the fungus strains from prills, loamy sand, and sand, but the fungi were recovered from few of the greenhouse pots. PMID:19277306

  15. Perturbations in the Primary Metabolism of Tomato and Arabidopsis thaliana Plants Infected with the Soil-Borne Fungus Verticillium dahliae

    PubMed Central

    Buhtz, Anja; Witzel, Katja; Strehmel, Nadine; Ziegler, Jörg; Abel, Steffen; Grosch, Rita

    2015-01-01

    The hemibiotrophic soil-borne fungus Verticillium dahliae is a major pathogen of a number of economically important crop species. Here, the metabolic response of both tomato and Arabidopsis thaliana to V. dahliae infection was analysed by first using non-targeted GC-MS profiling. The leaf content of both major cell wall components glucuronic acid and xylose was reduced in the presence of the pathogen in tomato but enhanced in A. thaliana. The leaf content of the two tricarboxylic acid cycle intermediates fumaric acid and succinic acid was increased in the leaf of both species, reflecting a likely higher demand for reducing equivalents required for defence responses. A prominent group of affected compounds was amino acids and based on the targeted analysis in the root, it was shown that the level of 12 and four free amino acids was enhanced by the infection in, respectively, tomato and A. thaliana, with leucine and histidine being represented in both host species. The leaf content of six free amino acids was reduced in the leaf tissue of diseased A. thaliana plants, while that of two free amino acids was raised in the tomato plants. This study emphasizes the role of primary plant metabolites in adaptive responses when the fungus has colonized the plant. PMID:26381754

  16. Suppression of the homeobox gene HDTF1 enhances resistance to Verticillium dahliae and Botrytis cinerea in cotton.

    PubMed

    Gao, Wei; Long, Lu; Xu, Li; Lindsey, Keith; Zhang, Xianlong; Zhu, Longfu

    2016-05-01

    Development of pathogen-resistant crops, such as fungus-resistant cotton, has significantly reduced chemical application and improved crop yield and quality. However, the mechanism of resistance to cotton pathogens such as Verticillium dahliae is still poorly understood. In this study, we characterized a cotton gene (HDTF1) that was isolated following transcriptome profiling during the resistance response of cotton to V. dahliae. HDTF1 putatively encodes a homeodomain transcription factor, and its expression was found to be down-regulated in cotton upon inoculation with V. dahliae and Botrytis cinerea. To characterise the involvement of HDTF1 in the response to these pathogens, we used virus-induced gene silencing (VIGS) to generate HDTF1-silenced cotton. VIGS reduction in HDTF1 expression significantly enhanced cotton plant resistance to both pathogens. HDTF1 silencing resulted in activation of jasmonic acid (JA)-mediated signaling and JA accumulation. However, the silenced plants were not altered in the accumulation of salicylic acid (SA) or the expression of marker genes associated with SA signaling. These results suggest that HDTF1 is a negative regulator of the JA pathway, and resistance to V. dahliae and B. cinerea can be engineered by activation of JA signaling. PMID:26407676

  17. Discovery and identification of candidate genes from the chitinase gene family for Verticillium dahliae resistance in cotton

    PubMed Central

    Xu, Jun; Xu, Xiaoyang; Tian, Liangliang; Wang, Guilin; Zhang, Xueying; Wang, Xinyu; Guo, Wangzhen

    2016-01-01

    Verticillium dahliae, a destructive and soil-borne fungal pathogen, causes massive losses in cotton yields. However, the resistance mechanism to V. dahilae in cotton is still poorly understood. Accumulating evidence indicates that chitinases are crucial hydrolytic enzymes, which attack fungal pathogens by catalyzing the fungal cell wall degradation. As a large gene family, to date, the chitinase genes (Chis) have not been systematically analyzed and effectively utilized in cotton. Here, we identified 47, 49, 92, and 116 Chis from four sequenced cotton species, diploid Gossypium raimondii (D5), G. arboreum (A2), tetraploid G. hirsutum acc. TM-1 (AD1), and G. barbadense acc. 3–79 (AD2), respectively. The orthologous genes were not one-to-one correspondence in the diploid and tetraploid cotton species, implying changes in the number of Chis in different cotton species during the evolution of Gossypium. Phylogenetic classification indicated that these Chis could be classified into six groups, with distinguishable structural characteristics. The expression patterns of Chis indicated their various expressions in different organs and tissues, and in the V. dahliae response. Silencing of Chi23, Chi32, or Chi47 in cotton significantly impaired the resistance to V. dahliae, suggesting these genes might act as positive regulators in disease resistance to V. dahliae. PMID:27354165

  18. Manipulating inoculum densities of Verticillium dahliae and Pratylenchus penetrans with green manure amendments and solarization influence potato yield.

    PubMed

    Macguidwin, A E; Knuteson, D L; Connell, T; Bland, W L; Bartelt, K D

    2012-05-01

    We used cover crops with demonstrated efficacy against Verticillium dahliae and Pratylenchus penetrans in combination with the biocidal practice of solarization to determine the importance of targeting both organisms for managing potato early dying, an issue relevant to the search for alternatives to soil fumigation. Two experiments were conducted in commercial fields using a split-plot design with cover crop treatments of rapeseed, marigold, forage pearl millet, sorghum-sudangrass, and corn as the main plot factor and solarization as the subplot factor. Cover crops were grown and solarization applied in year one, followed by potato in year two. The main effect of solarization was significant for reduced inoculum levels of both organisms in year two and increased tuber yields. The main effect of cover crop was also significant with lower population densities of P. penetrans following the marigold and millet treatments and of V. dahliae following rape and sorghum-sudangrass. The cover crop treatments influenced yield in only one of the experiments in the absence of solarization. The combinatorial effect of cover crops and solarization resulted in a wide range of pathogen population densities. Mean soil inoculum levels were negatively related to yield for V. dahliae in experiment 1, and for P. penetrans and the P. penetrans × V. dahliae interaction in both experiments. PMID:22494249

  19. VdThit, a Thiamine Transport Protein, Is Required for Pathogenicity of the Vascular Pathogen Verticillium dahliae.

    PubMed

    Qi, Xiliang; Su, Xiaofeng; Guo, Huiming; Qi, Juncang; Cheng, Hongmei

    2016-07-01

    Verticillium dahliae causes a serious wilt disease of important crops and is difficult to control. Few plasma-membrane transport proteins for nutrient acquisition have been identified for this fungus, and their involvement in the disease process is unknown. Here, a plasma-membrane protein, the V. dahliae thiamine transporter protein VdThit, was characterized functionally by deletion of the VdThit gene in V. dahliae. Disruption strains were viable, but growth and conidial germination and production were reduced and virulence was impaired. Interestingly, by supplementing exogenous thiamine, growth, conidiation, and virulence of the VdΔThit mutants were partially restored. Stress-tolerance assays showed that the VdΔThit mutant strains were markedly more susceptible to oxidative stress and UV damage. High-pressure liquid chromatography-mass spectrometry (HPLC-MS) and gas chromatography-mass spectrometry (GC-MS) analyses showed low levels of pyruvate metabolism intermediates acetoin and acetyl coenzyme A (acetyl-CoA) in the VdΔThit mutant strains, suggesting that pyruvate metabolism was suppressed. Expression analysis of VdThit confirmed the importance of VdThit in vegetative growth, reproduction, and invasive hyphal growth. Furthermore, a green fluorescent protein (GFP)-labeled VdΔThit mutant (VdΔThit-7-GFP) was suppressed in initial infection and root colonization, as viewed with light microscopy. Together, these results showed that VdThit plays an indispensable role in the pathogenicity of V. dahliae. PMID:27089469

  20. Detection and identification of phytopathogenic Xanthomonas strains by amplification of DNA sequences related to the hrp genes of Xanthomonas campestris pv. vesicatoria.

    PubMed Central

    Leite, R P; Minsavage, G V; Bonas, U; Stall, R E

    1994-01-01

    Three pairs of oligonucleotide primers specific for different regions of the hrp gene (hypersensitive reaction and pathogenicity) cluster of Xanthomonas campestris pv. vesicatoria were designed and tested for amplification of DNA isolated from a large number of different bacteria. DNA sequences related to the hrp genes were successfully amplified from X. fragariae and from 28 pathovars of X. campestris. No DNA amplification occurred with genomic DNA from phytopathogenic strains of X. campestris pv. secalis, X. campestris pv. translucens, and X. albilineans or from nonpathogenic opportunistic xanthomonads and phytopathogenic strains of the genera Acidovorax, Agrobacterium, Clavibacter, Erwinia, Pseudomonas, and Xylella. The DNA from those bacteria also failed to hybridize to hrp-specific fragments in Southern blot analysis. DNA fragments amplified with a particular primer pair were of identical size from each of the different phytopathogenic xanthomonads. However, restriction analysis of these fragments by using frequently cutting endonucleases revealed variation in the pattern for these hrp-related fragments amplified from the different Xanthomonas strains. The restriction patterns generated for the different fragments allowed distinction of the strains representing a pathovar or species of phytopathogenic xanthomonads. We believe that DNA amplification with hrp-specific oligonucleotide primers is a highly sensitive and specific method that can be applied for detection and identification of phytopathogenic xanthomonads. Images PMID:8017904

  1. Hypovirulence of the Phytopathogenic Fungus Botryosphaeria dothidea: Association with a Coinfecting Chrysovirus and a Partitivirus

    PubMed Central

    Wang, LiPing; Jiang, JingJing; Wang, YanFen; Hong, Ni; Zhang, Fangpeng

    2014-01-01

    ABSTRACT Botryosphaeria dothidea is an important pathogenic fungus causing fruit rot, leaf and stem ring spots and dieback, stem canker, stem death or stool mortality, and decline of pear trees. Seven double-stranded RNAs (dsRNAs; dsRNAs 1 to 7 with sizes of 3,654, 2,773, 2,597, 2,574, 1,823, 1,623, and 511 bp, respectively) were identified in an isolate of B. dothidea exhibiting attenuated growth and virulence and a sectoring phenotype. Characterization of the dsRNAs revealed that they belong to two dsRNA mycoviruses. The four largest dsRNAs (dsRNAs 1 to 4) are the genomic components of a novel member of the family Chrysoviridae (tentatively designated Botryosphaeria dothidea chrysovirus 1 [BdCV1]), a view supported by the morphology of the virions and phylogenetic analysis of the putative RNA-dependent RNA polymerases (RdRps). Two other dsRNAs (dsRNAs 5 and 6) are the genomic components of a novel member of the family Partitiviridae (tentatively designated Botryosphaeria dothidea partitivirus 1 [BdPV1]), which is placed in a clade distinct from other established partitivirus genera on the basis of the phylogenetic analysis of its RdRp. The smallest dsRNA, dsRNA7, seems to be a noncoding satellite RNA of BdPV1 on the basis of the conservation of its terminal sequences in BdPV1 genomic segments and its cosegregation with BdPV1 after horizontal transmission. This is the first report of a chrysovirus and a partitivirus infecting B. dothidea and of a chrysovirus associated with the hypovirulence of a phytopathogenic fungus. IMPORTANCE Our studies identified and characterized two novel mycoviruses, Botryosphaeria dothidea chrysovirus 1 (BdCV1) and Botryosphaeria dothidea partitivirus 1 (BdPV1), associated with the hypovirulence of an important fungus pathogenic to fruit trees. This is the first report of a chrysovirus and a partitivirus infecting B. dothidea and of a chrysovirus associated with the hypovirulence of a phytopathogenic fungus. BdCV1 appears to be a good

  2. Impact of phytopathogen infection and extreme weather stress on internalization of Salmonella Typhimurium in lettuce.

    PubMed

    Ge, Chongtao; Lee, Cheonghoon; Nangle, Ed; Li, Jianrong; Gardner, David; Kleinhenz, Matthew; Lee, Jiyoung

    2014-01-01

    Internalization of human pathogens, common in many types of fresh produce, is a threat to human health since the internalized pathogens cannot be fully inactivated/removed by washing with water or sanitizers. Given that pathogen internalization can be affected by many environmental factors, this study was conducted to investigate the influence of two types of plant stress on the internalization of Salmonella Typhimurium in iceberg lettuce during pre-harvest. The stresses were: abiotic (water stress induced by extreme weather events) and biotic (phytopathogen infection by lettuce mosaic virus [LMV]). Lettuce with and without LMV infection were purposefully contaminated with green fluorescence protein-labeled S. Typhimurium on the leaf surfaces. Lettuce was also subjected to water stress conditions (drought and storm) which were simulated by irrigating with different amounts of water. The internalized S. Typhimurium in the different parts of the lettuce were quantified by plate count and real-time quantitative PCR and confirmed with a laser scanning confocal microscope. Salmonella internalization occurred under the conditions outlined above; however internalization levels were not significantly affected by water stress alone. In contrast, the extent of culturable S. Typhimurium internalized in the leafy part of the lettuce decreased when infected with LMV under water stress conditions and contaminated with high levels of S. Typhimurium. On the other hand, LMV-infected lettuce showed a significant increase in the levels of culturable bacteria in the roots. In conclusion, internalization was observed under all experimental conditions when the lettuce surface was contaminated with S. Typhimurium. However, the extent of internalization was only affected by water stress when lettuce was infected with LMV. PMID:24220663

  3. Rhizospheric fungi of Panax notoginseng: diversity and antagonism to host phytopathogens

    PubMed Central

    Miao, Cui-Ping; Mi, Qi-Li; Qiao, Xin-Guo; Zheng, You-Kun; Chen, You-Wei; Xu, Li-Hua; Guan, Hui-Lin; Zhao, Li-Xing

    2015-01-01

    Background Rhizospheric fungi play an essential role in the plant–soil ecosystem, affecting plant growth and health. In this study, we evaluated the fungal diversity in the rhizosphere soil of 2-yr-old healthy Panax notoginseng cultivated in Wenshan, China. Methods Culture-independent Illumina MiSeq and culture-dependent techniques, combining molecular and morphological characteristics, were used to analyze the rhizospheric fungal diversity. A diffusion test was used to challenge the phytopathogens of P. notoginseng. Results A total of 16,130 paired-end reads of the nuclear ribosomal internal transcribed spacer 2 were generated and clustered into 860 operational taxonomic units at 97% sequence similarity. All the operational taxonomic units were assigned to five phyla and 79 genera. Zygomycota (46.2%) and Ascomycota (37.8%) were the dominant taxa; Mortierella and unclassified Mortierellales accounted for a large proportion (44.9%) at genus level. The relative abundance of Fusarium and Phoma sequences was high, accounting for 12.9% and 5.5%, respectively. In total, 113 fungal isolates were isolated from rhizosphere soil. They were assigned to five classes, eight orders (except for an Incertae sedis), 26 genera, and 43 species based on morphological characteristics and phylogenetic analysis of the internal transcribed spacer. Fusarium was the most isolated genus with six species (24 isolates, 21.2%). The abundance of Phoma was also relatively high (8.0%). Thirteen isolates displayed antimicrobial activity against at least one test fungus. Conclusion Our results suggest that diverse fungi including potential pathogenic ones exist in the rhizosphere soil of 2-yr-old P. notoginseng and that antagonistic isolates may be useful for biological control of pathogens. PMID:27158233

  4. Leaf-cutting ant fungi produce cell wall degrading pectinase complexes reminiscent of phytopathogenic fungi

    PubMed Central

    2010-01-01

    phytopathogens. PMID:21194476

  5. Methylated Cytokinins from the Phytopathogen Rhodococcus fascians Mimic Plant Hormone Activity1[OPEN

    PubMed Central

    Radhika, Venkatesan; Ueda, Nanae; Tsuboi, Yuuri; Kojima, Mikiko; Kikuchi, Jun; Kudo, Takuji; Sakakibara, Hitoshi

    2015-01-01

    Cytokinins (CKs), a class of phytohormones that regulate plant growth and development, are also synthesized by some phytopathogens to disrupt the hormonal balance and to facilitate niche establishment in their hosts. Rhodococcus fascians harbors the fasciation (fas) locus, an operon encoding several genes homologous to CK biosynthesis and metabolism. This pathogen causes unique leafy gall symptoms reminiscent of CK overproduction; however, bacterial CKs have not been clearly correlated with the severe symptoms, and no virulence-associated unique CKs or analogs have been identified. Here, we report the identification of monomethylated N6-(∆2-isopentenyl)adenine and dimethylated N6-(∆2-isopentenyl)adenine (collectively, methylated cytokinins [MeCKs]) from R. fascians. MeCKs were recognized by a CK receptor and up-regulated type-A ARABIDOPSIS THALIANA RESPONSE REGULATOR genes. Treatment with MeCKs inhibited root growth, a hallmark of CK action, whereas the receptor mutant was insensitive. MeCKs were retained longer in planta than canonical CKs and were poor substrates for a CK oxidase/dehydrogenase, suggesting enhanced biological stability. MeCKs were synthesized by S-adenosyl methionine-dependent methyltransferases (MT1 and MT2) that are present upstream of the fas genes. The best substrate for methylation was isopentenyl diphosphate. MT1 and MT2 catalyzed distinct methylation reactions; only the MT2 product was used by FAS4 to synthesize monomethylated N6-(∆2-isopentenyl)adenine. The MT1 product was dimethylated by MT2 and used as a substrate by FAS4 to produce dimethylated N6-(∆2-isopentenyl)adenine. Chemically synthesized MeCKs were comparable in activity. Our results strongly suggest that MeCKs function as CK mimics and play a role in this plant-pathogen interaction. PMID:26251309

  6. Synthesis and biological evaluation of benzofuroxan derivatives as fungicides against phytopathogenic fungi.

    PubMed

    Wang, Lili; Li, Cong; Zhang, Yingying; Qiao, Chunhua; Ye, Yonghao

    2013-09-11

    Forty-four benzofuroxan derivatives were designed and prepared as antifungal agents. Their structures were characterized by (1)H NMR, (13)C NMR, and HRMS. Their antifungal activities were tested in vitro with four important phytopathogenic fungi, namely, Rhizoctonia solani , Sclerotinia sclerotiorum , Fusarium graminearum and Phytophthora capsici , using the mycelium growth inhibition method. Compound A5 displayed the maximum antifungal activity against F. graminearum (IC50 = 1.1 μg/mL, which is about 2-fold higher than that of the well-known positive control carbendazim (IC50 = 0.5 μg/mL). A14 exhibited high antifungal effect against both S. sclerotiorum and F. graminearum Sehw., with IC50 values of 2.52 and 3.42 μg/mL, respectively. Among 14 benzofuroxan derivatives with substitutions at the R(2) and R(3) positions of the phenyl ring (B series), 7 compounds displayed strong growth inhibition against R. solani (IC50 ≤ 3.0 μg/mL). Analysis of the structure-activity relationship data of these compounds revealed that (1) introduction of an electron-donating amino group to the R(2) position of the phenyl ring favors antifungal activity against R. solani and (2) the presence of a nitro group at the R(4) position and substituent variation at the R(1) position of the phenyl ring can result in good antifungal candidates against F. graminearum Sehw. Overall, the benzofuroxan was discovered as a novel scaffold for the development of fungicides. Significantly, A14 was demonstrated to successfully suppress disease development in S. sclerotiorum infected cole in vivo. PMID:23937418

  7. Methylated Cytokinins from the Phytopathogen Rhodococcus fascians Mimic Plant Hormone Activity.

    PubMed

    Radhika, Venkatesan; Ueda, Nanae; Tsuboi, Yuuri; Kojima, Mikiko; Kikuchi, Jun; Kudo, Takuji; Sakakibara, Hitoshi

    2015-10-01

    Cytokinins (CKs), a class of phytohormones that regulate plant growth and development, are also synthesized by some phytopathogens to disrupt the hormonal balance and to facilitate niche establishment in their hosts. Rhodococcus fascians harbors the fasciation (fas) locus, an operon encoding several genes homologous to CK biosynthesis and metabolism. This pathogen causes unique leafy gall symptoms reminiscent of CK overproduction; however, bacterial CKs have not been clearly correlated with the severe symptoms, and no virulence-associated unique CKs or analogs have been identified. Here, we report the identification of monomethylated N(6)-(∆(2)-isopentenyl)adenine and dimethylated N(6)-(∆(2)-isopentenyl)adenine (collectively, methylated cytokinins [MeCKs]) from R. fascians. MeCKs were recognized by a CK receptor and up-regulated type-A ARABIDOPSIS THALIANA RESPONSE REGULATOR genes. Treatment with MeCKs inhibited root growth, a hallmark of CK action, whereas the receptor mutant was insensitive. MeCKs were retained longer in planta than canonical CKs and were poor substrates for a CK oxidase/dehydrogenase, suggesting enhanced biological stability. MeCKs were synthesized by S-adenosyl methionine-dependent methyltransferases (MT1 and MT2) that are present upstream of the fas genes. The best substrate for methylation was isopentenyl diphosphate. MT1 and MT2 catalyzed distinct methylation reactions; only the MT2 product was used by FAS4 to synthesize monomethylated N(6)-(∆(2)-isopentenyl)adenine. The MT1 product was dimethylated by MT2 and used as a substrate by FAS4 to produce dimethylated N(6)-(∆(2)-isopentenyl)adenine. Chemically synthesized MeCKs were comparable in activity. Our results strongly suggest that MeCKs function as CK mimics and play a role in this plant-pathogen interaction. PMID:26251309

  8. Ag doped hollow TiO2 nanoparticles as an effective green fungicide against Fusarium solani and Venturia inaequalis phytopathogens.

    PubMed

    Boxi, Siddhartha Sankar; Mukherjee, Khushi; Paria, Santanu

    2016-02-26

    Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag-S and disulfide bonds (R-S-S-R) in cellular protein, which leads to cell damage. During photocatalysis generated (•)OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling. PMID:26808118

  9. Ag doped hollow TiO2 nanoparticles as an effective green fungicide against Fusarium solani and Venturia inaequalis phytopathogens

    NASA Astrophysics Data System (ADS)

    Sankar Boxi, Siddhartha; Mukherjee, Khushi; Paria, Santanu

    2016-02-01

    Chemical-based pesticides are widely used in agriculture to protect crops from insect infestation and diseases. However, the excessive use of highly toxic pesticides causes several human health (neurological, tumor, cancer) and environmental problems. Therefore nanoparticle-based green pesticides have become of special importance in recent years. The antifungal activities of pure and Ag doped (solid and hollow) TiO2 nanoparticles are studied against two potent phytopathogens, Fusarium solani (which causes Fusarium wilt disease in potato, tomato, etc) and Venturia inaequalis (which causes apple scab disease) and it is found that hollow nanoparticles are more effective than the other two. The antifungal activities of the nanoparticles were further enhanced against these two phytopathogens under visible light exposure. The fungicidal effect of the nanoparticles depends on different parameters, such as particle concentration and the intensity of visible light. The minimum inhibitory dose of the nanoparticles for V. inaequalis and F. solani are 0.75 and 0.43 mg/plate. The presence of Ag as a dopant helps in the formation of stable Ag-S and disulfide bonds (R-S-S-R) in cellular protein, which leads to cell damage. During photocatalysis generated •OH radicals loosen the cell wall structure and this finally leads to cell death. The mechanisms of the fungicidal effect of nanoparticles against these two phytopathogens are supported by biuret and triphenyl tetrazolium chloride analyses and field emission electron microscopy. Apart from the fungicidal effect, at a very low dose (0.015 mg/plate) the nanoparticles are successful in arresting production of toxic napthoquinone pigment for F. solani which is related to the fungal pathogenecity. The nanoparticles are found to be effective in protecting potatoes affected by F. solani or other fungi from spoiling.

  10. Induced Resistance in Tomato Plants against Verticillium Wilt by the Binuclear Nickel Coordination Complex of the Ligand 2,5-Bis(pyridin-2-yl)-1,3,4-thiadiazole.

    PubMed

    Zine, Hanane; Rifai, Lalla Aicha; Faize, Mohamed; Bentiss, Fouad; Guesmi, Salaheddine; Laachir, Abdelhakim; Smaili, Amal; Makroum, Kacem; Sahibed-Dine, Abdelaziz; Koussa, Tayeb

    2016-04-01

    Verticillium wilt caused by Verticillium dahliae is a major limiting factor for tomato production. The objective of this study was to evaluate the effectiveness of ligand 2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole (L) and its complex bis[μ-2,5-bis(pyridin-2-yl)-1,3,4-thiadiazole-κ(4)N(2),N(3):N(4),N(5)]bis[dihydrato-κO)nickel(II)] as activators of plant defenses in controlling Verticillium wilt. In the greenhouse, they protected tomato plants against V. dahliae when they were applied twice as foliar sprays at 100 μg mL(-1). A synergistic effect was observed between the ligand L and the transition metal Ni, with disease incidence reduced by 38% with L and 57% with Ni2L2. Verticillium wilt foliar symptoms and vascular browning index were reduced by 82% for L and 95% for Ni2L2. This protection ability was associated with the induction of an oxidative burst and the activation of the total phenolic content as well as potentiation of the activity of peroxidase and polyphenol oxidase. These results demonstrated that L and Ni2L2 can be considered as new activators of plant defense responses. PMID:26991972

  11. Hirsutella rhossiliensisand Verticillium chlamydosporium as Biocontrol Agents of the Root-knot Nematode Meloidogyne hapla on Lettuce

    PubMed Central

    Vianene, Nicole M.; Abawi, George S.

    2000-01-01

    Hirsutella rhossiliensis and Verticillium chlamydosporium infected second-stage juveniles (J2) and eggs of Meloidogyne hapla, respectively, in petri dishes and in organic soil in pots planted to lettuce in the greenhouse. In vitro, H. rhossiliensis produced 78 to 124 spores/infected J2 of M. hapla. The number of J2 in roots of lettuce seedlings decreased exponentially with increasing numbers of vegetative colonies of H. rhossiliensis in the soil. At an infestation of 8 M. hapla eggs/cm³ soil, 1.9 colonies of H. rhossiliensis/cm³ soil were needed for a 50% decrease in J2 penetration of lettuce roots. Egg-mass colonization with V. chlamydosporium varied from 16% to 43% when soil was infested with 8 M. hapla eggs and treated with 5,000 or 10,000 chlamydospores of V. chlamydosporium/cm³ soil. This treatment resulted in fewer J2 entering roots of bioassay lettuce seedlings planted in the infested soils after harvesting the first lettuce plants 7 weeks after infestation with M. hapla. Hirsutella rhossiliensis (0 to 4.3 colonies/cm3 soil), V. chlamydosporium (500 to 10,000 chlamydospores/cm3 soil), or their combination, added to organic soils with 8 M. hapla eggs/cm³ soil, generally did not affect lettuce weight, root galling, or egg production of M. hapla. However, when lettuce was replanted in a mix of infested and uninfested soil (1:3 and 1:7, v:v), egg production was lower in soils with V. chlamydosporium than in soils without the fungus. Both fungi have potential to reduce the M. hapla population, but at densities below 8 eggs/cm³ soil. PMID:19270953

  12. Hirsutella rhossiliensisand Verticillium chlamydosporium as Biocontrol Agents of the Root-knot Nematode Meloidogyne hapla on Lettuce.

    PubMed

    Vianene, N M; Abawi, G S

    2000-03-01

    Hirsutella rhossiliensis and Verticillium chlamydosporium infected second-stage juveniles (J2) and eggs of Meloidogyne hapla, respectively, in petri dishes and in organic soil in pots planted to lettuce in the greenhouse. In vitro, H. rhossiliensis produced 78 to 124 spores/infected J2 of M. hapla. The number of J2 in roots of lettuce seedlings decreased exponentially with increasing numbers of vegetative colonies of H. rhossiliensis in the soil. At an infestation of 8 M. hapla eggs/cm(3) soil, 1.9 colonies of H. rhossiliensis/cm(3) soil were needed for a 50% decrease in J2 penetration of lettuce roots. Egg-mass colonization with V. chlamydosporium varied from 16% to 43% when soil was infested with 8 M. hapla eggs and treated with 5,000 or 10,000 chlamydospores of V. chlamydosporium/cm(3) soil. This treatment resulted in fewer J2 entering roots of bioassay lettuce seedlings planted in the infested soils after harvesting the first lettuce plants 7 weeks after infestation with M. hapla. Hirsutella rhossiliensis (0 to 4.3 colonies/cm3 soil), V. chlamydosporium (500 to 10,000 chlamydospores/cm3 soil), or their combination, added to organic soils with 8 M. hapla eggs/cm(3) soil, generally did not affect lettuce weight, root galling, or egg production of M. hapla. However, when lettuce was replanted in a mix of infested and uninfested soil (1:3 and 1:7, v:v), egg production was lower in soils with V. chlamydosporium than in soils without the fungus. Both fungi have potential to reduce the M. hapla population, but at densities below 8 eggs/cm(3) soil. PMID:19270953

  13. Effect of Initial Nematode Population Density on the Interaction of Pratylenchus penetrans and Verticillium dahliae on 'Russet Burbank' Potato.

    PubMed

    Saeed, I A; Macguidwin, A E; Rouse, D I

    1998-03-01

    Four similar growth chamber experiments were conducted to test the hypothesis that the initial population density (Pi) of Pratylenchus penetrans influences the severity of interactive effects of P. penetrans and Verticillium dahliae on shoot growth, photosynthesis, and tuber yield of Russet Burbank potato. In each experiment, three population densities of P. penetrans with and without concomitant inoculation with V. dahliae were compared with nematode-free controls. The three specific Pi of JR penetrans tested varied from experiment to experiment but fell in the ranges 0.8-2.5, 1.8-3.9, 2.1-8.8, and 7.5-32.4 nematodes/cm(3) soil. Inoculum of V. dahliaewas mixed into soil, and the assayed density was 5.4 propagules/gram dry soil. Plants were grown 60 to 80 days in a controlled environment. Plant growth parameters in two experiments indicated significant interactions between P. penetrans and V. dahliae. In the absence of V. dahliae, P. penetrans did not reduce plant growth and tuber yield below that of the nematode-free control or did so only at the highest one or two population densities tested. In the presence of K dahliae, the lowest population density significantly reduced shoot weight and photosynthesis in three and four experiments, respectively. Higher densities had no additional effect on shoot weight and caused additional reductions in photosynthesis in only one experiment. Population densities of 0.8 and 7.5 nematodes/cm(3) soil reduced tuber yield by 51% and 45%, whereas higher densities had no effect or a 15% additional effect, respectively. These data indicate that interactive effects between P. penetrans and V. dahliae on Russet Burbank potato are manifested at P. penetrans population densities less than 1 nematode/cm(3) soil and that the nematode population density must be substantially higher before additional effects are apparent. PMID:19274204

  14. The Thioredoxin GbNRX1 Plays a Crucial Role in Homeostasis of Apoplastic Reactive Oxygen Species in Response to Verticillium dahliae Infection in Cotton.

    PubMed

    Li, Yuan-Bao; Han, Li-Bo; Wang, Hai-Yun; Zhang, Jie; Sun, Shu-Tao; Feng, De-Qin; Yang, Chun-Lin; Sun, Yong-Duo; Zhong, Nai-Qin; Xia, Gui-Xian

    2016-04-01

    Examining the proteins that plants secrete into the apoplast in response to pathogen attack provides crucial information for understanding the molecular mechanisms underlying plant innate immunity. In this study, we analyzed the changes in the root apoplast secretome of the Verticillium wilt-resistant island cotton cv Hai 7124 (Gossypium barbadense) upon infection with Verticillium dahliae Two-dimensional differential gel electrophoresis and matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis identified 68 significantly altered spots, corresponding to 49 different proteins. Gene ontology annotation indicated that most of these proteins function in reactive oxygen species (ROS) metabolism and defense response. Of the ROS-related proteins identified, we further characterized a thioredoxin, GbNRX1, which increased in abundance in response to V. dahliae challenge, finding that GbNRX1 functions in apoplastic ROS scavenging after the ROS burst that occurs upon recognition of V. dahliae Silencing of GbNRX1 resulted in defective dissipation of apoplastic ROS, which led to higher ROS accumulation in protoplasts. As a result, the GbNRX1-silenced plants showed reduced wilt resistance, indicating that the initial defense response in the root apoplast requires the antioxidant activity of GbNRX1. Together, our results demonstrate that apoplastic ROS generation and scavenging occur in tandem in response to pathogen attack; also, the rapid balancing of redox to maintain homeostasis after the ROS burst, which involves GbNRX1, is critical for the apoplastic immune response. PMID:26869704

  15. Colonization process of olive tissues by Verticillium dahliae and its in planta interaction with the biocontrol root endophyte Pseudomonas fluorescens PICF7

    PubMed Central

    Prieto, Pilar; Navarro‐Raya, Carmen; Valverde‐Corredor, Antonio; Amyotte, Stefan G.; Dobinson, Katherine F.; Mercado‐Blanco, Jesús

    2009-01-01

    Summary The colonization process of Olea europaea by the defoliating pathotype of Verticillium dahliae, and the in planta interaction with the endophytic, biocontrol strain Pseudomonas fluorescens PICF7 were determined. Differential fluorescent protein tagging was used for the simultaneous visualization of P. fluorescens PICF7 and V. dahliae in olive tissues. Olive plants were bacterized with PICF7 and then transferred to V. dahliae‐infested soil. Monitoring olive colonization events by V. dahliae and its interaction with PICF7 was conducted using a non‐gnotobiotic system, confocal laser scanner microscopy and tissue vibratoming sections. A yellow fluorescently tagged V. dahliae derivative (VDAT‐36I) was obtained by Agrobacterium tumefaciens‐mediated transformation. Isolate VDAT‐36I quickly colonized olive root surface, successfully invaded root cortex and vascular tissues via macro‐ and micro‐breakages, and progressed to the aerial parts of the plant through xylem vessel cells. Strain PICF7 used root hairs as preferred penetration site, and once established on/in root tissues, hindered pathogen colonization. For the first time using this approach, the entire colonization process of a woody plant by V. dahliae is reported. Early and localized root surface and root endophytic colonization by P. fluorescens PICF7 is needed to impair full progress of verticillium wilt epidemics in olive. PMID:21255281

  16. VdCYC8, Encoding CYC8 Glucose Repression Mediator Protein, Is Required for Microsclerotia Formation and Full Virulence in Verticillium dahliae

    PubMed Central

    Li, Zhi-Fang; Liu, Yi-Jie; Feng, Zi-Li; Feng, Hong-Jie; Klosterman, Steven J.; Zhou, Fang-Fang; Zhao, Li-Hong; Shi, Yong-Qiang; Zhu, He-Qin

    2015-01-01

    Verticillium dahliae is the primary causal agent for Verticillium wilt disease on a diverse array of economically important crops, including cotton. In previous research, we obtained the low-pathogenicity mutant T286 from the T-DNA insertional mutant library of the highly virulent isolate Vd080 derived from cotton. In this study, the target disrupted gene VdCYC8 was identified by TAIL-PCR, encoding a homolog of CYC8 proteins involved in glucose repression. The deletion mutant ΔCYC8 exhibited several developmental deficiencies, including reduced microsclerotia formation, reduced sporulation, and slower growth. Moreover, compared with the wild type strain Vd080, the pathogenicity of strain ΔCYC8 was significantly decreased on cotton seedlings. However, the complementary mutants ΔCYC8-C led to restoration of the wild type phenotype or near wild type levels of virulence on cotton. Interestingly, pathogenicity of the strains was correlated with VdCYC8 gene expression levels in complemented mutants. Gene expression analyses in the wild type strain Vd080, the ΔCYC8-45 strain, and complemented strain ΔCYC8-C26 indicated that VdCYC8 regulates the transcription levels of several genes in V. dahliae that have roles in melanin and production. PMID:26633180

  17. Ectopic expression of a Ve homolog VvVe gene from Vitis vinifera enhances defense response to Verticillium dahliae infection in tobacco.

    PubMed

    Tang, Juan; Lin, Jing; Yang, Yuwen; Chen, Tianzi; Ling, Xitie; Zhang, Baolong; Chang, Youhong

    2016-01-15

    Verticillium wilt is a soil borne disease that can cause devastating losses to the production of many economically important crops. A Ve1 homologous gene responding to Verticillium dahliae infection was identified in Vitis vinifera cv. "HeiFeng" by semi-quantitative reverse transcription polymerase chain reaction and was designated as VvVe. The overexpression of VvVe in transgenic Nicotiana benthamiana plants significantly enhanced the resistance to isolate V991 of V. dahliae when compared with the wild type plants. The expressions of defense-related genes including the salicylic acid regulated gene pathogen-related 1 (PR1) but not PR2, the ethylene- and jasmonic acid-regulated genes ethylene response factor 1 (ERF1) and lipoxygenase (LOX) were significantly increased due to over expression of VvVe. And greater accumulation of active oxygen, callose and phenylalanine-ammonia lyase were observed in the leaves of transgenic VvVe tobacco plants than the wild type when under infection by V. dahliae. Moreover, the hypersensitive response mimicking cell death was exclusively occurred in the transgenic VvVe tobacco plants but not in the wild type. Taken together, the VvVe gene is a Ve1 like gene which involves in the signal cascade of salicylic acid, jasmonate, and ethylene defense pathways and enhances defense response to V. dahliae infection in the transgenic tobacco. PMID:26524501

  18. The Thioredoxin GbNRX1 Plays a Crucial Role in Homeostasis of Apoplastic Reactive Oxygen Species in Response to Verticillium dahliae Infection in Cotton1[OPEN

    PubMed Central

    Zhang, Jie; Sun, Shu-Tao; Feng, De-Qin; Yang, Chun-Lin; Sun, Yong-Duo; Zhong, Nai-Qin

    2016-01-01

    Examining the proteins that plants secrete into the apoplast in response to pathogen attack provides crucial information for understanding the molecular mechanisms underlying plant innate immunity. In this study, we analyzed the changes in the root apoplast secretome of the Verticillium wilt-resistant island cotton cv Hai 7124 (Gossypium barbadense) upon infection with Verticillium dahliae. Two-dimensional differential gel electrophoresis and matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis identified 68 significantly altered spots, corresponding to 49 different proteins. Gene ontology annotation indicated that most of these proteins function in reactive oxygen species (ROS) metabolism and defense response. Of the ROS-related proteins identified, we further characterized a thioredoxin, GbNRX1, which increased in abundance in response to V. dahliae challenge, finding that GbNRX1 functions in apoplastic ROS scavenging after the ROS burst that occurs upon recognition of V. dahliae. Silencing of GbNRX1 resulted in defective dissipation of apoplastic ROS, which led to higher ROS accumulation in protoplasts. As a result, the GbNRX1-silenced plants showed reduced wilt resistance, indicating that the initial defense response in the root apoplast requires the antioxidant activity of GbNRX1. Together, our results demonstrate that apoplastic ROS generation and scavenging occur in tandem in response to pathogen attack; also, the rapid balancing of redox to maintain homeostasis after the ROS burst, which involves GbNRX1, is critical for the apoplastic immune response. PMID:26869704

  19. A single genetic locus in the phytopathogen Pantoea stewartii enables gut colonization and pathogenicity in an insect host.

    PubMed

    Stavrinides, John; No, Alexander; Ochman, Howard

    2010-01-01

    Aphids are typically exposed to a variety of epiphytic and phytopathogenic bacteria, many of which have entomopathogenic potential. Here we describe the interaction between Pantoea stewartii ssp. stewartii DC283 (DC283), an enteric phytopathogen and causal agent of Stewart's wilt, and the pea aphid, Acyrthosiphon pisum. When ingested by aphids, DC283 establishes and aggregates in the crop and gut, preventing honeydew flow and excretion, resulting in aphid death in 72 h. A mutagenesis screen identified a single locus, termed ucp1 (youcannot pass), whose disruption abolishes aphid pathogenicity. Moreover, the expression of ucp1 in Escherichia coli is sufficient to mediate the hindgut aggregation phenotype by this normally avirulent species. Ucp1 is related to six other proteins in the DC283 genome, each having a common N-terminal region and a divergent C-terminus, but only ucp1 has a role in pathogenicity. Based on predicted motifs and secondary structure, Ucp1 is a membrane-bound protein that functions in bacterial adhesion and promotes the formation of aggregates that are lethal to the insect host. These results illustrate that the enteric plant pathogenic bacteria have the capacity to exploit alternative non-plant hosts, and retain genetic determinants for colonizing the gut. PMID:19788413

  20. The two-component system CpxAR is Essential for Virulence in the phytopathogen bacteria Dickeya dadantii EC3937

    PubMed Central

    Bontemps-Gallo, Sébastien; Madec, Edwige; Lacroix, Jean-Marie

    2015-01-01

    The CpxAR two-component system is present in many Proteobacteria. It controls expression of genes required to maintain envelope integrity in response to environmental injury. Consequently, this two-component system was shown to be required for virulence of several zoo-pathogens but it has never been investigated in phyto-pathogens. In this paper, we investigate the role of the CpxAR two-component system in vitro and in vivo in Dickeya dadantii, an enterobacterial phytopathogen that causes soft-rot disease in a large variety of plant species. cpxA null mutant displays a constitutively phosphorylated CpxR phenotype as shown by direct analysis of phosphorylation of CpxR by a Phos-Tag retardation gel approach. Virulence in plants is completely abolished in cpxA or cpxR mutants of D. dadantii. In planta, CpxAR is only activated at an early stage of the infection process as shown by Phos-Tag and gene fusion analyses. To our knowledge, this is the first time that the timing of CpxAR phosphorelay activation has been investigated during the infection process by direct monitoring of response regulator phosphorylation. PMID:25856505

  1. Selection of endophytic fungi from comfrey (Symphytum officinale L.) for in vitro biological control of the phytopathogen Sclerotinia sclerotiorum (Lib.).

    PubMed

    Rocha, Rafaeli; da Luz, Daniela Eleutério; Engels, Cibelle; Pileggi, Sônia Alvim Veiga; de Souza Jaccoud Filho, David; Matiello, Rodrigo Rodrigues; Pileggi, Marcos

    2009-01-01

    Biological control consists of using one organism to attack another that may cause economic damage to crops. Integrated Pest Management (IPM) is a very common strategy. The white mold produced by Sclerotinia sclerotiorum (Lib.) causes considerable damage to bean crops. This fungus is a soil inhabitant, the symptoms of which are characterized by water-soaked lesions covered by a white cottony fungal growth on the soil surface and/or the host plant. Possible biological control agents taken from plants are being investigated as phytopathogen inhibitors. These are endophytic microorganisms that inhabit the intercellular spaces of vegetal tissues and are often responsible for antimicrobial production. The objective of the present study was to select endophytic fungi isolated from comfrey (Symphytum officinale L.) leaves with in vitro antagonist potential against the phytopathogenic fungus S. sclerotiorum. Twelve isolates of endophytic fungi and a pathogenic strain of S. sclerotiorum were used in the challenge method. With the aid of this method, four endophytes with the best antagonistic activity against S. sclerotiorum were selected. Pathogen growth inhibition zones were considered indicative of antibiosis. The percentages of pathogenic mycelia growth were measured both with and without the antagonist, resulting in growth reductions of 46.7% to 50.0% for S. sclerotiorum. These analyses were performed by evaluating the endophytic/pathogenic mycelia growth in mm/day over an eight-day period of antagonistic tests. PMID:24031320

  2. Anti-phytopathogenic activity of sporothriolide, a metabolite from endophyte Nodulisporium sp. A21 in Ginkgo biloba.

    PubMed

    Cao, Ling-Ling; Zhang, Ying-Ying; Liu, Ying-Jie; Yang, Ting-Ting; Zhang, Jin-Long; Zhang, Zheng-Guang; Shen, Li; Liu, Jun-Yan; Ye, Yong-Hao

    2016-05-01

    Phytopathogenic fungi such as Rhizoctonia solani and Sclerotinia sclerotiorum caused multiple plant diseases resulting in severe loss of crop production. Increasing documents endorsed that endophytes are a striking resource pool for numerous metabolites with various bioactivities such as anti-fungal. Here we reported the characterization and anti-phytopathogenic activity of sporothriolide, a metabolite produced by Nodulisporium sp. A21-an endophytic fungus in the leaves of Ginkgo biloba. Among the total twenty-five endophytic fungi isolated from the healthy leaves of G. biloba, the fermentation broth (FB) of the strain A21 was found potently inhibitory activity against R. solani and S. sclerotiorum using mycelia growth inhibition method. A21 was then identified as Nodulisporium sp., the asexual stage of Hypoxylon sp., by microscopic examination and ITS rDNA sequence data comparison. Under the bioassay-guided fractionation, sporothriolide was isolated from the petroleum ether extract of the FB of A21, whose structure was established by integrated interpretation of HR-ESI-MS and (1)H- and (13)C-NMR. Furthermore, the crystal structure of sporothriolide was first reported. In addition, sporothriolide was validated to be potently antifungal against R. solani, S. sclerotiorum and inhibit conidium germination of Magnaporthe oryzae in vitro and in vivo, indicating that it could be used as a lead compound for new fungicide development. PMID:27017876

  3. Selection of endophytic fungi from comfrey (Symphytum officinale L.) for in vitro biological control of the phytopathogen Sclerotinia sclerotiorum (Lib.)

    PubMed Central

    Rocha, Rafaeli; da Luz, Daniela Eleutério; Engels, Cibelle; Pileggi, Sônia Alvim Veiga; de Souza Jaccoud Filho, David; Matiello, Rodrigo Rodrigues; Pileggi, Marcos

    2009-01-01

    Biological control consists of using one organism to attack another that may cause economic damage to crops. Integrated Pest Management (IPM) is a very common strategy. The white mold produced by Sclerotinia sclerotiorum (Lib.) causes considerable damage to bean crops. This fungus is a soil inhabitant, the symptoms of which are characterized by water-soaked lesions covered by a white cottony fungal growth on the soil surface and/or the host plant. Possible biological control agents taken from plants are being investigated as phytopathogen inhibitors. These are endophytic microorganisms that inhabit the intercellular spaces of vegetal tissues and are often responsible for antimicrobial production. The objective of the present study was to select endophytic fungi isolated from comfrey (Symphytum officinale L.) leaves with in vitro antagonist potential against the phytopathogenic fungus S. sclerotiorum. Twelve isolates of endophytic fungi and a pathogenic strain of S. sclerotiorum were used in the challenge method. With the aid of this method, four endophytes with the best antagonistic activity against S. sclerotiorum were selected. Pathogen growth inhibition zones were considered indicative of antibiosis. The percentages of pathogenic mycelia growth were measured both with and without the antagonist, resulting in growth reductions of 46.7% to 50.0% for S. sclerotiorum. These analyses were performed by evaluating the endophytic/pathogenic mycelia growth in mm/day over an eight-day period of antagonistic tests. PMID:24031320

  4. Identification and Characterization of Integron-Mediated Antibiotic Resistance in the Phytopathogen Xanthomonas oryzae pv. oryzae

    PubMed Central

    Zhou, Ming-guo

    2013-01-01

    integron in a phytopathogenic bacteria. PMID:23437082

  5. Vibrio rhizosphaerae sp. nov., a red-pigmented bacterium that antagonizes phytopathogenic bacteria.

    PubMed

    Kumar, N Ramesh; Nair, Sudha

    2007-10-01

    Two novel red-pigmented Vibrio strains, MSSRF3(T) and MSSRF10, with antibacterial activity against phytopathogens were isolated from the rhizosphere region of mangrove-associated wild rice (Porteresia coarctata Tateoka), in Pichavaram, India. The cells were Gram-negative, facultatively anaerobic and rod-shaped and were motile by means of single polar flagella. The two strains were catalase-positive and oxidase-negative, and were able to grow in 0.1-10 % NaCl (with optimum growth in 2 % NaCl) and at temperatures of 20-42 degrees C (optimum growth at 25-30 degrees C). Both strains produced acid and gas from D-glucose under anaerobic conditions and utilized a wide range of compounds as sole carbon and energy sources. The DNA G+C contents determined were 51.3 mol% for strain MSSRF3(T) and 51.0 mol% for strain MSSRF10. Phylogenetic analysis based on 16S rRNA, rpoA, recA and pyrH gene sequences showed that strains MSSRF3(T) and MSSRF10 belong to the genus Vibrio and are very closely related to Vibrio ruber JCM 11486(T), with which they share 98.3-98.5 % (16S rRNA), 98.3-99.7 % (rpoA), 90.2-99.8 % (recA) and 91.3-99.4 % (pyrH) gene sequence similarities, respectively. Levels of DNA-DNA relatedness were 44 % between strains MSSRF3(T) and MSSRF10, 80 % between strain MSSRF10 and V. ruber JCM 11486(T) and 45 % between strain MSSRF3(T) and V. ruber JCM 11486(T). Strain MSSRF3(T) was phenotypically similar to V. ruber JCM 11486(T). However, the inability to reduce nitrate to nitrite, the ability to grow in 0.1 % NaCl and the presence of caseinase were characteristics that allowed differentiation between V. ruber JCM 11486(T) and strain MSSRF3(T). In addition, strain MSSRF3(T) could be differentiated from strain MSSRF10 and its closest relative V. ruber JCM 11486(T) with respect to its genomic fingerprinting analysis (random amplified polymorphic DNA, GTG5, BOX, PCR-restriction fragment length polymorphism and ribotyping). Therefore, based on phenotypic, genotypic, phylogenetic

  6. Genes acquired by horizontal transfer are potentially involved in the evolution of phytopathogenicity in Moniliophthora perniciosa and Moniliophthora roreri, two of the major pathogens of cacao

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Moniliophthora perniciosa and Moniliophthora roreri are phytopathogenic basidiomycete species that infect cacao and cause the two main diseases in this crop: “Witches’ Broom” and “Frosty Pod”, respectively. The ability of species from this genus (Moniliophthora) to cause disease is exceptional in th...

  7. Study on interaction between root-knot nematode Meloidogyne javanica and wilt fungus Verticillium dahliae on olive seedlings in greenhouse.

    PubMed

    Saeedizadeh, A; Kheiri, A; Okhovat, M; Hoseininejad, A

    2003-01-01

    Verticillium dahliae has been reported as a limiting factor in cotton, olive, potato and tomato fields from several countries in the world. Root-knot nematodes Meloidogyne javanica causes considerable damage to olive groves in olive growing areas. Since the presence of these two pathogens in olive trees and seedlings were confirmed in Golestan Province, this study was proposed to find the mode of their action and interaction with olive seedlings in greenhouse. The non-defoliant strain of the fungus (SS-4) was isolated from olive groves showing symptom in Golestan Province. M. javanica was also recovered from the infested olive seedlings. After species identification, it was reared on tomato seedlings var. Rutgers. The larvae were used as a source of inoculum. Conidia and microsclerotia of V. dahliae were used as a source of inoculum for pathogenesis in this study. Stem cuttings of olive cultivar Zard were transplanted in different sets of pots containing 720 ml. of sterilized loamy soil and sandy soil. Experiment was conducted in Completely Randomized Design with 6 treatments and 8 replicates including control, nematode alone, fungus alone, nematode and fungus simultaneously, nematode and fungus concomitantly, fungus two weeks prior to nematode, nematode and fungus concomitantly, nematode two weeks prior to fungus. Pots were inoculated with 1500 larvae of nematodes and 7200 microsclerotia of V. dahliae. Experiment was terminated after 9 months and following parameters were determined i.e. fresh weight of roots, number of galls and females, per root system and discoloration of leaf and root tissues. Presence of nematode prior to fungus caused reduction in colonization of fungus in the roots and the stems and vis presence of fungus prior to nematode caused reduction in number of galls produced by nematode. Sever symptom on aerial parts of plant was observed when both pathogens were inoculated simultaneously. However fresh weight of roots was reduced in all treatments

  8. Disease Progress Based on Effects of Verticillium dahliae and Pratylenchus penetrans on Gas Exchange in Russet Burbank Potato.

    PubMed

    Saeed, I A; Macguidwin, A E; Rouse, D I

    1997-04-01

    ABSTRACT The interactive effects of concomitant infection by the nematode Pratylenchus penetrans and the fungus Verticillium dahliae on symptom expression in Russet Burbank potato was studied in growth chamber experiments. Treatments were P. penetrans at three initial densities, V. dahliae at one inoculum density, the combination of the nematode at these three densities and the fungus, and a noninfested control. Gas exchange was measured nondestructively in leaf cohorts of different ages, one to three times weekly, with a LI-COR portable photosynthesis system. The single-pathogen treatments had no effect on assimilation or transpiration rates, but joint infection had a significant impact. In concomitant infection, photosynthesis was impaired more than transpiration, so estimates of leaf health were based on carbon assimilation rates only. Reductions in assimilation rate were apparent before the onset of visual symptoms. Assimilation rates decreased as much as 44% in the top, and newest, leaves of concomitantly infected plants, compared to rates in control plants. Even so, the health of newly produced leaves did not become progressively worse through time. With light use efficiency less than 0.20 mol of CO(2) fixed per mol of photosynthetically active radiation used as the criterion for disease incidence, disease progressed acropetally from the oldest to the youngest leaves. In plants infected with P. penetrans (0.8 nematodes per cm(3) of soil) in combination with V. dahliae, all leaves in cohorts 1 and 2 were symptomatic by 45 days after planting, and leaves in cohorts 3 to 6 became symptomatic at weekly intervals thereafter. For the control and single-pathogen treatments, the first time that light use efficiency fell below 0.20 in all leaves in cohort 1 was 71 days after planting. Concomitant infection reduced leaf life span by about 3 weeks. Both visual and physiological symptom expression were invariant to differences in initial nematode inoculum densities

  9. [Elaboration of the in vitro model system to study the interaction of phytopathogenic mollicutes with plant cells].

    PubMed

    Korobkova, K S; Onyshchenko, A M; Panchenko, L P; Mamchur, O Ie; Dmytruk, O O; Red'ko, V I

    2009-01-01

    The model system based on the sugar beet calluses infected by mycoplasms (mollicutes) was elaborated, and changes in the callus cells morphology under the effect of these microorganisms were also studied. The calluses of sugar beet 3K51 cultivated on the Gamborg medium were infected by phytopathogenic mollicute Acholaplasma laidlawii var. granulum str.118. Under the effect of mollicute infection one could observe changes in the cell morphology of sugar beet calluses: the plant cells were transformed from round to lengthened, the intensity of polyploids forming was increased, their grouping and their total destruction were observed. Data of electron microscopy confirm the presence of the mollicute in the sugar beet calluses: acholeplasma cells were localized between and within undifferentiated plant cells. PMID:19938618

  10. Acyl-homoserine lactones from Erwinia psidii R. IBSBF 435T, a guava phytopathogen (Psidium guajava L.).

    PubMed

    Pomini, Armando M; Manfio, Gilson P; Araújo, Welington L; Marsaioli, Anita J

    2005-08-10

    The phytopathogen Erwinia psidii R. IBSBF 435T causes rot in branches, flowers, and fruits of guava (Psidium guajava L.), being responsible for crop losses, and has no effective control. It was demonstrated that this strain produces two compounds [S-(-)-N-hexanoyl and N-heptanoyl-homoserine lactone], both belonging to the class of quorum-sensing signaling substances. A protocol using gas chromatography-flame ionization detection with chiral stationary phase is described for the absolute configuration determination of a natural acyl-homoserine lactone. Biological assays with specific reporter and synthesis of identified substances are also described. This is the first report on the N-heptanoyl-homoserine lactone occurrence in the Erwinia genus. PMID:16076103

  11. Structural elucidation and biological activity of acyl-homoserine lactones from the phytopathogen Pantoea ananatis Serrano 1928.

    PubMed

    Pomini, Armando M; Araújo, Welington L; Marsaioli, Anita J

    2006-08-01

    In Gram-negative bacteria, the acyl-homoserine lactones (acyl-HSLs) are the main signaling substances employed in cell-to-cell communication systems. This paper describes the chemical characterization of acyl-HSLs produced by the worldwide-spread phytopathogen Pantoea ananatis (Serrano 1928) by using gas chromatography-electron impact mass spectrometry. The absolute configuration of the major identified substance, (S)-(--)-N-hexanoyl-HSL, was determined with gas chromatography-flame ionization detection with a chiral capillary column. Biological activities of extracts, fractions, and synthetic products were evaluated with the specific reporter Agrobacterium tumefaciensNTL4(pZLR4) in beta-galactosidase expression assays. PMID:16900431

  12. Plant Carbohydrate Scavenging through TonB-Dependent Receptors: A Feature Shared by Phytopathogenic and Aquatic Bacteria

    PubMed Central

    Boulanger, Alice; Lautier, Martine; Guynet, Catherine; Denancé, Nicolas; Vasse, Jacques

    2007-01-01

    TonB-dependent receptors (TBDRs) are outer membrane proteins mainly known for the active transport of iron siderophore complexes in Gram-negative bacteria. Analysis of the genome of the phytopathogenic bacterium Xanthomonas campestris pv. campestris (Xcc), predicts 72 TBDRs. Such an overrepresentation is common in Xanthomonas species but is limited to only a small number of bacteria. Here, we show that one Xcc TBDR transports sucrose with a very high affinity, suggesting that it might be a sucrose scavenger. This TBDR acts with an inner membrane transporter, an amylosucrase and a regulator to utilize sucrose, thus defining a new type of carbohydrate utilization locus, named CUT locus, involving a TBDR for the transport of substrate across the outer membrane. This sucrose CUT locus is required for full pathogenicity on Arabidopsis, showing its importance for the adaptation to host plants. A systematic analysis of Xcc TBDR genes and a genome context survey suggested that several Xcc TBDRs belong to other CUT loci involved in the utilization of various plant carbohydrates. Interestingly, several Xcc TBDRs and CUT loci are conserved in aquatic bacteria such as Caulobacter crescentus, Colwellia psychrerythraea, Saccharophagus degradans, Shewanella spp., Sphingomonas spp. or Pseudoalteromonas spp., which share the ability to degrade a wide variety of complex carbohydrates and display TBDR overrepresentation. We therefore propose that TBDR overrepresentation and the presence of CUT loci designate the ability to scavenge carbohydrates. Thus CUT loci, which seem to participate to the adaptation of phytopathogenic bacteria to their host plants, might also play a very important role in the biogeochemical cycling of plant-derived nutrients in marine environments. Moreover, the TBDRs and CUT loci identified in this study are clearly different from those characterized in the human gut symbiont Bacteroides thetaiotaomicron, which allow glycan foraging, suggesting a convergent

  13. Glucanases and chitinases as causal agents in the protection of Acacia extrafloral nectar from infestation by phytopathogens.

    PubMed

    González-Teuber, Marcia; Pozo, María J; Muck, Alexander; Svatos, Ales; Adame-Alvarez, Rosa M; Heil, Martin

    2010-03-01

    Nectars are rich in primary metabolites and attract mutualistic animals, which serve as pollinators or as an indirect defense against herbivores. Their chemical composition makes nectars prone to microbial infestation. As protective strategy, floral nectar of ornamental tobacco (Nicotiana langsdorffii x Nicotiana sanderae) contains "nectarins," proteins producing reactive oxygen species such as hydrogen peroxide. By contrast, pathogenesis-related (PR) proteins were detected in Acacia extrafloral nectar (EFN), which is secreted in the context of defensive ant-plant mutualisms. We investigated whether these PR proteins protect EFN from phytopathogens. Five sympatric species (Acacia cornigera, A. hindsii, A. collinsii, A. farnesiana, and Prosopis juliflora) were compared that differ in their ant-plant mutualism. EFN of myrmecophytes, which are obligate ant-plants that secrete EFN constitutively to nourish specialized ant inhabitants, significantly inhibited the growth of four out of six tested phytopathogenic microorganisms. By contrast, EFN of nonmyrmecophytes, which is secreted only transiently in response to herbivory, did not exhibit a detectable inhibitory activity. Combining two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis with nanoflow liquid chromatography-tandem mass spectrometry analysis confirmed that PR proteins represented over 90% of all proteins in myrmecophyte EFN. The inhibition of microbial growth was exerted by the protein fraction, but not the small metabolites of this EFN, and disappeared when nectar was heated. In-gel assays demonstrated the activity of acidic and basic chitinases in all EFNs, whereas glucanases were detected only in EFN of myrmecophytes. Our results demonstrate that PR proteins causally underlie the protection of Acacia EFN from microorganisms and that acidic and basic glucanases likely represent the most important prerequisite in this defensive function. PMID:20023149

  14. Complete genome sequence of Pseudomonas fluorescens strain PICF7, an indigenous root endophyte from olive (Olea europaea L.) and effective biocontrol agent against Verticillium dahliae

    PubMed Central

    2015-01-01

    Pseudomonas fluorescens strain PICF7 is a native endophyte of olive roots. Previous studies have shown this motile, Gram-negative, non-sporulating bacterium is an effective biocontrol agent against the soil-borne fungus Verticillium dahliae, the causal agent of one of the most devastating diseases for olive (Olea europaea L.) cultivation. Here, we announce and describe the complete genome sequence of Pseudomonas fluorescens strain PICF7 consisting of a circular chromosome of 6,136,735 bp that encodes 5,567 protein-coding genes and 88 RNA-only encoding genes. Genome analysis revealed genes predicting factors such as secretion systems, siderophores, detoxifying compounds or volatile components. Further analysis of the genome sequence of PICF7 will help in gaining insights into biocontrol and endophytism. PMID:25685259

  15. The cotton MYB108 forms a positive feedback regulation loop with CML11 and participates in the defense response against Verticillium dahliae infection

    PubMed Central

    Cheng, Huan-Qing; Han, Li-Bo; Yang, Chun-Lin; Wu, Xiao-Min; Zhong, Nai-Qin; Wu, Jia-He; Wang, Fu-Xin; Xia, Gui-Xian

    2016-01-01

    Accumulating evidence indicates that plant MYB transcription factors participate in defense against pathogen attack, but their regulatory targets and related signaling processes remain largely unknown. Here, we identified a defense-related MYB gene (GhMYB108) from upland cotton (Gossypium hirsutum) and characterized its functional mechanism. Expression of GhMYB108 in cotton plants was induced by Verticillium dahliae infection and responded to the application of defense signaling molecules, including salicylic acid, jasmonic acid, and ethylene. Knockdown of GhMYB108 expression led to increased susceptibility of cotton plants to V. dahliae, while ecotopic overexpression of GhMYB108 in Arabidopsis thaliana conferred enhanced tolerance to the pathogen. Further analysis demonstrated that GhMYB108 interacted with the calmodulin-like protein GhCML11, and the two proteins form a positive feedback loop to enhance the transcription of GhCML11 in a calcium-dependent manner. Verticillium dahliae infection stimulated Ca2+ influx into the cytosol in cotton root cells, but this response was disrupted in both GhCML11-silenced plants and GhMYB108-silenced plants in which expression of several calcium signaling-related genes was down-regulated. Taken together, these results indicate that GhMYB108 acts as a positive regulator in defense against V. dahliae infection by interacting with GhCML11. Furthermore, the data also revealed the important roles and synergetic regulation of MYB transcription factor, Ca2+, and calmodulin in plant immune responses. PMID:26873979

  16. The cotton MYB108 forms a positive feedback regulation loop with CML11 and participates in the defense response against Verticillium dahliae infection.

    PubMed

    Cheng, Huan-Qing; Han, Li-Bo; Yang, Chun-Lin; Wu, Xiao-Min; Zhong, Nai-Qin; Wu, Jia-He; Wang, Fu-Xin; Wang, Hai-Yun; Xia, Gui-Xian

    2016-04-01

    Accumulating evidence indicates that plant MYB transcription factors participate in defense against pathogen attack, but their regulatory targets and related signaling processes remain largely unknown. Here, we identified a defense-related MYB gene (GhMYB108) from upland cotton (Gossypium hirsutum) and characterized its functional mechanism. Expression of GhMYB108 in cotton plants was induced by Verticillium dahliae infection and responded to the application of defense signaling molecules, including salicylic acid, jasmonic acid, and ethylene. Knockdown of GhMYB108 expression led to increased susceptibility of cotton plants to V. dahliae, while ecotopic overexpression of GhMYB108 in Arabidopsis thaliana conferred enhanced tolerance to the pathogen. Further analysis demonstrated that GhMYB108 interacted with the calmodulin-like protein GhCML11, and the two proteins form a positive feedback loop to enhance the transcription of GhCML11 in a calcium-dependent manner. Verticillium dahliae infection stimulated Ca(2+) influx into the cytosol in cotton root cells, but this response was disrupted in both GhCML11-silenced plants and GhMYB108-silenced plants in which expression of several calcium signaling-related genes was down-regulated. Taken together, these results indicate that GhMYB108 acts as a positive regulator in defense against V. dahliae infection by interacting with GhCML11. Furthermore, the data also revealed the important roles and synergetic regulation of MYB transcription factor, Ca(2+), and calmodulin in plant immune responses. PMID:26873979

  17. Evaluation of reference genes for RT-qPCR expression studies in hop (Humulus lupulus L.) during infection with vascular pathogen verticillium albo-atrum.

    PubMed

    Štajner, Nataša; Cregeen, Sara; Javornik, Branka

    2013-01-01

    Hop plant (Humulus lupulus L.), cultivated primarily for its use in the brewing industry, is faced with a variety of diseases, including severe vascular diseases, such as Verticillium wilt, against which no effective protection is available. The understanding of disease resistance with tools such as differentially expressed gene studies is an important objective of plant defense mechanisms. In this study, we evaluated twenty-three reference genes for RT-qPCR expression studies on hop under biotic stress conditions. The candidate genes were validated on susceptible and resistant hop cultivars sampled at three different time points after infection with Verticillium albo-atrum. The stability of expression and the number of genes required for accurate normalization were assessed by three different Excel-based approaches (geNorm v.3.5 software, NormFinder, and RefFinder). High consistency was found among them, identifying the same six best reference genes (YLS8, DRH1, TIP41, CAC, POAC and SAND) and five least stably expressed genes (CYCL, UBQ11, POACT, GAPDH and NADH). The candidate genes in different experimental subsets/conditions resulted in different rankings. A combination of the two best reference genes, YLS8 and DRH1, was used for normalization of RT-qPCR data of the gene of interest (PR-1) implicated in biotic stress of hop. We outlined the differences between normalized and non-normalized values and the importance of RT-qPCR data normalization. The high correlation obtained among data standardized with different sets of reference genes confirms the suitability of the reference genes selected for normalization. Lower correlations between normalized and non-normalized data may reflect different quantity and/or quality of RNA samples used in RT-qPCR analyses. PMID:23874551

  18. Expression of antimicrobial peptides thanatin(S) in transgenic Arabidopsis enhanced resistance to phytopathogenic fungi and bacteria.

    PubMed

    Wu, Tingquan; Tang, Dingzhong; Chen, Weida; Huang, Hexun; Wang, Rui; Chen, Yongfang

    2013-09-15

    Thanatin(S) is an analog of thanatin, an insect antimicrobial peptide possessing strong and broad spectrum of antimicrobial activity. In order to investigate if the thanatin could be used in engineering transgenic plants for increased resistance against phytopathogens, the synthetic thanatin(S) was introduced into Arabidopsis thaliana plants. To increase the expression level of thanatin(S) in plants, the coding sequence was optimized by plant-preference codon. To avoid cellular protease degradation, signal peptide of rice Cht1 was fused to N terminal of thanatin(S) for secreting the expressed thanatin(S) into intercellular spaces. To evaluate the application value of thanatin(S) in plant disease control, the synthesized coding sequence of Cht1 signal peptide (Cht1SP)-thanatin(S) was ligated to plant gateway destination binary vectors pGWB11 (with FLAG tag). Meanwhile, in order to observe the subcellular localization of Cht1SP-thanatin(S)-GFP and thanatin(S)-GFP, the sequences of Cht1SP-thanatin(S) and thanatin(S) were respectively linked to pGWB5 (with GFP tag). The constructs were transformed into Arabidopsis ecotype Col-0 and mutant pad4-1 via Agrobacterium-mediated transformation. The transformants with Cht1SP-thanatin(S)-FLAG fusion gene were analyzed by genomic PCR, real-time PCR, and western blots and the transgenic Arabidopsis plants introduced respectively Cht1SP-thanatin(S)-GFP and thanatin(S)-GFP were observed by confocal microscopy. Transgenic plants expressing Cht1SP-thanatin(S)-FLAG fusion protein showed antifungal activity against Botrytis cinerea and powdery mildew, as well as antibacterial activity against Pseudomonas syringae pv. tomato. And the results from confocal observation showed that the GFP signal from Cht1SP-thanatin(S)-GFP transgenic Arabidopsis plants occurred mainly in intercellular space, while that from thanatin(S)-GFP transgenic plants was mainly detected in the cytoplasm and that from empty vector transgenic plants was distributed

  19. Synthesis and biological evaluation of novel fluorine-containing stilbene derivatives as fungicidal agents against phytopathogenic fungi.

    PubMed

    Jian, Weilin; He, Daohang; Xi, Pinggen; Li, Xinwei

    2015-11-18

    The rising development of resistance to conventional fungicides is driving the search for new alternative candidates to control plant diseases. In this study, a series of new fluorine-containing stilbene derivatives was synthesized on the basis of our previous quantitative structure-activity relationship analysis results. Bioassays in vivo revealed that the title compounds exhibited potent fungicidal activities against phytopathogenic fungi (Colletotrichum lagenarium and Pseudoperonospora cubensis) from cucumber plants. In comparison to the previous results, the introduction of a fluorine moiety showed improved activities of some compounds against those fungi. Notably, compound 9 exhibited a control efficacy against C. lagenarium (83.4 ± 1.3%) comparable to that of commercial fungicide (82.7 ± 1.7%). For further understanding the possible mode of action of the stilbene against C. lagenarium, the effects on hyphal morphology, electrolyte leakage, and respiration of mycelial cell suspension were studied. Microscopic observation showed considerably deformed mycelial morphology. The conductivity of mycelial suspension increased in the presence of compound 9, whereas no significantly inhibitory effect on respiration was observed. Taken together, the fungicidal mechanism of this stilbene is associated with its membrane disruption effect, resulting in increased membrane permeability. These results provide important clues for mechanistic study and derivatization of stilbenes as alternative sources of fungicidal agents for plant disease control. PMID:26515556

  20. Chitinase genes revealed and compared in bacterial isolates, DNA extracts and a metagenomic library from a phytopathogen suppressive soil

    SciTech Connect

    Hjort, K.; Bergstrom, M.; Adesina, M.F.; Jansson, J.K.; Smalla, K.; Sjoling, S.

    2009-09-01

    Soil that is suppressive to disease caused by fungal pathogens is an interesting source to target for novel chitinases that might be contributing towards disease suppression. In this study we screened for chitinase genes, in a phytopathogen-suppressive soil in three ways: (1) from a metagenomic library constructed from microbial cells extracted from soil, (2) from directly extracted DNA and (3) from bacterial isolates with antifungal and chitinase activities. Terminal-restriction fragment length polymorphism (T-RFLP) of chitinase genes revealed differences in amplified chitinase genes from the metagenomic library and the directly extracted DNA, but approximately 40% of the identified chitinase terminal-restriction fragments (TRFs) were found in both sources. All of the chitinase TRFs from the isolates were matched to TRFs in the directly extracted DNA and the metagenomic library. The most abundant chitinase TRF in the soil DNA and the metagenomic library corresponded to the TRF{sup 103} of the isolate, Streptomyces mutomycini and/or Streptomyces clavifer. There were good matches between T-RFLP profiles of chitinase gene fragments obtained from different sources of DNA. However, there were also differences in both the chitinase and the 16S rRNA gene T-RFLP patterns depending on the source of DNA, emphasizing the lack of complete coverage of the gene diversity by any of the approaches used.

  1. Identification of a Polyketide Synthase Gene in the Synthesis of Phleichrome of the Phytopathogenic Fungus Cladosporium phlei

    PubMed Central

    So, Kum-Kang; Chung, Yun-Jo; Kim, Jung-Mi; Kim, Beom-Tae; Park, Seung-Moon; Kim, Dae-Hyuk

    2015-01-01

    Phleichrome, a pigment produced by the phytopathogenic fungus Cladosporium phlei, is a fungal perylenequinone whose photodynamic activity has been studied intensively. To determine the biological function of phleichrome and to engineer a strain with enhanced production of phleichrome, we identified the gene responsible for the synthesis of phleichrome. Structural comparison of phleichrome with other fungal perylenequinones suggested that phleichrome is synthesized via polyketide pathway. We recently identified four different polyketide synthase (PKS) genes encompassing three major clades of fungal PKSs that differ with respect to reducing conditions for the polyketide product. Based on in silico analysis of cloned genes, we hypothesized that the non-reducing PKS gene, Cppks1, is involved in phleichrome biosynthesis. Increased accumulation of Cppks1 transcript was observed in response to supplementation with the application of synthetic inducer cyclo-(l-Pro-l-Phe). In addition, heterologous expression of the Cppks1 gene in Cryphonectria parasitica resulted in the production of phleichrome. These results provide convincing evidence that the Cppks1 gene is responsible for the biosynthesis of phleichrome. PMID:26612679

  2. Draft genome sequencing and secretome analysis of fungal phytopathogen Ascochyta rabiei provides insight into the necrotrophic effector repertoire

    PubMed Central

    Verma, Sandhya; Gazara, Rajesh Kumar; Nizam, Shadab; Parween, Sabiha; Chattopadhyay, Debasis; Verma, Praveen Kumar

    2016-01-01

    Constant evolutionary pressure acting on pathogens refines their molecular strategies to attain successful pathogenesis. Recent studies have shown that pathogenicity mechanisms of necrotrophic fungi are far more intricate than earlier evaluated. However, only a few studies have explored necrotrophic fungal pathogens. Ascochyta rabiei is a necrotrophic fungus that causes devastating blight disease of chickpea (Cicer arietinum). Here, we report a 34.6 megabase draft genome assembly of A. rabiei. The genome assembly covered more than 99% of the gene space and 4,259 simple sequence repeats were identified in the assembly. A total of 10,596 high confidence protein-coding genes were predicted which includes a large and diverse inventory of secretory proteins, transporters and primary and secondary metabolism enzymes reflecting the necrotrophic lifestyle of A. rabiei. A wide range of genes encoding carbohydrate-active enzymes capable for degradation of complex polysaccharides were also identified. Comprehensive analysis predicted a set of 758 secretory proteins including both classical and non-classical secreted proteins. Several of these predicted secretory proteins showed high cysteine content and numerous tandem repeats. Together, our analyses would broadly expand our knowledge and offer insights into the pathogenesis and necrotrophic lifestyle of fungal phytopathogens. PMID:27091329

  3. The transition from a phytopathogenic smut ancestor to an anamorphic biocontrol agent deciphered by comparative whole-genome analysis.

    PubMed

    Lefebvre, François; Joly, David L; Labbé, Caroline; Teichmann, Beate; Linning, Rob; Belzile, François; Bakkeren, Guus; Bélanger, Richard R

    2013-06-01

    Pseudozyma flocculosa is related to the model plant pathogen Ustilago maydis yet is not a phytopathogen but rather a biocontrol agent of powdery mildews; this relationship makes it unique for the study of the evolution of plant pathogenicity factors. The P. flocculosa genome of ~23 Mb includes 6877 predicted protein coding genes. Genome features, including hallmarks of pathogenicity, are very similar in P. flocculosa and U. maydis, Sporisorium reilianum, and Ustilago hordei. Furthermore, P. flocculosa, a strict anamorph, revealed conserved and seemingly intact mating-type and meiosis loci typical of Ustilaginales. By contrast, we observed the loss of a specific subset of candidate secreted effector proteins reported to influence virulence in U. maydis as the singular divergence that could explain its nonpathogenic nature. These results suggest that P. flocculosa could have once been a virulent smut fungus that lost the specific effectors necessary for host compatibility. Interestingly, the biocontrol agent appears to have acquired genes encoding secreted proteins not found in the compared Ustilaginales, including necrosis-inducing-Phytophthora-protein- and Lysin-motif- containing proteins believed to have direct relevance to its lifestyle. The genome sequence should contribute to new insights into the subtle genetic differences that can lead to drastic changes in fungal pathogen lifestyles. PMID:23800965

  4. Draft genome sequencing and secretome analysis of fungal phytopathogen Ascochyta rabiei provides insight into the necrotrophic effector repertoire.

    PubMed

    Verma, Sandhya; Gazara, Rajesh Kumar; Nizam, Shadab; Parween, Sabiha; Chattopadhyay, Debasis; Verma, Praveen Kumar

    2016-01-01

    Constant evolutionary pressure acting on pathogens refines their molecular strategies to attain successful pathogenesis. Recent studies have shown that pathogenicity mechanisms of necrotrophic fungi are far more intricate than earlier evaluated. However, only a few studies have explored necrotrophic fungal pathogens. Ascochyta rabiei is a necrotrophic fungus that causes devastating blight disease of chickpea (Cicer arietinum). Here, we report a 34.6 megabase draft genome assembly of A. rabiei. The genome assembly covered more than 99% of the gene space and 4,259 simple sequence repeats were identified in the assembly. A total of 10,596 high confidence protein-coding genes were predicted which includes a large and diverse inventory of secretory proteins, transporters and primary and secondary metabolism enzymes reflecting the necrotrophic lifestyle of A. rabiei. A wide range of genes encoding carbohydrate-active enzymes capable for degradation of complex polysaccharides were also identified. Comprehensive analysis predicted a set of 758 secretory proteins including both classical and non-classical secreted proteins. Several of these predicted secretory proteins showed high cysteine content and numerous tandem repeats. Together, our analyses would broadly expand our knowledge and offer insights into the pathogenesis and necrotrophic lifestyle of fungal phytopathogens. PMID:27091329

  5. Differential in vitro and in vivo effect of barley cysteine and serine protease inhibitors on phytopathogenic microorganisms.

    PubMed

    Carrillo, Laura; Herrero, Ignacio; Cambra, Inés; Sánchez-Monge, Rosa; Diaz, Isabel; Martinez, Manuel

    2011-10-01

    Protease inhibitors from plants have been involved in defence mechanisms against pests and pathogens. Phytocystatins and trypsin/α-amylase inhibitors are two of the best characterized protease inhibitor families in plants. In barley, thirteen cystatins (HvCPI-1 to 13) and the BTI-CMe trypsin inhibitor have been previously studied. Their capacity to inhibit pest digestive proteases, and the negative in vivo effect caused by plants expressing these inhibitors on pests support the defence function of these proteins. Barley cystatins are also able to inhibit in vitro fungal growth. However, the antifungal effect of these inhibitors in vivo had not been previously tested. Moreover, their in vitro and in vivo effect on plant pathogenous bacteria is still unknown. In order to obtain new insights on this feature, in vitro assays were made against different bacterial and fungal pathogens of plants using the trypsin inhibitor BTI-CMe and the thirteen barley cystatins. Most barley cystatins and the BTI-CMe inhibitor were able to inhibit mycelial growth but no bacterial growth. Transgenic Arabidopsis plants independently expressing the BTI-CMe inhibitor and the cystatin HvCPI-6 were tested against the same bacterial and fungal pathogens. Neither the HvCPI-6 expressing transgenic plants nor the BTI-CMe ones were more resistant to plant pathogen fungi and bacteria than control Arabidopsis plants. The differences observed between the in vitro and in planta assays against phytopathogenic fungi are discussed. PMID:21482127

  6. Characterization of an oxidative stress response regulator, homologous to Escherichia coli OxyR, from the phytopathogen Xylella fastidiosa.

    PubMed

    Toledo, M A S; Schneider, D R; Azzoni, A R; Favaro, M T P; Pelloso, A C; Santos, C A; Saraiva, A M; Souza, A P

    2011-02-01

    The OxyR oxidative stress transcriptional regulator is a DNA-binding protein that belongs to the LysR-type transcriptional regulators (LTTR) family. It has the ability to sense oxidative species inside the cell and to trigger the cell's response, activating the transcription of genes involved in scavenging oxidative species. In the present study, we have overexpressed, purified and characterized the predicted OxyR homologue (orf xf1273) of the phytopathogen Xylella fastidiosa. This bacterium is the causal agent of citrus variegated chlorosis (CVC) disease caused by the 9a5c strain, resulting in economic and social losses. The secondary structure of the recombinant protein was analyzed by circular dichroism. Gel filtration showed that XfoxyR is a dimer in solution. Gel shift assays indicated that it does bind to its own predicted promoter under in vitro conditions. However, considering our control experiment we cannot state that this interaction occurs in vivo. Functional complementation assays indicated that xfoxyR is able to restore the oxidative stress response in an oxyr knockout Escherichia coli strain. These results show that the predicted orfxf1273 codes for a transcriptional regulator, homologous to E. coli OxyR, involved in the oxidative stress response. This may be important for X. fastidiosa to overcome the defense mechanisms of its host during the infection and colonization processes. PMID:20951212

  7. Antifungal effects of different organic extracts from Melia azedarach L. on phytopathogenic fungi and their isolated active components.

    PubMed

    Carpinella, María C; Giorda, Laura M; Ferrayoli, Carlos G; Palacios, Sara M

    2003-04-23

    Extracts from different parts of Melia azedarach L. were studied as potential antifungal agents for selected phytopathogenic fungi. In a serial agar dilution method, hexanic and ethanolic extracts from fruit, seed kernels, and senescent leaves exhibited fungistatic activity against Aspergillus flavus,Diaporthe phaseolorum var. meridionales, Fusarium oxysporum, Fusarium solani, Fusarium verticillioides, and Sclerotinia sclerotiorum. Both hexanic extract from senescent leaves and ethanolic extract from seed kernel were highly effective on all tested fungi, with minimum inhibitory concentration (MIC) values ranging from 0.5 to 25 mg/mL and 0.5 to 5 mg/mL, respectively. In addition, all of the above-mentioned extracts showed fungicidal activity on these fungi, with ethanolic seed kernel extract being the most active. Three compounds displaying activity against F. verticillioides were isolated from the ethanolic seed kernel extract and were characterized as vanillin (1), 4-hydroxy-3-methoxycinnamaldehyde (2), and (+/-)-pinoresinol (3), with MICs of 0.6, 0.4, and 1.0 mg/mL, respectively. These compounds also showed a synergistic effect when combined in different concentrations, needing four times less concentration to reach complete inhibition in the growth of F. verticillioides. PMID:12696928

  8. Phosphoproteome profiles of the phytopathogenic fungi Alternaria brassicicola and Botrytis cinerea during exponential growth in axenic cultures.

    PubMed

    Davanture, Marlène; Dumur, Jérôme; Bataillé-Simoneau, Nelly; Campion, Claire; Valot, Benoît; Zivy, Michel; Simoneau, Philippe; Fillinger, Sabine

    2014-07-01

    This study describes the gel-free phosphoproteomic analysis of the phytopathogenic fungi Alternaria brassicicola and Botrytis cinerea grown in vitro under nonlimiting conditions. Using a combination of strong cation exchange and IMAC prior to LC-MS, we identified over 1350 phosphopeptides per fungus representing over 800 phosphoproteins. The preferred phosphorylation sites were found on serine (>80%) and threonine (>15%), whereas phosphorylated tyrosine residues were found at less than 1% in A. brassicicola and at a slightly higher ratio in B. cinerea (1.5%). Biological processes represented principally among the phoshoproteins were those involved in response and transduction of stimuli as well as in regulation of cellular and metabolic processes. Most known elements of signal transduction were found in the datasets of both fungi. This study also revealed unexpected phosphorylation sites in histidine kinases, a category overrepresented in filamentous ascomycetes compared to yeast. The data have been deposited to the ProteomeXchange database with identifier PXD000817 (http://proteomecentral.proteomexchange.org/dataset/PXD000817). PMID:24825570

  9. Biosynthesis of Auxin by the Gram-Positive Phytopathogen Rhodococcus fascians Is Controlled by Compounds Specific to Infected Plant Tissues

    PubMed Central

    Vandeputte, Olivier; Öden, Sevgi; Mol, Adeline; Vereecke, Danny; Goethals, Koen; El Jaziri, Mondher; Prinsen, Els

    2005-01-01

    The role and metabolism of indole-3-acetic acid in gram-negative bacteria is well documented, but little is known about indole-3-acetic acid biosynthesis and regulation in gram-positive bacteria. The phytopathogen Rhodococcus fascians, a gram-positive organism, incites diverse developmental alterations, such as leafy galls, on a wide range of plants. Phenotypic analysis of a leafy gall suggests that auxin may play an important role in the development of the symptoms. We show here for the first time that R. fascians produces and secretes the auxin indole-3-acetic acid. Interestingly, whereas noninfected-tobacco extracts have no effect, indole-3-acetic acid synthesis is highly induced in the presence of infected-tobacco extracts when tryptophan is not limiting. Indole-3-acetic acid production by a plasmid-free strain shows that the biosynthetic genes are located on the bacterial chromosome, although plasmid-encoded genes contribute to the kinetics and regulation of indole-3-acetic acid biosynthesis. The indole-3-acetic acid intermediates present in bacterial cells and secreted into the growth media show that the main biosynthetic route used by R. fascians is the indole-3-pyruvic acid pathway with a possible rate-limiting role for indole-3-ethanol. The relationship between indole-3-acetic acid production and the symptoms induced by R. fascians is discussed. PMID:15746315

  10. Sequence analysis and structural characterization of a glyceraldehyde-3-phosphate dehydrogenase gene from the phytopathogenic fungus Eremothecium ashbyi.

    PubMed

    Sengupta, Sudeshna; Chandra, T S

    2011-02-01

    Eremothecium ashbyi is a phytopathogenic fungus infesting cotton, soybeans and several other plants. This highly flavinogenic fungus has been phylogenetically characterized, but the genetic aspects of its central metabolic and riboflavin biosynthetic pathways are unknown. An ORF of 996 bp was obtained from E. ashbyi by using degenerate primers for glyceraldehyde-3-phosphate dehydrogenase (GPD) through reverse transcriptase polymerase chain reaction (RT-PCR) and 5'-3' rapid amplification of cDNA ends (RACE-PCR). This nucleotide sequence had a high similarity of 88% with GPD sequence of Ashbya gossypii. The putative GPD peptide of 331-aa had a high similarity of 85% with the GPD sequence from other ascomycetes. The ORF had an unusually strong codon bias with 5 amino acids showing strict preference of a single codon. The theoretical molecular weight for the putative peptide was 35.58 kDa with an estimated pI of 5.7. A neighbor-joining tree showed that the putative peptide from E. ashbyi displayed the highest similarity to GPD of A. gossypii. The gene sequence is available at the GenBank, accession number EU717696. Homology modeling done with Kluyveromyces marxianus GPD (PDB: 2I5P) as template indicated high structural similarity. PMID:20820924

  11. Antimicrobial activities of novel mannosyl lipids isolated from the biocontrol fungus Simplicillium lamellicola BCP against phytopathogenic bacteria.

    PubMed

    Le Dang, Quang; Shin, Teak Soo; Park, Myung Soo; Choi, Yong Ho; Choi, Gyung Ja; Jang, Kyoung Soo; Kim, In Seon; Kim, Jin-Cheol

    2014-04-16

    The antagonistic fungus Simplicillium lamellicola BCP has been developed as a microbial biopesticide that effectively controls the development of various plant diseases caused by both pathogenic bacteria and pathogenic fungi. Antibacterial bioassay-directed fractionation was used to isolate mannosyl lipids from S. lamellicola BCP, and the structures of these compounds were elucidated using spectral analysis and chemical degradation. Three novel mannosyl lipids were characterized and identified as halymecins F and G and (3R,5R)-3-O-β-D-mannosyl-3,5-dihydrodecanoic acid. Massoia lactone and (3R, 5R)-3-hydroxydecan-5-olide were also isolated from S. lamellicola BCP. The three novel compounds inhibited the growth of the majority of phytopathogenic bacteria that were tested, and halymecin F displayed the strongest antibacterial activity. Agrobacterium tumefaciens was the most sensitive to the three novel compounds, with IC₅₀ values ranging from 1.58 to 24.8 μg/mL. The ethyl acetate extract of the fermentation broth from the antagonistic fungus effectively reduced the bacterial wilt caused by Ralstonia solanacearum on tomato seedlings. These results indicate that S. lamellicola BCP suppresses the development of plant bacterial diseases through the production of antibacterial metabolites. PMID:24660753

  12. Complete sequence of a double-stranded RNA from the phytopathogenic fungus Erysiphe cichoracearum that might represent a novel endornavirus.

    PubMed

    Du, Zhenguo; Lin, Wenzhong; Qiu, Ping; Liu, Xiaojuan; Guo, Lingfang; Wu, Kangcheng; Zhang, Songbai; Wu, Zujian

    2016-08-01

    A double-stranded RNA (dsRNA) HBJZ1506 recovered from the phytopathogenic fungus Erysiphe cichoracearum infecting Calendula officinalis in Jingzhou, Hubei Province, China, was sequenced. HBJZ1506 comprises 11,908 nucleotides (nt) and contains a 11,859-nt-long open reading frame (ORF) coding for a polypeptide that is 61 % identical to that of a putative endornavirus named grapevine endophyte endornavirus (GeEV). The putative polyprotein has an RNA-dependent RNA polymerase (RdRp) domain and an RNA helicase domain, which show homology to and have an arrangement that is similar to that of their counterparts in approved or putative endornaviruses. In a phylogenetic tree constructed using amino acid sequences of the RdRp region of HBJZ1506 and selected endornaviruses, HBJZ1506 clustered with endornaviruses and formed a well-supported monophyletic branch with GeEV. These results suggest that HBJZ1506 might represent a novel endornavirus, for which the name Erysiphe cichoracearum endornavirus (EcEV) is proposed. PMID:27255746

  13. Insights into the diversity of φRSM phages infecting strains of the phytopathogen Ralstonia solanacearum complex: regulation and evolution.

    PubMed

    Askora, Ahmed; Kawasaki, Takeru; Fujie, Makoto; Yamada, Takashi

    2014-08-01

    The filamentous φRSM phages (φRSM1 and φRSM3) have integration/excision capabilities in the phytopathogenic bacterium Ralstonia solanacearum. In the present study, we further investigated φRSM-like sequences present in the genomes of R. solanacearum strains belonging to the four major evolutionary lineages (phylotypes I-IV). Based on bioinformatics and comparative genomic analyses, we found that φRSM homologs are highly diverse in R. solanacearum complex strains. We detected an open reading frame (ORF)15 located upstream of the gene for φRSM integrase, which exhibited amino acid sequence similarity to phage repressor proteins. ORF15-encoded protein (a putative repressor) was found to encode a 104-residue polypeptide containing a DNA-binding (helix-turn-helix) domain and was expressed in R. solanacearum lysogenic strains. This suggested that φRSM3-ORF15 might be involved in the establishment and maintenance of a lysogenic state, as well as in phage immunity. Comparison of the putative repressor proteins and their binding sites within φRSM-related prophages provides insights into how these regulatory systems of filamentous phages have evolved and diverged in the R. solanacearum complex. In conclusion, φRSM phages represent a unique group of filamentous phages that are equipped with innate integration/excision (ORF14) and regulatory systems (ORF15). PMID:24619102

  14. Genome, Proteome and Structure of a T7-Like Bacteriophage of the Kiwifruit Canker Phytopathogen Pseudomonas syringae pv. actinidiae.

    PubMed

    Frampton, Rebekah A; Acedo, Elena Lopez; Young, Vivienne L; Chen, Danni; Tong, Brian; Taylor, Corinda; Easingwood, Richard A; Pitman, Andrew R; Kleffmann, Torsten; Bostina, Mihnea; Fineran, Peter C

    2015-07-01

    Pseudomonas syringae pv. actinidiae is an economically significant pathogen responsible for severe bacterial canker of kiwifruit (Actinidia sp.). Bacteriophages infecting this phytopathogen have potential as biocontrol agents as part of an integrated approach to the management of bacterial canker, and for use as molecular tools to study this bacterium. A variety of bacteriophages were previously isolated that infect P. syringae pv. actinidiae, and their basic properties were characterized to provide a framework for formulation of these phages as biocontrol agents. Here, we have examined in more detail φPsa17, a phage with the capacity to infect a broad range of P. syringae pv. actinidiae strains and the only member of the Podoviridae in this collection. Particle morphology was visualized using cryo-electron microscopy, the genome was sequenced, and its structural proteins were analysed using shotgun proteomics. These studies demonstrated that φPsa17 has a 40,525 bp genome, is a member of the T7likevirus genus and is closely related to the pseudomonad phages φPSA2 and gh-1. Eleven structural proteins (one scaffolding) were detected by proteomics and φPsa17 has a capsid of approximately 60 nm in diameter. No genes indicative of a lysogenic lifecycle were identified, suggesting the phage is obligately lytic. These features indicate that φPsa17 may be suitable for formulation as a biocontrol agent of P. syringae pv. actinidiae. PMID:26114474

  15. Characterization of the BMR1 gene encoding a transcription factor for melanin biosynthesis genes in the phytopathogenic fungus Bipolaris oryzae.

    PubMed

    Kihara, Junichi; Moriwaki, Akihiro; Tanaka, Nozomi; Tanaka, Chihiro; Ueno, Makoto; Arase, Sakae

    2008-04-01

    We isolated and characterized Bipolaris melanin regulation 1 gene (BMR1) encoding a transcription factor for melanin biosynthesis genes in the phytopathogenic fungus Bipolaris oryzae. Sequence analysis showed that the BMR1 gene encodes a putative protein of 1012 amino acids that has 99% sequence similarity to transcription factor Cmr1 of Cochliobolus heterostrophus. The predicted B. oryzae Bmr1 protein has two DNA-binding motifs, two Cys2His2 zinc finger domains, and a Zn(II)2Cys6 binuclear cluster domain at the N-terminal region of Bmr1. Targeted disruption of the BMR1 gene showed that BMR1 is essential for melanin biosynthesis in B. oryzae. The overexpression of the BMR1 gene led to more dark colonies than in the wild-type strain under dark conditions. Real-time PCR analysis showed that the BMR1 expression of the overexpression transformant was about 10-fold that of the wild type under dark conditions and of the expression of three melanin biosynthesis genes. These results indicated that BMR1 encodes the transcription factor of melanin biosynthesis genes in B. oryzae. PMID:18312572

  16. The Comprehensive Phytopathogen Genomics Resource: a web-based resource for data-mining plant pathogen genomes

    PubMed Central

    Hamilton, John P.; Neeno-Eckwall, Eric C.; Adhikari, Bishwo N.; Perna, Nicole T.; Tisserat, Ned; Leach, Jan E.; Lévesque, C. André; Buell, C. Robin

    2011-01-01

    The Comprehensive Phytopathogen Genomics Resource (CPGR) provides a web-based portal for plant pathologists and diagnosticians to view the genome and trancriptome sequence status of 806 bacterial, fungal, oomycete, nematode, viral and viroid plant pathogens. Tools are available to search and analyze annotated genome sequences of 74 bacterial, fungal and oomycete pathogens. Oomycete and fungal genomes are obtained directly from GenBank, whereas bacterial genome sequences are downloaded from the A Systematic Annotation Package (ASAP) database that provides curation of genomes using comparative approaches. Curated lists of bacterial genes relevant to pathogenicity and avirulence are also provided. The Plant Pathogen Transcript Assemblies Database provides annotated assemblies of the transcribed regions of 82 eukaryotic genomes from publicly available single pass Expressed Sequence Tags. Data-mining tools are provided along with tools to create candidate diagnostic markers, an emerging use for genomic sequence data in plant pathology. The Plant Pathogen Ribosomal DNA (rDNA) database is a resource for pathogens that lack genome or transcriptome data sets and contains 131 755 rDNA sequences from GenBank for 17 613 species identified as plant pathogens and related genera. Database URL: http://cpgr.plantbiology.msu.edu. PMID:22120664

  17. Specific genomic fingerprints of phytopathogenic Xanthomonas and Pseudomonas pathovars and strains generated with repetitive sequences and PCR.

    PubMed Central

    Louws, F J; Fulbright, D W; Stephens, C T; de Bruijn, F J

    1994-01-01

    DNA primers corresponding to conserved motifs in bacterial repetitive (REP, ERIC, and BOX) elements and PCR were used to show that REP-, ERIC-, and BOX-like DNA sequences are widely distributed in phytopathogenic Xanthomonas and Pseudomonas strains. REP-, ERIC, and BOX-PCR (collectively known as rep-PCR) were used to generate genomic fingerprints of a variety of Xanthomonas and Pseudomonas isolates and to identify pathovars and strains that were previously not distinguishable by other classification methods. Analogous rep-PCR-derived genomic fingerprints were generated from purified genomic DNA, colonies on agar plates, liquid cultures, and directly from lesions on infected plants. REP, ERIC, and BOX-PCR-generated fingerprints of specific Xanthomonas and Pseudomonas strains were found to yield similar conclusions wtih regard to the identity of and relationship between these strains. This suggests that the distribution of REP-, ERIC, and BOX-like sequences in these strains is a reflection of their genomic structure. Thus, the rep-PCR technique appears to be a rapid, simple, and reproducible method to identify and classify Xanthomonas and Pseudomonas strains, and it may be a useful diagnostic tool for these important plant pathogens. Images PMID:8074510

  18. VdSNF1, the sucrose nonfermenting protein kinase gene of Verticillium dahliae, is required for virulence and expression of genes involved in cell-wall degradation.

    PubMed

    Tzima, Aliki K; Paplomatas, Epaminondas J; Rauyaree, Payungsak; Ospina-Giraldo, Manuel D; Kang, Seogchan

    2011-01-01

    Verticillium dahliae is a soilborne fungus causing vascular wilt in a diverse array of plant species. Its virulence has been attributed, among other factors, to the activity of hydrolytic cell wall-degrading enzymes (CWDE). The sucrose nonfermenting 1 gene (VdSNF1), which regulates catabolic repression, was disrupted in V. dahliae tomato race 1. Expression of CWDE in the resulting mutants was not induced in inductive medium and in simulated xylem fluid medium. Growth of the mutants was significantly reduced when grown with pectin or galactose as a carbon source whereas, with glucose, sucrose, and xylose, they grew similarly to wild-type and ectopic transformants. The mutants were severely impaired in virulence on tomato and eggplant (final disease severity reduced by an average of 87%). Microscopic observation of the infection behavior of a green fluorescent protein (gfp)-labeled VdSNF1 mutant (70ΔSF-gfp1) showed that it was defective in initial colonization of roots. Cross sections of tomato stem at the cotyledonary level showed that 70ΔSF-gfp1 colonized xylem vessels considerably less than the wild-type strain. The wild-type strain heavily colonized xylem vessels and adjacent parenchyma cells. Quantification of fungal biomass in plant tissues further confirmed reduced colonization of roots, stems, and cotyledons by 70ΔSF-gfp1 relative to that by the wild-type strain. PMID:20839958

  19. The mitogen-activated protein kinase gene, VdHog1, regulates osmotic stress response, microsclerotia formation and virulence in Verticillium dahliae.

    PubMed

    Wang, Yonglin; Tian, Longyan; Xiong, Dianguang; Klosterman, Steven J; Xiao, Shuxiao; Tian, Chengming

    2016-03-01

    The fungus Verticillium dahliae has gained worldwide notoriety as a destructive plant pathogen, causing vascular wilt diseases on diverse plant species. V. dahliae produces melanized resting bodies, known as microsclerotia, which can survive for 15years in the soil, and are thus critically important in its disease cycle. However, the molecular mechanisms that underpin microsclerotia formation, survival, and germination remain poorly understood. In this study, we observed that deletion of VdHog1 (ΔVdHog1), encoding a homolog of a high-osmolarity glycerol (HOG) response mitogen-activated protein kinase, displayed decreased numbers of melanized microsclerotia in culture, heightened sensitivity to hyperosmotic stress, and increased resistance to the fungicide fludioxonil. Through RNA-Seq analysis, we identified 221 genes differentially expressed in the ΔVdHog1 strain. Interestingly, the expression levels of genes involved in melanin biosynthesis, as well as the hydrophobin gene VDH1, involved in the early stage of microsclerotia formation, were significantly decreased in the ΔVdHog1 strains relative to the wild-type expression levels. The ΔVdHog1 strains exhibited decreased virulence relative to the wild type strain on smoke tree seedlings. These results indicate that VdHog1 regulates hyperosmotic stress responses in V. dahliae, and establishes the Hog1-mediated pathway as a target to further probe the up- and downstream processes that regulate asexual development in this fungus. PMID:26812120

  20. Influence of soil type, cultivar and Verticillium dahliae on the structure of the root and rhizosphere soil fungal microbiome of strawberry.

    PubMed

    Nallanchakravarthula, Srivathsa; Mahmood, Shahid; Alström, Sadhna; Finlay, Roger D

    2014-01-01

    Sustainable management of crop productivity and health necessitates improved understanding of the ways in which rhizosphere microbial populations interact with each other, with plant roots and their abiotic environment. In this study we examined the effects of different soils and cultivars, and the presence of a soil-borne fungal pathogen, Verticillium dahliae, on the fungal microbiome of the rhizosphere soil and roots of strawberry plants, using high-throughput pyrosequencing. Fungal communities of the roots of two cultivars, Honeoye and Florence, were statistically distinct from those in the rhizosphere soil of the same plants, with little overlap. Roots of plants growing in two contrasting field soils had high relative abundance of Leptodontidium sp. C2 BESC 319 g whereas rhizosphere soil was characterised by high relative abundance of Trichosporon dulcitum or Cryptococcus terreus, depending upon the soil type. Differences between different cultivars were not as clear. Inoculation with the pathogen V. dahliae had a significant influence on community structure, generally decreasing the number of rhizosphere soil- and root-inhabiting fungi. Leptodontidium sp. C2 BESC 319 g was the dominant fungus responding positively to inoculation with V. dahliae. The results suggest that 1) plant roots select microorganisms from the wider rhizosphere pool, 2) that both rhizosphere soil and root inhabiting fungal communities are influenced by V. dahliae and 3) that soil type has a stronger influence on both of these communities than cultivar. PMID:25347069

  1. Cultivation-independent analysis of Pseudomonas species in soil and in the rhizosphere of field-grown Verticillium dahliae host plants.

    PubMed

    Costa, Rodrigo; Salles, Joana Falcão; Berg, Gabriele; Smalla, Kornelia

    2006-12-01

    Despite their importance for rhizosphere functioning, rhizobacterial Pseudomonas spp. have been mainly studied in a cultivation-based manner. In this study a cultivation-independent method was used to determine to what extent the factors plant species, sampling site and year-to-year variation influence Pseudomonas community structure in bulk soil and in the rhizosphere of two Verticillium dahliae host plants, oilseed rape and strawberry. Community DNA was extracted from bulk and rhizosphere soil samples of flowering plants collected at three different sites in Germany in two consecutive years. Pseudomonas community structure and diversity were assessed using a polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) system to fingerprint Pseudomonas-specific 16S rRNA gene fragments amplified from community DNA. Dominant and differentiating DGGE bands were excised from the gels, cloned and sequenced. The factors sampling site, plant species and year-to-year variation were shown to significantly influence the community structure of Pseudomonas in rhizosphere soils. The composition of Pseudomonas 16S rRNA gene fragments in the rhizosphere differed from that in the adjacent bulk soil and the rhizosphere effect tended to be plant-specific. The clone sequences of most dominant bands analysed belonged to the Pseudomonas fluorescens lineage and showed closest similarity to culturable Pseudomonas known for displaying antifungal properties. This report provides a better understanding of how different factors drive Pseudomonas community structure and diversity in bulk and rhizosphere soils. PMID:17107555

  2. Influence of Soil Type, Cultivar and Verticillium dahliae on the Structure of the Root and Rhizosphere Soil Fungal Microbiome of Strawberry

    PubMed Central

    Nallanchakravarthula, Srivathsa; Mahmood, Shahid; Alström, Sadhna; Finlay, Roger D.

    2014-01-01

    Sustainable management of crop productivity and health necessitates improved understanding of the ways in which rhizosphere microbial populations interact with each other, with plant roots and their abiotic environment. In this study we examined the effects of different soils and cultivars, and the presence of a soil-borne fungal pathogen, Verticillium dahliae, on the fungal microbiome of the rhizosphere soil and roots of strawberry plants, using high-throughput pyrosequencing. Fungal communities of the roots of two cultivars, Honeoye and Florence, were statistically distinct from those in the rhizosphere soil of the same plants, with little overlap. Roots of plants growing in two contrasting field soils had high relative abundance of Leptodontidium sp. C2 BESC 319 g whereas rhizosphere soil was characterised by high relative abundance of Trichosporon dulcitum or Cryptococcus terreus, depending upon the soil type. Differences between different cultivars were not as clear. Inoculation with the pathogen V. dahliae had a significant influence on community structure, generally decreasing the number of rhizosphere soil- and root-inhabiting fungi. Leptodontidium sp. C2 BESC 319 g was the dominant fungus responding positively to inoculation with V. dahliae. The results suggest that 1) plant roots select microorganisms from the wider rhizosphere pool, 2) that both rhizosphere soil and root inhabiting fungal communities are influenced by V. dahliae and 3) that soil type has a stronger influence on both of these communities than cultivar. PMID:25347069

  3. Molecular cloning and functional analysis of GbRVd, a gene in Gossypium barbadense that plays an important role in conferring resistance to Verticillium wilt.

    PubMed

    Yang, Jun; Ma, Qing; Zhang, Yan; Wang, Xingfen; Zhang, Guiyin; Ma, Zhiying

    2016-01-10

    Most of the disease resistance genes already characterized in plants encode nucleotide-binding site-leucine rich repeat (NBS-LRR) proteins that have key roles in resistance to Verticillium dahliae. Using a cDNA library and RACE protocols, we cloned a coiled-coil (CC)-NBS-LRR-type gene, GbRVd, from a resistant tetraploid cotton species, Gossypium barbadense (RVd=Resistance to V. dahliae). We also applied RT-qPCR and VIGS technologies to analyze how expression of GbRVd was induced upon attack by V. dahliae. Its 2862-bp ORF encodes a predicted protein containing 953 amino acid residues, with a predicted molecular weight of 110.17kDa and an isoelectric point of 5.87. GbRVd has three domains - CC, NBS, and LRR - and is most closely related to Gossypium raimondii RVd (88% amino acid identity). Profiling demonstrated that GbRVd is constitutively expressed in all tested tissues, and transcript levels are especially high in the leaves. In plants inoculated with V. dahliae, GbRVd was significantly up-regulated when compared with the control, with expression peaking at 48h post-inoculation. Silencing of GbRVd in cotton through VIGS dramatically down-regulated SA, NO, and H2O2 production, resulting in greater susceptibility to V. dahliae. Taken together, these results suggest that GbRVd has an important role in protecting G. barbadense against infection by V. dahliae. PMID:26407869

  4. In silico prediction of drug targets in phytopathogenic Pseudomonas syringae pv. phaseolicola: charting a course for agrigenomics translation research.

    PubMed

    Katara, Pramod; Grover, Atul; Sharma, Vinay

    2012-12-01

    Pseudomonas syringae pv. phaseolicola is a major plant pathogen causing halo blight disease and has world-wide importance. The emerging post-genomics field of agrigenomics, together with the availability of whole genome sequences of a number of pathogens and host organisms, offer the promise for identification of potential drug targets using sequence comparison approaches. On the other hand, lack of gene expression data for most of the phytopathogenic microbes still remains a formidable barrier. The present study aimed at the prediction of drug targets in Pseudomonas syringae pv. phaseolicola by exploiting the knowledge of Codon Usage bias for gene expression subtractively, supported by gene expression analysis and sequence comparisons. Based on screening of the Database of Essential Genes using blastx, 158 of the total 5172 genes of P. syringae pv. phaseolicola were enlisted as vitally essential genes. Similarity search for these 158 essential genes against available host-plant sequences (Phaseolous vulgaris) led to the identification of homologues of 21 genes in the host genome, thus leaving behind a subset of 137 genes. Expression analysis of these 137 genes using RSCU(gene,) validated by microarray gene expression data suggested 22 genes had higher expression levels in the cell, and therefore their products have been identified as putative drug targets. The gene ontology analysis of these 22 genes revealed their indispensable roles in pivotal metabolic pathways of P. syringae pv. phaseolicola. Upon comparison of the sequences of these genes with other soil bacteria, we identified two genes that were unique to P. syringae pv. phaseolicola. The products of these genes can potentially be utilized for drug development so as to control the halo blight disease and thereby accelerate translation research in the nascent field of agrigenomics. PMID:23215808

  5. Identification and characterization of naturally occurring DSF-family quorum sensing signal turnover system in the phytopathogen Xanthomonas.

    PubMed

    Zhou, Lian; Wang, Xing-Yu; Sun, Shuang; Yang, Li-Chao; Jiang, Bo-Le; He, Ya-Wen

    2015-11-01

    Molecules of the diffusible signal factor (DSF)-family are a class of quorum sensing (QS) signals used by the phytopathogens Xanthomonas. Studies during the last decade have outlined how Xanthomonas cells enter the QS phase. However, information on the mechanism underlying its exit from the QS phase is limited. RpfB has recently been reported as a fatty acyl-CoA ligase (FCL) that activates a wide range of fatty acids to their CoA esters in vitro. Here, we establish an improved quantification assay for DSF-family signals using liquid chromatography-mass spectrometry in X. campestris pv. campestris (Xcc). We first demonstrated that RpfB represents a naturally occurring DSF-family signal turnover system. RpfB effectively turns over DSF-family signals DSF and BDSF in vivo. RpfB FCL enzymatic activity is required for DSF and BDSF turnover. Deletion of rpfB slightly increased Xcc virulence in the Chinese radish and overexpression of rpfB significantly decreased virulence. We further showed that the expression of rpfB is growth phase-dependent, and its expression is significantly enhanced when Xcc cells enter the stationary phase. DSF regulates rpfB expression in a concentration-dependent manner. rpfB expression is also negatively regulated by the DSF signalling components RpfC, RpfG and Clp. The global transcription factor Clp directly binds to the AATGC-tgctgc-GCATC motif in the promoter region of rpfB to repress its expression. Finally, RpfB-dependent signal turnover system was detected in a wide range of bacterial species, suggesting that it is a conserved mechanism. PMID:26234930

  6. Comparison of ATPase-Encoding Type III Secretion System hrcN Genes in Biocontrol Fluorescent Pseudomonads and in Phytopathogenic Proteobacteria

    PubMed Central

    Rezzonico, Fabio; Défago, Geneviève; Moënne-Loccoz, Yvan

    2004-01-01

    Type III protein secretion systems play a key role in the virulence of many pathogenic proteobacteria, but they also occur in nonpathogenic, plant-associated bacteria. Certain type III protein secretion genes (e.g., hrcC) have been found in Pseudomonas sp. strain SBW25 (and other biocontrol pseudomonads), but other type III protein secretion genes, such as the ATPase-encoding gene hrcN, have not been found. Using both colony hybridization and a PCR approach, we show here that hrcN is nevertheless present in many biocontrol fluorescent pseudomonads. The phylogeny of biocontrol Pseudomonas strains based on partial hrcN sequences was largely congruent with the phylogenies derived from analyses of rrs (encoding 16S rRNA) and, to a lesser extent, biocontrol genes, such as phlD (for 2,4-diacetylphloroglucinol production) and hcnBC (for HCN production). Most biocontrol pseudomonads clustered separately from phytopathogenic proteobacteria, including pathogenic pseudomonads, in the hrcN tree. The exception was strain KD, which clustered with phytopathogenic pseudomonads, such as Pseudomonas syringae, suggesting that hrcN was acquired from the latter species. Indeed, strain KD (unlike strain SBW25) displayed the same organization of the hrpJ operon, which contains hrcN, as P. syringae. These results indicate that the occurrence of hrcN in most biocontrol pseudomonads is not the result of recent horizontal gene transfer from phytopathogenic bacteria, although such transfer might have occurred for a minority of biocontrol strains. PMID:15345390

  7. Rapid isolation of both double-stranded RNA and PCR-suitable DNA from the obligate biotrophic phytopathogenic fungus Uncinula necator using a commercially available reagent.

    PubMed

    Délye, C; Corio-Costet, M F

    1998-10-01

    A method for rapid extraction of both double-stranded RNA (dsRNA) and DNA from an obligate biotrophic phytopathogenic fungus is described. Lyophilised fungal material is incubated in a commercial guanidium thiocyanate reagent. Proteins and cell debris are centrifuged by chloroform precipitation. After precipitation in isopropanol and washing in 75% ethanol, nucleic acids are resuspended in water (10 microl/mg fungal dry weight). DsRNA is directly visualised by agarose gel electrophoresis. DNA contained in 10-fold dilutions of the samples proved to be suitable for PCR-based experiments. PMID:9779614

  8. Cloning, functional analysis and expression of a scytalone dehydratase gene ( SCD1) involved in melanin biosynthesis of the phytopathogenic fungus Bipolaris oryzae.

    PubMed

    Kihara, Junichi; Moriwaki, Akihiro; Ueno, Makoto; Tokunaga, Toshiko; Arase, Sakae; Honda, Yuichi

    2004-04-01

    Scytalone dehydratase is involved in the production of fungal dihydroxynaphthalene melanin. We isolated and characterized SCD1, a gene encoding scytalone dehydratase, from the phytopathogenic fungus Bipolaris oryzae. Sequence analysis showed that SCD1 encodes a putative protein that has 185 amino acids, a molecular weight of 21 kDa and 51-75% sequence identity to other fungal scytalone dehydratases. Targeted disruption of SCD1 showed that this gene is necessary for melanin biosynthesis in B. oryzae. Northern blot analysis showed that SCD1 transcripts are specifically enhanced by near-ultraviolet (300-400 nm) radiation. PMID:14716498

  9. The opgC gene is required for OPGs succinylation and is osmoregulated through RcsCDB and EnvZ/OmpR in the phytopathogen Dickeya dadantii

    PubMed Central

    Bontemps-Gallo, Sébastien; Madec, Edwige; Robbe-Masselot, Catherine; Souche, Erika; Dondeyne, Jacqueline; Lacroix, Jean-Marie

    2016-01-01

    Osmoregulated periplasmic glucans (OPGs) are a family of periplasmic oligosaccharides found in the envelope of most Proteobacteria. They are required for virulence of zoo- and phyto-pathogens. The glucose backbone of OPGs is substituted by various kinds of molecules depending on the species, O-succinyl residues being the most widely distributed. In our model, Dickeya dadantii, a phytopathogenic bacteria causing soft rot disease in a wide range of plant species, the backbone of OPGs is substituted by O-succinyl residues in media of high osmolarity and by O-acetyl residues whatever the osmolarity. The opgC gene encoding a transmembrane protein required for the succinylation of the OPGs in D. dadantii was found after an in silico search of a gene encoding a protein with the main characteristics recovered in the two previously characterized OpgC of E. coli and R. sphaeroides, i.e. 10 transmembrane segments and one acyl-transferase domain. Characterization of the opgC gene revealed that high osmolarity expression of the succinyl transferase is controlled by both the EnvZ-OmpR and RcsCDB phosphorelay systems. The loss of O-succinyl residue did not affect the virulence of D. dadantii, suggesting that only the glucose backbone of OPGs is required for virulence. PMID:26790533

  10. The Lysobacter capsici AZ78 Genome Has a Gene Pool Enabling it to Interact Successfully with Phytopathogenic Microorganisms and Environmental Factors.

    PubMed

    Puopolo, Gerardo; Tomada, Selena; Sonego, Paolo; Moretto, Marco; Engelen, Kristof; Perazzolli, Michele; Pertot, Ilaria

    2016-01-01

    Lysobacter capsici AZ78 has considerable potential for biocontrol of phytopathogenic microorganisms. However, lack of information about genetic cues regarding its biological characteristics may slow down its exploitation as a biofungicide. In order to obtain a comprehensive overview of genetic features, the L. capsici AZ78 genome was sequenced, annotated and compared with the phylogenetically related pathogens Stenotrophomonas malthophilia K729a and Xanthomonas campestris pv. campestris ATCC 33913. Whole genome comparison, supported by functional analysis, indicated that L. capsici AZ78 has a larger number of genes responsible for interaction with phytopathogens and environmental stress than S. malthophilia K729a and X. c. pv. campestris ATCC 33913. Genes involved in the production of antibiotics, lytic enzymes and siderophores were specific for L. capsici AZ78, as well as genes involved in resistance to antibiotics, environmental stressors, fungicides and heavy metals. The L. capsici AZ78 genome did not encompass genes involved in infection of humans and plants included in the S. malthophilia K729a and X. c. pv. campestris ATCC 33913 genomes, respectively. The L. capsici AZ78 genome provides a genetic framework for detailed analysis of other L. capsici members and the development of novel biofungicides based on this bacterial strain. PMID:26903975

  11. Chemical composition and antimicrobial activity of essential oils from Acantholippia deserticola, Artemisia proceriformis, Achillea micrantha and Libanotis buchtormensis against phytopathogenic bacteria and fungi.

    PubMed

    Sampietro, Diego A; Lizarraga, Emilio F; Ibatayev, Zharkyn A; Omarova, Akerke B; Suleimen, Yerlan M; Catalán, Cesar A N

    2016-09-01

    Essential oils from aerial parts of Acantholippia deserticola, Artemisia proceriformis, Achillea micrantha and Libanotis buchtormensis were analysed by GC-MS. The major compounds identified were β-thujone (66.5 ± 0.2%), and trans-sabinyl acetate (12.1 ± 0.2%) in A. deserticola; α-thujone (66.9 ± 0.4%) in A. proceriformis; 1,8-cineole (26.9 ± 0.5%), and camphor (17.7 ± 0.3%) in A. micrantha and cis-β-ocimene (23.3 ± 0.3%), and trans-β-ocimene (18.4 ± 0.2%) in L. buchtormensis. The oils showed a weak antimicrobial effect (MIC100 > 1.5 mg/ml) on most phytopathogens tested. A moderate antimicrobial activity (MIC100 between 0.5 and 1.5 mg/ml) was displayed by the oils of A. deserticola, A. micrantha and L. buchtormensis on Septoria tritici and by the oil of A. deserticola on Septoria glycine. The antimicrobial activity was associated to the contents of β-thujone, trans-sabinyl acetate and trans-sabinol. Our results indicate that the tested essential oils have little inhibitory potency not suitable for use as plant protection products against the phytopathogens assayed. PMID:26404704

  12. The Lysobacter capsici AZ78 Genome Has a Gene Pool Enabling it to Interact Successfully with Phytopathogenic Microorganisms and Environmental Factors

    PubMed Central

    Puopolo, Gerardo; Tomada, Selena; Sonego, Paolo; Moretto, Marco; Engelen, Kristof; Perazzolli, Michele; Pertot, Ilaria

    2016-01-01

    Lysobacter capsici AZ78 has considerable potential for biocontrol of phytopathogenic microorganisms. However, lack of information about genetic cues regarding its biological characteristics may slow down its exploitation as a biofungicide. In order to obtain a comprehensive overview of genetic features, the L. capsici AZ78 genome was sequenced, annotated and compared with the phylogenetically related pathogens Stenotrophomonas malthophilia K729a and Xanthomonas campestris pv. campestris ATCC 33913. Whole genome comparison, supported by functional analysis, indicated that L. capsici AZ78 has a larger number of genes responsible for interaction with phytopathogens and environmental stress than S. malthophilia K729a and X. c. pv. campestris ATCC 33913. Genes involved in the production of antibiotics, lytic enzymes and siderophores were specific for L. capsici AZ78, as well as genes involved in resistance to antibiotics, environmental stressors, fungicides and heavy metals. The L. capsici AZ78 genome did not encompass genes involved in infection of humans and plants included in the S. malthophilia K729a and X. c. pv. campestris ATCC 33913 genomes, respectively. The L. capsici AZ78 genome provides a genetic framework for detailed analysis of other L. capsici members and the development of novel biofungicides based on this bacterial strain. PMID:26903975

  13. Analysis of Phaseolus vulgaris Response to Its Association with Trichoderma harzianum (ALL-42) in the Presence or Absence of the Phytopathogenic Fungi Rhizoctonia solani and Fusarium solani

    PubMed Central

    Pereira, Jackeline L.; Queiroz, Rayner M. L.; Charneau, Sébastien O.; Felix, Carlos R.; Ricart, Carlos A. O.; da Silva, Francilene Lopes; Steindorff, Andrei Stecca; Ulhoa, Cirano J.; Noronha, Eliane F.

    2014-01-01

    The present study was carried out to evaluate the ability of Trichoderma harzianum (ALL 42-isolated from Brazilian Cerrado soil) to promote common bean growth and to modulate its metabolism and defense response in the presence or absence of the phytopathogenic fungi Rhizoctonia solani and Fusarium solani using a proteomic approach. T. harzianum was able to promote common bean plants growth as shown by the increase in root/foliar areas and by size in comparison to plants grown in its absence. The interaction was shown to modulate the expression of defense-related genes (Glu1, pod3 and lox1) in roots of P. vulgaris. Proteomic maps constructed using roots and leaves of plants challenged or unchallenged by T. harzianum and phytopathogenic fungi showed differences. Reference gels presented differences in spot distribution (absence/presence) and relative volumes of common spots (up or down-regulation). Differential spots were identified by peptide fingerprinting MALDI-TOF mass spectrometry. A total of 48 identified spots (19 for leaves and 29 for roots) were grouped into protein functional classes. For leaves, 33%, 22% and 11% of the identified proteins were categorized as pertaining to the groups: metabolism, defense response and oxidative stress response, respectively. For roots, 17.2%, 24.1% and 10.3% of the identified proteins were categorized as pertaining to the groups: metabolism, defense response and oxidative stress response, respectively. PMID:24878929

  14. A New Synthetic Amphiploid (AADDAA) between Gossypium hirsutum and G. arboreum Lays the Foundation for Transferring Resistances to Verticillium and Drought.

    PubMed

    Chen, Yu; Wang, Yingying; Zhao, Ting; Yang, Jianwei; Feng, Shouli; Nazeer, Wajad; Zhang, Tianzhen; Zhou, Baoliang

    2015-01-01

    Gossypium arboreum, a cultivated cotton species (2n = 26, AA) native to Asia, possesses invaluable characteristics unavailable in the tetraploid cultivated cotton gene pool, such as resistance to pests and diseases and tolerance to abiotic stresses. However, it is quite difficult to transfer favorable traits into Upland cotton through conventional methods due to the cross-incompatibility of G. hirsutum (2n = 52, AADD) and G. arboreum. Here, we improved an embryo rescue technique to overcome the cross-incompatibility between these two parents for transferring favorable genes from G. arboreum into G. hirsutum. Our results indicate that MSB2K supplemented with 0.5 mg l(-1) kinetin and 250 mg(-1) casein hydrolysate is an efficient initial medium for rescuing early (3 d after pollination) hybrid embryos. Eight putative hybrids were successfully obtained, which were further verified and characterized by cytology, molecular markers and morphological analysis. The putative hybrids were subsequently treated with different concentrations of colchicine solution to double their chromosomes. The results demonstrate that four putative hybrid plants were successfully chromosome-doubled by treatment with 0.1% colchicine for 24 h and become amphiploid, which were confirmed by cytological observation, self-fertilization and backcrossing. Preliminary assessments of resistance at seedling stage indicate that the synthetic amphiploid showed highly resistant to Verticillium and drought. The synthetic amphiploid between G. hirsutum × G. arboreum would lay the foundation for developing G. arboreum-introgressed lines with the uniform genetic background of G. hirsutum acc TM-1, which would greatly enhance and simplify the mining, isolation, characterization, cloning and use of G. arboreum-specific desirable genes in future cotton breeding programs. PMID:26061996

  15. A New Synthetic Amphiploid (AADDAA) between Gossypium hirsutum and G. arboreum Lays the Foundation for Transferring Resistances to Verticillium and Drought

    PubMed Central

    Chen, Yu; Wang, Yingying; Zhao, Ting; Yang, Jianwei; Feng, Shouli; Nazeer, Wajad; Zhang, Tianzhen; Zhou, Baoliang

    2015-01-01

    Gossypium arboreum, a cultivated cotton species (2n = 26, AA) native to Asia, possesses invaluable characteristics unavailable in the tetraploid cultivated cotton gene pool, such as resistance to pests and diseases and tolerance to abiotic stresses. However, it is quite difficult to transfer favorable traits into Upland cotton through conventional methods due to the cross-incompatibility of G. hirsutum (2n = 52, AADD) and G. arboreum. Here, we improved an embryo rescue technique to overcome the cross-incompatibility between these two parents for transferring favorable genes from G. arboreum into G. hirsutum. Our results indicate that MSB2K supplemented with 0.5 mgl-1 kinetin and 250 mg-1 casein hydrolysate is an efficient initial medium for rescuing early (3 d after pollination) hybrid embryos. Eight putative hybrids were successfully obtained, which were further verified and characterized by cytology, molecular markers and morphological analysis. The putative hybrids were subsequently treated with different concentrations of colchicine solution to double their chromosomes. The results demonstrate that four putative hybrid plants were successfully chromosome-doubled by treatment with 0.1% colchicine for 24 h and become amphiploid, which were confirmed by cytological observation, self-fertilization and backcrossing. Preliminary assessments of resistance at seedling stage indicate that the synthetic amphiploid showed highly resistant to Verticillium and drought. The synthetic amphiploid between G. hirsutum × G. arboreum would lay the foundation for developing G. arboreum-introgressed lines with the uniform genetic background of G. hirsutum acc TM-1, which would greatly enhance and simplify the mining, isolation, characterization, cloning and use of G. arboreum-specific desirable genes in future cotton breeding programs. PMID:26061996

  16. A study of the changes in quantitative activity of some enzymes in olive cultivars during the interaction between Verticillium wilt and root-knot nematode.

    PubMed

    Saeedizadeh, Ayatollah; Kheiri, Ahmad; Zad, Javad; Etebarian, Hasan Reza; Bandani, Ali Reza; Sharifi, Rouhollah

    2009-01-01

    Second stage juvenile (J2) of root-knot nematode, Meloidogyne javanica, and microsclerotia of verticilliosis, Verticillium dahliae, were used as the source of inoculum for nematode and fungus respectively. One-year-old seedlings of olive cultivar, Zard, Roghani, Koroneiki and Manzanilla, were transplanted to pots containing 2000g of sterilized sandy loam soil. Experiment was conducted in completely randomized design with 32 Treatments and five replications. Treatments were as follows: control, nematode alone, fungus alone and fungus+nematode. Pots were inoculated with (0, 2000, 3000, 4000) J2 of nematode and/or (10 no/g soil) microsclerotia of fungus according to the treatments. Quantitative activity of soluble proxidase, cell wall bounded proxidase, beta-1,3-glucanase and B-1,4-glucanase were determined by the pirocatechol, hydrogen proxide, guaiacol and laminarin-dinitrosalicylilate methods, respectively, on 1,10, 20 and 30 days after inoculation. Results showed that these enzymes in leaves and roots of seedlings inoculated with pathogens increased (p < or = 0/05). In this study changes of these enzymes as compared with nematode alone and fungus alone treatments were increased in fungus+nematode treatments in seedlings (p < or = 0/05). Maximum of quantitative changes of these enzymes were observed in fungus+nematode (4000J2) treatment on cv. Koroneiki. Based on the results obtained in this study, quantitative activity of these enzymes in olive roots and leaves were be more on cvs. Koroneiki, Roghani, Zard and Manzanilla, respectively (p < or = 0/05). PMID:20222618

  17. Purification, characterization of a CkChn134 protein from Cynanchum komarovii seeds and synergistic effect with CkTLP against Verticillium dahliae

    PubMed Central

    Wang, Qinghua; Zhang, Yongan; Hou, Yuxia; Wang, Ping; Zhou, Sihong; Ma, Xiaowen; Zhang, Ning

    2012-01-01

    Cynanchum komarovii Al Iljinski is a desert plant that has been used as analgesic, anthelminthic, and antidiarrheal, but also as herbal medicine to treat cholecystitis in people. In this work, an antifungal protein with sequence homology to chitinase was isolated from C. komarovii seeds and named CkChn134. The three-dimensional structure prediction of CkChn134 indicated that the protein has a loop domain formed a thin cleft, which is able to bind molecules and substrates. The protein and CkTLP synergistically inhibited the fungal growth of Verticillium dahliae, Fusarium oxysporum, Rhizoctonia solani, Botrytis cinerea, and Valsa mali in vitro. The full-length cDNA was cloned by RT-PCR and RACE-PCR according to the partial protein sequences obtained by nanoESI-MS/MS. The real-time PCR showed that the transcription level of CkChn134 had a significant increase under the stress of ethylene, NaCl, low temperature, drought, and pathogen infection, which indicates that CkChn134 may play an important role in response to abiotic and biotic stresses. The CkChn134 protein was located in the extracellular space/cell wall by CkChn134::GFP fusion protein in transgenic Arabidopsis. Furthermore, overexpression of CkChn134 significantly enhanced the resistance of transgenic Arabidopsis against V. dahliae. Interestingly, the coexpression of CkChn134 and CkTLP showed substantially greater protection against the fungal pathogen V. dahliae than either transgene alone. The results suggest that the CkChn134 is a good candidate protein or gene, and it had a potential synergistic effect with CkTLP for contributing to the development of disease-resistant crops. PMID:22532259

  18. Lignin metabolism has a central role in the resistance of cotton to the wilt fungus Verticillium dahliae as revealed by RNA-Seq-dependent transcriptional analysis and histochemistry

    PubMed Central

    Xu, Li; Zhu, Longfu; Tu, Lili; Liu, Linlin; Yuan, Daojun; Jin, Li; Long, Lu; Zhang, Xianlong

    2011-01-01

    The incompatible pathosystem between resistant cotton (Gossypium barbadense cv. 7124) and Verticillium dahliae strain V991 was used to study the cotton transcriptome changes after pathogen inoculation by RNA-Seq. Of 32 774 genes detected by mapping the tags to assembly cotton contigs, 3442 defence-responsive genes were identified. Gene cluster analyses and functional assignments of differentially expressed genes indicated a significant transcriptional complexity. Quantitative real-time PCR (qPCR) was performed on selected genes with different expression levels and functional assignments to demonstrate the utility of RNA-Seq for gene expression profiles during the cotton defence response. Detailed elucidation of responses of leucine-rich repeat receptor-like kinases (LRR-RLKs), phytohormone signalling-related genes, and transcription factors described the interplay of signals that allowed the plant to fine-tune defence responses. On the basis of global gene regulation of phenylpropanoid metabolism-related genes, phenylpropanoid metabolism was deduced to be involved in the cotton defence response. A closer look at the expression of these genes, enzyme activity, and lignin levels revealed differences between resistant and susceptible cotton plants. Both types of plants showed an increased level of expression of lignin synthesis-related genes and increased phenylalanine-ammonia lyase (PAL) and peroxidase (POD) enzyme activity after inoculation with V. dahliae, but the increase was greater and faster in the resistant line. Histochemical analysis of lignin revealed that the resistant cotton not only retains its vascular structure, but also accumulates high levels of lignin. Furthermore, quantitative analysis demonstrated increased lignification and cross-linking of lignin in resistant cotton stems. Overall, a critical role for lignin was believed to contribute to the resistance of cotton to disease. PMID:21862479

  19. A cupin domain-containing protein with a quercetinase activity (VdQase) regulates Verticillium dahliae's pathogenicity and contributes to counteracting host defenses

    PubMed Central

    El Hadrami, Abdelbasset; Islam, Md. Rashidul; Adam, Lorne R.; Daayf, Fouad

    2015-01-01

    We previously identified rutin as part of potato root responses to its pathogen Verticillium dahliae. Rutin was directly toxic to the pathogen at doses greater than 160 μM, a threshold below which many V. dahliae pathogenicity-related genes were up-regulated. We identified and characterized a cupin domain-containing protein (VdQase) with a dioxygenase activity and a potential role in V. dahliae-potato interactions. The pathogenicity of VdQase knock-out mutants generated through Agrobacterium tumefasciens-mediated transformation was significantly reduced on susceptible potato cultivar Kennebec compared to wild type isolates. Fluorescence microscopy revealed a higher accumulation of flavonols in the stems of infected potatoes and a higher concentration of rutin in the leaves in response to the VdQase mutants as compared to wild type isolates. This, along with the HPLC characterization of high residual and non-utilized quercetin in presence of the knockout mutants, indicates the involvement of VdQase in the catabolism of quercetin and possibly other flavonols in planta. Quantification of Salicylic and Jasmonic Acids (SA, JA) in response to the mutants vs. wild type isolates revealed involvement of VdQase in the interference with signaling, suggesting a role in pathogenicity. It is hypothesized that the by-product of dioxygenation 2-protocatechuoylphloroglucinolcarboxylic acid, after dissociating into phloroglucinol and protocatechuoyl moieties, becomes a starting point for benzoic acid and SA, thereby interfering with the JA pathway and affecting the interaction outcome. These events may be key factors for V. dahliae in countering potato defenses and becoming notorious in the rhizosphere. PMID:26113857

  20. Genome-Wide Identification of HrpL-Regulated Genes in the Necrotrophic Phytopathogen Dickeya dadantii 3937

    PubMed Central

    Yang, Shihui; Peng, Quan; Zhang, Qiu; Zou, Lifang; Li, Yan; Robert, Christelle; Pritchard, Leighton; Liu, Hui; Hovey, Raymond; Wang, Qi; Birch, Paul; Toth, Ian K.; Yang, Ching-Hong

    2010-01-01

    Background Dickeya dadantii is a necrotrophic pathogen causing disease in many plants. Previous studies have demonstrated that the type III secretion system (T3SS) of D. dadantii is required for full virulence. HrpL is an alternative sigma factor that binds to the hrp box promoter sequence of T3SS genes to up-regulate their expression. Methodology/Principal Findings To explore the inventory of HrpL-regulated genes of D. dadantii 3937 (3937), transcriptome profiles of wild-type 3937 and a hrpL mutant grown in a T3SS-inducing medium were examined. Using a cut-off value of 1.5, significant differential expression was observed in sixty-three genes, which are involved in various cellular functions such as type III secretion, chemotaxis, metabolism, regulation, and stress response. A hidden Markov model (HMM) was used to predict candidate hrp box binding sites in the intergenic regions of 3937, including the promoter regions of HrpL-regulated genes identified in the microarray assay. In contrast to biotrophic phytopathgens such as Pseudomonas syringae, among the HrpL up-regulated genes in 3937 only those within the T3SS were found to contain a hrp box sequence. Moreover, direct binding of purified HrpL protein to the hrp box was demonstrated for hrp box-containing DNA fragments of hrpA and hrpN using the electrophoretic mobility shift assay (EMSA). In this study, a putative T3SS effector DspA/E was also identified as a HrpL-upregulated gene, and shown to be translocated into plant cells in a T3SS-dependent manner. Conclusion/Significances We provide the genome-wide study of HrpL-regulated genes in a necrotrophic phytopathogen (D. dadantii 3937) through a combination of transcriptomics and bioinformatics, which led to identification of several effectors. Our study indicates the extent of differences for T3SS effector protein inventory requirements between necrotrophic and biotrophic pathogens, and may allow the development of different strategies for disease control for

  1. The bacterial lipopeptide iturins induce Verticillium dahliae cell death by affecting fungal signalling pathways and mediate plant defence responses involved in pathogen-associated molecular pattern-triggered immunity.

    PubMed

    Han, Qin; Wu, Fengli; Wang, Xiaonan; Qi, Hong; Shi, Liang; Ren, Ang; Liu, Qinghai; Zhao, Mingwen; Tang, Canming

    2015-04-01

    Verticillium wilt in cotton caused by Verticillium dahliae is one of the most serious plant diseases worldwide. Because no known fungicides or cotton cultivars provide sufficient protection against this pathogen, V. dahliae causes major crop yield losses. Here, an isolated cotton endophytic bacterium, designated Bacillus amyloliquefaciens 41B-1, exhibited greater than 50% biocontrol efficacy against V. dahliae in cotton plants under greenhouse conditions. Through high-performance liquid chromatography and mass analysis of the filtrate, we found that the antifungal compounds present in the strain 41B-1 culture filtrate were a series of isoforms of iturins. The purified iturins suppressed V. dahliae microsclerotial germination in the absence or presence of cotton. Treatment with the iturins induced reactive oxygen species bursts, Hog1 mitogen-activated protein kinase (MAPK) activation and defects in cell wall integrity. The oxidative stress response and high-osmolarity glycerol pathway contribute to iturins resistance in V. dahliae. In contrast, the Slt2 MAPK pathway may be involved in iturins sensitivity in this fungus. In addition to antagonism, iturins could induce plant defence responses as activators and mediate pathogen-associated molecular pattern-triggered immunity. These findings suggest that iturins may affect fungal signalling pathways and mediate plant defence responses against V. dahliae. PMID:24934960

  2. Draft Genome Sequences of Pseudomonas fluorescens Strains PA4C2 and PA3G8 and Pseudomonas putida PA14H7, Three Biocontrol Bacteria against Dickeya Phytopathogens

    PubMed Central

    Cigna, Jérémy; Raoul des Essarts, Yannick; Mondy, Samuel; Hélias, Valérie; Beury-Cirou, Amélie

    2015-01-01

    Pseudomonas fluorescens strains PA4C2 and PA3G8 and Pseudomonas putida strain PA14H7 were isolated from potato rhizosphere and show an ability to inhibit the growth of Dickeya phytopathogens. Here, we report their draft genome sequences, which provide a basis for understanding the molecular mechanisms involved in antibiosis against Dickeya. PMID:25635023

  3. Anti-phytopathogen potential of endophytic actinobacteria isolated from tomato plants (Lycopersicon esculentum) in southern Brazil, and characterization of Streptomyces sp. R18(6), a potential biocontrol agent.

    PubMed

    de Oliveira, Margaroni Fialho; da Silva, Mariana Germano; Van Der Sand, Sueli T

    2010-09-01

    Tomato plants (Lycopersicon esculentum) are highly susceptible to phytopathogen attack. The resulting intensive application of pesticides on tomato crops can affect the environment and health of humans and animals. The objective of this study was to select potential biocontrol agents among actinobacteria from tomato plants, in a search for alternative phytopathogen control. We evaluated 70 endophytic actinobacteria isolated from tomato plants in southern Brazil, testing their antimicrobial activity, siderophore production, indoleacetic acid production, and phosphate solubility. The actinomycete isolate with the highest antimicrobial potential was selected using the agar-well diffusion method, in order to optimize conditions for the production of compounds with antimicrobial activity. For this study, six growth media (starch casein-SC, ISP2, Bennett's, Sahin, Czapek-Dox, and TSB), three temperatures (25 degrees C, 30 degrees C, and 35 degrees C) and different pH were tested. Of the actinobacteria tested, 88.6% showed antimicrobial activity against at least one phytopathogen, 72.1% showed a positive reaction for indoleacetic acid production, 86.8% produced siderophores and 16.2% showed a positive reaction for phosphate solubility. Isolate R18(6) was selected due to its antagonistic activity against all phytopathogenic microorganisms tested in this study. The best conditions for production were observed in the SC medium, at 30 degrees C and pH 7.0. The isolate R18(6) showed close biochemical and genetic similarity to Streptomyces pluricolorescens. PMID:20542109

  4. Cloning, functional characterization, and near-ultraviolet radiation-enhanced expression of a photolyase gene (PHR1) from the phytopathogenic fungus Bipolaris oryzae.

    PubMed

    Kihara, Junichi; Moriwaki, Akihiro; Matsuo, Nobuhito; Arase, Sakae; Honda, Yuichi

    2004-07-01

    Photolyase is a DNA repair enzyme that can absorb blue/ultraviolet A light as energy and split a pyrimidine dimer induced by ultraviolet radiation. We isolated and characterized PHR1, a gene encoding photolyase, from the phytopathogenic fungus Bipolaris oryzae. Sequence analysis showed that PHR1 encodes a putative protein that has 634 amino acids, a molecular mass of 72.6 kDa, and 51.3-55.5% sequence identity to other fungal photolyases. Complementation of the photoreactivation-deficient Escherichia coli mutant by PHR1 cDNA demonstrated that the PHR1 gene from B. oryzae encodes a functional photolyase. Real-time PCR analysis showed that the PHR1 transcripts were specifically enhanced by near-ultraviolet radiation (300-400 nm) and by sunlight. PMID:15138697

  5. Verticillium dahliae race 2-specific PCR reveals a high frequency of race 2 strains in commercial spinach seed lots and delineates race structure.

    PubMed

    Short, Dylan P G; Gurung, Suraj; Maruthachalam, Karunakaran; Atallah, Zahi K; Subbarao, Krishna V

    2014-07-01

    Two pathogenic races of Verticillium dahliae have been described on lettuce and tomato. Host resistance to race 1 is governed by plant immune receptors that recognize the race 1-specific fungal effector Ave1. Only partial resistance to race 2 exists in lettuce. Although polymerase chain reaction (PCR) assays are available to identify race 1, no complementary test exists to positively identify race 2, except for lengthy pathogenicity assays on host differentials. Using the genome sequences of two isolates of V. dahliae, one each from races 1 and 2, we identified potential markers and PCR primers to distinguish the two races. Several primer pairs based on polymorphisms between the races were designed and tested on reference isolates of known race. One primer pair, VdR2F-VdR2R, consistently yielded a 256-bp amplicon in all race 2 isolates exclusively. We screened DNA from 677 V. dahliae isolates, including 340 from spinach seedlots, with the above primer pair and a previously published race 1-specific primer pair. DNA from isolates that did not amplify with race 1-specific PCRs amplified with the race 2-specific primers. To validate this, two differential lines of lettuce were inoculated with 53 arbitrarily selected isolates from spinach seed and their pathogenicity and virulence were assessed in a greenhouse. The reactions of the differential cultivars strongly supported the PCR data. V. dahliae race structure was investigated in crops in coastal California and elsewhere using primers specific to the two races. All artichoke isolates from California were race 1, whereas nearly all tomato isolates were race 2. Isolates from lettuce, pepper, and strawberry from California as well as isolates from spinach seed from two of four countries comprised both races, whereas only race 2 was observed in cotton, mint, olive, and potato. This highlights the importance of identifying resistance against race 2 in different hosts. The technique developed in this study will benefit

  6. An ethylene response-related factor, GbERF1-like, from Gossypium barbadense improves resistance to Verticillium dahliae via activating lignin synthesis.

    PubMed

    Guo, Weifeng; Jin, Li; Miao, Yuhuan; He, Xin; Hu, Qin; Guo, Kai; Zhu, Longfu; Zhang, Xianlong

    2016-06-01

    An ethylene response-related factor, GbERF1-like, from Gossypium barbadense cv. '7124' involved in the defence response to Verticillium dahliae was characterized. GbERF1-like transcripts present ubiquitously in various tissues, with higher accumulation in flower organs. GbERF1-like was also responsive to defence-related phytohormones and V. dahliae infection. The downregulation of GbERF1-like increased the susceptibility of cotton plants to V. dahliae infection, while overexpression of this gene improved disease resistance in both cotton and Arabidopsis, coupled with activation of the pathogenesis-related proteins. Further analysis revealed that genes involved in lignin synthesis, such as PAL, C4H, C3H, HCT, CCoAOMT, CCR and F5H, showed higher expression levels in the overexpressing cotton and Arabidopsis lines and lower expression levels in the RNAi cotton lines. The expression levels of these genes increased obviously when the GbERF1-like-overexpressing plants were inoculated with V. dahliae. Meanwhile, significant differences in the content of whole lignin could be found in the stems of transgenic and wild-type plants after inoculation with V. dahliae, as revealed by metabolic and histochemical analysis. More lignin could be detected in GbERF1-like-overexpressing cotton and Arabidopsis but less in GbERF1-like-silencing cotton compared with wild-type plants. The ratio of S and G monomers in GbERF1-like-overexpressing cotton and Arabidopsis increased significantly after infection by V. dahliae. Moreover, our results showed that the promoters of GhHCT1 and AtPAL3 could be transactivated by GbERF1-like in vivo based on yeast one-hybrid assays and dual-luciferase reporter assays. Knockdown of GhHCT1 in GbERF1-like over-expressing cotton decreases resistance to V. dahliae. Collectively, our results suggest that GbERF1-like acts as a positive regulator in lignin synthesis and contributes substantially to resistance to V. dahliae in plants. PMID:26971283

  7. Effect of crude plant extracts from some Oaxacan flora on two deleterious fungal phytopathogens and extract compatibility with a biofertilizer strain

    PubMed Central

    Lira-De León, Karla I.; Ramírez-Mares, Marco V.; Sánchez-López, Vladimir; Ramírez-Lepe, Mario; Salas-Coronado, Raúl; Santos-Sánchez, Norma F.; Valadez-Blanco, Rogelio; Hernández-Carlos, Beatriz

    2014-01-01

    The antimicrobial activity of 12 plant extracts was tested against the phytopathogens Alternaria alternata and Fusarium solani. In addition, the compatibility of the extracts toward Bacillus liqueniformis, a biofertilizer and a non-target microorganism, was assessed. Plants tested belong to the Euphorbiaceae, Asteraceae, Crassulaceae, Rubiaceae, Convolvulaceae, Verbenaceae, Orchidaceae, Nyctaginaceae, Boraginaceae, and Tiliaceae families and were collected in the State of Oaxaca. The antifungal activity of the plant extracts (50–100 mg/mL) against A. alternata and F. solani, was determined by measuring the mycelium radial growth and obtaining the minimum inhibitory concentration (MIC) of fungal growth. In addition, with the aim of finding plant extracts which are compatible with a B. licheniformis biofertilizer strain and to test the non-toxic nature of the treatments, the toxicity of the extracts toward this strain was evaluated using the agar diffusion method. Azoxystrobin (12 μg) and chloramphenicol (30 μg) were used as positive controls for the pathogens and for the non-target bacteria, respectively. Plant extracts inhibited fungal growth in the ranges of 0.76–56.17% against F. solani and 2.02–69.07% against A. alternata. The extracts of Acalypha subviscida, Ipomoea murucoides, Tournefortia densiflora and Lantana achyranthifolia showed MIC values between 5.77–12.5 mg/mL for at least one of the fungal species. The best treatment, Adenophyllum aurantium, exhibited a maximum inhibition for both F. solani (56.17%, MIC = 7.78 mg/mL) and A. alternata (68.64% MIC = 7.78 mg/mL), and resulted innocuous toward B. licheniformis. Therefore, this plant has an outstanding potential for the agroecological control of fungal phytopathogens in industrial crops. PMID:25147544

  8. lpxC and yafS are the Most Suitable Internal Controls to Normalize Real Time RT-qPCR Expression in the Phytopathogenic Bacteria Dickeya dadantii

    PubMed Central

    Oger-Desfeux, Christine; Pineau-Chapelle, Emilie; Van Gijsegem, Frederique; Nasser, William; Reverchon, Sylvie

    2011-01-01

    Background Quantitative RT-PCR is the method of choice for studying, with both sensitivity and accuracy, the expression of genes. A reliable normalization of the data, using several reference genes, is critical for an accurate quantification of gene expression. Here, we propose a set of reference genes, of the phytopathogenic bacteria Dickeya dadantii and Pectobacterium atrosepticum, which are stable in a wide range of growth conditions. Results We extracted, from a D. dadantii micro-array transcript profile dataset comprising thirty-two different growth conditions, an initial set of 49 expressed genes with very low variation in gene expression. Out of these, we retained 10 genes representing different functional categories, different levels of expression (low, medium, and high) and with no systematic variation in expression correlating with growth conditions. We measured the expression of these reference gene candidates using quantitative RT-PCR in 50 different experimental conditions, mimicking the environment encountered by the bacteria in their host and directly during the infection process in planta. The two most stable genes (ABF-0017965 (lpxC) and ABF-0020529 (yafS) were successfully used for normalization of RT-qPCR data. Finally, we demonstrated that the ortholog of lpxC and yafS in Pectobacterium atrosepticum also showed stable expression in diverse growth conditions. Conclusions We have identified at least two genes, lpxC (ABF-0017965) and yafS (ABF-0020509), whose expressions are stable in a wide range of growth conditions and during infection. Thus, these genes are considered suitable for use as reference genes for the normalization of real-time RT-qPCR data of the two main pectinolytic phytopathogenic bacteria D. dadantii and P. atrosepticum and, probably, of other Enterobacteriaceae. Moreover, we defined general criteria to select good reference genes in bacteria. PMID:21637857

  9. Glucanases and Chitinases as Causal Agents in the Protection of Acacia Extrafloral Nectar from Infestation by Phytopathogens1[W][OA

    PubMed Central

    González-Teuber, Marcia; Pozo, María J.; Muck, Alexander; Svatos, Ales; Adame-Álvarez, Rosa M.; Heil, Martin

    2010-01-01

    Nectars are rich in primary metabolites and attract mutualistic animals, which serve as pollinators or as an indirect defense against herbivores. Their chemical composition makes nectars prone to microbial infestation. As protective strategy, floral nectar of ornamental tobacco (Nicotiana langsdorffii × Nicotiana sanderae) contains “nectarins,” proteins producing reactive oxygen species such as hydrogen peroxide. By contrast, pathogenesis-related (PR) proteins were detected in Acacia extrafloral nectar (EFN), which is secreted in the context of defensive ant-plant mutualisms. We investigated whether these PR proteins protect EFN from phytopathogens. Five sympatric species (Acacia cornigera, A. hindsii, A. collinsii, A. farnesiana, and Prosopis juliflora) were compared that differ in their ant-plant mutualism. EFN of myrmecophytes, which are obligate ant-plants that secrete EFN constitutively to nourish specialized ant inhabitants, significantly inhibited the growth of four out of six tested phytopathogenic microorganisms. By contrast, EFN of nonmyrmecophytes, which is secreted only transiently in response to herbivory, did not exhibit a detectable inhibitory activity. Combining two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis with nanoflow liquid chromatography-tandem mass spectrometry analysis confirmed that PR proteins represented over 90% of all proteins in myrmecophyte EFN. The inhibition of microbial growth was exerted by the protein fraction, but not the small metabolites of this EFN, and disappeared when nectar was heated. In-gel assays demonstrated the activity of acidic and basic chitinases in all EFNs, whereas glucanases were detected only in EFN of myrmecophytes. Our results demonstrate that PR proteins causally underlie the protection of Acacia EFN from microorganisms and that acidic and basic glucanases likely represent the most important prerequisite in this defensive function. PMID:20023149

  10. Effect of crude plant extracts from some Oaxacan flora on two deleterious fungal phytopathogens and extract compatibility with a biofertilizer strain.

    PubMed

    Lira-De León, Karla I; Ramírez-Mares, Marco V; Sánchez-López, Vladimir; Ramírez-Lepe, Mario; Salas-Coronado, Raúl; Santos-Sánchez, Norma F; Valadez-Blanco, Rogelio; Hernández-Carlos, Beatriz

    2014-01-01

    The antimicrobial activity of 12 plant extracts was tested against the phytopathogens Alternaria alternata and Fusarium solani. In addition, the compatibility of the extracts toward Bacillus liqueniformis, a biofertilizer and a non-target microorganism, was assessed. Plants tested belong to the Euphorbiaceae, Asteraceae, Crassulaceae, Rubiaceae, Convolvulaceae, Verbenaceae, Orchidaceae, Nyctaginaceae, Boraginaceae, and Tiliaceae families and were collected in the State of Oaxaca. The antifungal activity of the plant extracts (50-100 mg/mL) against A. alternata and F. solani, was determined by measuring the mycelium radial growth and obtaining the minimum inhibitory concentration (MIC) of fungal growth. In addition, with the aim of finding plant extracts which are compatible with a B. licheniformis biofertilizer strain and to test the non-toxic nature of the treatments, the toxicity of the extracts toward this strain was evaluated using the agar diffusion method. Azoxystrobin (12 μg) and chloramphenicol (30 μg) were used as positive controls for the pathogens and for the non-target bacteria, respectively. Plant extracts inhibited fungal growth in the ranges of 0.76-56.17% against F. solani and 2.02-69.07% against A. alternata. The extracts of Acalypha subviscida, Ipomoea murucoides, Tournefortia densiflora and Lantana achyranthifolia showed MIC values between 5.77-12.5 mg/mL for at least one of the fungal species. The best treatment, Adenophyllum aurantium, exhibited a maximum inhibition for both F. solani (56.17%, MIC = 7.78 mg/mL) and A. alternata (68.64% MIC = 7.78 mg/mL), and resulted innocuous toward B. licheniformis. Therefore, this plant has an outstanding potential for the agroecological control of fungal phytopathogens in industrial crops. PMID:25147544

  11. FTIR spectroscopic evaluation of changes in the cellular biochemical composition of the phytopathogenic fungus Alternaria alternata induced by extracts of some Greek medicinal and aromatic plants

    NASA Astrophysics Data System (ADS)

    Skotti, Efstathia; Kountouri, Sophia; Bouchagier, Pavlos; Tsitsigiannis, Dimitrios I.; Polissiou, Moschos; Tarantilis, Petros A.

    2014-06-01

    In this study, the biological activity of aquatic extracts of selected Greek medicinal and aromatic plants to the phytopathogenic fungus Alternaria alternata was investigated. Lamiaceae species (Hyssopus officinalis L., Melissa officinalis L., Origanum dictamnus L., Origanum vulgare L. and Salvia officinalis L.) were found to enhance significantly the mycelium growth whereas Crocus sativus appears to inhibit it slightly. M. officinalis and S. officinalis caused the highest stimulation in mycelium growth (+97%) and conidia production (+65%) respectively. In order to further investigate the bioactivity of plant extracts to A. alternata, we employed Fourier Transform Infrared Spectroscopy (FTIR). Differences of original spectra were assigned mainly to amides of proteins. The second derivative transformation of spectra revealed changes in spectral regions corresponding to absorptions of the major cellular constituents such as cell membrane and proteins. Principal component analysis of the second derivative transformed spectra confirmed that fatty acids of the cell membranes, amides of proteins and polysaccharides of the cell wall had the major contribution to data variation. FTIR band area ratios were found to correlate with fungal mycelium growth.

  12. Green synthesis of protein capped silver nanoparticles from phytopathogenic fungus Macrophomina phaseolina (Tassi) Goid with antimicrobial properties against multidrug-resistant bacteria

    NASA Astrophysics Data System (ADS)

    Chowdhury, Supriyo; Basu, Arpita; Kundu, Surekha

    2014-07-01

    In recent years, green synthesis of nanoparticles, i.e., synthesizing nanoparticles using biological sources like bacteria, algae, fungus, or plant extracts have attracted much attention due to its environment-friendly and economic aspects. The present study demonstrates an eco-friendly and low-cost method of biosynthesis of silver nanoparticles using cell-free filtrate of phytopathogenic fungus Macrophomina phaseolina. UV-visible spectrum showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) revealed the presence of spherical silver nanoparticles of the size range 5 to 40 nm, most of these being 16 to 20 nm in diameter. X-ray diffraction (XRD) spectrum of the nanoparticles exhibited 2 θ values corresponding to silver nanoparticles. These nanoparticles were found to be naturally protein coated. SDS-PAGE analysis showed the presence of an 85-kDa protein band responsible for capping and stabilization of the silver nanoparticles. Antimicrobial activities of the silver nanoparticles against human as well as plant pathogenic multidrug-resistant bacteria were assayed. The particles showed inhibitory effect on the growth kinetics of human and plant bacteria. Furthermore, the genotoxic potential of the silver nanoparticles with increasing concentrations was evaluated by DNA fragmentation studies using plasmid DNA.

  13. Green synthesis of protein capped silver nanoparticles from phytopathogenic fungus Macrophomina phaseolina (Tassi) Goid with antimicrobial properties against multidrug-resistant bacteria.

    PubMed

    Chowdhury, Supriyo; Basu, Arpita; Kundu, Surekha

    2014-01-01

    In recent years, green synthesis of nanoparticles, i.e., synthesizing nanoparticles using biological sources like bacteria, algae, fungus, or plant extracts have attracted much attention due to its environment-friendly and economic aspects. The present study demonstrates an eco-friendly and low-cost method of biosynthesis of silver nanoparticles using cell-free filtrate of phytopathogenic fungus Macrophomina phaseolina. UV-visible spectrum showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) revealed the presence of spherical silver nanoparticles of the size range 5 to 40 nm, most of these being 16 to 20 nm in diameter. X-ray diffraction (XRD) spectrum of the nanoparticles exhibited 2θ values corresponding to silver nanoparticles. These nanoparticles were found to be naturally protein coated. SDS-PAGE analysis showed the presence of an 85-kDa protein band responsible for capping and stabilization of the silver nanoparticles. Antimicrobial activities of the silver nanoparticles against human as well as plant pathogenic multidrug-resistant bacteria were assayed. The particles showed inhibitory effect on the growth kinetics of human and plant bacteria. Furthermore, the genotoxic potential of the silver nanoparticles with increasing concentrations was evaluated by DNA fragmentation studies using plasmid DNA. PMID:25114655

  14. Functional Annotation of the Ophiostoma novo-ulmi Genome: Insights into the Phytopathogenicity of the Fungal Agent of Dutch Elm Disease

    PubMed Central

    Comeau, André M.; Dufour, Josée; Bouvet, Guillaume F.; Jacobi, Volker; Nigg, Martha; Henrissat, Bernard; Laroche, Jérôme; Levesque, Roger C.; Bernier, Louis

    2015-01-01

    The ascomycete fungus Ophiostoma novo-ulmi is responsible for the pandemic of Dutch elm disease that has been ravaging Europe and North America for 50 years. We proceeded to annotate the genome of the O. novo-ulmi strain H327 that was sequenced in 2012. The 31.784-Mb nuclear genome (50.1% GC) is organized into 8 chromosomes containing a total of 8,640 protein-coding genes that we validated with RNA sequencing analysis. Approximately 53% of these genes have their closest match to Grosmannia clavigera kw1407, followed by 36% in other close Sordariomycetes, 5% in other Pezizomycotina, and surprisingly few (5%) orphans. A relatively small portion (∼3.4%) of the genome is occupied by repeat sequences; however, the mechanism of repeat-induced point mutation appears active in this genome. Approximately 76% of the proteins could be assigned functions using Gene Ontology analysis; we identified 311 carbohydrate-active enzymes, 48 cytochrome P450s, and 1,731 proteins potentially involved in pathogen–host interaction, along with 7 clusters of fungal secondary metabolites. Complementary mating-type locus sequencing, mating tests, and culturing in the presence of elm terpenes were conducted. Our analysis identified a specific genetic arsenal impacting the sexual and vegetative growth, phytopathogenicity, and signaling/plant–defense–degradation relationship between O. novo-ulmi and its elm host and insect vectors. PMID:25539722

  15. FTIR spectroscopic evaluation of changes in the cellular biochemical composition of the phytopathogenic fungus Alternaria alternata induced by extracts of some Greek medicinal and aromatic plants.

    PubMed

    Skotti, Efstathia; Kountouri, Sophia; Bouchagier, Pavlos; Tsitsigiannis, Dimitrios I; Polissiou, Moschos; Tarantilis, Petros A

    2014-06-01

    In this study, the biological activity of aquatic extracts of selected Greek medicinal and aromatic plants to the phytopathogenic fungus Alternaria alternata was investigated. Lamiaceae species (Hyssopus officinalis L., Melissa officinalis L., Origanum dictamnus L., Origanum vulgare L. and Salvia officinalis L.) were found to enhance significantly the mycelium growth whereas Crocus sativus appears to inhibit it slightly. M. officinalis and S. officinalis caused the highest stimulation in mycelium growth (+97%) and conidia production (+65%) respectively. In order to further investigate the bioactivity of plant extracts to A. alternata, we employed Fourier Transform Infrared Spectroscopy (FTIR). Differences of original spectra were assigned mainly to amides of proteins. The second derivative transformation of spectra revealed changes in spectral regions corresponding to absorptions of the major cellular constituents such as cell membrane and proteins. Principal component analysis of the second derivative transformed spectra confirmed that fatty acids of the cell membranes, amides of proteins and polysaccharides of the cell wall had the major contribution to data variation. FTIR band area ratios were found to correlate with fungal mycelium growth. PMID:24657421

  16. Tallow amphopolycarboxyglycinate-stabilized silver nanoparticles: new frontiers in development of plant protection products with a broad spectrum of action against phytopathogens

    NASA Astrophysics Data System (ADS)

    Krutyakov, Yurii A.; Kudrinskiy, Alexey A.; Zherebin, Pavel M.; Yapryntsev, Alexey D.; Pobedinskaya, Marina A.; Elansky, Sergey N.; Denisov, Albert N.; Mikhaylov, Dmitry M.; Lisichkin, Georgii V.

    2016-07-01

    Sustainable agriculture calls for minimal use of agrochemicals in order to protect the environment. It has caused an increase in the rate of nanoparticles use, in particular silver nanoparticles (AgNPs) due to their safety for mammals, unique biological activity and a broad spectrum of action against fungal and bacterial pathogens. Until now the use of AgNPs dispersions in the agricultural sector has been essentially limited due to many factors decreased their stability (mixing with other pesticides, presence of electrolytes). We present a versatile synthesis of polyampholyte surfactant (tallow amphopolycarboxyglycinate) stabilized AgNPs. We took a close look at unique aggregation behavior (via dynamic light scattering and UV–vis spectroscopy) and biocidal activity of obtained silver colloids. AgNPs are characterized by exclusively high aggregative stability in the presence of coagulating agents NaNO3 and NaSO4 (up to 1 M), during drying/redispergation, and frost/defrost cycles. The dispersion of AgNPs shows high biocidal activity (EC50 is ten times lower than commercial species ones) with respect to Phytophthora infestans and phytopathogenic fungi. This points to the possibility of successful application of silver preparations within agriculture with the goal of partial reduction of the use of toxic and expensive synthetic antibiotics and pesticides.

  17. Green synthesis of protein capped silver nanoparticles from phytopathogenic fungus Macrophomina phaseolina (Tassi) Goid with antimicrobial properties against multidrug-resistant bacteria

    PubMed Central

    2014-01-01

    In recent years, green synthesis of nanoparticles, i.e., synthesizing nanoparticles using biological sources like bacteria, algae, fungus, or plant extracts have attracted much attention due to its environment-friendly and economic aspects. The present study demonstrates an eco-friendly and low-cost method of biosynthesis of silver nanoparticles using cell-free filtrate of phytopathogenic fungus Macrophomina phaseolina. UV-visible spectrum showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) revealed the presence of spherical silver nanoparticles of the size range 5 to 40 nm, most of these being 16 to 20 nm in diameter. X-ray diffraction (XRD) spectrum of the nanoparticles exhibited 2θ values corresponding to silver nanoparticles. These nanoparticles were found to be naturally protein coated. SDS-PAGE analysis showed the presence of an 85-kDa protein band responsible for capping and stabilization of the silver nanoparticles. Antimicrobial activities of the silver nanoparticles against human as well as plant pathogenic multidrug-resistant bacteria were assayed. The particles showed inhibitory effect on the growth kinetics of human and plant bacteria. Furthermore, the genotoxic potential of the silver nanoparticles with increasing concentrations was evaluated by DNA fragmentation studies using plasmid DNA. PMID:25114655

  18. Disruption of SRM1, a mitogen-activated protein kinase gene, affects sensitivity to osmotic and ultraviolet stressors in the phytopathogenic fungus Bipolaris oryzae.

    PubMed

    Moriwaki, Akihiro; Kubo, Emiko; Arase, Sakae; Kihara, Junichi

    2006-04-01

    Mitogen-activated protein kinases (MAPKs) play key roles in biological processes including differentiation, growth, proliferation, survival, and stress responses. We isolated and characterized the SRM1 gene, which encodes an MAPK related to yeast High-osmolarity glycerol 1 (Hog1), from the rice leaf pathogen Bipolaris oryzae. The deduced amino sequence of the SRM1 gene showed significant homology with Hog1-type MAPK homologues from other phytopathogenic fungi and contained a TGY motif for phosphorylation. The B. oryzae mutants with disruption of the SRM1 gene (Deltasrm1) showed growth inhibition under hyperosmotic, hydrogen peroxide, and UV exposure conditions. The Deltasrm1 mutants showed moderate resistance to dicarboximide and phenylpyrrole fungicides. The Deltasrm1 mutations caused a defect in the expression of the gene that encodes antioxidant enzyme catalase (CAT2) under UV and hyperosmotic conditions. Furthermore, the transcriptional patterns of the three melanin biosynthesis genes (PKS1, THR1, and SCD1) and of a gene of unknown function, uvi-1, which are specifically induced by near-ultraviolet (NUV) radiation, gradually decreased in comparison with the wild-type expression patterns. These results suggest that Srm1 contributes to responses to not only osmostress but also to hydrogen peroxide and UV stress, whereas Srm1 does not appear to regulate directly the expression of genes related to NUV-induced photomorphogenesis. PMID:16553861

  19. Isolation, characterization and molecular three-dimensional structural predictions of metalloprotease from a phytopathogenic fungus, Alternaria solani (Ell. and Mart.) Sor.

    PubMed

    Chandrasekaran, Murugesan; Chandrasekar, Raman; Chun, Se-Chul; Sathiyabama, Muthukrishnan

    2016-08-01

    The present study aims at isolation, identification, characterization and prediction of three-dimensional molecular architecture of a proteolytic enzyme from the early blight pathogen, Alternaria solani which are hypothesized to be a marker of phytopathogenicity. Maximum enzyme production by A. solani was observed in Czapex's Dox broth amended with 2% (w/v) casein than other inducer amendments. Results indicate that the enzyme remained highly active in a pH range of 7.0-10.0 and a temperature range of 45-50°C. The enzyme was strongly inhibited by EDTA, whereas phenylmethylsulfonyl fluoride and monovalent cations (Na(+), K(+)) had little effect. Metal ions such as MgSO4, CaCl2, KCl at 10 mM concentration showed a stimulatory effect (>85%) on protease activity. Matrix-assisted laser desorption and ionization time of flight/mass spectrometry analysis of partially purified enzyme revealed the presence of protease belonging to a keratinolytic protein (metalloprotease) of exopeptidase nature. Putative A. solani keratinolytic enzyme (AsK) is made up of 216 amino acid residues with molecular weight (MW) 24.5 kDa, having a molecular formula of C1094H1704N290O342S4. Ramachandran plot analysis of the protein residues falling into the most favored secondary structures was observed at 84.2%. The major protein structural blocks, 2-β-sheets, and 9-α-helices have a greater tendency to be conserved during the evolutionary process than do mere sequences of amino acids. Besides, AsK, model prediction showed the presence of a Zinc atom at helix regions (Helix 3, 6, 7: His(57), His(130), His(169), and Cys(123)). Thus, it can be concluded that the major proteinases of AsK are divalent cation-requiring metalloproteinases and make them potential targets of protease inhibitors designing. PMID:26924427

  20. MRN- and 9-1-1-Independent Activation of the ATR-Chk1 Pathway during the Induction of the Virulence Program in the Phytopathogen Ustilago maydis

    PubMed Central

    Tenorio-Gómez, María; de Sena-Tomás, Carmen; Pérez-Martín, Jose

    2015-01-01

    DNA damage response (DDR) leads to DNA repair, and depending on the extent of the damage, to further events, including cell death. Evidence suggests that cell differentiation may also be a consequence of the DDR. During the formation of the infective hypha in the phytopathogenic fungus Ustilago maydis, two DDR kinases, Atr1 and Chk1, are required to induce a G2 cell cycle arrest, which in turn is essential to display the virulence program. However, the triggering factor of DDR in this process has remained elusive. In this report we provide data suggesting that no DNA damage is associated with the activation of the DDR during the formation of the infective filament in U. maydis. We have analyzed bulk DNA replication during the formation of the infective filament, and we found no signs of impaired DNA replication. Furthermore, using RPA-GFP fusion as a surrogate marker of the presence of DNA damage, we were unable to detect any sign of DNA damage at the cellular level. In addition, neither MRN nor 9-1-1 complexes, both instrumental to transmit the DNA damage signal, are required for the induction of the above mentioned cell cycle arrest, as well as for virulence. In contrast, we have found that the claspin-like protein Mrc1, which in other systems serves as scaffold for Atr1 and Chk1, was required for both processes. We discuss possible alternative ways to trigger the DDR, independent of DNA damage, in U. maydis during virulence program activation. PMID:26367864

  1. MRN- and 9-1-1-Independent Activation of the ATR-Chk1 Pathway during the Induction of the Virulence Program in the Phytopathogen Ustilago maydis.

    PubMed

    Tenorio-Gómez, María; de Sena-Tomás, Carmen; Pérez-Martín, Jose

    2015-01-01

    DNA damage response (DDR) leads to DNA repair, and depending on the extent of the damage, to further events, including cell death. Evidence suggests that cell differentiation may also be a consequence of the DDR. During the formation of the infective hypha in the phytopathogenic fungus Ustilago maydis, two DDR kinases, Atr1 and Chk1, are required to induce a G2 cell cycle arrest, which in turn is essential to display the virulence program. However, the triggering factor of DDR in this process has remained elusive. In this report we provide data suggesting that no DNA damage is associated with the activation of the DDR during the formation of the infective filament in U. maydis. We have analyzed bulk DNA replication during the formation of the infective filament, and we found no signs of impaired DNA replication. Furthermore, using RPA-GFP fusion as a surrogate marker of the presence of DNA damage, we were unable to detect any sign of DNA damage at the cellular level. In addition, neither MRN nor 9-1-1 complexes, both instrumental to transmit the DNA damage signal, are required for the induction of the above mentioned cell cycle arrest, as well as for virulence. In contrast, we have found that the claspin-like protein Mrc1, which in other systems serves as scaffold for Atr1 and Chk1, was required for both processes. We discuss possible alternative ways to trigger the DDR, independent of DNA damage, in U. maydis during virulence program activation. PMID:26367864

  2. Antioxidant and Antifungal Activity of Extracts of the Aerial Parts of Thymus capitatus (L.) Hoffmanns Against Four Phytopathogenic Fungi of Citrus sinensis

    PubMed Central

    Tabti, Leila; Dib, Mohammed El Amine; Gaouar, Nassira; Samira, Bouayad; Tabti, Boufeldja

    2014-01-01

    Background: Many medicinal plants from the Lamiaceae family can be easily found in Algeria. These plants have been used as traditional medicines by local ethnic groups. Thymus capitatus is known in Algeria as "Zaatar" and has been commonly used as a spice, and reported to have many biological effects. Objectives: This paper focused on the assessment of the antioxidant potential and antifungal activity of essential oil and solvent extracts of T. capitatus against the growth of certain fungi. Materials and Methods: Essential oil, ethanol and hexane extracts of T. capitatus were tested for their antioxidant and antifungal activities. The 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the free radical quenching capacity. Antifungal activity was assessed using the radial growth technique. Results: DPPH free radical scavenging effect of the extracts was compared with standard antioxidant ascorbic acid and showed significant results. The ethanol extract showed high activity at the concentration of 80 g/mL, but less than the standard ascorbic acid. The essential oil was effective against all the fungi used in the experiment. The highest inhibitory effect on the growth of Aspergillus niger, Aspergillus oryzae, Penicillium digitatum, and Fusarium solani was exhibited by the essential oil at concentrations between 0.1 and 0.5 μg/mL. Conclusions: These findings demonstrated that ethanol extract obtained from T. capitatus is a potential source of natural antioxidant, while the essential oil extract can be exploited as an ideal alternative to synthetic fungicides for use in the treatment of many fungal phytopathogens. PMID:24644439

  3. A novel single-stranded RNA virus isolated from a phytopathogenic filamentous fungus, Rosellinia necatrix, with similarity to hypo-like viruses

    PubMed Central

    Zhang, Rui; Liu, Shengxue; Chiba, Sotaro; Kondo, Hideki; Kanematsu, Satoko; Suzuki, Nobuhiro

    2014-01-01

    Here we report a biological and molecular characterization of a novel positive-sense RNA virus isolated from a field isolate (NW10) of a filamentous phytopathogenic fungus, the white root rot fungus that is designated as Rosellinia necatrix fusarivirus 1 (RnFV1). A recently developed technology using zinc ions allowed us to transfer RnFV1 to two mycelially incompatible Rosellinia necatrix strains. A biological comparison of the virus-free and -recipient isogenic fungal strains suggested that RnFV1 infects latently and thus has no potential as a virocontrol agent. The virus has an undivided positive-sense RNA genome of 6286 nucleotides excluding a poly (A) tail. The genome possesses two non-overlapping open reading frames (ORFs): a large ORF1 that encodes polypeptides with RNA replication functions and a smaller ORF2 that encodes polypeptides of unknown function. A lack of coat protein genes was suggested by the failure of virus particles from infected mycelia. No evidence was obtained by Northern analysis or classical 5′-RACE for the presence of subgenomic RNA for the downstream ORF. Sequence similarities were found in amino-acid sequence between RnFV1 putative proteins and counterparts of a previously reported mycovirus, Fusarium graminearum virus 1 (FgV1). Interestingly, several related sequences were detected by BLAST searches of independent transcriptome assembly databases one of which probably represents an entire virus genome. Phylogenetic analysis based on the conserved RNA-dependent RNA polymerase showed that RnFV1, FgV1, and these similar sequences are grouped in a cluster distinct from distantly related hypoviruses. It is proposed that a new taxonomic family termed Fusariviridae be created to include RnFV1 and FgV1. PMID:25101066

  4. Cloning and characterization of a pectin lyase gene from Colletotrichum lindemuthianum and comparative phylogenetic/structural analyses with genes from phytopathogenic and saprophytic/opportunistic microorganisms

    PubMed Central

    2011-01-01

    Background Microorganisms produce cell-wall-degrading enzymes as part of their strategies for plant invasion/nutrition. Among these, pectin lyases (PNLs) catalyze the depolymerization of esterified pectin by a β-elimination mechanism. PNLs are grouped together with pectate lyases (PL) in Family 1 of the polysaccharide lyases, as they share a conserved structure in a parallel β-helix. The best-characterized fungal pectin lyases are obtained from saprophytic/opportunistic fungi in the genera Aspergillus and Penicillium and from some pathogens such as Colletotrichum gloeosporioides. The organism used in the present study, Colletotrichum lindemuthianum, is a phytopathogenic fungus that can be subdivided into different physiological races with different capacities to infect its host, Phaseolus vulgaris. These include the non-pathogenic and pathogenic strains known as races 0 and 1472, respectively. Results Here we report the isolation and sequence analysis of the Clpnl2 gene, which encodes the pectin lyase 2 of C. lindemuthianum, and its expression in pathogenic and non-pathogenic races of C. lindemuthianum grown on different carbon sources. In addition, we performed a phylogenetic analysis of the deduced amino acid sequence of Clpnl2 based on reported sequences of PNLs from other sources and compared the three-dimensional structure of Clpnl2, as predicted by homology modeling, with those of other organisms. Both analyses revealed an early separation of bacterial pectin lyases from those found in fungi and oomycetes. Furthermore, two groups could be distinguished among the enzymes from fungi and oomycetes: one comprising enzymes from mostly saprophytic/opportunistic fungi and the other formed mainly by enzymes from pathogenic fungi and oomycetes. Clpnl2 was found in the latter group and was grouped together with the pectin lyase from C. gloeosporioides. Conclusions The Clpnl2 gene of C. lindemuthianum shares the characteristic elements of genes coding for pectin

  5. Cotton WRKY1 Mediates the Plant Defense-to-Development Transition during Infection of Cotton by Verticillium dahliae by Activating JASMONATE ZIM-DOMAIN1 Expression1[C][W

    PubMed Central

    Li, Chao; He, Xin; Luo, Xiangyin; Xu, Li; Liu, Linlin; Min, Ling; Jin, Li; Zhu, Longfu; Zhang, Xianlong

    2014-01-01

    Plants have evolved an elaborate signaling network to ensure an appropriate level of immune response to meet the differing demands of developmental processes. Previous research has demonstrated that DELLA proteins physically interact with JASMONATE ZIM-DOMAIN1 (JAZ1) and dynamically regulate the interaction of the gibberellin (GA) and jasmonate (JA) signaling pathways. However, whether and how the JAZ1-DELLA regulatory node is regulated at the transcriptional level in plants under normal growth conditions or during pathogen infection is not known. Here, we demonstrate multiple functions of cotton (Gossypium barbadense) GbWRKY1 in the plant defense response and during development. Although GbWRKY1 expression is induced rapidly by methyl jasmonate and infection by Verticillium dahliae, our results show that GbWRKY1 is a negative regulator of the JA-mediated defense response and plant resistance to the pathogens Botrytis cinerea and V. dahliae. Under normal growth conditions, GbWRKY1-overexpressing lines displayed GA-associated phenotypes, including organ elongation and early flowering, coupled with the down-regulation of the putative targets of DELLA. We show that the GA-related phenotypes of GbWRKY1-overexpressing plants depend on the constitutive expression of Gossypium hirsutum GhJAZ1. We also show that GhJAZ1 can be transactivated by GbWRKY1 through TGAC core sequences, and the adjacent sequences of this binding site are essential for binding specificity and affinity to GbWRKY1, as revealed by dual-luciferase reporter assays and electrophoretic mobility shift assays. In summary, our data suggest that GbWRKY1 is a critical regulator mediating the plant defense-to-development transition during V. dahliae infection by activating JAZ1 expression. PMID:25301887

  6. Expression of THR1, a 1,3,8-trihydroxynaphthalene reductase gene involved in melanin biosynthesis in the phytopathogenic fungus Bipolaris oryzae, is enhanced by near-ultraviolet radiation.

    PubMed

    Kihara, Junichi; Moriwaki, Akihiro; Ito, Machiko; Arase, Sakae; Honda, Yuichi

    2004-02-01

    1,3,8-Trihydroxynaphthalene (1,3,8-THN) reductase is involved in the production of fungal dihydroxynaphthalene (DHN) melanin. We isolated and characterized THR1, a gene encoding 1,3,8-THN reductase, from the phytopathogenic fungus Bipolaris oryzae. Sequence analysis showed that THR1 encodes a putative protein of 267 amino acids having a molecular weight of 28.5 kDa and 68-98% sequence identity to other fungal 1,3,8-THN reductases. Targeted disruption of the THR1 gene showed that it is essential for melanin biosynthesis in B. oryzae. Northern blot analysis showed that THR1 transcripts are constitutively expressed during normal growth but are specifically enhanced by near-ultraviolet (NUV) radiation in a dose-dependent manner. These results indicate that THR1 expression is transcriptionally enhanced by NUV radiation in B. oryzae. PMID:14717841

  7. Complete genome sequences of the Serratia plymuthica strains 3Rp8 and 3Re4-18, two rhizosphere bacteria with antagonistic activity towards fungal phytopathogens and plant growth promoting abilities.

    PubMed

    Adam, Eveline; Müller, Henry; Erlacher, Armin; Berg, Gabriele

    2016-01-01

    The Serratia plymuthica strains 3Rp8 and 3Re4-18 are motile, Gram-negative, non-sporulating bacteria. Strain 3Rp8 was isolated from the rhizosphere of Brassica napus L. and strain 3Re4-18 from the endorhiza of Solanum tuberosum L. Studies have shown in vitro activity against the soil-borne fungi Verticillium dahliae Kleb., Rhizoctonia solani Kühn, and Sclerotinia sclerotiorum. Here, we announce and describe the complete genome sequence of S. plymuthica 3Rp8 consisting of a single circular chromosome of 5.5 Mb that encodes 4954 protein-coding and 108 RNA-only encoding genes and of S. plymuthica 3Re4-18 consisting of a single circular chromosome of 5.4 Mb that encodes 4845 protein-coding and 109 RNA-only encoding genes. The whole genome sequences and annotations are available in NCBI under the locus numbers CP012096 and CP012097, respectively. The genome analyses revealed genes putatively responsible for the promising plant growth promoting and biocontrol properties including predicting factors such as secretion systems, iron scavenging siderophores, chitinases, secreted proteases, glucanases and non-ribosomal peptide synthetases, as well as unique genomic islands. PMID:27602183

  8. An Oxalyl-CoA Dependent Pathway of Oxalate Catabolism Plays a Role in Regulating Calcium Oxalate Crystal Accumulation and Defending against Oxalate-Secreting Phytopathogens in Medicago truncatula

    PubMed Central

    Foster, Justin; Luo, Bin; Nakata, Paul A.

    2016-01-01

    Considering the widespread occurrence of oxalate in nature and its broad impact on a host of organisms, it is surprising that so little is known about the turnover of this important acid. In plants, oxalate oxidase is the most well studied enzyme capable of degrading oxalate, but not all plants possess this activity. Recently, an Acyl Activating Enzyme 3 (AAE3), encoding an oxalyl-CoA synthetase, was identified in Arabidopsis. AAE3 has been proposed to catalyze the first step in an alternative pathway of oxalate degradation. Whether this enzyme and proposed pathway is important to other plants is unknown. Here, we identify the Medicago truncatula AAE3 (MtAAE3) and show that it encodes an oxalyl-CoA synthetase activity exhibiting high activity against oxalate with a Km = 81 ± 9 μM and Vmax = 19 ± 0.9 μmoles min-1mg protein-1. GFP-MtAAE3 localization suggested that this enzyme functions within the cytosol of the cell. Mtaae3 knock-down line showed a reduction in its ability to degrade oxalate into CO2. This reduction in the capacity to degrade oxalate resulted in the accumulation of druse crystals of calcium oxalate in the Mtaae3 knock-down line and an increased susceptibility to oxalate-secreting phytopathogens such as Sclerotinia sclerotiorum. Taken together, these results suggest that AAE3 dependent turnover of oxalate is important to different plants and functions in the regulation of tissue calcium oxalate crystal accumulation and in defense against oxalate-secreting phytopathogens. PMID:26900946

  9. 3-Anhydro-6-hydroxy-ophiobolin A, a new sesterterpene inhibiting the growth of methicillin-resistant Staphylococcus aureus and inducing the cell death by apoptosis on K562, from the phytopathogenic fungus Bipolaris oryzae.

    PubMed

    Wang, Quan-Xin; Yang, Jian-Ling; Qi, Qiu-Yue; Bao, Li; Yang, Xiao-Li; Liu, Miao-Miao; Huang, Pei; Zhang, Li-Xin; Chen, Ji-Long; Cai, Lei; Liu, Hong-Wei

    2013-06-15

    A new ophiobolin derivative, 3-anhydro-6-hydroxy-ophiobolin A (1), as well as two known ophiobolin derivatives 3-anhydro-ophiobolin A (2) and 3-anhydro-6-epi-ophiobolin A (3) were isolated from the PDB culture of a phytopathogenic fungus Bipolaris oryzae. The structure of 1 was elucidated through 2D NMR and other spectroscopic techniques. Compound 1 exhibited strong antimicrobial activity against Bacille Calmette-Guerin, Bacillus subtilis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus with MIC value of 12.5 μg/mL, and potent antiproliferative activity against cell lines HepG2 and K562 with IC50 of 6.49 μM and 4.06 μM, respectively. Further studies on the cytotoxicity of compound 1 against K562 cells demonstrated that it induced apoptosis, observed by flow cytometric method. Preliminary structure-activity relationships of these ophiobolins and the mechanism of apoptosis induced by 1 were analyzed. PMID:23668986

  10. Enzymatic response of cotton plants to the pathogen, Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pathogen infection initiates a set of local and systemic responses in plants. These responses include local oxidative burst, which may lead to death of infected cells, and changes of cell walls composition in neighbouring tissues, and de novo synthesis of antimicrobial compounds (phytoalexins) and P...

  11. Brassica napus L. cultivars show a broad variability in their morphology, physiology and metabolite levels in response to sulfur limitations and to pathogen attack

    PubMed Central

    Weese, Annekathrin; Pallmann, Philip; Papenbrock, Jutta; Riemenschneider, Anja

    2015-01-01

    Under adequate sulfur supply, plants accumulate sulfate in the vacuoles and use sulfur-containing metabolites as storage compounds. Under sulfur-limiting conditions, these pools of stored sulfur-compounds are depleted in order to balance the nitrogen to sulfur ratio for protein synthesis. Stress conditions like sulfur limitation and/or pathogen attack induce changes in the sulfate pool and the levels of sulfur-containing metabolites, which often depend on the ecotypes or cultivars. We are interested in investigating the influence of the genetic background of canola (Brassica napus) cultivars in sulfur-limiting conditions on the resistance against Verticillium longisporum. Therefore, four commercially available B. napus cultivars were analyzed. These high-performing cultivars differ in some characteristics described in their cultivar pass, such as several agronomic traits, differences in the size of the root system, and resistance to certain pathogens, such as Phoma and Verticillium. The objectives of the study were to examine and explore the patterns of morphological, physiological and metabolic diversity in these B. napus cultivars at different sulfur concentrations and in the context of plant defense. Results indicate that the root systems are influenced differently by sulfur deficiency in the cultivars. Total root dry mass and length of root hairs differ not only among the cultivars but also vary in their reaction to sulfur limitation and pathogen attack. As a sensitive indicator of stress, several parameters of photosynthetic activity determined by PAM imaging showed a broad variability among the treatments. These results were supported by thermographic analysis. Levels of sulfur-containing metabolites also showed large variations. The data were interrelated to predict the specific behavior during sulfur limitation and/or pathogen attack. Advice for farming are discussed. PMID:25699060

  12. Keeping Control: The Role of Senescence and Development in Plant Pathogenesis and Defense

    PubMed Central

    Häffner, Eva; Konietzki, Sandra; Diederichsen, Elke

    2015-01-01

    Many plant pathogens show interactions with host development. Pathogens may modify plant development according to their nutritional demands. Conversely, plant development influences pathogen growth. Biotrophic pathogens often delay senescence to keep host cells alive, and resistance is achieved by senescence-like processes in the host. Necrotrophic pathogens promote senescence in the host, and preventing early senescence is a resistance strategy of plants. For hemibiotrophic pathogens both patterns may apply. Most signaling pathways are involved in both developmental and defense reactions. Increasing knowledge about the molecular components allows to distinguish signaling branches, cross-talk and regulatory nodes that may influence the outcome of an infection. In this review, recent reports on major molecular players and their role in senescence and in pathogen response are reviewed. Examples of pathosystems with strong developmental implications illustrate the molecular basis of selected control strategies. A study of gene expression in the interaction between the hemibiotrophic vascular pathogen Verticillium longisporum and its cruciferous hosts shows processes that are fine-tuned to counteract early senescence and to achieve resistance. The complexity of the processes involved reflects the complex genetic control of quantitative disease resistance, and understanding the relationship between disease, development and resistance will support resistance breeding. PMID:27135337

  13. Anti-Phytopathogenic Activities of Macro-Algae Extracts

    PubMed Central

    Jiménez, Edra; Dorta, Fernando; Medina, Cristian; Ramírez, Alberto; Ramírez, Ingrid; Peña-Cortés, Hugo

    2011-01-01

    Aqueous and ethanolic extracts obtained from nine Chilean marine macro-algae collected at different seasons were examined in vitro and in vivo for properties that reduce the growth of plant pathogens or decrease the injury severity of plant foliar tissues following pathogen infection. Particular crude aqueous or organic extracts showed effects on the growth of pathogenic bacteria whereas others displayed important effects against pathogenic fungi or viruses, either by inhibiting fungal mycelia growth or by reducing the disease symptoms in leaves caused by pathogen challenge. Organic extracts obtained from the brown-alga Lessonia trabeculata inhibited bacterial growth and reduced both the number and size of the necrotic lesion in tomato leaves following infection with Botrytis cinerea. Aqueous and ethanolic extracts from the red-alga Gracillaria chilensis prevent the growth of Phytophthora cinnamomi, showing a response which depends on doses and collecting-time. Similarly, aqueous and ethanolic extracts from the brown-alga Durvillaea antarctica were able to diminish the damage caused by tobacco mosaic virus (TMV) in tobacco leaves, and the aqueous procedure is, in addition, more effective and seasonally independent. These results suggest that macro-algae contain compounds with different chemical properties which could be considered for controlling specific plant pathogens. PMID:21673886

  14. Multilocus sequence analysis of phytopathogenic species of the genus Streptomyces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The identification and classification of species within the genus Streptomyces is difficult because there are presently 576 validly described species and this number increases every year. The value of the application of multilocus sequence analysis scheme to the systematics of Streptomyces species h...

  15. Comparative Analyses of Exoproteinases Produced by Three Phytopathogenic Microorganisms

    PubMed Central

    Valueva, Tatiana A.; Kudryavtseva, Natalia N.; Sof'in, Alexis V.; Revina, Tatiana A.; Gvozdeva, Ekaterina L.; Ievleva, Elena V.

    2011-01-01

    Proteinases secreted by the oomycete Phytophthora infestans (Mont.) de Bary, Rhizoctonia solani, and Fusarium culmorum belonging to different families of fungi have been studied to determine if the exoenzyme secretion depends on the environmental conditions and the phylogenetic position of the pathogen. The substrate specificity of the extracellular proteinases of F. culmorum, R. solani, and P. infestans and their sensitivity to the action of synthetic and protein inhibitors suggest that they contain trypsin-like and subtilisin-like enzymes regardless of culture medium composition. The relation of trypsin-like and subtilisin-like enzymes is dependent on the culture medium composition, especially on the form of nitrogen nutrition, particularly in the case of the exoenzymes secreted by R. solani. Phylogenetic analyses have shown that the exoproteinase set of ascomycetes and oomycetes has more similarities than basidiomycetes although they are more distant relatives. Our data suggests that the multiple proteinases secreted by pathogenic fungi could play different roles in pathogenesis, increasing the adaptability and host range, or could have different functions in survival in various ecological habitats outside the host. PMID:22567343

  16. Myconanoparticles: synthesis and their role in phytopathogens management

    PubMed Central

    Alghuthaymi, Mousa A.; Almoammar, Hassan; Rai, Mahindra; Said-Galiev, Ernest; Abd-Elsalam, Kamel A.

    2015-01-01

    Nanotechnology can offer green and eco-friendly alternatives for plant disease management. Apart from being eco-friendly, fungi are used as bio-manufacturing units, which will provide an added benefit in being easy to use, as compared to other microbes. The non-pathogenic nature of some fungal species in combination with the simplicity of production and handling will improve the mass production of silver nanoparticles. Recently, a diverse range of fungi have been screened for their ability to create silver nanoparticles. Mycosynthesis of gold, silver, gold–silver alloy, selenium, tellurium, platinum, palladium, silica, titania, zirconia, quantum dots, usnic acid, magnetite, cadmium telluride and uraninite nanoparticles has also been reported by various researchers. Nanotechnological application in plant pathology is still in the early stages. For example, nanofungicides, nanopesticides and nanoherbicides are being used extensively in agriculture practices. Remote activation and monitoring of intelligent nano-delivery systems can assist agricultural growers of the future to minimize fungicides and pesticides use. Nanoparticle-mediated gene transfer would be useful for improvement of crops resistant to pathogens and pest. This review critically assesses the role of fungi in the synthesis of nanoparticles, the mechanism involved in the synthesis, the effect of different factors on the reduction of metal ions in developing low-cost techniques for the synthesis and recovery of nanoparticles. Moreover, the application of nanoparticles in plant disease control, antimicrobial mechanisms, and nanotoxicity on plant ecosystem and soil microbial communities has also been discussed in detail. PMID:26019636

  17. Genomic analysis of novel phytopathogenic Georgenia sp. strain SUB25

    PubMed Central

    Patel, Pooja P.; Rakhashiya, Purvi M.; Thaker, Vrinda S.

    2015-01-01

    A Gram positive bacterium, Georgenia sp. SUB25 was isolated from infected leaves of Solanum lycopersicum L. in Rajkot (22.30°N, 70.78°E), Gujarat, India. We sequenced and analyzed Georgenia sp. SUB25 that is novel plant pathogen using next generation sequencing platform and assembly yielded contigs representing a size of 4.84 Mb with 81 tRNAs and 88 rRNAs. The whole genome sequencing has been deposited in DDBJ/EMBL/GenBank under the accession number JNFL00000000. This genome sequence contains Type II secretion system genes, which involved in pathogenicity mechanism that may help to understand plant microbial interaction. PMID:26484278

  18. ACTIVITY OF NATURAL PRODUCTS AGAINST SOME PHYTOPATHOGENIC FUNGI.

    PubMed

    La Torre, A; Caradonia, F; Gianferro, M; Molinu, M G; Battaglia, V

    2014-01-01

    The requirement of environmental protection and food safety is perceived with always major interest by public opinion and it is consistent with European Union legislation on the sustainable use of pesticides (Directive 2009/128/EC). This directive requires member states to promote low pesticide-input, giving priority to non-chemical methods and low risk plant protection products. In order to contribute to the achievement of these objectives antifungal activity of natural substances, characterized by a good toxicological and ecotoxicological profile, was tested. Essential oil of Melaleuca alternifolia, essential oil of Syzygium aromaticum and extract from Mimosa tenuiflora were tested against Alternaria alternata, Botrytis cinerea and Fusarium oxysporum f. sp. lycopersici (races 1 and 2). In vitro tests involved determination of radial growth of the colonies of fungi in the presence of varying concentrations of tested products in agar media and determination of germination percentage in the presence of tested product at various concentrations. The products based on essential oil of M. alternifolia were also tested in vivo on tomato fruits wounded and artificially inoculated with A. alternata or with B. cinerea. The in vitro tests showed the antifungal activity of both essential oils instead the extract from M. tenuiflora exhibited poor antifungal activity and only against A. alternata and B. cinerea. The results on tomato fruits showed inhibition of grey mould and black mould by essential oil of M. alternifolia. The antifungal activity increased with increasing concentrations. In conclusion, the obtained results in the present study showed promising prospects for the utilisation of investigated products to reduce the using of antifungal chemicals and to achieve a more sustainable use of pesticides. PMID:26080478

  19. Antifungal Activity of Nor-securinine Against Some Phytopathogenic Fungi

    PubMed Central

    Sahni, Sangita; Maurya, S.; Singh, A. K.; Singh, V. P.; Pandey, V. B.

    2005-01-01

    Crude extracts and active principles from medicinal plants have shown potential role in controlling plant diseases in glasshouses as well as in fields as one of the safest and ecofriendly methods. The effect of nor-securinine (an alkaloid) isolated from Phyllanthus amarus has been seen against spore germination of some fungi (Alternaria brassicae, A. solani, Curvularia pennisetti, Curvularia sp., Erysiphe pisi, Helminthosporium frumentacei) as well as pea powdery mildew (Erysiphe pisi) under glasshouse conditions. The sensitivity of fungi to nor-securinine varied considerably. Nor-securinine was effective against most of the fungi. H. frumentacei was more sensitive even at the lowest concentration (1,000 µg/ml). Likewise conidia of E. pisi were also inhibited in partially or completely appressorium formation. Pre-inoculation treatment showed greater efficacy than post-inoculation in inhibiting powdery mildew development on pea plants in a glasshouse. Maximum inhibition occurred at 2000 µg/ml PMID:24049481

  20. Anti-phytopathogenic activities of macro-algae extracts.

    PubMed

    Jiménez, Edra; Dorta, Fernando; Medina, Cristian; Ramírez, Alberto; Ramírez, Ingrid; Peña-Cortés, Hugo

    2011-01-01

    Aqueous and ethanolic extracts obtained from nine Chilean marine macro-algae collected at different seasons were examined in vitro and in vivo for properties that reduce the growth of plant pathogens or decrease the injury severity of plant foliar tissues following pathogen infection. Particular crude aqueous or organic extracts showed effects on the growth of pathogenic bacteria whereas others displayed important effects against pathogenic fungi or viruses, either by inhibiting fungal mycelia growth or by reducing the disease symptoms in leaves caused by pathogen challenge. Organic extracts obtained from the brown-alga Lessonia trabeculata inhibited bacterial growth and reduced both the number and size of the necrotic lesion in tomato leaves following infection with Botrytis cinerea. Aqueous and ethanolic extracts from the red-alga Gracillaria chilensis prevent the growth of Phytophthora cinnamomi, showing a response which depends on doses and collecting-time. Similarly, aqueous and ethanolic extracts from the brown-alga Durvillaea antarctica were able to diminish the damage caused by tobacco mosaic virus (TMV) in tobacco leaves, and the aqueous procedure is, in addition, more effective and seasonally independent. These results suggest that macro-algae contain compounds with different chemical properties which could be considered for controlling specific plant pathogens. PMID:21673886

  1. Comparative analyses of exoproteinases produced by three phytopathogenic microorganisms.

    PubMed

    Valueva, Tatiana A; Kudryavtseva, Natalia N; Sof'in, Alexis V; Revina, Tatiana A; Gvozdeva, Ekaterina L; Ievleva, Elena V

    2011-01-01

    Proteinases secreted by the oomycete Phytophthora infestans (Mont.) de Bary, Rhizoctonia solani, and Fusarium culmorum belonging to different families of fungi have been studied to determine if the exoenzyme secretion depends on the environmental conditions and the phylogenetic position of the pathogen. The substrate specificity of the extracellular proteinases of F. culmorum, R. solani, and P. infestans and their sensitivity to the action of synthetic and protein inhibitors suggest that they contain trypsin-like and subtilisin-like enzymes regardless of culture medium composition. The relation of trypsin-like and subtilisin-like enzymes is dependent on the culture medium composition, especially on the form of nitrogen nutrition, particularly in the case of the exoenzymes secreted by R. solani. Phylogenetic analyses have shown that the exoproteinase set of ascomycetes and oomycetes has more similarities than basidiomycetes although they are more distant relatives. Our data suggests that the multiple proteinases secreted by pathogenic fungi could play different roles in pathogenesis, increasing the adaptability and host range, or could have different functions in survival in various ecological habitats outside the host. PMID:22567343

  2. Molecular Taxonomy of Phytopathogenic Fungi: A Case Study in Peronospora

    PubMed Central

    Göker, Markus; García-Blázquez, Gema; Voglmayr, Hermann; Tellería, M. Teresa; Martín, María P.

    2009-01-01

    Background Inappropriate taxon definitions may have severe consequences in many areas. For instance, biologically sensible species delimitation of plant pathogens is crucial for measures such as plant protection or biological control and for comparative studies involving model organisms. However, delimiting species is challenging in the case of organisms for which often only molecular data are available, such as prokaryotes, fungi, and many unicellular eukaryotes. Even in the case of organisms with well-established morphological characteristics, molecular taxonomy is often necessary to emend current taxonomic concepts and to analyze DNA sequences directly sampled from the environment. Typically, for this purpose clustering approaches to delineate molecular operational taxonomic units have been applied using arbitrary choices regarding the distance threshold values, and the clustering algorithms. Methodology Here, we report on a clustering optimization method to establish a molecular taxonomy of Peronospora based on ITS nrDNA sequences. Peronospora is the largest genus within the downy mildews, which are obligate parasites of higher plants, and includes various economically important pathogens. The method determines the distance function and clustering setting that result in an optimal agreement with selected reference data. Optimization was based on both taxonomy-based and host-based reference information, yielding the same outcome. Resampling and permutation methods indicate that the method is robust regarding taxon sampling and errors in the reference data. Tests with newly obtained ITS sequences demonstrate the use of the re-classified dataset in molecular identification of downy mildews. Conclusions A corrected taxonomy is provided for all Peronospora ITS sequences contained in public databases. Clustering optimization appears to be broadly applicable in automated, sequence-based taxonomy. The method connects traditional and modern taxonomic disciplines by specifically addressing the issue of how to optimally account for both traditional species concepts and genetic divergence. PMID:19641601

  3. One stop shop: Backbones trees for important phytopathogenic genera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The number of described species in the plant pathogen genus Phytophthora has essentially doubled in the past 10 years and is continually expanding. This manuscript provides some background on the genus and discusses morphological features used for species identification. More contemporary means of...

  4. SaxA-Mediated Isothiocyanate Metabolism in Phytopathogenic Pectobacteria.

    PubMed

    Welte, Cornelia U; Rosengarten, Jamila F; de Graaf, Rob M; Jetten, Mike S M

    2016-04-01

    Pectobacteria are devastating plant pathogens that infect a large variety of crops, including members of the family Brassicaceae. To infect cabbage crops, these plant pathogens need to overcome the plant's antibacterial defense mechanisms, where isothiocyanates are liberated by hydrolysis of glucosinolates. Here, we found that a Pectobacterium isolate from the gut of cabbage root fly larvae was particularly resistant to isothiocyanate and even seemed to benefit from the abundant Brassica root metabolite 2-phenylethyl isothiocyanate as a nitrogen source in an ecosystem where nitrogen is scarce. The Pectobacterium isolate harbored a naturally occurring mobile plasmid that contained a sax operon. We hypothesized that SaxA was the enzyme responsible for the breakdown of 2-phenylethyl isothiocyanate. Subsequently, we heterologously produced and purified the SaxA protein and characterized the recombinant enzyme. It hydrolyzed 2-phenylethyl isothiocyanate to yield the products carbonyl sulfide and phenylethylamine. It was also active toward another aromatic isothiocyanate but hardly toward aliphatic isothiocyanates. It belongs to the class B metal-dependent beta-lactamase fold protein family but was not, however, able to hydrolyze beta-lactam antibiotics. We discovered that several copies of the saxA gene are widespread in full and draft Pectobacterium genomes and therefore hypothesize that SaxA might be a new pathogenicity factor of the genus Pectobacterium, possibly compromising food preservation strategies using isothiocyanates. PMID:26873319

  5. Antifungal effects of volatile compounds from black zira (Bunium persicum) and other spices and herbs.

    PubMed

    Sekine, Takayuki; Sugano, Mami; Majid, Azizi; Fujii, Yoshiharu

    2007-11-01

    The dish pack method, which measures growth inhibition or promotion effects of volatile compounds on germinating seeds, was applied to measure the antifungal effects of 52 dried samples of spices and herbs against a soil-borne phytopathogenic fungus, Fusarium oxysporum. Black zira showed the strongest effect, followed by cumin and cardamom. Headspace sampling and gas chromatography-mass spectrometry analysis of black zira identified seven volatile compounds, gamma-terpinene, limonene, p-cymene, beta-pinene, alpha-pinene, cuminaldehyde, and myrcene. Among these, cuminaldehyde and p-cymene showed the strongest antifungal activities against F. oxysporum, suggesting roles in the antifungal activity of black zira. The same compounds also showed antifungal activities against another soil-borne phytopathogenic fungus, Verticillium dahliae, and foliar phytopathogenic fungi, Botrytis cinerea and Alternaria mali. The total activity calculated from the concentration of cuminaldehyde contained in black zira and its EC(50) against F. oxysporum demonstrated that cuminaldehyde is the main antifungal compound detected in black zira. PMID:17932718

  6. Benzimidazole-1,2,3-triazole Hybrid Molecules: Synthesis and Evaluation for Antibacterial/Antifungal Activity

    PubMed Central

    Ouahrouch, Abdelaaziz; Ighachane, Hana; Taourirte, Moha; Engels, Joachim W; Sedra, My Hassan; Lazrek, Hassan B

    2014-01-01

    A novel series of hybrid molecules 4a–i and 5a–i were prepared by condensation of 4-(trimethylsilylethynyl)benzaldehyde 1 with substituted o-phenylenediamines. These in turn were reacted with 2-(azidomethoxy)ethyl acetate in a Cu alkyne–azide cycloaddition (CuAAC) to generate the 1,2,3-triazole pharmacophore under microwave assistance. The newly synthesized compounds were examined for their in vitro antimicrobial activities against Gram-positive and Gram-negative bacteria and the phytopathogenic fungi Verticillium dahliae and Fusarium oxysporum f. sp. albedinis. 2-((4-(4-(5-Trifluoromethyl benzimidazol-2-yl)phenyl)-1,2,3-triazol-1-yl)methoxy)ethanol 5e showed a moderate inhibition of 30% in the Foa sporulation test. PMID:25088180

  7. A PLAUSIBLE ROLE FOR POLLEN-RESIDING MOLDS IN AGRICULTURAL PURPOSES.

    PubMed

    Belhadj, H; Harzallah, D; Dahamna, S; Ghadbane, M

    2015-01-01

    Pollen microbial content of 15 samples was investigated. Pollen was collected by honeybees. Total aerobic mesophilic count ranged from 3.00 to 5.48 Log CFU/g. Total mold and yeast count ranged from 2.3 to 6.99 Log CFU/g. Selected strains of isolated molds from pollen samples were characterized by conventional methods. Potent phytopathogenic and food spoilage species such as Penicillium sp., Alternaria alternata, Alternaria sp., Cladosporium werneckii, Mucor hiemalis, Rhizomucor pusillus, Aspergillus flavus, Aspergillus niger, Drechslera tritici-repentis, Verticillium albo-atrum, and Aspergillus alliaceus were recovered. Other fungal species with valuable biotechnological and plant diseases control purposes were isolated. They were characterized as Geotrichum candidum, Monilia sitophilia, and Sepedonium chrysospermum. Animal pathogenic molds were also isolated. Bee pollen may be considered as a source for a highly diverse fungal flora with different applications. PMID:27141752

  8. High throughput analysis of gene expression in microsclerotia of Verticillium dahliae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The processes of microsclerotia formation, maintenance, and germination are critically important in the disease cycle of V. dahliae. To shed additional light on the molecular processes involved in microsclerotia biogenesis and melanin synthesis in V. dahliae, three replicate RNA-seq libraries were p...

  9. Anaerobic Soil Disinfestation for Suppressing Verticillium dahliae in Strawberry Production in California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic soil disinfestation (ASD), a non-chemical alternative to methyl bromide (MB) fumigation developed in Japan and the Netherlands, can control soilborne pathogens and nematodes in strawberries and vegetables. To optimize ASD for California strawberries, field experiments were conducted in Wat...

  10. Dakota Trailblazer: A new, dual-purpose russet cultivar with Verticillium wilt resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dakota Trailblazer, a new, full-season, dual-purpose cultivar was released in 2009 by the North Dakota Agricultural Experiment Station. It has medium russet skin, white to creamy flesh, and long and blocky tuber type. Dakota Trailblazer originated from the cross of A89163-3LS x A8914-4, parental s...

  11. Genomic Analysis of Verticillium Wilt Resistance and Drought Tolerance in Alfalfa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Alfalfa (Medicago sativa L.) is the fourth largest crop in the United States. Changing trends to multipurpose uses increases demand for alfalfa. However, the production of alfalfa is challenged by endemic and emerging diseases and adverse environmental factors. Identification of genes/loci controlli...

  12. Blue mold to genomics and beyond: Insights into the biology and virulence of phytopathogenic Penicillium species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pomes, mainly apples and pears, are economically important fruits produced and consumed worldwide. The United States is the second largest producer of pome fruit in the world behind China. Penicillium expansum and other Penicillium spp. are the most common fungal plant pathogens that cause blue mold...

  13. Biological role of pigment production for the bacterial phytopathogen Pantoea stewartii subsp. stewartii.

    PubMed

    Mohammadi, Mojtaba; Burbank, Lindsey; Roper, M Caroline

    2012-10-01

    Pantoea stewartii subsp. stewartii, the causal agent of Stewart's wilt of sweet corn, produces a yellow carotenoid pigment. A nonpigmented mutant was selected from a bank of mutants generated by random transposon mutagenesis. The transposon insertion site was mapped to the crtB gene, encoding a putative phytoene synthase, an enzyme involved in the early steps of carotenoid biosynthesis. We demonstrate here that the carotenoid pigment imparts protection against UV radiation and also contributes to the complete antioxidant pathway of P. stewartii. Moreover, production of this pigment is regulated by the EsaI/EsaR quorum-sensing system and significantly contributes to the virulence of the pathogen in planta. PMID:22820327

  14. Association between Virulence and Triazole Tolerance in the Phytopathogenic Fungus Mycosphaerella graminicola

    PubMed Central

    Yang, Lina; Gao, Fangluan; Shang, Liping; Zhan, Jiasui; McDonald, Bruce A.

    2013-01-01

    Host resistance and synthetic antimicrobials such as fungicides are two of the main approaches used to control plant diseases in conventional agriculture. Although pathogens often evolve to overcome host resistance and antimicrobials, the majority of reports have involved qualitative host – pathogen interactions or antimicrobials targeting a single pathogen protein or metabolic pathway. Studies that consider jointly the evolution of virulence, defined as the degree of damage caused to a host by parasite infection, and antimicrobial resistance are rare. Here we compared virulence and fungicide tolerance in the fungal pathogen Mycosphaerella graminicola sampled from wheat fields across three continents and found a positive correlation between virulence and tolerance to a triazole fungicide. We also found that quantitative host resistance selected for higher pathogen virulence. The possible mechanisms responsible for these observations and their consequences for sustainable disease management are discussed. PMID:23555044

  15. Cloning, expression, and characterization of a new phytase from the phytopathogenic bacterium Pectobacterium wasabiae DSMZ 18074.

    PubMed

    Shao, Na; Huang, Huoqing; Meng, Kun; Luo, Huiying; Wang, Yaru; Yang, Peilong; Yao, Bin

    2008-07-01

    The soft rot bacterium Pectobacterium wasabiae is an economically important pathogen of many crops. A new phytase gene, appA, was cloned from P. wasabiae by degenerate PCR and TAIL-PCR. The open reading frame of appA consisted of 1,302 bp encoding 433 amino acid residues, including 27 residues of a putative signal peptide. The mature protein had a molecular mass of 45 kDa and a theoretical pI of 5.5. The amino acid sequence contained the conserved active site residues RHGXRXP and HDTN of typical histidine acid phosphatases, and showed the highest identity of 48.5% to PhyM from Pseudomonas syringae. The gene fragment encoding the mature phytase was expressed in Escherichia coli BL21 (DE3), and the purified recombinant phytase had a specific activity of 1,072+/-47 U/mg for phytate substrate. The optimum pH and temperature for the purified phytase were pH 5.0 and 50 degrees C, respectively. The Km value was 0.17 mM, with a Vmax of 1,714 micromol/min/mg. This is the first report of the identification and isolation of phytase from Pectobacterium. PMID:18667849

  16. Whole genome sequences and annotation of Micrococcus luteus SUBG006, a novel phytopathogen of mango

    PubMed Central

    Rakhashiya, Purvi M.; Patel, Pooja P.; Thaker, Vrinda S.

    2015-01-01

    Actinobaceria, Micrococcus luteus SUBG006 was isolated from infected leaves of Mangifera indica L. vr. Nylon in Rajkot, (22.30°N, 70.78°E), Gujarat, India. The genome size is 3.86 Mb with G + C content of 69.80% and contains 112 rRNA sequences (5S, 16S and 23S). The whole genome sequencing has been deposited in DDBJ/EMBL/GenBank under the accession number JOKP00000000. PMID:26697318

  17. Gall-ID: tools for genotyping gall-causing phytopathogenic bacteria

    PubMed Central

    Tabima, Javier F.; Grunwald, Niklaus J.

    2016-01-01

    Understanding the population structure and genetic diversity of plant pathogens, as well as the effect of agricultural practices on pathogen evolution, is important for disease management. Developments in molecular methods have contributed to increase the resolution for accurate pathogen identification, but those based on analysis of DNA sequences can be less straightforward to use. To address this, we developed Gall-ID, a web-based platform that uses DNA sequence information from 16S rDNA, multilocus sequence analysis and whole genome sequences to group disease-associated bacteria to their taxonomic units. Gall-ID was developed with a particular focus on gall-forming bacteria belonging to Agrobacterium, Pseudomonas savastanoi, Pantoea agglomerans, and Rhodococcus. Members of these groups of bacteria cause growth deformation of plants, and some are capable of infecting many species of field, orchard, and nursery crops. Gall-ID also enables the use of high-throughput sequencing reads to search for evidence for homologs of characterized virulence genes, and provides downloadable software pipelines for automating multilocus sequence analysis, analyzing genome sequences for average nucleotide identity, and constructing core genome phylogenies. Lastly, additional databases were included in Gall-ID to help determine the identity of other plant pathogenic bacteria that may be in microbial communities associated with galls or causative agents in other diseased tissues of plants. The URL for Gall-ID is http://gall-id.cgrb.oregonstate.edu/. PMID:27547538

  18. Interactions between a cotton phytopathogen and the host using a genomics analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton (Gossypium hirsutum L.) is an economic crop grown worldwide. Numerous G. hirsutum polyploids have been sequenced. Bacterial infections of cotton can cause major yield losses. Pantoea ananatis is a known bacterial pathogen of both cotton buds and bolls. Thus, we conducted a whole genome an...

  19. Small RNA-Based Antiviral Defense in the Phytopathogenic Fungus Colletotrichum higginsianum

    PubMed Central

    Carrington, James C.

    2016-01-01

    Even though the fungal kingdom contains more than 3 million species, little is known about the biological roles of RNA silencing in fungi. The Colletotrichum genus comprises fungal species that are pathogenic for a wide range of crop species worldwide. To investigate the role of RNA silencing in the ascomycete fungus Colletotrichum higginsianum, knock-out mutants affecting genes for three RNA-dependent RNA polymerase (RDR), two Dicer-like (DCL), and two Argonaute (AGO) proteins were generated by targeted gene replacement. No effects were observed on vegetative growth for any mutant strain when grown on complex or minimal media. However, Δdcl1, Δdcl1Δdcl2 double mutant, and Δago1 strains showed severe defects in conidiation and conidia morphology. Total RNA transcripts and small RNA populations were analyzed in parental and mutant strains. The greatest effects on both RNA populations was observed in the Δdcl1, Δdcl1Δdcl2, and Δago1 strains, in which a previously uncharacterized dsRNA mycovirus [termed Colletotrichum higginsianum non-segmented dsRNA virus 1 (ChNRV1)] was derepressed. Phylogenetic analyses clearly showed a close relationship between ChNRV1 and members of the segmented Partitiviridae family, despite the non-segmented nature of the genome. Immunoprecipitation of small RNAs associated with AGO1 showed abundant loading of 5’U-containing viral siRNA. C. higginsianum parental and Δdcl1 mutant strains cured of ChNRV1 revealed that the conidiation and spore morphology defects were primarily caused by ChNRV1. Based on these results, RNA silencing involving ChDCL1 and ChAGO1 in C. higginsianum is proposed to function as an antiviral mechanism. PMID:27253323

  20. Gall-ID: tools for genotyping gall-causing phytopathogenic bacteria.

    PubMed

    Davis Ii, Edward W; Weisberg, Alexandra J; Tabima, Javier F; Grunwald, Niklaus J; Chang, Jeff H

    2016-01-01

    Understanding the population structure and genetic diversity of plant pathogens, as well as the effect of agricultural practices on pathogen evolution, is important for disease management. Developments in molecular methods have contributed to increase the resolution for accurate pathogen identification, but those based on analysis of DNA sequences can be less straightforward to use. To address this, we developed Gall-ID, a web-based platform that uses DNA sequence information from 16S rDNA, multilocus sequence analysis and whole genome sequences to group disease-associated bacteria to their taxonomic units. Gall-ID was developed with a particular focus on gall-forming bacteria belonging to Agrobacterium, Pseudomonas savastanoi, Pantoea agglomerans, and Rhodococcus. Members of these groups of bacteria cause growth deformation of plants, and some are capable of infecting many species of field, orchard, and nursery crops. Gall-ID also enables the use of high-throughput sequencing reads to search for evidence for homologs of characterized virulence genes, and provides downloadable software pipelines for automating multilocus sequence analysis, analyzing genome sequences for average nucleotide identity, and constructing core genome phylogenies. Lastly, additional databases were included in Gall-ID to help determine the identity of other plant pathogenic bacteria that may be in microbial communities associated with galls or causative agents in other diseased tissues of plants. The URL for Gall-ID is http://gall-id.cgrb.oregonstate.edu/. PMID:27547538

  1. Multitrophic interactions of the silverleaf whitefly,host plants, competing herbivores, and phytopathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our laboratory confirmed that silverleaf whitefly (SLW; Bemisia argentifolii, Bellows & Perring) feeding alters host plant anatomy, physiology and chemistry. The SLW induces a number host plant defenses, including pathogenesis-related (PR) protein accumulation e.g., chitinases, B-1,3-glucanases, pe...

  2. Genomic diversity of large-plaque-forming podoviruses infecting the phytopathogen Ralstonia solanacearum.

    PubMed

    Kawasaki, Takeru; Narulita, Erlia; Matsunami, Minaho; Ishikawa, Hiroki; Shimizu, Mio; Fujie, Makoto; Bhunchoth, Anjana; Phironrit, Namthip; Chatchawankanphanich, Orawan; Yamada, Takashi

    2016-05-01

    The genome organization, gene structure, and host range of five podoviruses that infect Ralstonia solanacearum, the causative agent of bacterial wilt disease were characterized. The phages fell into two distinctive groups based on the genome position of the RNA polymerase gene (i.e., T7-type and ϕKMV-type). One-step growth experiments revealed that ϕRSB2 (a T7-like phage) lysed host cells more efficiently with a shorter infection cycle (ca. 60min corresponding to half the doubling time of the host) than ϕKMV-like phages such as ϕRSB1 (with an infection cycle of ca. 180min). Co-infection experiments with ϕRSB1 and ϕRSB2 showed that ϕRSB2 always predominated in the phage progeny independent of host strains. Most phages had wide host-ranges and the phage particles usually did not attach to the resistant strains; when occasionally some did, the phage genome was injected into the resistant strain׳s cytoplasm, as revealed by fluorescence microscopy with SYBR Gold-labeled phage particles. PMID:26901487

  3. Population genetic analysis reveals cryptic sex in the phytopathogenic fungus Alternaria alternata

    PubMed Central

    Meng, Jing-Wen; Zhu, Wen; He, Meng-Han; Wu, E-Jiao; Duan, Guo-Hua; Xie, Ye-Kun; Jin, Yu-Jia; Yang, Li-Na; Shang, Li-Ping; Zhan, Jiasui

    2015-01-01

    Reproductive mode can impact population genetic dynamics and evolutionary landscape of plant pathogens as well as on disease epidemiology and management. In this study, we monitored the spatial dynamics and mating type idiomorphs in ~700 Alternaria alternata isolates sampled from the main potato production areas in China to infer the mating system of potato early blight. Consistent with the expectation of asexual species, identical genotypes were recovered from different locations separated by hundreds of kilometers of geographic distance and spanned across many years. However, high genotype diversity, equal MAT1-1 and MAT1-2 frequencies within and among populations, no genetic differentiation and phylogenetic association between two mating types, combined with random association amongst neutral markers in some field populations, suggested that sexual reproduction may also play an important role in the epidemics and evolution of the pathogen in at least half of the populations assayed despite the fact that no teleomorphs have been observed yet naturally or artificially. Our results indicated that A. alternata may adopt an epidemic mode of reproduction by combining many cycles of asexual propagation with fewer cycles of sexual reproduction, facilitating its adaptation to changing environments and making the disease management on potato fields even more difficult. PMID:26666175

  4. Relative potency of culture supernatants of Xenorhabdus and Photorhabdus spp. on growth of some fungal phytopathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We evaluated the potency of 10% v/v cell-free culture supernatants of cultures of the bacteria X. bovienii, X. nematophila, X. cabanillasii, X. szentirmaii, P. temperata, P. luminescens (VS) and P. luminescens (K22) against Fusicladium carpophilum (peach scab), Fusicladium effusum (pecan scab), Moni...

  5. The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri

    PubMed Central

    Stockton, Dara G.; Martini, Xavier; Patt, Joseph M.; Stelinski, Lukasz L.

    2016-01-01

    Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a) whether development on specific host plant species influenced host plant preference in mature D. citri; and b) the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24–48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate Rutaceae in the area being monitored. PMID:26930355

  6. The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri.

    PubMed

    Stockton, Dara G; Martini, Xavier; Patt, Joseph M; Stelinski, Lukasz L

    2016-01-01

    Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a) whether development on specific host plant species influenced host plant preference in mature D. citri; and b) the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24-48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate Rutaceae in the area being monitored. PMID:26930355

  7. Development of conductive polymer analysis for the rapid detection and identification of phytopathogenic microbes.

    PubMed

    Wilson, A D; Lester, D G; Oberle, C S

    2004-05-01

    ABSTRACT Conductive polymer analysis, a type of electronic aroma detection technology, was evaluated for its efficacy in the detection, identification, and discrimination of plant-pathogenic microorganisms on standardized media and in diseased plant tissues. The method is based on the acquisition of a diagnostic electronic fingerprint derived from multisensor responses to distinct mixtures of volatile metabolites released into sampled headspace. Protocols were established to apply this technology specifically to plant disease diagnosis. This involved development of standardized cultural methods, new instrument architecture for sampling, sample preparation, prerun procedures, run parameters and schedules, recognition files and libraries, data manipulations, and validation protocols for interpretations of results. The collective output from a 32-sensor array produced unique electronic aroma signature patterns diagnostic of individual microbial species in culture and specific pathogen-host combinations associated with diseased plants. The level of discrimination applied in identifications of unknowns was regulated by confidence level and sensitivity settings during construction of application-specific reference libraries for each category of microbe or microbe-host combination identified. Applications of this technology were demonstrated for the diagnosis of specific disease systems, including bacterial and fungal diseases and decays of trees; for host identifications; and for determinations of levels of infection and relatedness between microbial species. Other potential applications to plant pathology are discussed with some advantages and limitations for each type of diagnostic application. PMID:18943759

  8. The rhizobacterium Arthrobacter agilis produces dimethylhexadecylamine, a compound that inhibits growth of phytopathogenic fungi in vitro.

    PubMed

    Velázquez-Becerra, Crisanto; Macías-Rodríguez, Lourdes I; López-Bucio, José; Flores-Cortez, Idolina; Santoyo, Gustavo; Hernández-Soberano, Christian; Valencia-Cantero, Eduardo

    2013-12-01

    Plant diseases caused by fungal pathogens such as Botrytis cinerea and the oomycete Phytophthora cinnamomi affect agricultural production worldwide. Control of these pests can be done by the use of fungicides such as captan, which may have deleterious effects on human health. This study demonstrates that the rhizobacterium Arthrobacter agilis UMCV2 produces volatile organic compounds that inhibit the growth of B. cinerea in vitro. A single compound from the volatile blends, namely dimethylhexadecylamine (DMHDA), could inhibit the growth of both B. cinerea and P. cinnamomi when supplied to the growth medium in low concentrations. DMHDA also inhibited the growth of beneficial fungi Trichoderma virens and Trichoderma atroviride but at much higher concentrations. DMHDA-related aminolipids containing 4, 8, 10, 12, and 14 carbons in the alkyl chain were tested for their inhibitory effect on the growth of the pathogens. The results show that the most active compound from those tested was dimethyldodecylamine. This effect correlates with a decrease in the number of membrane lipids present in the mycelium of the pathogen including eicosanoic acid, (Z)-9-hexadecenoic acid, methyl ester, and (Z)-9-octadecenoic acid, methyl ester. Strawberry leaflets treated with DMHDA were not injured by the compound. These data indicate that DMHDA and related compounds, which can be produced by microorganisms may effectively inhibit the proliferation of certain plant pathogens. PMID:23674267

  9. Whole genome sequences and annotation of Micrococcus luteus SUBG006, a novel phytopathogen of mango.

    PubMed

    Rakhashiya, Purvi M; Patel, Pooja P; Thaker, Vrinda S

    2015-12-01

    Actinobaceria, Micrococcus luteus SUBG006 was isolated from infected leaves of Mangifera indica L. vr. Nylon in Rajkot, (22.30°N, 70.78°E), Gujarat, India. The genome size is 3.86 Mb with G + C content of 69.80% and contains 112 rRNA sequences (5S, 16S and 23S). The whole genome sequencing has been deposited in DDBJ/EMBL/GenBank under the accession number JOKP00000000. PMID:26697318

  10. Population genetic analysis reveals cryptic sex in the phytopathogenic fungus Alternaria alternata.

    PubMed

    Meng, Jing-Wen; Zhu, Wen; He, Meng-Han; Wu, E-Jiao; Duan, Guo-Hua; Xie, Ye-Kun; Jin, Yu-Jia; Yang, Li-Na; Shang, Li-Ping; Zhan, Jiasui

    2015-01-01

    Reproductive mode can impact population genetic dynamics and evolutionary landscape of plant pathogens as well as on disease epidemiology and management. In this study, we monitored the spatial dynamics and mating type idiomorphs in ~700 Alternaria alternata isolates sampled from the main potato production areas in China to infer the mating system of potato early blight. Consistent with the expectation of asexual species, identical genotypes were recovered from different locations separated by hundreds of kilometers of geographic distance and spanned across many years. However, high genotype diversity, equal MAT1-1 and MAT1-2 frequencies within and among populations, no genetic differentiation and phylogenetic association between two mating types, combined with random association amongst neutral markers in some field populations, suggested that sexual reproduction may also play an important role in the epidemics and evolution of the pathogen in at least half of the populations assayed despite the fact that no teleomorphs have been observed yet naturally or artificially. Our results indicated that A. alternata may adopt an epidemic mode of reproduction by combining many cycles of asexual propagation with fewer cycles of sexual reproduction, facilitating its adaptation to changing environments and making the disease management on potato fields even more difficult. PMID:26666175

  11. Detection and characterization of a novel Gammapartitivirus in the phytopathogenic fungus Colletotrichum acutatum strain HNZJ001.

    PubMed

    Zhong, Jie; Chen, Dan; Lei, Xiang Hua; Zhu, Hong Jian; Zhu, Jun Zi; Da Gao, Bi

    2014-09-22

    Spherical virus-like particles about 40nm in diameter were observed under transmission electron microscope (TEM) and two dsRNA bands (dsRNA-1 and dsRNA-2) were detected on agarose gel after extraction from the mycelial preparation of a Colletotrichum acutatum strain HNZJ001 that isolated from an anthracnose lesion on immature pepper fruit. The complete nucleotide sequences of the dsRNAs were determined. DsRNA-1 (1762 nt) and dsRNA-2 (1381 nt) each contained a single open reading frame and potentially encoded 62 kDa and 40 kDa proteins, respectively. The 62 kDa protein showed similarity to the RNA-dependent RNA polymerase (RdRp) of partitiviruses, while the 40 kDa product had no significant similarity to any published capsid protein throughout all databases, besides of low homology with the hypothetical "capsid" protein of a few partitiviruses in fungus Ustilaginoidea virens. Genome comparison and phylogenetic analysis indicated that the virus is closely related to the mycovirus in the family Partitiviridae. The results suggested a novel two-segment dsRNA virus be detected. We name it Colletotrichum acutatum partitivirus 1 (CaPV1). RT-PCR detection, using a primer pair based on the RdRp of the dsRNA-1 showed very high efficiency of CaPV1 transmission into the progenies of the fungus. Virus curing and fungal phenotype observation for evaluation of the impact of CaPV1 in host fungus were also carried out. PMID:25008759

  12. Characterization of Volatile Constituents of Scaligeria tripartita and Studies on the Antifungal Activity Against Phytopathogenic Fungi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The chemical composition of the essential oils obtained from stems and leaves, fruits and roots of Scaligeria tripartita oil was analyzed by gas chromatography-mass spectrometry. A total of 38 compounds were identified ranging 89 to 94% of the oil samples. Geijerene was found as a main compound in t...

  13. Microbial diversity inside pumpkins: microhabitat-specific communities display a high antagonistic potential against phytopathogens.

    PubMed

    Fürnkranz, Michael; Lukesch, Birgit; Müller, Henry; Huss, Herbert; Grube, Martin; Berg, Gabriele

    2012-02-01

    Recent and substantial yield losses of Styrian oil pumpkin (Cucurbita pepo L. subsp. pepo var. styriaca Greb.) are primarily caused by the ascomycetous fungus Didymella bryoniae but bacterial pathogens are frequently involved as well. The diversity of endophytic microbial communities from seeds (spermosphere), roots (endorhiza), flowers (anthosphere), and fruits (carposphere) of three different pumpkin cultivars was studied to develop a biocontrol strategy. A multiphasic approach combining molecular, microscopic, and cultivation techniques was applied to select a consortium of endophytes for biocontrol. Specific community structures for Pseudomonas and Bacillus, two important plant-associated genera, were found for each microenvironment by fingerprinting of 16S ribosomal RNA genes. All microenvironments were dominated by bacteria; fungi were less abundant. Of the 2,320 microbial isolates analyzed in dual culture assays, 165 (7%) were tested positively for in vitro antagonism against D. bryoniae. Out of these, 43 isolates inhibited the growth of bacterial pumpkin pathogens (Pectobacterium carotovorum, Pseudomonas viridiflava, Xanthomonas cucurbitae); here only bacteria were selected. Microenvironment-specific antagonists were found, and the spermosphere and anthosphere were revealed as underexplored reservoirs for antagonists. In the latter, a potential role of pollen grains as bacterial vectors between flowers was recognized. Six broad spectrum antagonists selected according to their activity, genotypic diversity, and occurrence were evaluated under greenhouse conditions. Disease severity on pumpkins of D. bryoniae was significantly reduced by Pseudomonas chlororaphis treatment and by a combined treatment of strains (Lysobacter gummosus, P. chlororaphis, Paenibacillus polymyxa, and Serratia plymuthica). This result provides a promising prospect to biologically control pumpkin diseases. PMID:21947430

  14. Trypsin-like Proteins of the Fungi as Possible Markers of Phytopathogenicity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sequences of peptidases with conserved motifs around the active site residues that are characteristic of trypsins (similar to trypsin peptidases, STP) were obtained from publicly available fungal genomes and related databases. Among the 74 fungal genomes, 30 species of parasitic Ascomycota contained...

  15. Bacteriocin-resistant mutants of Erwinia chrysanthemi: possible involvement of iron acquisition in phytopathogenicity.

    PubMed

    Expert, D; Toussaint, A

    1985-07-01

    A series of bacteriocin-resistant mutants of Erwinia chrysanthemi 3937JRH were unable to elicit soft-rot symptoms on saintpaulia plants. The loss of pathogenicity was correlated with the disappearance of one to three outer membrane polypeptides (molecular weights, about 80,000 to 90,000) whose production in wild-type strains was greatly enhanced under iron-limited growth conditions. The mutants did not exhibit altered extracellular pectinolytic or cellulolytic activities. PMID:4008442

  16. Characterization of rhizosphere bacteria for control of phytopathogenic fungi of tomato.

    PubMed

    Pastor, Nicolás; Carlier, Evelin; Andrés, Javier; Rosas, Susana B; Rovera, Marisa

    2012-03-01

    Fluorescent Pseudomonas spp., isolated from rhizosphere soil of tomato and pepper plants, were evaluated in vitro as potential antagonists of fungal pathogens. Strains were characterized using the API 20NE biochemical system, and tested against the causal agents of stem canker and leaf blight (Alternaria alternata f. sp. lycopersici), southern blight (Sclerotium rolfsii Sacc.), and root rot (Fusarium solani). To this end, dual culture antagonism assays were carried out on 25% Tryptic Soy Agar, King B medium, and Potato Dextrose Agar to determine the effect of the strains on mycelial growth of the pathogens. The effect of two concentrations of FeCl(3) on antagonism against Alternaria alternata f. sp. lycopersici was also tested. In addition, strains were screened for ability to produce exoenzymes and siderophores. Finally, the selected Pseudomonas strain, PCI2, was evaluated for effect on tomato seedling development and as a potential candidate for controlling tomato damping-off caused by Sclerotium rolfsii Sacc., under growth chamber conditions. All strains significantly inhibited Alternaria alternata f. sp. lycopersici, particularly in 25% TSA medium. Antagonistic effect on Sclerotium rolfsii Sacc. and Fusarium solani was greater on King B medium. Protease was produced by 30% of the strains, but no strains produced cellulase or chitinase. Growth chamber studies resulted in significant increases in plant stand as well as in root dry weight. PCI2 was able to establish and survive in tomato plants rhizosphere after 40 days following planting of bacterized seeds. PMID:21507555

  17. Fluorescent Pseudomonads in the Phyllosphere of Wheat: Potential Antagonists Against Fungal Phytopathogens.

    PubMed

    Müller, Thomas; Behrendt, Undine; Ruppel, Silke; von der Waydbrink, Grit; Müller, Marina E H

    2016-04-01

    Fluorescent pseudomonads isolated from wheat leaves were characterized regarding their antagonistic potential and taxonomy in relation to protect crop plants from infestation by Fusarium and Alternaria fungi causing diseases in wheat. Using a dual culture assay, inhibition of fungal growth was found for 40 isolates of 175 fluorescent pseudomonads. Twenty-two of the antagonists were able to suppress strains of Fusarium as well as Alternaria. By means of real-time qPCR, the phlD gene encoding the antibiotic 2,4-diacetylphloroglucinol was detected in 20 isolates. On the basis of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry spectral patterns, the isolates with antagonistic activity were assigned to the phylogenetic subgroup Pseudomonas fluorescens and the closely related Pseudomonas gessardii subgroup. The results of the study suggest that pseudomonads in the phyllosphere of crop plants may possibly contribute to natural plant protection. PMID:26687461

  18. A functional 4-hydroxybenzoate degradation pathway in the phytopathogen Xanthomonas campestris is required for full pathogenicity

    PubMed Central

    Wang, Jia-Yuan; Zhou, Lian; Chen, Bo; Sun, Shuang; Zhang, Wei; Li, Ming; Tang, Hongzhi; Jiang, Bo-Le; Tang, Ji-Liang; He, Ya-Wen

    2015-01-01

    Plants contain significant levels of natural phenolic compounds essential for reproduction and growth, as well as defense mechanisms against pathogens. Xanthomonas campestris pv. campestris (Xcc) is the causal agent of crucifers black rot. Here we showed that genes required for the synthesis, utilization, transportation, and degradation of 4-hydroxybenzoate (4-HBA) are present in Xcc. Xcc rapidly degrades 4-HBA, but has no effect on 2-hydroxybenzoate and 3-hydroxybenzoate when grown in XOLN medium. The genes for 4-HBA degradation are organized in a superoperonic cluster. Bioinformatics, biochemical, and genetic data showed that 4-HBA is hydroxylated by 4-HBA 3-hydroxylase (PobA), which is encoded by Xcc0356, to yield PCA. The resulting PCA is further metabolized via the PCA branches of the β-ketoadipate pathway, including Xcc0364, Xcc0365, and PcaFHGBDCR. Xcc0364 and Xcc0365 encode a new form of β-ketoadipate succinyl-coenzyme A transferase that is required for 4-HBA degradation. pobA expression was induced by 4-HBA via the transcriptional activator, PobR. Radish and cabbage hydrolysates contain 2-HBA, 3-HBA, 4-HBA, and other phenolic compounds. Addition of radish and cabbage hydrolysates to Xcc culture significantly induced the expression of pobA via PobR. The 4-HBA degradation pathway is required for full pathogenicity of Xcc in radish. PMID:26672484

  19. Peltaster fructicola genome reveals evolution from an invasive phytopathogen to an ectophytic parasite.

    PubMed

    Xu, Chao; Chen, Huan; Gleason, Mark L; Xu, Jin-Rong; Liu, Huiquan; Zhang, Rong; Sun, Guangyu

    2016-01-01

    Sooty blotch and flyspeck (SBFS) fungi are unconventional plant pathogens that cause economic losses by blemishing the surface appearance of infected fruit. Here, we introduce the 18.14-Mb genome of Peltaster fructicola, one of the most prevalent SBFS species on apple. This undersized assembly contains only 8,334 predicted protein-coding genes and a very small repertoire of repetitive elements. Phylogenomics and comparative genomics revealed that P. fructicola had undergone a reductive evolution, during which the numbers of orphan genes and genes involved in plant cell wall degradation, secondary metabolism, and secreted peptidases and effectors were drastically reduced. In contrast, the genes controlling 1,8-dihydroxynaphthalene (DHN)-melanin biosynthesis and appressorium-mediated penetration were retained substantially. Additionally, microscopic examination of the surfaces of infected apple indicated for the first time that P. fructicola can not only dissolve epicuticular waxes but also partially penetrate the cuticle proper. Our findings indicate that genome contraction, characterized mainly by the massive loss of pathogenicity-related genes, has played an important role in the evolution of P. fructicola (and by implication other SBFS species) from a plant-penetrating ancestor to a non-invasive ectophyte, displaying a novel form of trophic interaction between plants and fungi. PMID:26964666

  20. Small RNA-Based Antiviral Defense in the Phytopathogenic Fungus Colletotrichum higginsianum.

    PubMed

    Campo, Sonia; Gilbert, Kerrigan B; Carrington, James C

    2016-06-01

    Even though the fungal kingdom contains more than 3 million species, little is known about the biological roles of RNA silencing in fungi. The Colletotrichum genus comprises fungal species that are pathogenic for a wide range of crop species worldwide. To investigate the role of RNA silencing in the ascomycete fungus Colletotrichum higginsianum, knock-out mutants affecting genes for three RNA-dependent RNA polymerase (RDR), two Dicer-like (DCL), and two Argonaute (AGO) proteins were generated by targeted gene replacement. No effects were observed on vegetative growth for any mutant strain when grown on complex or minimal media. However, Δdcl1, Δdcl1Δdcl2 double mutant, and Δago1 strains showed severe defects in conidiation and conidia morphology. Total RNA transcripts and small RNA populations were analyzed in parental and mutant strains. The greatest effects on both RNA populations was observed in the Δdcl1, Δdcl1Δdcl2, and Δago1 strains, in which a previously uncharacterized dsRNA mycovirus [termed Colletotrichum higginsianum non-segmented dsRNA virus 1 (ChNRV1)] was derepressed. Phylogenetic analyses clearly showed a close relationship between ChNRV1 and members of the segmented Partitiviridae family, despite the non-segmented nature of the genome. Immunoprecipitation of small RNAs associated with AGO1 showed abundant loading of 5'U-containing viral siRNA. C. higginsianum parental and Δdcl1 mutant strains cured of ChNRV1 revealed that the conidiation and spore morphology defects were primarily caused by ChNRV1. Based on these results, RNA silencing involving ChDCL1 and ChAGO1 in C. higginsianum is proposed to function as an antiviral mechanism. PMID:27253323

  1. Expression of a plant defensin in rice confers resistance to fungal phytopathogens.

    PubMed

    Jha, Sanjay; Chattoo, Bharat B

    2010-06-01

    Transgenic rice (Oryza sativa L. cv. Pusa basmati 1), overexpressing the Rs-AFP2 defensin gene from the Raphanus sativus was generated by Agrobacterium tumefaciens-mediated transformation. Expression levels of Rs-AFP2 ranged from 0.45 to 0.53% of total soluble protein in transgenic plants. It was observed that constitutive expression of Rs-AFP2 suppresses the growth of Magnaporthe oryzae and Rhizoctonia solani by 77 and 45%, respectively. No effect on plant morphology was observed in the Rs-AFP2 expressing rice lines. The inhibitory activity of protein extracts prepared from leaves of Rs-AFP2 plants on the in vitro growth of M. oryzae indicated that the Rs-AFP2 protein produced by transgenic rice plants was biologically active. Transgene expression of Rs-AFP2 was not accompanied by an induction of pathogenesis-related (PR) gene expression, suggesting that the expression of Rs-AFP2 directly inhibits the pathogens. Here, we demonstrate that transgenic rice plants expressing the Rs-AFP2 gene show enhanced resistance to M. oryzae and R. solani, two of the most important pathogens of rice. PMID:19690975

  2. Genome Sequences of Three Phytopathogenic Species of the Magnaporthaceae Family of Fungi

    PubMed Central

    Okagaki, Laura H.; Nunes, Cristiano C.; Sailsbery, Joshua; Clay, Brent; Brown, Doug; John, Titus; Oh, Yeonyee; Young, Nelson; Fitzgerald, Michael; Haas, Brian J.; Zeng, Qiandong; Young, Sarah; Adiconis, Xian; Fan, Lin; Levin, Joshua Z.; Mitchell, Thomas K.; Okubara, Patricia A.; Farman, Mark L.; Kohn, Linda M.; Birren, Bruce; Ma, Li-Jun; Dean, Ralph A.

    2015-01-01

    Magnaporthaceae is a family of ascomycetes that includes three fungi of great economic importance: Magnaporthe oryzae, Gaeumannomyces graminis var. tritici, and Magnaporthe poae. These three fungi cause widespread disease and loss in cereal and grass crops, including rice blast disease (M. oryzae), take-all disease in wheat and other grasses (G. graminis), and summer patch disease in turf grasses (M. poae). Here, we present the finished genome sequence for M. oryzae and draft sequences for M. poae and G. graminis var. tritici. We used multiple technologies to sequence and annotate the genomes of M. oryzae, M. poae, and G. graminis var. tritici. The M. oryzae genome is now finished to seven chromosomes whereas M. poae and G. graminis var. tritici are sequenced to 40.0× and 25.0× coverage respectively. Gene models were developed by the use of multiple computational techniques and further supported by RNAseq data. In addition, we performed preliminary analysis of genome architecture and repetitive element DNA. PMID:26416668

  3. Growth and enzymatic responses of phytopathogenic fungi to glucose in culture media and soil

    PubMed Central

    Costa, Beatriz de Oliveira; Nahas, Ely

    2012-01-01

    The effect of inoculation of Aspergillus flavus , Fusarium verticillioides , and Penicillium sp. in Dystrophic Red Latosol (DRL) and Eutroferric Red Latosol (ERL) soils with or without glucose on the total carbohydrate content and the dehydrogenase and amylase activities was studied. The fungal growth and spore production in culture medium with and without glucose were also evaluated. A completely randomized design with factorial arrangement was used. The addition of glucose in the culture medium increased the growth rate of A. flavus and Penicillium sp. but not of F. verticillioides . The number of spores increased 1.2 for F. verticillioides and 8.2 times for A. flavus in the medium with glucose, but was reduced 3.5 times for Penicillium sp. The total carbohydrates contents reduced significantly according to first and second degree equations. The consumption of total carbohydrates by A. flavus and Penicillium sp. was higher than the control or soil inoculated with F. verticillioides . The addition of glucose to soils benefited the use of carbohydrates, probably due to the stimulation of fungal growth. Dehydrogenase activity increased between 1.5 to 1.8 times ( p <0.05) in soils with glucose and inoculated with the fungi (except F. verticillioides ), in relation to soil without glucose. Amylase activity increased 1.3 to 1.5 times due to the addition of glucose in the soil. Increased amylase activity was observed in the DRL soil with glucose and inoculated with A. flavus and Penicillium sp. when compared to control. PMID:24031836

  4. Antifungal tests in phytochemical investigations: comparison of bioautographic methods using phytopathogenic and human pathogenic fungi.

    PubMed

    Rahalison, L; Hamburger, M; Monod, M; Frenk, E; Hostettmann, K

    1994-02-01

    The detection limits in two bioautographic assays have been determined for a series of antifungal compounds, including clinically used antimycotics, fungicidal agrochemicals, and various classes of secondary plant metabolites. Target organisms were the filamentous fungus Cladosporium cucumerinum and the yeast Candida albicans. For clinical agents and agrochemicals, the detection limits in the two assays reflected to a certain extent their known spectrum of activity. Most of the plant-derived compounds tested showed a positive response in both assays, but with detection limits varying by a factor up to tenfold. For screening purposes, it is thus advisable to use both tests, as some activities would otherwise go undetected. The MIC values of these substances were determined in order to verify a possible correlation with the detection limit in the bioautographic assays. PMID:8134415

  5. Identification and characterization of polymorphic minisatellites in the phytopathogenic ascomycete Leptosphaeria maculans.

    PubMed

    Eckert, Maria; Gout, Lilian; Rouxel, Thierry; Blaise, Françoise; Jedryczka, Malgorzata; Fitt, Bruce; Balesdent, Marie-Hélène

    2005-01-01

    Leptosphaeria maculans causes phoma stem canker, the most serious disease of oilseed rape world-wide. Sexual recombination is important in the pathogen life cycle and increases the risk of plant resistance genes being overcome rapidly. Thus, there is a need to develop easy-to-use molecular markers suitable for large-scale population genetic studies. The minisatellite MinLm1, showing six alleles in natural populations, has previously been used as a marker to survey populations. Here, we report the characterization of five new minisatellites (MinLm2-MinLm6), of which four were identified by a systematic search for tandemly repeated polymorphic regions in BAC-end sequencing data from L. maculans. Of 782 BAC-end sequences analysed, 43 possessed putative minisatellite-type repeats and four of these (MinLm3-MinLm6) displayed both consistent PCR amplification and size polymorphism in a collection of L. maculans isolates of diverse origins. Cloning and sequencing of each allele confirmed that polymorphism was due to variation in the repeat number of a core motif ranging from 11 bp (MinLm3) to 51 bp (MinLm4). The number of alleles found for each minisatellite ranged from three (MinLm4) to nine (MinLm2), with eight, five and six for MinLm3, MinLm5 and MinLm6, respectively. MinLm2-MinLm6 are all single locus markers specific to L. maculans and share some common features, such as conservation of core motifs and incomplete direct repeats in the flanking regions. To our knowledge, L. maculans is the first fungal species for which six polymorphic single locus minisatellite markers have been reported. PMID:15614492

  6. Complex regulation of secondary metabolism controlling pathogenicity in the phytopathogenic fungus Alternaria alternata.

    PubMed

    Takaoka, Shinya; Kurata, Mariko; Harimoto, Yoshiaki; Hatta, Rieko; Yamamoto, Mikihiro; Akimitsu, Kazuya; Tsuge, Takashi

    2014-06-01

    The filamentous fungus Alternaria alternata includes seven pathogenic variants (pathotypes), which produce different host-selective toxins and cause disease on different plants. The Japanese pear, strawberry and tangerine pathotypes produce AK-toxin, AF-toxin and ACT-toxin, respectively, which have a common structural moiety, 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid (EDA). Here, we identified a new gene, AKT7 (AK-toxin biosynthetic gene 7), from the Japanese pear pathotype, which encodes a cytochrome P450 monooxygenase and functions to limit AK-toxin production. AKT7 homologs were found in the strawberry pathotype, but not the tangerine pathotype. However, the strawberry pathotype homolog appeared to include a premature stop codon. Although the Japanese pear pathotype strain has multiple copies of AKT7, a single-copy disruption resulted in mutants with increased production of AK-toxin and EDA. AKT7 overexpression in the three pathotypes caused marked reductions of toxin and EDA production, suggesting that Akt7 catalyzes a side reaction of EDA or its precursor. AKT7 overexpression caused reduced virulence in these pathotypes. We also found that AKT7 transcripts predominantly include misspliced mRNAs, which have premature stop codons. Our observations suggest that the AK-toxin production required for full virulence is regulated in a complex way by the copy number and intron information content of AKT7. PMID:24611558

  7. Synthesis, Biological Evaluation, and Molecular Modeling Studies of New Oxadiazole-Stilbene Hybrids against Phytopathogenic Fungi

    PubMed Central

    Jian, Weilin; He, Daohang; Song, Shaoyun

    2016-01-01

    Natural stilbenes (especially resveratrol) play important roles in plant protection by acting as both constitutive and inducible defenses. However, their exogenous applications on crops as fungicidal agents are challenged by their oxidative degradation and limited availability. In this study, a new class of resveratrol-inspired oxadiazole-stilbene hybrids was synthesized via Wittig-Horner reaction. Bioassay results indicated that some of the compounds exhibited potent fungicidal activity against Botrytis cinerea in vitro. Among these stilbene hybrids, compounds 11 showed promising inhibitory activity with the EC50 value of 144.6 μg/mL, which was superior to that of resveratrol (315.6 μg/mL). Remarkably, the considerably abnormal mycelial morphology was observed in the presence of compound 11. The inhibitory profile was further proposed by homology modeling and molecular docking studies, which showed the possible interaction of resveratrol and oxadiazole-stilbene hybrids with the cytochrome P450-dependent sterol 14α-demethylase from B. cinerea (BcCYP51) for the first time. Taken together, these results would provide new insights into the fungicidal mechanism of stilbenes, as well as an important clue for biology-oriented synthesis of stilbene hybrids with improved bioactivity against plant pathogenic fungi in crop protection. PMID:27530962

  8. The Sesquiterpene Synthase from the Botrydial Biosynthetic Gene Cluster of the Phytopathogen Botrytis cinerea

    PubMed Central

    Pinedo, Cristina; Wang, Chieh-Mei; Pradier, Jean-Marc; Dalmais, Bérengère; Choquer, Mathias; Pêcheur, Pascal Le; Morgant, Guillaume; Collado, Isidro G.; Cane, David E.; Viaud, Muriel

    2009-01-01

    The fungus Botrytis cinerea is the causal agent of the economically important gray mold disease that affects more than 200 ornamental and agriculturally important plant species. B. cinerea is a necrotrophic plant pathogen that secretes nonspecific phytotoxins, including the sesquiterpene botrydial and the polyketide botcinic acid. The region surrounding the previously characterized BcBOT1 gene has now been identified as the botrydial biosynthetic gene cluster. Five genes including BcBOT1 and BcBOT2 were shown by quantitative Reverse Transcription-PCR to be co-regulated through the calcineurin signaling pathway. Inactivation of the BcBOT2 gene, encoding a putative sesquiterpene cyclase, abolished botrydial biosynthesis, which could be restored by in trans complementation. Inactivation of BcBOT2 also resulted in over-production of botcinic acid that was observed to be strain-dependent. Recombinant BcBOT2 protein converted farnesyl diphosphate to the parent sesquiterpene of the botrydial biosynthetic pathway, the tricyclic alcohol presilphiperfolan-8β-ol. PMID:19035644

  9. Trichoderma volatiles effecting Arabidopsis: from inhibition to protection against phytopathogenic fungi

    PubMed Central

    Kottb, Metwally; Gigolashvili, Tamara; Großkinsky, Dominik K.; Piechulla, Birgit

    2015-01-01

    Trichoderma species are present in many ecosystems and some strains have the ability to reduce the severity of plant diseases by activating various defense pathways via specific biologically active signaling molecules. Hence we investigated the effects of low molecular weight volatile compounds of Trichoderma asperellum IsmT5 on Arabidopsis thaliana. During co-cultivation of T. asperellum IsmT5 without physical contact to A. thaliana we observed smaller but vital and robust plants. The exposed plants exhibit increased trichome numbers, accumulation of defense-related compounds such as H2O2, anthocyanin, camalexin, and increased expression of defense-related genes. We conclude that A. thaliana perceives the Trichoderma volatiles as stress compounds and subsequently initiates multilayered adaptations including activation of signaling cascades to withstand this environmental influence. The prominent headspace volatile of T. asperellum IsmT5 was identified to be 6-pentyl-α-pyrone (6PP), which was solely applied to A. thaliana to verify the growth and defense reactions. Most noticeable is that A. thaliana preexposed to 6PP showed significantly reduced symptoms when challenged with Botrytis cinerea and Alternaria brassicicola, indicating that defense-activated plants subsequently became more resistant to pathogen attack. Together, these results support that products that are based on Trichoderma volatiles have the potential being a useful biocontrol agent in agriculture. PMID:26483761

  10. Ancestral state reconstruction infers phytopathogenic origins of sooty blotch and flyspeck fungi on apple.

    PubMed

    Ismail, Siti Izera; Batzer, Jean Carlson; Harrington, Thomas C; Crous, Pedro W; Lavrov, Dennis V; Li, Huanyu; Gleason, Mark L

    2016-01-01

    Members of the sooty blotch and flyspeck (SBFS) complex are epiphytic fungi in the Ascomycota that cause economically damaging blemishes of apples worldwide. SBFS fungi are polyphyletic, but approx. 96% of SBFS species are in the Capnodiales. Evolutionary origins of SBFS fungi remain unclear, so we attempted to infer their origins by means of ancestral state reconstruction on a phylogenetic tree built utilizing genes for the nuc 28S rDNA (approx. 830 bp from near the 59 end) and the second largest subunit of RNA polymerase II (RPB2). The analyzed taxa included the well-known genera of SBFS as well as non-SBFS fungi from seven families within the Capnodiales. The non-SBFS taxa were selected based on their distinct ecological niches, including plant-parasitic and saprophytic species. The phylogenetic analyses revealed that most SBFS species in the Capnodiales are closely related to plant-parasitic fungi. Ancestral state reconstruction provided strong evidence that plant-parasitic fungi were the ancestors of the major SBFS lineages. Knowledge gained from this study may help to better understand the ecology and evolution of epiphytic fungi. PMID:26740537

  11. Genome sequences of three phytopathogenic species of the Magnaporthaceae family of fungi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Magnaporthaceae is a family of ascomycetes that includes three fungi of great economic importance: Magnaporthe oryzae, Gaeumannomyces graminis var. tritici, and Magnaporthe poae. These three fungi cause widespread disease and loss in cereal and grass crops, including rice blast disease (M. oryzae), ...

  12. Purification and characterization of the extracellular aspartyl protease APSm1 from the phytopathogen fungus Stenocarpella maydis.

    PubMed

    Mandujano-González, Virginia; Téllez-Jurado, Alejandro; Anducho-Reyes, Miguel Angel; Arana-Cuenca, Ainhoa; Mercado-Flores, Yuridia

    2016-01-01

    The extracellular protease APSm1 was purified to homogeneity from Stenocarpella maydis that was grown in acidic minimal media with glucose and ammonium sulfate. The purification procedure consisted of ion exchange chromatography coupled to an FPLC (Fast Protein Liquid Chromatography) system, resulting in a 15.3% recovery and a 2.3-fold increase in specific activity. The molecular weight of the purified enzyme was estimated to be 56.8 kDa by SDS-PAGE. Enzymatic activity toward hemoglobin was optimal at pH 2.0 and at 25 °C. The effects of six protease inhibitors on APSm1 activity were tested. Pepstatin A inhibited APSm1 activity, as the protein is in fact an aspartyl protease. The pure enzyme degraded hemoglobin, albumin and proteins obtained from corn germ at pH 3 but did not have any milk-clotting activities. The Km and Vmax values obtained were 0.514 mg/mL and 0.222 μmol/min, respectively, using hemoglobin as the substrate. This work is the first to report the purification of a secreted aspartyl protease from S. maydis. PMID:26384707

  13. Biochemical study of the extracellular aspartyl protease Eap1 from the phytopathogen fungus Sporisorium reilianum.

    PubMed

    Mandujano-González, Virginia; Arana-Cuenca, Ainhoa; Anducho-Reyes, Miguel Ángel; Téllez-Jurado, Alejandro; González-Becerra, Aldo E; Mercado-Flores, Yuridia

    2013-12-01

    In this work, the extracellular protease Eap1 from Sporisorium reilianum was characterized in solid and liquid cultures using different culture media. The results showed that Eap1 was produced in all media and under all culture conditions, with the most activity in solid culture at an acidic pH of 3-5. Following purification, the 41 kDa protease demonstrated aspartyl protease activity. The enzyme was stable at a wide range of temperatures and pH values, but 45°C and pH 3 were optimal. The K(m) and V(max( values obtained were 0.69 mg/mL and 0.66 μmol/min, respectively, with albumin as the substrate. Eap1 degraded hemoglobin as well as proteins obtained from corn germ, roots, stems and slides at pH 3 and also had milk-clotting activity. Sequencing analysis showed that this protein has 100% similarity to the peptide sequence theoretically obtained from the sr11394 gene, which encodes an aspartyl protease secreted by S. reilianum. PMID:24128693

  14. The influence of learning on host plant preference in a significant phytopathogen vector, Diaphorina citri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri, vector ...

  15. Suppressive effects of metabolites from Photorhabdus spp. and Xenorhabdus spp. on phytopathogens of peach and pecan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our objective was to determine the suppressive abilities of bacterial metabolites derived from Photorhabdus and Xenorhabdus spp. on Glomerella cingulata, Phomopsis sp., Phytophthora cactorum, and Fusicladosporium effusum, which are fungal or oomycete pathogens of pecan, and Monilinia fructicola, a f...

  16. Characterization of a new aryl-alcohol oxidase secreted by the phytopathogenic fungus Ustilago maydis.

    PubMed

    Couturier, Marie; Mathieu, Yann; Li, Ai; Navarro, David; Drula, Elodie; Haon, Mireille; Grisel, Sacha; Ludwig, Roland; Berrin, Jean-Guy

    2016-01-01

    The discovery of novel fungal lignocellulolytic enzymes is essential to improve the breakdown of plant biomass for the production of second-generation biofuels or biobased materials in green biorefineries. We previously reported that Ustilago maydis grown on maize secreted a diverse set of lignocellulose-acting enzymes including hemicellulases and putative oxidoreductases. One of the most abundant proteins of the secretome was a putative glucose-methanol-choline (GMC) oxidoreductase. The phylogenetic prediction of its function was hampered by the few characterized members within its clade. Therefore, we cloned the gene and produced the recombinant protein to high yield in Pichia pastoris. Functional screening using a library of substrates revealed that this enzyme was able to oxidize several aromatic alcohols. Of the tested aryl-alcohols, the highest oxidation rate was obtained with 4-anisyl alcohol. Oxygen, 1,4-benzoquinone, and 2,6-dichloroindophenol can serve as electron acceptors. This GMC oxidoreductase displays the characteristics of an aryl-alcohol oxidase (E.C.1.1.3.7), which is suggested to act on the lignin fraction in biomass. PMID:26452496

  17. Optimization for rapid synthesis of silver nanoparticles and its effect on phytopathogenic fungi

    NASA Astrophysics Data System (ADS)

    Krishnaraj, C.; Ramachandran, R.; Mohan, K.; Kalaichelvan, P. T.

    In this present study, silver nanoparticles were synthesized by green chemistry approach using Acalypha indica leaf extract as reducing agents. The reaction medium employed in the synthesis process was optimized to attain better yield, controlled size and stability. Further, the biosynthesized silver nanoparticles were conformed through UV-vis spectrum, XRD and HR-TEM analyses. Different concentration of silver nanoparticles were tested to know the inhibitory effect of fungal plant pathogens namely Alternaria alternata, Sclerotinia sclerotiorum, Macrophomina phaseolina, Rhizoctonia solani, Botrytis cinerea and Curvularia lunata. Interestingly, 15 mg concentration of silver nanoparticles showed excellent inhibitory activity against all the tested pathogens. Thus, the obtained results clearly suggest that silver nanoparticles may have important applications in controlling various plant diseases caused by fungi.

  18. Antibacterial activity of carob (Ceratonia siliqua L.) extracts against phytopathogenic bacteria Pectobacterium atrosepticum.

    PubMed

    Meziani, Saïda; Oomah, B Dave; Zaidi, Farid; Simon-Levert, Annabel; Bertrand, Cédric; Zaidi-Yahiaoui, Rachida

    2015-01-01

    Acetone and ethanol extracts of carob (Ceratonia siliqua L.) leaf and pods were evaluated for their in vitro inhibitory ability against the pectinolytic Gram negative Pectobacterium atrosepticum (Pca, CFBP-5384) bacteria, the causal agent of potato soft rot. Potato (Solanum tuberosum, var nicola) tuber rot tissues obtained after 5 day bacterial inoculation was analyzed by LC-MS and GC-MS to study Pca pathogenicity. Trans/cis N-feruloylputrescine was identified in potato tuber after 5-day inoculation with Pca in a dark moist chamber. Although glycoalkoloid (α-chaconine and α-solanine) production increased due to Pca soft rot infection, it was not a resistance-determining factor. Many secondary metabolites were identified including the phytoalexins solavetivone and fatty acids responsible for plant defence responses. Acetone extract of carob leaf (FCA) exhibited the strongest inhibitory effect (IC50 = 1.5 mg/ml) and displayed synergistic antimicrobial effect in the presence of infected potato tuber extract (Pdt-Pca extract) against Pca. This synergy could be used in an integrated control program against potato soft rot pathogens, thereby reducing chemical treatments. PMID:25489722

  19. Non-cultivable phytopathogenic mycoplasmas: characterization, detection and perspectives for control.

    PubMed

    Garnier, M

    1997-08-01

    Phytoplasmas (ex MLOs) and spiroplasmas are important groups of plant pathogenic mollicutes, discovered in 1967 and 1970 respectively. Spiroplasmas, like other mollicutes, can be cultured in artificial media and are thus well characterized. On the contrary, phytoplasmas have resisted in vitro cultivation and their study was difficult until the recent development of molecular techniques. From the sequence of their 16S rDNA, phytoplasmas have been shown to be true mollicutes. Fourteen phytoplasma subclasses have been defined, but only two phytoplasmas have so far been named at the genus and species level. Monoclonal antibodies, DNA probes and PCR primers for the specific detection of various phytoplasmas have been obtained. These showed that a given phytoplasma can infect a broad range of plants, while others are restricted to a single plant species. Specific reagents are also used for identification of insect vectors and reservoir plants of the various phytoplasmas. Plant pathogenic mollicutes cannot be controlled chemically today, since the use of antibiotic treatment is forbidden in agriculture. However, the growth and metabolism of mollicutes are known to be inhibited by antibodies and this provides a hopeful approach for future control of these agents in plants. Indeed, it has been shown recently that plants can be engineered to express and assemble functional immunoglobulin chains. Transgenic tobacco plants expressing an antibody against the stolbur phytoplasmas have been developed. They have now to be challenged with the phytoplasma to determine if they have acquired resistance to this mollicute. PMID:9286069

  20. Suppression of phytopathogenic fungi by hexane extract of Nepenthes ventricosa x maxima leaf.

    PubMed

    Shin, Kwang-Soo; Lee, Samkeun; Cha, Byeong Jin

    2007-12-01

    The hexane extract of Nepenthes ventricosa x maxima leaf exhibited antifungal activity against Alternaria alternata, Aspergillus niger, Bipolaris oryzae, Fusarium oxysporum, Phytophthora capsici, Rhizoctonia solani, Rhizopus stolonifer var. stolonifer and Sclerotinia sclerotiorum. PMID:17573203

  1. Cloning and expression analysis of two opsin-like genes in the phytopathogenic fungus Bipolaris oryzae.

    PubMed

    Kihara, Junichi; Tanaka, Nozomi; Ueno, Makoto; Arase, Sakae

    2009-06-01

    Two opsin-like genes, OPS1 and OPS2, were identified from a subtracted cDNA library for the identification of near-UV (NUV) radiation-enhanced genes using suppression subtractive hybridization methods in the brown leaf spot fungus Bipolaris oryzae. The OPS1 and OPS2 genes encode predicted proteins of 306 and 304 amino acids, respectively. Real-time PCR analysis showed that the OPS1 transcript is expressed weakly in mycelia under dark conditions but shows enhanced expression after NUV irradiation. By contrast, the OPS2 transcript is constitutively expressed at a high level in mycelia under dark conditions but is only weakly enhanced after NUV irradiation. These enhancement patterns of OPS1 and OPS2 gene expression after NUV irradiation did not occur in the blue-light regulator 1 (BLR1)-deficient mutant, suggesting that NUV radiation-enhanced gene expression of OPS1 and OPS2 could be controlled by the BLR1 in B. oryzae. PMID:19456867

  2. RNA-mediated gene silencing in the phytopathogenic fungus Bipolaris oryzae.

    PubMed

    Moriwaki, Akihiro; Ueno, Makoto; Arase, Sakae; Kihara, Junichi

    2007-04-01

    The Ascomycetous fungus Bipolaris oryzae is the causal agent of brown leaf spot disease in rice and is a model for studying photomorphogenetic responses by near-UV radiation. Targeted gene disruption (knockout) for functional analysis of photomorphogenesis-related genes in B. oryzae can be achieved by homologous recombination with low efficiency. Here, the applicability of RNA silencing (knockdown) as a tool for targeting endogenous genes in B. oryzae is reported. A polyketide synthase gene (PKS1), involved in fungal DHN melanin biosynthesis pathways, was targeted by gene silencing as a marker. The silencing vector encoding hairpin RNA of the PKS1 fragment was constructed in a two-step PCR-based cloning, and introduced into the B. oryzae genomic DNA. Silencing of the PKS1 gene resulted in albino phenotypes and reduction of PKS1 mRNA expression. These results demonstrate the applicability of targeted gene silencing as a useful reverse-genetics approach in B. oryzae. PMID:17227462

  3. A functional 4-hydroxybenzoate degradation pathway in the phytopathogen Xanthomonas campestris is required for full pathogenicity.

    PubMed

    Wang, Jia-Yuan; Zhou, Lian; Chen, Bo; Sun, Shuang; Zhang, Wei; Li, Ming; Tang, Hongzhi; Jiang, Bo-Le; Tang, Ji-Liang; He, Ya-Wen

    2015-01-01

    Plants contain significant levels of natural phenolic compounds essential for reproduction and growth, as well as defense mechanisms against pathogens. Xanthomonas campestris pv. campestris (Xcc) is the causal agent of crucifers black rot. Here we showed that genes required for the synthesis, utilization, transportation, and degradation of 4-hydroxybenzoate (4-HBA) are present in Xcc. Xcc rapidly degrades 4-HBA, but has no effect on 2-hydroxybenzoate and 3-hydroxybenzoate when grown in XOLN medium. The genes for 4-HBA degradation are organized in a superoperonic cluster. Bioinformatics, biochemical, and genetic data showed that 4-HBA is hydroxylated by 4-HBA 3-hydroxylase (PobA), which is encoded by Xcc0356, to yield PCA. The resulting PCA is further metabolized via the PCA branches of the β-ketoadipate pathway, including Xcc0364, Xcc0365, and PcaFHGBDCR. Xcc0364 and Xcc0365 encode a new form of β-ketoadipate succinyl-coenzyme A transferase that is required for 4-HBA degradation. pobA expression was induced by 4-HBA via the transcriptional activator, PobR. Radish and cabbage hydrolysates contain 2-HBA, 3-HBA, 4-HBA, and other phenolic compounds. Addition of radish and cabbage hydrolysates to Xcc culture significantly induced the expression of pobA via PobR. The 4-HBA degradation pathway is required for full pathogenicity of Xcc in radish. PMID:26672484

  4. Genome structure and reproductive behaviour influence the evolutionary potential of a fungal phytopathogen.

    PubMed

    Daverdin, Guillaume; Rouxel, Thierry; Gout, Lilian; Aubertot, Jean-Noël; Fudal, Isabelle; Meyer, Michel; Parlange, Francis; Carpezat, Julien; Balesdent, Marie-Hélène

    2012-01-01

    Modern agriculture favours the selection and spread of novel plant diseases. Furthermore, crop genetic resistance against pathogens is often rendered ineffective within a few years of its commercial deployment. Leptosphaeria maculans, the cause of phoma stem canker of oilseed rape, develops gene-for-gene interactions with its host plant, and has a high evolutionary potential to render ineffective novel sources of resistance in crops. Here, we established a four-year field experiment to monitor the evolution of populations confronted with the newly released Rlm7 resistance and to investigate the nature of the mutations responsible for virulence against Rlm7. A total of 2551 fungal isolates were collected from experimental crops of a Rlm7 cultivar or a cultivar without Rlm7. All isolates were phenotyped for virulence and a subset was genotyped with neutral genetic markers. Virulent isolates were investigated for molecular events at the AvrLm4-7 locus. Whilst virulent isolates were not found in neighbouring crops, their frequency had reached 36% in the experimental field after four years. An extreme diversity of independent molecular events leading to virulence was identified in populations, with large-scale Repeat Induced Point mutations or complete deletion of AvrLm4-7 being the most frequent. Our data suggest that increased mutability of fungal genes involved in the interactions with plants is directly related to their genomic environment and reproductive system. Thus, rapid allelic diversification of avirulence genes can be generated in L. maculans populations in a single field provided that large population sizes and sexual reproduction are favoured by agricultural practices. PMID:23144620

  5. Peltaster fructicola genome reveals evolution from an invasive phytopathogen to an ectophytic parasite

    PubMed Central

    Xu, Chao; Chen, Huan; Gleason, Mark L.; Xu, Jin-Rong; Liu, Huiquan; Zhang, Rong; Sun, Guangyu

    2016-01-01

    Sooty blotch and flyspeck (SBFS) fungi are unconventional plant pathogens that cause economic losses by blemishing the surface appearance of infected fruit. Here, we introduce the 18.14-Mb genome of Peltaster fructicola, one of the most prevalent SBFS species on apple. This undersized assembly contains only 8,334 predicted protein-coding genes and a very small repertoire of repetitive elements. Phylogenomics and comparative genomics revealed that P. fructicola had undergone a reductive evolution, during which the numbers of orphan genes and genes involved in plant cell wall degradation, secondary metabolism, and secreted peptidases and effectors were drastically reduced. In contrast, the genes controlling 1,8-dihydroxynaphthalene (DHN)-melanin biosynthesis and appressorium-mediated penetration were retained substantially. Additionally, microscopic examination of the surfaces of infected apple indicated for the first time that P. fructicola can not only dissolve epicuticular waxes but also partially penetrate the cuticle proper. Our findings indicate that genome contraction, characterized mainly by the massive loss of pathogenicity-related genes, has played an important role in the evolution of P. fructicola (and by implication other SBFS species) from a plant-penetrating ancestor to a non-invasive ectophyte, displaying a novel form of trophic interaction between plants and fungi. PMID:26964666

  6. Maize ZmRACK1 Is Involved in the Plant Response to Fungal Phytopathogens

    PubMed Central

    Wang, Baosheng; Yu, Jingjuan; Zhu, Dengyun; Chang, Yujie; Zhao, Qian

    2014-01-01

    The receptor for activated C kinase 1 (RACK1) belongs to a protein subfamily containing a tryptophan-aspartic acid-domain (WD) repeat structure. Compelling evidence indicates that RACK1 can interact with many signal molecules and affect different signal transduction pathways. In this study, we cloned a maize RACK1 gene (ZmRACK1) by RT-PCR. The amino acid sequence of ZmRACK1 had seven WD repeats in which there were typical GH (glycine-histidine) and WD dipeptides. Comparison with OsRACK1 from rice revealed 89% identity at the amino acid level. Expression pattern analysis by RT-PCR showed that ZmRACK1 was expressed in all analyzed tissues of maize and that its transcription in leaves was induced by abscisic acid and jasmonate at a high concentration. Overexpression of ZmRACK1 in maize led to a reduction in symptoms caused by Exserohilum turcicum (Pass.) on maize leaves. The expression levels of the pathogenesis-related protein genes, PR-1 and PR-5, increased 2.5–3 times in transgenic maize, and reactive oxygen species production was more active than in the wild-type. Yeast two-hybrid assays showed that ZmRACK1 could interact with RAC1, RAR1 and SGT1. This study and previous work leads us to believe that ZmRACK1 may form a complex with regulators of plant disease resistance to coordinate maize reactions to pathogens. PMID:24865494

  7. Effects of Verticillium dahliae infection on stem-end chip defect development in potatoes (Solanum tuberosum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Potato chips are America's favorite snack food with annual retail sales of over $6 billion. Stem-end chip defect, which is characterized by discoloration of the vasculature and surrounding tissues at the tuber stem end portion of chips, is an important tuber quality concern for US chip production. T...

  8. Root hairs play a key role in the endophytic colonization of olive roots by Pseudomonas spp. with biocontrol activity.

    PubMed

    Prieto, Pilar; Schilirò, Elisabetta; Maldonado-González, María Mercedes; Valderrama, Raquel; Barroso-Albarracín, Juan Bautista; Mercado-Blanco, Jesús

    2011-08-01

    The use of indigenous bacterial root endophytes with biocontrol activity against soil-borne phytopathogens is an environmentally-friendly and ecologically-efficient action within an integrated disease management framework. The earliest steps of olive root colonization by Pseudomonas fluorescens PICF7 and Pseudomonas putida PICP2, effective biocontrol agents (BCAs) against Verticillium wilt of olive (Olea europaea L.) caused by the fungus Verticillium dahliae Kleb., are here described. A gnotobiotic study system using in vitro propagated olive plants, differential fluorescent-protein tagging of bacteria, and confocal laser scanning microscopy analysis have been successfully used to examine olive roots-Pseudomonas spp. interactions at the single-cell level. In vivo simultaneous visualization of PICF7 and PICP2 cells on/in root tissues enabled to discard competition between the two bacterial strains during root colonization. Results demonstrated that both BCAs are able to endophytically colonized olive root tissues. Moreover, results suggest a pivotal role of root hairs in root colonization by both biocontrol Pseudomonas spp. However, colonization of root hairs appeared to be a highly specific event, and only a very low number of root hairs were effectively colonized by introduced bacteria. Strains PICF7 and PICP2 can simultaneously colonize the same root hair, demonstrating that early colonization of a given root hair by one strain did not hinder subsequent attachment and penetration by the other. Since many environmental factors can affect the number, anatomy, development, and physiology of root hairs, colonization competence and biocontrol effectiveness of BCAs may be greatly influenced by root hair's fitness. Finally, the in vitro study system here reported has shown to be a suitable tool to investigate colonization processes of woody plant roots by microorganisms with biocontrol potential. PMID:21347721

  9. An In Vitro Attempt for Controlling Severe Phytopathogens and Human Pathogens Using Essential Oils from Mediterranean Plants of Genus Schinus.

    PubMed

    Elshafie, Hazem Salaheldin; Ghanney, Nadia; Mang, Stefania Mirela; Ferchichi, Ali; Camele, Ippolito

    2016-03-01

    Growing concerns about food safety and environmental protection enhanced the need for new and safe plant disease control strategies. The chemical composition of the three essential oils (EOs) extracted from leaves and fruits of Schinus terebinthifolius and leaves of Schinus molle, growing in Tunisia, was studied by GC and GC-MS. In all, 12 compounds were identified. The oils were mainly composed of terpene compounds. α-Pinene, α-phellandrene, and D-limonene were the major constituents. The aim of the current study was to evaluate the in vitro antimicrobial effectiveness of three EOs derived from plants of genus Schinus and extracted from leaves and fruits of S. terebinthifolius and leaves of S. molle. Both antifungal and antibacterial activities of the EOs were examined. The antifungal activity of the studied EOs was investigated against Colletotrichum acutatum and Botrytis cinerea in comparison with the systemic fungicide azoxystrobin used at 0.8 μL mL(-1). The antibacterial activity was evaluated against three strains of Gram-positive (G+ve) bacteria (Bacillus megaterium, Bacillus mojavensis and Clavibacter michiganensis) and four strains of Gram-negative (G-ve) bacteria (Escherichia coli, Xanthomonas campestris, Pseudomonas savastanoi, and Pseudomonas syringae pv. phaseolicola) compared with the synthetic antibiotic tetracycline at a concentration of 1600 μg mL(-1). The minimum inhibitory concentration of the studied EOs has been evaluated against the above microorganisms using the 96-well microplate method. Tested microorganisms exhibited different levels of sensitivity to each tested EO. All investigated EOs reduced the fungal mycelial growth when used at low concentrations from 250 to 1000 ppm and from 2000 to 8000 ppm against C. acutatum and B. cinerea, respectively. Higher concentrations of the same EOs exhibited a fungicidal effect against both mitosporic fungi. The EO extracted from leaves of S. terebinthifolius significantly inhibited the growth of tested bacterial strains. Nevertheless, E. coli showed a weak resistance toward the same EO and a high resistance toward the other two tested EOs. Finally, P. savastanoi and P. syringae pv. phaseolicola showed a high resistance toward all tested EOs. PMID:26836214

  10. A Critical Examination of the Specificity of the Salkowski Reagent for Indolic Compounds Produced by Phytopathogenic Bacteria

    PubMed Central

    Glickmann, E.; Dessaux, Y.

    1995-01-01

    We examined the sensitivity and the specificity of three versions of the Salkowski colorimetric technique. Two of these allowed the detection of indoleacetic acid (IAA) over a low range of concentrations (0.5 to 20 (mu)g/ml), while the third permitted the detection of IAA over a range of higher concentrations (5 to 200 (mu)g/ml). Overall, the three formulations reacted not only with auxin (IAA) but also with indolepyruvic acid and indoleacetamide. Therefore, these techniques appear to be specific for IAA, indolepyruvic acid, and indoleacetamide rather than for IAA alone. PMID:16534942

  11. Cyclic Lipopeptide Biosynthetic Genes and Products, and Inhibitory Activity of Plant-Associated Bacillus against Phytopathogenic Bacteria.

    PubMed

    Mora, Isabel; Cabrefiga, Jordi; Montesinos, Emilio

    2015-01-01

    The antibacterial activity against bacterial plant pathogens and its relationships with the presence of the cyclic lipopeptide (cLP) biosynthetic genes ituC (iturin), bmyB (bacillomycin), fenD (fengycin) and srfAA (surfactin), and their corresponding antimicrobial peptide products have been studied in a collection of 64 strains of Bacillus spp. isolated from plant environments. The most frequent antimicrobial peptide (AMP) genes were bmyB, srfAA and fenD (34-50% of isolates). Most isolates (98.4%) produced surfactin isoforms, 90.6% iturins and 79.7% fengycins. The antibacterial activity was very frequent and generally intense among the collection of strains because 75% of the isolates were active against at least 6 of the 8 bacterial plant pathogens tested. Hierarchical and correspondence analysis confirmed the presence of two clearly differentiated groups. One group consisted of Bacillus strains that showed a strong antibacterial activity, presented several cLPs genes and produced several isoforms of cLPs simultaneously, mainly composed of B. subtilis and B. amyloliquefaciens, although the last one was exclusive to this group. Another group was characterized by strains with very low or none antibacterial activity, that showed one or none of the cLP genes and produced a few or none of the corresponding cLPs, and was the most heterogenous group including B. subtilis, B. licheniformis, B. megaterium, B. pumilus, B. cereus and B. thuringiensis, although the last two were exclusive to this group. This work demonstrated that the antagonistic capacity of plant-associated Bacillus against plant pathogenic bacteria is related to the presence of cLP genes and to the production of the corresponding cLPs, and it is mainly associated to the species B. subtilis and B. amyloliquefaciens. Our findings would help to increase the yield and efficiency of screening methods to obtain candidate strains to biocontrol agents with a mechanism of action relaying on the production of antimicrobial cLPs. PMID:26024374

  12. The Trk Potassium Transporter Is Required for RsmB-Mediated Activation of Virulence in the Phytopathogen Pectobacterium wasabiae

    PubMed Central

    Valente, Rita S.

    2015-01-01

    ABSTRACT Pectobacterium wasabiae (previously known as Erwinia carotovora) is an important plant pathogen that regulates the production of plant cell wall-degrading enzymes through an N-acyl homoserine lactone-based quorum sensing system and through the GacS/GacA two-component system (also known as ExpS/ExpA). At high cell density, activation of GacS/GacA induces the expression of RsmB, a noncoding RNA that is essential for the activation of virulence in this bacterium. A genetic screen to identify regulators of RsmB revealed that mutants defective in components of a putative Trk potassium transporter (trkH and trkA) had decreased rsmB expression. Further analysis of these mutants showed that changes in potassium concentration influenced rsmB expression and consequent tissue damage in potato tubers and that this regulation required an intact Trk system. Regulation of rsmB expression by potassium via the Trk system occurred even in the absence of the GacS/GacA system, demonstrating that these systems act independently and are both required for full activation of RsmB and for the downstream induction of virulence in potato infection assays. Overall, our results identified potassium as an essential environmental factor regulating the Rsm system, and the consequent induction of virulence, in the plant pathogen P. wasabiae. IMPORTANCE Crop losses from bacterial diseases caused by pectolytic bacteria are a major problem in agriculture. By studying the regulatory pathways involved in controlling the expression of plant cell wall-degrading enzymes in Pectobacterium wasabiae, we showed that the Trk potassium transport system plays an important role in the regulation of these pathways. The data presented further identify potassium as an important environmental factor in the regulation of virulence in this plant pathogen. We showed that a reduction in virulence can be achieved by increasing the extracellular concentration of potassium. Therefore, this work highlights how elucidation of the mechanisms involved in regulating virulence can lead to the identification of environmental factors that can influence the outcome of infection. PMID:26483524

  13. Revised Phylogeny and Novel Horizontally Acquired Virulence Determinants of the Model Soft Rot Phytopathogen Pectobacterium wasabiae SCC3193

    PubMed Central

    Koskinen, Patrik; Nokso-Koivisto, Jussi; Pasanen, Miia; Broberg, Martin; Plyusnin, Ilja; Törönen, Petri; Holm, Liisa; Pirhonen, Minna; Palva, E. Tapio

    2012-01-01

    Soft rot disease is economically one of the most devastating bacterial diseases affecting plants worldwide. In this study, we present novel insights into the phylogeny and virulence of the soft rot model Pectobacterium sp. SCC3193, which was isolated from a diseased potato stem in Finland in the early 1980s. Genomic approaches, including proteome and genome comparisons of all sequenced soft rot bacteria, revealed that SCC3193, previously included in the species Pectobacterium carotovorum, can now be more accurately classified as Pectobacterium wasabiae. Together with the recently revised phylogeny of a few P. carotovorum strains and an increasing number of studies on P. wasabiae, our work indicates that P. wasabiae has been unnoticed but present in potato fields worldwide. A combination of genomic approaches and in planta experiments identified features that separate SCC3193 and other P. wasabiae strains from the rest of soft rot bacteria, such as the absence of a type III secretion system that contributes to virulence of other soft rot species. Experimentally established virulence determinants include the putative transcriptional regulator SirB, two partially redundant type VI secretion systems and two horizontally acquired clusters (Vic1 and Vic2), which contain predicted virulence genes. Genome comparison also revealed other interesting traits that may be related to life in planta or other specific environmental conditions. These traits include a predicted benzoic acid/salicylic acid carboxyl methyltransferase of eukaryotic origin. The novelties found in this work indicate that soft rot bacteria have a reservoir of unknown traits that may be utilized in the poorly understood latent stage in planta. The genomic approaches and the comparison of the model strain SCC3193 to other sequenced Pectobacterium strains, including the type strain of P. wasabiae, provides a solid basis for further investigation of the virulence, distribution and phylogeny of soft rot bacteria and, potentially, other bacteria as well. PMID:23133391

  14. Revised phylogeny and novel horizontally acquired virulence determinants of the model soft rot phytopathogen Pectobacterium wasabiae SCC3193.

    PubMed

    Nykyri, Johanna; Niemi, Outi; Koskinen, Patrik; Nokso-Koivisto, Jussi; Pasanen, Miia; Broberg, Martin; Plyusnin, Ilja; Törönen, Petri; Holm, Liisa; Pirhonen, Minna; Palva, E Tapio

    2012-01-01

    Soft rot disease is economically one of the most devastating bacterial diseases affecting plants worldwide. In this study, we present novel insights into the phylogeny and virulence of the soft rot model Pectobacterium sp. SCC3193, which was isolated from a diseased potato stem in Finland in the early 1980s. Genomic approaches, including proteome and genome comparisons of all sequenced soft rot bacteria, revealed that SCC3193, previously included in the species Pectobacterium carotovorum, can now be more accurately classified as Pectobacterium wasabiae. Together with the recently revised phylogeny of a few P. carotovorum strains and an increasing number of studies on P. wasabiae, our work indicates that P. wasabiae has been unnoticed but present in potato fields worldwide. A combination of genomic approaches and in planta experiments identified features that separate SCC3193 and other P. wasabiae strains from the rest of soft rot bacteria, such as the absence of a type III secretion system that contributes to virulence of other soft rot species. Experimentally established virulence determinants include the putative transcriptional regulator SirB, two partially redundant type VI secretion systems and two horizontally acquired clusters (Vic1 and Vic2), which contain predicted virulence genes. Genome comparison also revealed other interesting traits that may be related to life in planta or other specific environmental conditions. These traits include a predicted benzoic acid/salicylic acid carboxyl methyltransferase of eukaryotic origin. The novelties found in this work indicate that soft rot bacteria have a reservoir of unknown traits that may be utilized in the poorly understood latent stage in planta. The genomic approaches and the comparison of the model strain SCC3193 to other sequenced Pectobacterium strains, including the type strain of P. wasabiae, provides a solid basis for further investigation of the virulence, distribution and phylogeny of soft rot bacteria and, potentially, other bacteria as well. PMID:23133391

  15. The phytopathogenic basidiomycete Moniliophthora perniciosa senesces and contains a kalilo-like plasmid stably integrated in its large mitochondrial genome

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work we show that the necrotrophic mycelia of the hemibiotrophic basidiomycete Moniliophthora perniciosa, the causal agent of the witches’ broom disease in Theobroma cacao, undergoes senescence, a feature that was associated with a decline in the content of mitochondrial DNA per cell. The mi...

  16. Beyond plant defense: insights on the potential of salicylic and methylsalicylic acid to contain growth of the phytopathogen Botrytis cinerea.

    PubMed

    Dieryckx, Cindy; Gaudin, Vanessa; Dupuy, Jean-William; Bonneu, Marc; Girard, Vincent; Job, Dominique

    2015-01-01

    Using Botrytis cinerea we confirmed in the present work several previous studies showing that salicylic acid, a main plant hormone, inhibits fungal growth in vitro. Such an inhibitory effect was also observed for the two salicylic acid derivatives, methylsalicylic and acetylsalicylic acid. In marked contrast, 5-sulfosalicylic acid was totally inactive. Comparative proteomics from treated vs. control mycelia showed that both the intracellular and extracellular proteomes were affected in the presence of salicylic acid or methylsalicylic acid. These data suggest several mechanisms that could potentially account for the observed fungal growth inhibition, notably pH regulation, metal homeostasis, mitochondrial respiration, ROS accumulation and cell wall remodeling. The present observations support a role played by the phytohormone SA and derivatives in directly containing the pathogen. Data are available via ProteomeXchange with identifier PXD002873. PMID:26528317

  17. Antifungal efficiency of a lipopeptide biosurfactant derived from Bacillus subtilis SPB1 versus the phytopathogenic fungus, Fusarium solani.

    PubMed

    Mnif, Ines; Hammami, Ines; Triki, Mohamed Ali; Azabou, Manel Cheffi; Ellouze-Chaabouni, Semia; Ghribi, Dhouha

    2015-11-01

    Bacillus subtilis SPB1 lipopeptides were evaluated as a natural antifungal agent against Fusarium solani infestation. In vitro antifungal assay showed a minimal inhibitory concentration of about 3 mg/ml with a fungicidal mode of action. In fact, treatment of F. solani by SPB1 lipopeptides generated excessive lyses of the mycelium and caused polynucleation and destruction of the related spores together with a total inhibition of spore production. Furthermore, an inhibition of germination potency accompanied with a high spore blowing was observed. Moreover, in order to be applied in agricultural field, in vivo antifungal activity was proved against the dry rot potato tubers caused by F. solani. Preventive treatment appeared as the most promising as after 20 days of fungi inoculation, rot invasion was reduced by almost 78%, in comparison to that of non-treated one. When treating infected tomato plants, disease symptoms were reduced by almost 100% when applying the curative method. Results of this study are very promising as it enables the use of the crude lipopeptide preparation of B. subtilis SPB1 as a potent natural fungicide that could effectively control the infection of F. solani in tomato and potato tubers at a concentration similar to the commercial fungicide hymexazol and therefore prevent the damage of olive tree. PMID:26178831

  18. Characterization of a Novel Bipartite Double-Stranded RNA Mycovirus Conferring Hypovirulence in the Phytopathogenic Fungus Botrytis porri

    PubMed Central

    Wu, Mingde; Jin, Fengyin; Zhang, Jing; Yang, Long; Jiang, Daohong

    2012-01-01

    The ascomycete Botrytis porri causes clove rot and leaf blight of garlic worldwide. We report here the biological and molecular features of a novel bipartite double-stranded RNA (dsRNA) mycovirus named Botrytis porri RNA virus 1 (BpRV1) from the hypovirulent strain GarlicBc-72 of B. porri. The BpRV1 genome comprises two dsRNAs, dsRNA-1 (6,215 bp) and dsRNA-2 (5,879 bp), which share sequence identities of 62 and 95% at the 3′- and 5′-terminal regions, respectively. Two open reading frames (ORFs), ORF I (dsRNA-1) and ORF II (dsRNA-2), were detected. The protein encoded by the 3′-proximal coding region of ORF I shows sequence identities of 19 to 23% with RNA-dependent RNA polymerases encoded by viruses in the families Totiviridae, Chrysoviridae, and Megabirnaviridae. However, the proteins encoded by the 5′-proximal coding region of ORF I and by the entire ORF II lack sequence similarities to any reported virus proteins. Phylogenetic analysis showed that BpRV1 belongs to a separate clade distinct from those of other known RNA mycoviruses. Purified virions of ∼35 nm in diameter encompass dsRNA-1 and dsRNA-2, and three structural proteins (SPs) of 70, 80, and 85 kDa, respectively. Peptide mass fingerprinting analysis revealed that the 80- and 85-kDa SPs are encoded by ORF I, while the 70-kDa SP is encoded by ORF II. Introducing BpRV1 purified virions into the virulent strain GarlicBc-38 of B. porri caused derivative 38T reduced mycelial growth and hypovirulence. These combined results suggest that BpRV1 is a novel bipartite dsRNA virus that possibly belongs to a new virus family. PMID:22496220

  19. Characterization of a novel double-stranded RNA mycovirus conferring hypovirulence from the phytopathogenic fungus Botryosphaeria dothidea.

    PubMed

    Zhai, Lifeng; Xiang, Jun; Zhang, Meixin; Fu, Min; Yang, Zuokun; Hong, Ni; Wang, Guoping

    2016-06-01

    A novel double-stranded RNA (dsRNA) virus, designated as Botryosphaeria dothidea RNA virus 1 (BdRV1), isolated from a hypovirulent strain YZN115 of Botryosphaeria dothidea was biologically and molecularly characterized. The genome of BdRV1 comprises of five dsRNAs. Each dsRNA contains a single open reading frame. The proteins encoded by dsRNA1-4 shared significant amino acid identities of 55%, 47%, 43% and 53% with the corresponding proteins of Aspergillus fumigatus tetramycovirus-1. DsRNA1, 3, and 4 of BdRV1 encoded an RNA-dependent RNA polymerase, a viral methyltransferase, and a P-A-S-rich protein, respectively. Function of proteins encoded by the dsRNA2 and dsRNA5 were unknown. BdRV1 conferred hypovirulence for its host and could be transmitted through conidia and hyphae contact. PMID:27015523

  20. Cyclic Lipopeptide Biosynthetic Genes and Products, and Inhibitory Activity of Plant-Associated Bacillus against Phytopathogenic Bacteria

    PubMed Central

    Mora, Isabel; Cabrefiga, Jordi; Montesinos, Emilio

    2015-01-01

    The antibacterial activity against bacterial plant pathogens and its relationships with the presence of the cyclic lipopeptide (cLP) biosynthetic genes ituC (iturin), bmyB (bacillomycin), fenD (fengycin) and srfAA (surfactin), and their corresponding antimicrobial peptide products have been studied in a collection of 64 strains of Bacillus spp. isolated from plant environments. The most frequent antimicrobial peptide (AMP) genes were bmyB, srfAA and fenD (34-50% of isolates). Most isolates (98.4%) produced surfactin isoforms, 90.6% iturins and 79.7% fengycins. The antibacterial activity was very frequent and generally intense among the collection of strains because 75% of the isolates were active against at least 6 of the 8 bacterial plant pathogens tested. Hierarchical and correspondence analysis confirmed the presence of two clearly differentiated groups. One group consisted of Bacillus strains that showed a strong antibacterial activity, presented several cLPs genes and produced several isoforms of cLPs simultaneously, mainly composed of B. subtilis and B. amyloliquefaciens, although the last one was exclusive to this group. Another group was characterized by strains with very low or none antibacterial activity, that showed one or none of the cLP genes and produced a few or none of the corresponding cLPs, and was the most heterogenous group including B. subtilis, B. licheniformis, B. megaterium, B. pumilus, B. cereus and B. thuringiensis, although the last two were exclusive to this group. This work demonstrated that the antagonistic capacity of plant-associated Bacillus against plant pathogenic bacteria is related to the presence of cLP genes and to the production of the corresponding cLPs, and it is mainly associated to the species B. subtilis and B. amyloliquefaciens. Our findings would help to increase the yield and efficiency of screening methods to obtain candidate strains to biocontrol agents with a mechanism of action relaying on the production of antimicrobial cLPs. PMID:26024374

  1. [Isolation of endophytic bacteria in roots of Panax ginseng and screening of antagonistic strains against phytopathogens prevalent in P. ginseng].

    PubMed

    Li, Yong; Zhao, Dongyue; Ding, Wanlong; Ying, Yixin

    2012-06-01

    In this study, endophytic bacteria were isolated from roots of P. ginseng by plate culture method, and as a result, 40 endophytic bacterial strains were isolated, Bacillus spp. and Pseudomonas spp. were predominant. By confront culture method, two antagonistic endophytic bacterial strain, ge15 (Stenotrophomonas maltophilia) and ge25 (Bacillus sp. ) against Cylindrocarpon destructans, Sclerotinia schinseng and Alternaria pana were identified. The inhibition zone of ge15 to them were 5.5, 22.0, 14.8 mm, respectively; and which were 12.7,16.5,9.0 mm for ge25. The Results indicate that endophytic bacteria have biocontrol potential on ginseng pathogens, and which can be used as a bio-control factor on ginseng soilborne diseases control. PMID:22993975

  2. Unraveling the in vitro secretome of the phytopathogen Botrytis cinerea to understand the interaction with its hosts

    PubMed Central

    González-Fernández, Raquel; Valero-Galván, José; Gómez-Gálvez, Francisco J.; Jorrín-Novo, Jesús V.

    2015-01-01

    Botrytis cinerea is a necrotrophic fungus with high adaptability to different environments and hosts. It secretes a large number of extracellular proteins, which favor plant tissue penetration and colonization, thus contributing to virulence. Secretomics is a proteomics sub-discipline which study the secreted proteins and their secretion mechanisms, so-called secretome. By using proteomics as experimental approach, many secreted proteins by B. cinerea have been identified from in vitro experiments, and belonging to different functional categories: (i) cell wall-degrading enzymes such as pectinesterases and endo-polygalacturonases; (ii) proteases involved in host protein degradation such as an aspartic protease; (iii) proteins related to the oxidative burst such as glyoxal oxidase; (iv) proteins which may induce the plant hypersensitive response such as a cerato-platanin domain-containing protein; and (v) proteins related to production and secretion of toxins such as malate dehydrogenase. In this mini-review, we made an overview of the proteomics contribution to the study and knowledge of the B. cinerea extracellular secreted proteins based on our current work carried out from in vitro experiments, and recent published papers both in vitro and in planta studies on this fungi. We hypothesize on the putative functions of these secreted proteins, and their connection to the biology of the B. cinerea interaction with its hosts. PMID:26500673

  3. Production of antioomycete compounds active against the phytopathogens Phytophthora sojae and Aphanomyces cochlioides by clavicipitoid entomopathogenic fungi.

    PubMed

    Putri, Sastia Prama; Ishido, Kei-Ichi; Kinoshita, Hiroshi; Kitani, Shigeru; Ihara, Fumio; Sakihama, Yasuko; Igarashi, Yasuhiro; Nihira, Takuya

    2014-05-01

    A total of 412 strains belonging to 14 genera of clavicipitoid entomopathogenic fungi (EPF) were screened for activities against two economically important plant pathogenic oomycetes, Phytophthora sojae and Aphanomyces cochlioides. To identify the antioomycete compounds produced by EPF, the extracts of 13 highly active EPF strains were characterized in detail by high performance liquid chromatography with diode array detection and high-resolution mass spectrometric detection and antioomycete assay. The antioomycete activity of several Metarhizium extracts was associated with previously isolated aurovertins, fungerin, N-(methyl-3-oxodec-6-enoyl)-2-pyrroline, and N-(methyl-3-oxodecanoyl)-2-pyrroline. The depsipeptide beauvericin was confirmed to be one of the active principles of three strains of Isaria tenuipes, which strongly inhibited mycelial growth of both P. sojae and A. cochlioides. Two known bioactive metabolites, paecilosetin and aranorosinol A, together with a novel and potent antioomycete compound, farinomalein, were isolated from the extracts of Isaria farinosa and all compounds were confirmed to have antioomycete activity. Identification of 8 antioomycete compounds from 13 clavicipitioid EPF demonstrated a new potential use of EPF as a source of compounds for the control of soil-borne plant pathogenic oomycetes. PMID:24268864

  4. Analysis of the LacI family regulators of Erwinia chrysanthemi 3937, involvement in the bacterial phytopathogenicity.

    PubMed

    Van Gijsegem, Frédérique; Wlodarczyk, Aleksandra; Cornu, Amandine; Reverchon, Sylvie; Hugouvieux-Cotte-Pattat, Nicole

    2008-11-01

    Analysis of the regulators of the LacI family was performed in order to identify those potentially involved in pathogenicity of Erwinia chrysanthemi (Dickeya dadantii). Among the 18 members of the LacI family, the function of 11 members is either known or predicted and only 7 members have, as yet, no proposed function. Inactivation of these seven genes, called lfaR, lfbR, lfcR, lfdR, lfeR, lffR, and lfgR, demonstrated that four of them are important for plant infection. The lfaR and lfcR mutants showed a reduced virulence on chicory, Saintpaulia sp., and Arabidopsis. The lfeR mutant showed a reduced virulence on Arabidopsis. The lfdR mutant was more efficient than the wild-type strain in initiating maceration on Saintpaulia sp. The genetic environment of each regulator was examined to detect adjacent genes potentially involved in a common function. Construction of transcriptional fusions in these neighboring genes demonstrated that five regulators, LfaR, LfcR, LfeR, LffR, and LfgR, act as repressors of adjacent genes. Analysis of these fusions also indicated that the genes controlled by LfaR, LfcR, LfgR, and LffR are expressed during plant infection. Moreover, addition of crude plant extracts to culture medium demonstrated that the expression of the LfaR- and LfgR-controlled genes is specifically induced by plant components. PMID:18842096

  5. PecS Is a Global Regulator of the Symptomatic Phase in the Phytopathogenic Bacterium Erwinia chrysanthemi 3937▿ †

    PubMed Central

    Hommais, Florence; Oger-Desfeux, Christine; Van Gijsegem, Frédérique; Castang, Sandra; Ligori, Sandrine; Expert, Dominique; Nasser, William; Reverchon, Sylvie

    2008-01-01

    Pathogenicity of the enterobacterium Erwinia chrysanthemi (Dickeya dadantii), the causative agent of soft-rot disease in many plants, is a complex process involving several factors whose production is subject to temporal regulation during infection. PecS is a transcriptional regulator that controls production of various virulence factors. Here, we used microarray analysis to define the PecS regulon and demonstrated that PecS notably regulates a wide range of genes that could be linked to pathogenicity and to a group of genes concerned with evading host defenses. Among the targets are the genes encoding plant cell wall-degrading enzymes and secretion systems and the genes involved in flagellar biosynthesis, biosurfactant production, and the oxidative stress response, as well as genes encoding toxin-like factors such as NipE and hemolysin-coregulated proteins. In vitro experiments demonstrated that PecS interacts with the regulatory regions of five new targets: an oxidative stress response gene (ahpC), a biosurfactant synthesis gene (rhlA), and genes encoding exported proteins related to other plant-associated bacterial proteins (nipE, virK, and avrL). The pecS mutant provokes symptoms more rapidly and with more efficiency than the wild-type strain, indicating that PecS plays a critical role in the switch from the asymptomatic phase to the symptomatic phase. Based on this, we propose that the temporal regulation of the different groups of genes required for the asymptomatic phase and the symptomatic phase is, in part, the result of a gradual modulation of PecS activity triggered during infection in response to changes in environmental conditions emerging from the interaction between both partners. PMID:18790868

  6. Transformation of the phytopathogenic bacterium Clavibacter michiganense subsp. michiganense by electroporation and development of a cloning vector.

    PubMed Central

    Meletzus, D; Eichenlaub, R

    1991-01-01

    We constructed a cloning vector for use in the plant pathogenic bacterium Clavibacter michiganense subsp. michiganense. The vector pDM100 consists of a 3.2-kb restriction fragment of the Clavibacter plasmid pCM1 joined to a pBR325 derivative carrying the neomycin phosphotransferase of transposon Tn5 and the gentamicin acetyltransferase of Tn1696. Both antibiotic resistance genes are efficiently expressed in C. michiganense subsp. michiganense. Although polyethylene glycol-mediated transfection of spheroplasts with the DNA of the C. michiganense subsp. michiganense-specific bacteriophage CMP1 yielded about 3 x 10(3) transfectants per microgram of DNA, in transformations with plasmid DNA only a very few transformants were obtained. However, the transformation efficiency could be improved by electroporation of intact cells, giving about 2 x 10(3) transformants per microgram of plasmid DNA. Since a transformation procedure and a cloning vector are now available, pathogenicity in C. michiganense subsp. michiganense can now be analyzed genetically. PMID:1898919

  7. Evidence for plasmid-encoded virulence factors in the phytopathogenic bacterium Clavibacter michiganensis subsp. michiganensis NCPPB382.

    PubMed Central

    Meletzus, D; Bermphol, A; Dreier, J; Eichenlaub, R

    1993-01-01

    The tomato pathogen Clavibacter michiganensis subsp. michiganensis NCPPB382, which causes bacterial wilt, harbors two plasmids pCM1 (27.5 kb) and pCM2 (72 kb). After curing of the plasmids, bacterial derivatives were still proficient in the ability to colonize the host plant and in the production of exopolysaccharides but exhibited a reduced virulence. When one of the two plasmids is lost, there is a significant delay in the development of wilting symptoms after infection and a plasmid-free derivative is not able to induce disease symptoms. By cloning of restriction fragments of both plasmids in the plasmid-free strain CMM100, two DNA fragments which restored the virulent phenotype were identified. Further analysis suggested that a fragment of plasmid pCM1 encodes an endocellulase which is involved in the expression of the pathogenic phenotype. Images PMID:8458855

  8. Stable transformation of the gram-positive phytopathogenic bacterium Clavibacter michiganensis subsp. sepedonicus with several cloning vectors.

    PubMed Central

    Laine, M J; Nakhei, H; Dreier, J; Lehtilä, K; Meletzus, D; Eichenlaub, R; Metzler, M C

    1996-01-01

    In this paper we describe transformation of Clavibacter michiganensis subsp. sepedonicus, the potato ring rot bacterium, with plasmid vectors. Three of the plasmids used, pDM100, pDM302, and pDM306, contain the origin of replication from pCM1, a native plasmid of C. michiganensis subsp. michiganensis. We constructed two new cloning vectors, pHN205 and pHN216, by using the origin of replication of pCM2, another native plasmid of C. michiganensis subsp. michiganensis. Plasmids pDM302, pHN205, and pHN216 were stably maintained without antibiotic selection in various strains of C. michiganensis subsp. sepedonicus. We observed that for a single plasmid, different strains of C. michiganensis subsp. sepedonicus showed significantly different transformation efficiencies. We also found unexplained strain-to-strain differences in stability with various plasmid constructions containing different arrangements of antibiotic resistance genes and origins of replication. We examined the effect of a number of factors on transformation efficiency. The best transformation efficiencies were obtained when C. michiganensis subsp. sepedonicus cells were grown on DM agar plates, harvested during the early exponential growth phase, and used fresh (without freezing) for electroporation. The maximal transformation efficiency obtained was 4.6 x 10(4) CFU/microgram of pHN216 plasmid DNA. To demonstrate the utility of this transformation system, we cloned a beta-1,4-endoglucanase-encoding gene from C. michiganensis subsp. sepedonicus into pHN216. When this construction, pHN216:C8, was electroporated into competent cells of a cellulase-deficient mutant, it restored cellulase production to almost wild-type levels. PMID:8633849

  9. Erwinia amylovora Novel Plasmid pEI70: Complete Sequence, Biogeography, and Role in Aggressiveness in the Fire Blight Phytopathogen

    PubMed Central

    Llop, Pablo; Cabrefiga, Jordi; Smits, Theo H. M.; Dreo, Tanja; Barbé, Silvia; Pulawska, Joanna; Bultreys, Alain; Blom, Jochen; Duffy, Brion; Montesinos, Emilio; López, María M.

    2011-01-01

    Comparative genomics of several strains of Erwinia amylovora, a plant pathogenic bacterium causal agent of fire blight disease, revealed that its diversity is primarily attributable to the flexible genome comprised of plasmids. We recently identified and sequenced in full a novel 65.8 kb plasmid, called pEI70. Annotation revealed a lack of known virulence-related genes, but found evidence for a unique integrative conjugative element related to that of other plant and human pathogens. Comparative analyses using BLASTN showed that pEI70 is almost entirely included in plasmid pEB102 from E. billingiae, an epiphytic Erwinia of pome fruits, with sequence identities superior to 98%. A duplex PCR assay was developed to survey the prevalence of plasmid pEI70 and also that of pEA29, which had previously been described in several E. amylovora strains. Plasmid pEI70 was found widely dispersed across Europe with frequencies of 5–92%, but it was absent in E. amylovora analyzed populations from outside of Europe. Restriction analysis and hybridization demonstrated that this plasmid was identical in at least 13 strains. Curing E. amylovora strains of pEI70 reduced their aggressiveness on pear, and introducing pEI70 into low-aggressiveness strains lacking this plasmid increased symptoms development in this host. Discovery of this novel plasmid offers new insights into the biogeography, evolution and virulence determinants in E. amylovora. PMID:22174857

  10. Carbon regulation of environmental pH by secreted small molecules that modulate pathogenicity in phytopathogenic fungi.

    PubMed

    Bi, Fangcheng; Barad, Shiri; Ment, Dana; Luria, Neta; Dubey, Amit; Casado, Virginia; Glam, Nofar; Mínguez, Jose Diaz; Espeso, Eduardo A; Fluhr, Robert; Prusky, Dov

    2016-10-01

    Fruit pathogens can contribute to the acidification or alkalinization of the host environment. This capability has been used to divide fungal pathogens into acidifying and/or alkalinizing classes. Here, we show that diverse classes of fungal pathogens-Colletotrichum gloeosporioides, Penicillium expansum, Aspergillus nidulans and Fusarium oxysporum-secrete small pH-affecting molecules. These molecules modify the environmental pH, which dictates acidic or alkaline colonizing strategies, and induce the expression of PACC-dependent genes. We show that, in many organisms, acidification is induced under carbon excess, i.e. 175 mm sucrose (the most abundant sugar in fruits). In contrast, alkalinization occurs under conditions of carbon deprivation, i.e. less than 15 mm sucrose. The carbon source is metabolized by glucose oxidase (gox2) to gluconic acid, contributing to medium acidification, whereas catalysed deamination of non-preferred carbon sources, such as the amino acid glutamate, by glutamate dehydrogenase 2 (gdh2), results in the secretion of ammonia. Functional analyses of Δgdh2 mutants showed reduced alkalinization and pathogenicity during growth under carbon deprivation, but not in high-carbon medium or on fruit rich in sugar, whereas analysis of Δgox2 mutants showed reduced acidification and pathogencity under conditions of excess carbon. The induction pattern of gdh2 was negatively correlated with the expression of the zinc finger global carbon catabolite repressor creA. The present results indicate that differential pH modulation by fruit fungal pathogens is a host-dependent mechanism, affected by host sugar content, that modulates environmental pH to enhance fruit colonization. PMID:26666972

  11. Draft genome sequence of Pantoea agglomerans R190, a producer of antibiotics against phytopathogens and foodborne pathogens.

    PubMed

    Lim, Jeong-A; Lee, Dong Hwan; Kim, Byoung-Young; Heu, Sunggi

    2014-10-20

    Pantoea agglomerans R190, isolated from an apple orchard, showed antibacterial activity against various spoilage bacteria, including Pectobacterium carotovorum subsp. carotovorum, and foodborne pathogens such as Escherichia coli O157:H7. Here, we report the genome sequence of P. agglomerans R190. This report will raise the value of P. agglomerans as an agent for biocontrol of disease. PMID:25087741

  12. Crystallization, data collection and phasing of the molybdate-binding protein of the phytopathogen Xanthomonas axonopodis pv. citri

    SciTech Connect

    Santacruz, C. P.; Balan, A.; Ferreira, L. C. S.; Barbosa, J. A. R. G.

    2006-03-01

    The molybdate-binding protein (ModA) from X. axonopodis pv. citri was crystallized with sodium molybdate in the presence of PEG or sulfate. The crystal diffracted to a maximum resolution of 1.7 Å and belongs to the orthorhombic space group C222{sub 1,} with unit-cell parameters a = 68.15, b = 172.14, c = 112.04 Å. Xanthomonas axonopodis pv. citri ModA protein is the ABC periplasmic binding component responsible for the capture of molybdate. The protein was crystallized with sodium molybdate using the hanging-drop vapour-diffusion method in the presence of PEG or sulfate. X-ray diffraction data were collected to a maximum resolution of 1.7 Å using synchrotron radiation. The crystal belongs to the orthorhombic space group C222{sub 1}, with unit-cell parameters a = 68.15, b = 172.14, c = 112.04 Å. The crystal structure was solved by molecular-replacement methods and structure refinement is in progress.

  13. Horizontal gene transfer confers adaptive advantages to phytopathogenic fungi: a case study of catalase-peroxidase in Fusarium verticillioides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Horizontal gene transfer (HGT), the exchange and stable integration of genetic material between different evolutionary lineages, is widely observed in fungi. We hypothesize that successful stabilization of HGT elements provides adaptive advantages (e.g., virulence). Catalase/peroxidases (KatGs) are ...

  14. The Wor1-like protein Fgp1 regulates pathogenicity, toxin synthesis and reproduction in the phytopathogenic fungus Fusarium graminearum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    WOR1 is a gene for a conserved fungal regulatory protein controlling the dimorphic switch and pathogenicity in Candida albicans and its ortholog in the plant pathogen Fusarium oxysporum, called SGE1, is also required for pathogenicity and expression of plant effector proteins. F. graminearum, an imp...

  15. Identification of effector genes from the phytopathogenic Oomycete Plasmopara viticola through the analysis of gene expression in germinated zoospores.

    PubMed

    Mestre, Pere; Piron, Marie-Christine; Merdinoglu, Didier

    2012-07-01

    Grapevine downy mildew caused by the Oomycete Plasmopara viticola is one of the most important diseases affecting Vitis spp. The current strategy of control relies on chemical fungicides. An alternative to the use of fungicides is using downy mildew resistant varieties, which is cost-effective and environmentally friendly. Knowledge about the genetic basis of the resistance to P. viticola has progressed in the recent years, but little data are available about P. viticola genetics, in particular concerning the nature of its avirulence genes. Identifying pathogen effectors as putative avirulence genes is a necessary step in order to understand the biology of the interaction. It is also important in order to select the most efficient combination of resistance genes in a strategy of pyramiding. On the basis of knowledge from other Oomycetes, P. viticola effectors can be identified by using a candidate gene strategy based on data mining of genomic resources. In this paper we describe the development of Expressed Sequence Tags (ESTs) from P. viticola by creating a cDNA library from in vitro germinated zoospores and the sequencing of 1543 clones. We present 563 putative nuclear P. viticola unigenes. Sequence analysis reveals 54 ESTs from putative secreted hydrolytic enzymes and effectors, showing the suitability of this material for the analysis of the P. viticola secretome and identification of effector genes. Next generation sequencing of cDNA from in vitro germinated zoospores should result in the identification of numerous candidate avirulence genes in the grapevine/downy mildew interaction. PMID:22749169

  16. [Study of the effect of volatile metabolites of Trichoderma hamatum on the growth of phytopathogenic soilborne fungi.].

    PubMed

    Dal Bello, G M; Mónaco, C I; Cháves, A R

    1997-09-01

    Volatile compounds produced by Trichoderma hamatum were tested for their capacity to suppress in vitro the growth of Alternaria citri, Bipolaris cynodontis, Bipolaris sorokiniana, Curvularia brachyspora, Curvularia lunata, Curvularia oryzae-sativae, Drechslera tritici-repentis, Rhizoctonia solani, Sclerotinia minor and Sclerotium rolfsii. The organisms were cultured in an apparatus made with two Erlenmeyer flasks assembled by their top parts. With the aid of the gas chromatographic technique the variation of carbon dioxide, oxygen and ethylene in the internal system was determined. Acetaldehyde and ethanol were not found. Due to the respiratory metabolism of T. hamatum the carbon dioxide level progressively increased while the oxygen content decreased. Ethylene production was low and after three days remained constant. Excepting C. oryzae-sativae and B. cynodontis the other species showed changes in the growth and development. These results suggest the inhibitory volatiles of T. hamatum as one possible mechanism of biological control. PMID:17655390

  17. Characterization of the BLR1 gene encoding a putative blue-light regulator in the phytopathogenic fungus Bipolaris oryzae.

    PubMed

    Kihara, Junichi; Moriwaki, Akihiro; Tanaka, Nozomi; Ueno, Makoto; Arase, Sakae

    2007-01-01

    Bipolaris oryzae is a filamentous ascomycetous fungus that causes brown leaf spot disease in rice. We isolated and characterized BLR1, a gene that encodes a putative blue-light regulator similar to Neurospora crassa white-collar 1 (WC-1). The deduced amino acid sequence of BLR1 showed high degrees of similarity to other fungal blue-light regulator protein. Disruption of the BLR1 gene demonstrated that this gene is essential for conidial development after conidiophore formation and for near-UV radiation-enhanced photolyase gene expression. PMID:17233721

  18. Beyond plant defense: insights on the potential of salicylic and methylsalicylic acid to contain growth of the phytopathogen Botrytis cinerea

    PubMed Central

    Dieryckx, Cindy; Gaudin, Vanessa; Dupuy, Jean-William; Bonneu, Marc; Girard, Vincent; Job, Dominique

    2015-01-01

    Using Botrytis cinerea we confirmed in the present work several previous studies showing that salicylic acid, a main plant hormone, inhibits fungal growth in vitro. Such an inhibitory effect was also observed for the two salicylic acid derivatives, methylsalicylic and acetylsalicylic acid. In marked contrast, 5-sulfosalicylic acid was totally inactive. Comparative proteomics from treated vs. control mycelia showed that both the intracellular and extracellular proteomes were affected in the presence of salicylic acid or methylsalicylic acid. These data suggest several mechanisms that could potentially account for the observed fungal growth inhibition, notably pH regulation, metal homeostasis, mitochondrial respiration, ROS accumulation and cell wall remodeling. The present observations support a role played by the phytohormone SA and derivatives in directly containing the pathogen. Data are available via ProteomeXchange with identifier PXD002873. PMID:26528317

  19. Clavibacter michiganensis subsp. michiganensis: first steps in the understanding of virulence of a Gram-positive phytopathogenic bacterium.

    PubMed

    Gartemann, Karl-Heinz; Kirchner, Oliver; Engemann, Jutta; Gräfen, Ines; Eichenlaub, Rudolf; Burger, Annette

    2003-12-19

    Clavibacter michiganensis subsp. michiganensis is a plant-pathogenic actinomycete. It infects tomato, spreads through the xylem and causes bacterial wilt and canker. The wild-type strain NCPPB382 carries two plasmids, pCM1 and pCM2. The cured plasmid-free derivative CMM100 is still able to colonize tomato, but no disease symptoms develop indicating that all genes required for successful infection, establishment and growth in the plant reside on the chromosome. Both plasmids carry one virulence factor, a gene encoding a cellulase, CelA in case of pCM1 and a putative serine protease Pat-1 on pCM2. These genes can independently convert the non-virulent strain CMM100 into a pathogen causing wilt on tomatoes. Currently, genome projects for Cmm and the closely related potato-pathogen C. michiganensis subsp. sepedonicus have been initiated. The data from the genome project shall give clues on further genes involved in plant-microbe interaction that can be tested experimentally. Especially, identification of genes related to host-specificity through genome comparison of the two subspecies might be possible. PMID:14651860

  20. Pseudomonas fluorescens PICF7 displays an endophytic lifestyle in cultivated cereals and enhances yield in barley.

    PubMed

    Mercado-Blanco, Jesús; Alós, Enriqueta; Rey, María Dolores; Prieto, Pilar

    2016-08-01

    Pseudomonas fluorescens PICF7, an indigenous inhabitant of olive roots, displays an endophytic lifestyle in this woody crop and exerts biocontrol against the fungal phytopathogen Verticillium dahliae Here we report microscopy evidence that the strain PICF7 is also able to colonize and persist on or in wheat and barley root tissues. Root colonization of both cereal species followed a similar pattern to that previously reported in olive, including inner colonization of the root hairs. This demonstrates that strain PICF7 can colonize root systems of distant botanical species. Barley plants germinated from PICF7-treated seeds showed enhanced vegetative growth. Moreover, significant increases in the number of grains (up to 19.5%) and grain weight (up to 20.5%) per plant were scored in this species. In contrast, growth and yield were not significantly affected in wheat plants by the presence of PICF7. Proteomics analysis of the root systems revealed that different proteins were exclusively found depending on the presence or absence of PICF7 and only one protein with hydrogen ion transmembrane transporter activity was exclusively found in both PICF7-inoculated barley and wheat plants but not in the controls. PMID:27130938

  1. Detection, quantification and vegetative compatibility of Verticillium dahliae in potato and mint production soils in the Columbia Basin of Oregon and Washington

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil samples from 87 fields intended for potato production in the Columbia Basin of Washington and Oregon and 51 fields intended for mint production in Washington were assayed on a semi-selective medium to quantify populations of V. dahliae. The pathogen was isolated from 77 (89%) of the fields int...

  2. Production of anti-fungal volatiles by non-pathogenic Fusarium oxysporum and its efficacy in suppression of verticillium wilt of cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: The study aimed to identify volatile organic compounds (VOCs) produced by the non-pathogenic Fusarium oxysporum (Fo) strain CanR-46, and to determine the anti-fungal spectrum and the control efficacy of the Fo-VOCs. Methods: The Fo-VOCs were identified by GC-MS. The antifungal activity of the...

  3. Pseudomonas community structure and antagonistic potential in the rhizosphere: insights gained by combining phylogenetic and functional gene-based analyses.

    PubMed

    Costa, Rodrigo; Gomes, Newton C M; Krögerrecklenfort, Ellen; Opelt, Katja; Berg, Gabriele; Smalla, Kornelia

    2007-09-01

    The Pseudomonas community structure and antagonistic potential in the rhizospheres of strawberry and oilseed rape (host plants of the fungal phytopathogen Verticillium dahliae) were assessed. The use of a new PCR-DGGE system, designed to target Pseudomonas-specific gacA gene fragments in environmental DNA, circumvented common biases of 16S rRNA gene-based DGGE analyses and proved to be a reliable tool to unravel the diversity of uncultured Pseudomonas in bulk and rhizosphere soils. Pseudomonas-specific gacA fingerprints of total-community (TC) rhizosphere DNA were surprisingly diverse, plant-specific and differed markedly from those of the corresponding bulk soils. By combining multiple culture-dependent and independent surveys, a group of Pseudomonas isolates antagonistic towards V. dahliae was shown to be genotypically conserved, to carry the phlD biosynthetic locus (involved in the biosynthesis of 2,4-diacetylphloroglucinol - 2,4-DAPG), and to correspond to a dominant and highly frequent Pseudomonas population in the rhizosphere of field-grown strawberries planted at three sites in Germany which have different land use histories. This population belongs to the Pseudomonas fluorescens phylogenetic lineage and showed closest relatedness to P. fluorescens strain F113 (97% gacA gene sequence identity in 492-bp sequences), a biocontrol agent and 2,4-DAPG producer. Partial gacA gene sequences derived from isolates, clones of the strawberry rhizosphere and DGGE bands retrieved in this study represent previously undescribed Pseudomonas gacA gene clusters as revealed by phylogenetic analysis. PMID:17686023

  4. Siderophore-mediated iron acquisition influences motility and is required for full virulence of the xylem-dwelling bacterial phytopathogen Pantoea stewartii subsp. stewartii.

    PubMed

    Burbank, Lindsey; Mohammadi, Mojtaba; Roper, M Caroline

    2015-01-01

    Iron is a key micronutrient for microbial growth but is often present in low concentrations or in biologically unavailable forms. Many microorganisms overcome this challenge by producing siderophores, which are ferric-iron chelating compounds that enable the solubilization and acquisition of iron in a bioactive form. Pantoea stewartii subsp. stewartii, the causal agent of Stewart's wilt of sweet corn, produces a siderophore under iron-limiting conditions. The proteins involved in the biosynthesis and export of this siderophore are encoded by the iucABCD-iutA operon, which is homologous to the aerobactin biosynthetic gene cluster found in a number of enteric pathogens. Mutations in iucA and iutA resulted in a decrease in surface-based motility that P. stewartii utilizes during the early stages of biofilm formation, indicating that active iron acquisition impacts surface motility for P. stewartii. Furthermore, bacterial movement in planta is also dependent on a functional siderophore biosynthesis and uptake pathway. Most notably, siderophore-mediated iron acquisition is required for full virulence in the sweet corn host, indicating that active iron acquisition is essential for pathogenic fitness for this important xylem-dwelling bacterial pathogen. PMID:25326304

  5. Ectopic Expression in Arabidopsis thaliana of an NB-ARC Encoding Putative Disease Resistance Gene from Wild Chinese Vitis pseudoreticulata Enhances Resistance to Phytopathogenic Fungi and Bacteria

    PubMed Central

    Wen, Zhifeng; Yao, Liping; Wan, Ran; Li, Zhi; Liu, Chonghuai; Wang, Xiping

    2015-01-01

    Plant resistance proteins mediate pathogen recognition and activate innate immune responses to restrict pathogen proliferation. One common feature of these proteins is an NB-ARC domain. In this study, we characterized a gene encoding a protein with an NB-ARC domain from wild Chinese grapevine Vitis pseudoreticulata accession “Baihe-35-1,” which was identified in a transcriptome analysis of the leaves following inoculation with Erysiphe necator (Schw.), a causal agent of powdery mildew. Transcript levels of this gene, designated VpCN (GenBank accession number KT265084), increased strongly after challenge of grapevine leaves with E. necator. The deduced amino acid sequence was predicted to contain an NB-ARC domain in the C-terminus and an RxCC-like domain similar to CC domain of Rx protein in the N-terminus. Ectopic expression of VpCN in Arabidopsis thaliana resulted in either a wild-type phenotype or a dwarf phenotype. The phenotypically normal transgenic A. thaliana showed enhance resistance to A. thaliana powdery mildew Golovinomyces cichoracearum, as well as to a virulent bacterial pathogen Pseudomonas syringae pv. tomato DC3000. Moreover, promoter::GUS (β-glucuronidase) analysis revealed that powdery mildew infection induced the promoter activity of VpCN in grapevine leaves. Finally, a promoter deletion analysis showed that TC rich repeat elements likely play an important role in the response to E. necator infection. Taken together, our results suggest that VpCN contribute to powdery mildew disease resistant in grapevine. PMID:26697041

  6. Siderophore-Mediated Iron Acquisition Influences Motility and Is Required for Full Virulence of the Xylem-Dwelling Bacterial Phytopathogen Pantoea stewartii subsp. stewartii

    PubMed Central

    Burbank, Lindsey; Mohammadi, Mojtaba

    2014-01-01

    Iron is a key micronutrient for microbial growth but is often present in low concentrations or in biologically unavailable forms. Many microorganisms overcome this challenge by producing siderophores, which are ferric-iron chelating compounds that enable the solubilization and acquisition of iron in a bioactive form. Pantoea stewartii subsp. stewartii, the causal agent of Stewart's wilt of sweet corn, produces a siderophore under iron-limiting conditions. The proteins involved in the biosynthesis and export of this siderophore are encoded by the iucABCD-iutA operon, which is homologous to the aerobactin biosynthetic gene cluster found in a number of enteric pathogens. Mutations in iucA and iutA resulted in a decrease in surface-based motility that P. stewartii utilizes during the early stages of biofilm formation, indicating that active iron acquisition impacts surface motility for P. stewartii. Furthermore, bacterial movement in planta is also dependent on a functional siderophore biosynthesis and uptake pathway. Most notably, siderophore-mediated iron acquisition is required for full virulence in the sweet corn host, indicating that active iron acquisition is essential for pathogenic fitness for this important xylem-dwelling bacterial pathogen. PMID:25326304

  7. Lipopolysaccharide modulates the vector-pathogen interface of the xylem-limited phytopathogen, Xylella fastidiosa, the causal agent of Pierce’s disease of grapevine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Xylella fastidiosa Wells et al. is a gram-negative, insect-transmitted bacterium that causes a lethal disease of grapevine called Pierce’s disease. Lipopolysaccharide (LPS) is the most dominant macromolecule displayed on the cell surface of gram-negative bacteria. Bacterial interactions with the env...

  8. Metabolomic-Based Study of the Leafy Gall, the Ecological Niche of the Phytopathogen Rhodococcus Fascians, as a Potential Source of Bioactive Compounds

    PubMed Central

    Nacoulma, Aminata P.; Vandeputte, Olivier M.; De Lorenzi, Manuella; El Jaziri, Mondher; Duez, Pierre

    2013-01-01

    Leafy gall is a plant hyperplasia induced upon Rhodococcus fascians infection. Previously, by genomic and transcriptomic analysis, it has been reported that, at the early stage of symptom development, both primary and secondary metabolisms are modified. The present study is based on the hypothesis that fully developed leafy gall, could represent a potential source of new bioactive compounds. Therefore, non-targeted metabolomic analysis of aqueous and chloroform extracts of leafy gall and non-infected tobacco was carried out by 1H-NMR coupled to principal component analysis (PCA) and orthogonal projections to latent structures-discriminant analysis (OPLS-DA). Polar metabolite profiling reflects modifications mainly in the primary metabolites and in some polyphenolics. In contrast, main modifications occurring in non-polar metabolites concern secondary metabolites, and gas chromatography and mass spectrometry (GC-MS) evidenced alterations in diterpenoids family. Analysis of crude extracts of leafy galls and non-infected tobacco leaves exhibited a distinct antiproliferative activity against all four tested human cancer cell lines. A bio-guided fractionation of chloroformic crude extract yield to semi-purified fractions, which inhibited proliferation of glioblastoma U373 cells with IC50 between 14.0 and 2.4 μg/mL. Discussion is focused on the consequence of these metabolic changes, with respect to plant defense mechanisms following infection. Considering the promising role of diterpenoid family as bioactive compounds, leafy gall may rather be a propitious source for drug discovery. PMID:23771021

  9. Draft genome sequence of Streptomyces sp. strain Wb2n-11, a desert isolate with broad-spectrum antagonism against soilborne phytopathogens

    SciTech Connect

    Koeberl, Martina; White, Richard A.; Erschen, Sabine; El-Arabi, Tarek F.; Jansson, Janet K.; Berg, Gabriele

    2015-08-06

    Streptomyces sp. strain Wb2n-11, isolated from native desert soil, exhibited broad-spectrum antagonism against plant pathogenic fungi, bacteria and nematodes. The 8.2 Mb draft genome reveals genes putatively responsible for its promising biocontrol activity and genes which enable the soil bacterium to directly interact beneficially with plants.

  10. Draft Genome Sequence of Streptomyces sp. Strain Wb2n-11, a Desert Isolate with Broad-Spectrum Antagonism against Soilborne Phytopathogens

    DOE PAGESBeta

    Köberl, Martina; White, Richard A.; Erschen, Sabine; El-Arabi, Tarek F.; Jansson, Janet K.; Berg, Gabriele

    2015-08-06

    Streptomyces sp. strain Wb2n-11, isolated from native desert soil, exhibited broad-spectrum antagonism against plant pathogenic fungi, bacteria, and nematodes. The 8.2-Mb draft genome reveals genes putatively responsible for its promising biocontrol activity and genes which enable the soil bacterium to directly interact beneficially with plants.

  11. Draft Genome Sequence of Streptomyces sp. Strain Wb2n-11, a Desert Isolate with Broad-Spectrum Antagonism against Soilborne Phytopathogens

    SciTech Connect

    Köberl, Martina; White, Richard A.; Erschen, Sabine; El-Arabi, Tarek F.; Jansson, Janet K.; Berg, Gabriele

    2015-08-06

    Streptomyces sp. strain Wb2n-11, isolated from native desert soil, exhibited broad-spectrum antagonism against plant pathogenic fungi, bacteria, and nematodes. The 8.2-Mb draft genome reveals genes putatively responsible for its promising biocontrol activity and genes which enable the soil bacterium to directly interact beneficially with plants.

  12. Mycoparasitism of endophytic fungi isolated from reed on soilborne phytopathogenic fungi and production of cell wall-degrading enzymes in vitro.

    PubMed

    Cao, Ronghua; Liu, Xiaoguang; Gao, Kexiang; Mendgen, Kurt; Kang, Zhensheng; Gao, Jianfeng; Dai, Yang; Wang, Xue

    2009-12-01

    Antagonism of three endophytic fungi isolated from common reed (Phragmites australis) against eight soilborne pathogenic fungi was investigated on potato dextrose agar by light microscopy, scanning electron microscopy, and transmission electron microscopy. Inhibitory zones were not observed. The microscopical studies suggested that the endophytes inhibit growth of soilborne pathogens by means of coiling around hyphae and, after penetration, the degradation of hyphal cytoplasm. Since penetration of hyphae seems to play a major role in parasitism, we studied the production of cell wall degrading enzymes by the three endophytes. Choiromyces aboriginum produced higher activities of beta-1,3-glucanases compared to Stachybotrys elegans and Cylindrocarpon sp. For C. aboriginum and S. elegans, colloidal chitin was the best substrate for the induction of beta-1,3-glucanases and chitinases, respectively. This result suggests that mycoparasitism by endophytes on soilborne plant pathogens can be explained by their mycoparasitic activity. PMID:19705202

  13. Diversity of bacterial endophytes in 3 and 15 year-old grapevines of Vitis vinifera cv. Corvina and their potential for plant growth promotion and phytopathogen control.

    PubMed

    Andreolli, Marco; Lampis, Silvia; Zapparoli, Giacomo; Angelini, Elisa; Vallini, Giovanni

    2016-02-01

    This study represents the first investigation on ecology of endophytic bacteria isolated from 3 and 15 year-old vine stems of Vitis vinifera cv. Corvina. The analysis was performed by means of culture-dependent techniques. The obtained results showed that new grapevine endophytic genera are being discovered. Moreover, Bacilli and Actinobacteria are frequently isolated from 3 year-old plants, whereas Alpha- and Gamma- Proteobacteria classes are more prevalent in the 15 year-old plants. Shannon-Wiener (H) index and analysis of rarefaction curves revealed greater genus richness in young grapevine plants. Furthermore, results evidenced an increase of genotypic group number within specific genera (e.g., Rhizobium and Pantoea). Among isolated strains from 3 and 15 year-old stems, respectively, 34 and 39% produce siderophores; 22 and 15% secrete ammonia; 22 and 21% produce indole-3-acetic acid; 8.7 and 41% solubilize phosphate. Besides, two strains isolated from 15 year-old grapevines showed 1-aminocyclopropane-1-carboxylate deaminase activity. Antifungal activity analysis evidenced that two Bacillus strains possess growth antagonistic effect toward all the tested fungal strains. Therefore, the present study extends our knowledge of the diversity of the endophytic bacteria by providing new insights into the complexity of the grapevine microbiome. PMID:26805617

  14. Genomic overview of the phytopathogen Pectobacterium wasabiae strain RNS 08.42.1A suggests horizontal acquisition of quorum-sensing genes.

    PubMed

    Khayi, Slimane; Raoul des Essarts, Yannick; Quêtu-Laurent, Angélique; Moumni, Mohieddine; Hélias, Valérie; Faure, Denis

    2015-04-01

    The blackleg and soft-rot diseases caused by pectinolytic enterobacteria such as Pectobacterium and Dickeya are major causes of losses affecting potato crop in the field and upon storage. In this work, we report the isolation, characterization and genome analysis of the Pectobacterium wasabiae (formerly identified as Pectobacterium carotovorum subsp. carotovorum) strain RNS 08.42.1A, that has been isolated from a Solanum tuberosum host plant in France. Comparative genomics with 3 other P. wasabiae strains isolated from potato plants in different areas in North America and Europe, highlighted both a strong similarity at the whole genome level (ANI > 99 %) and a conserved synteny of the virulence genes. In addition, our analyses evidenced a robust separation between these four P. wasabiae strains and the type strain P. wasabiae CFBP 3304(T), isolated from horseradish in Japan. In P. wasabiae RNS 08.42.1A, the expI and expR nucleotidic sequences are more related to those of some Pectobacterium atrosepticum and P. carotovorum strains (90 % of identity) than to those of the other potato P. wasabiae strains (70 to 74 % of identity). This could suggest a recruitment of these genes in the P. wasabiae strain RNS 08.42.1A by an horizontal transfer between pathogens infecting the same potato host plant. PMID:25297844

  15. Draft Genome Sequence of Streptomyces sp. Strain Wb2n-11, a Desert Isolate with Broad-Spectrum Antagonism against Soilborne Phytopathogens.

    PubMed

    Köberl, Martina; White, Richard A; Erschen, Sabine; El-Arabi, Tarek F; Jansson, Janet K; Berg, Gabriele

    2015-01-01

    Streptomyces sp. strain Wb2n-11, isolated from native desert soil, exhibited broad-spectrum antagonism against plant pathogenic fungi, bacteria, and nematodes. The 8.2-Mb draft genome reveals genes putatively responsible for its promising biocontrol activity and genes which enable the soil bacterium to directly interact beneficially with plants. PMID:26251492

  16. Salicylic Acid, Yersiniabactin, and Pyoverdin Production by the Model Phytopathogen Pseudomonas syringae pv. tomato DC3000: Synthesis, Regulation, and Impact on Tomato and Arabidopsis Host Plants▿ †

    PubMed Central

    Jones, Alexander M.; Lindow, Steven E.; Wildermuth, Mary C.

    2007-01-01

    A genetically tractable model plant pathosystem, Pseudomonas syringae pv. tomato DC3000 on tomato and Arabidopsis thaliana hosts, was used to investigate the role of salicylic acid (SA) and iron acquisition via siderophores in bacterial virulence. Pathogen-induced SA accumulation mediates defense in these plants, and DC3000 contains the genes required for the synthesis of SA, the SA-incorporated siderophore yersiniabactin (Ybt), and the fluorescent siderophore pyoverdin (Pvd). We found that DC3000 synthesizes SA, Ybt, and Pvd under iron-limiting conditions in culture. Synthesis of SA and Ybt by DC3000 requires pchA, an isochorismate synthase gene in the Ybt genomic cluster, and exogenous SA can restore Ybt production by the pchA mutant. Ybt was also produced by DC3000 in planta, suggesting that Ybt plays a role in DC3000 pathogenesis. However, the pchA mutant did not exhibit any growth defect or altered virulence in plants. This lack of phenotype was not attributable to plant-produced SA restoring Ybt production, as the pchA mutant grew similarly to DC3000 in an Arabidopsis SA biosynthetic mutant, and in planta Ybt was not detected in pchA-infected wild-type plants. In culture, no growth defect was observed for the pchA mutant versus DC3000 for any condition tested. Instead, enhanced growth of the pchA mutant was observed under stringent iron limitation and additional stresses. This suggests that SA and Ybt production by DC3000 is costly and that Pvd is sufficient for iron acquisition. Further exploration of the comparative synthesis and utility of Ybt versus Pvd production by DC3000 found siderophore-dependent amplification of ybt gene expression to be absent, suggesting that Ybt may play a yet unknown role in DC3000 pathogenesis. PMID:17660289

  17. Comparative genomic and transcriptional analyses of the carbohydrate-active enzymes and secretomes of phytopathogenic fungi reveal their significant roles during infection and development.

    PubMed

    Lyu, Xueliang; Shen, Cuicui; Fu, Yanping; Xie, Jiatao; Jiang, Daohong; Li, Guoqing; Cheng, Jiasen

    2015-01-01

    Our comparative genomic analysis showed that the numbers of plant cell wall (PCW)- and fungal cell wall (FCW)-degradation-associated carbohydrate-active enzymes (CAZymes) in necrotrophic and hemibiotrophic fungi are significantly larger than that in most biotrophic fungi. However, our transcriptional analyses of CAZyme-encoding genes in Melampsora larici-populina, Puccinia graminis and Sclerotinia sclerotiorum showed that many genes encoding PCW- and FCW-degradation-associated CAZymes were significantly up-regulated during the infection of both necrotrophic fungi and biotrophic fungi, indicating an existence of a universal mechanism underlying PCW degradation and FCW reorganization or modification, which are both intimately involved in necrotrophic and biotrophic fungal infection. Furthermore, our results showed that the FCW reorganization or modification was also related to the fungal development. Additionally, our transcriptional analysis of the secretome of S. sclerotiorum showed that many secreted protein-encoding genes were dramatically induced during infection. Among them, a small, cysteine-rich protein SsCVNH was experimentally confirmed to be essential for the virulence and sclerotial development, indicating that the small secreted proteins might also play crucial roles as potential effectors in host-non-specific necrotrophic fungi. PMID:26531059

  18. Gram-negative phytopathogenic and soil bacteria enhance the presence of Escherichia coli O157:H7 in dual-species biofilms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Biofilms formed by native microflora may provide a pathway for human bacterial pathogens to survive and cause cross-contamination in centralized fresh-cut processing manufactures, consequently leading to severe foodborne outbreaks. The objective of this study is to determine the influence of indivi...

  19. Transcriptome analysis of the phytopathogenic fungus Rhizoctonia solani AG1-IB 7/3/14 applying high-throughput sequencing of expressed sequence tags (ESTs).

    PubMed

    Wibberg, Daniel; Jelonek, Lukas; Rupp, Oliver; Kröber, Magdalena; Goesmann, Alexander; Grosch, Rita; Pühler, Alfred; Schlüter, Andreas

    2014-01-01

    Rhizoctonia solani is a soil-borne plant pathogenic fungus of the phylum Basidiomycota. It affects a wide range of agriculturally important crops and hence is responsible for economically relevant crop losses. Transcriptome analysis of the bottom rot pathogen R. solani AG1-1B (isolate 7/3/14) by applying high-throughput sequencing and bioinformatics methods addressing Expressed Sequence Tag (EST) data interpretation provided new insights in expressed genes of this fungus. Two normalized cDNA libraries representing different cultivation conditions of the fungus were sequenced on the 454 FLX (Roche) system. Subsequent to cDNA sequence assembly and quality control, ESTs were analysed applying advanced bioinformatics methods. More than 14 000 transcript isoforms originating from approximately 10 000 predictable R. solani AG1-IB 7/3/14 genes are represented in each dataset. Comparative analyses revealed several differentially expressed genes depending on the growth conditions applied. Determinants with predicted functions in recognition processes between the fungus and the host plant were identified. Moreover, many R. solani AG1-IB ESTs were predicted to encode putative cellulose, pectin, and lignin degrading enzymes. Furthermore, genes playing a possible role in mitogen-activated protein (MAP) kinase cascades, 4-aminobutyric acid (GABA) metabolism, melanin synthesis, plant defence antagonism, phytotoxin, and mycotoxin synthesis were detected. PMID:25209639

  20. Analysis of cytochrome b5 reductase-mediated metabolism in the phytopathogenic fungus Zymoseptoria tritici reveals novel functionalities implicated in virulence

    PubMed Central

    Derbyshire, Mark C.; Michaelson, Louise; Parker, Josie; Kelly, Steven; Thacker, Urvashi; Powers, Stephen J.; Bailey, Andy; Hammond-Kosack, Kim; Courbot, Mikael; Rudd, Jason

    2015-01-01

    Septoria tritici blotch (STB) caused by the Ascomycete fungus Zymoseptoria tritici is one of the most economically damaging diseases of wheat worldwide. Z. tritici is currently a major target for agricultural fungicides, especially in temperate regions where it is most prevalent. Many fungicides target electron transfer enzymes because these are often important for cell function. Therefore characterisation of genes encoding such enzymes may be important for the development of novel disease intervention strategies. Microsomal cytochrome b5 reductases (CBRs) are an important family of electron transfer proteins which in eukaryotes are involved in the biosynthesis of fatty acids and complex lipids including sphingolipids and sterols. Unlike the model yeast Saccharomyces cerevisiae which possesses only one microsomal CBR, the fully sequenced genome of Z. tritici bears three possible microsomal CBRs. RNA sequencing analysis revealed that ZtCBR1 is the most highly expressed of these genes under all in vitro and in planta conditions tested, therefore ΔZtCBR1 mutant strains were generated through targeted gene disruption. These strains exhibited delayed disease symptoms on wheat leaves and severely limited asexual sporulation. ΔZtCBR1 strains also exhibited aberrant spore morphology and hyphal growth in vitro. These defects coincided with alterations in fatty acid, sphingolipid and sterol biosynthesis observed through GC–MS and HPLC analyses. Data is presented which suggests that Z. tritici may use ZtCBR1 as an additional electron donor for key steps in ergosterol biosynthesis, one of which is targeted by azole fungicides. Our study reports the first functional characterisation of CBR gene family members in a plant pathogenic filamentous fungus. This also represents the first direct observation of CBR functional ablation impacting upon fungal sterol biosynthesis. PMID:26074495