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1

Genetic transformation of the fungal plant wilt pathogen, Fusarium oxysporum  

Microsoft Academic Search

A system for transformation of the fungal plant pathogen Fusarium oxysporum has been developed. The system employs plasmids which contain a bacterial hygromycin B phosphotransferase gene (hph) linked to Aspergillus regulatory sequences and which confer hygromycin B resistance in Fusarium. Transformation resulted from integration of the vectors into heterologous regions of the Fusarium genome and occurred at a frequency of

H. Corby Kistler; Ulla K. Benny

1988-01-01

2

Molecular characterization of pathogenic Fusarium species in cucurbit plants from Kermanshah province, Iran.  

PubMed

Fusarium is one of the important phytopathogenic genera of microfungi causing serious losses on cucurbit plants in Kermanshah province, the largest area of cucurbits plantation in Iran. Therefore, the objectives in this study were to isolate and identify disease-causing Fusarium spp. from infected cucurbit plants, to ascertain their pathogenicity, and to determine their phylogenetic relationships. A total of 100 Fusarium isolates were obtained from diseased cucurbit plants collected from fields in different geographic regions in Kermanshah province, Iran. According to morphological characters, all isolates were identified as Fusarium oxysporum, Fusarium proliferatum, Fusarium equiseti, Fusarium semitectum and Fusarium solani. All isolates of the five Fusarium spp. were evaluated for their pathogenicity on healthy cucumber (Cucumis sativus) and honeydew melon (Cucumis melo) seedlings in the glasshouse. F. oxysporum caused damping-off in 20-35 days on both cucurbit seedlings tested. Typical stem rot symptoms were observed within 15 days after inoculation with F. solani on both seedlings. Based on the internal transcribed spacer (ITS) regions of ribosomal DNA (rDNA) restriction fragment length polymorphism (RFLP) analysis, the five Fusarium species were divided into two major groups. In particular, isolates belonging to the F. solani species complex (FSSC) were separated into two RFLP types. Grouping among Fusarium strains derived from restriction analysis was in agreement with criteria used in morphological classification. Therefore, the PCR-ITS-RFLP method provides a simple and rapid procedure for the differentiation of Fusarium strains at species level. This is the first report on identification and pathogenicity of major plant pathogenic Fusarium spp. causing root and stem rot on cucurbits in Iran. PMID:23961146

Chehri, K; Salleh, B; Yli-Mattila, T; Reddy, K R N; Abbasi, S

2011-10-01

3

Monitoring of pathogenic and non-pathogenic Fusarium oxysporum strains during tomato plant infection  

PubMed Central

Summary Monitoring of pathogenic strains of Fusarium oxysporum (Fox), which cause wilt and rots on agricultural and ornamental plants, is important for predicting disease outbreaks. Since both pathogenic and non?pathogenic strains of Fox are ubiquitous and are able to colonize plant roots, detection of Fox DNA in plant material is not the ultimate proof of an ongoing infection which would cause damage to the plant. We followed the colonization of tomato plants by strains Fox f. sp. radicis?lycopersici ZUM2407 (a tomato foot and root rot pathogen), Fox f. sp. radicis?cucumerinum V03?2g (a cucumber root rot pathogen) and Fox Fo47 (a well?known non?pathogenic biocontrol strain). We determined fungal DNA concentrations in tomato plantlets by quantitative PCR (qPCR) with primers complementary to the intergenic spacer region (IGS) of these three Fox strains. Two weeks after inoculation of tomato seedlings with these Fox strains, the DNA concentration of Forl ZUM2407 was five times higher than that of the non?compatible pathogen Forc V03?2g and 10 times higher than that of Fo47. In 3?week?old plantlets the concentration of Forl ZUM2407 DNA was at least 10 times higher than those of the other strains. The fungal DNA concentration, as determined by qPCR, appeared to be in good agreement with data of the score of visible symptoms of tomato foot and root rot obtained 3 weeks after inoculation of tomato with Forl ZUM2407. Our results show that targeting of the multicopy ribosomal operon results in a highly sensitive qPCR reaction for the detection of Fox DNA. Since formae speciales of Fox cannot be distinguished by comparison of ribosomal operons, detection of Fox DNA is not evidence of plant infection by a compatible pathogen. Nevertheless, the observed difference in levels of plant colonization between pathogenic and non?pathogenic strains strongly suggests that a concentration of Fox DNA in plant material above the threshold level of 0.005% is due to proliferation of pathogenic Fox. PMID:21255375

Validov, Shamil Z.; Kamilova, Faina D.; Lugtenberg, Ben J. J.

2011-01-01

4

FGDB: a comprehensive fungal genome resource on the plant pathogen Fusarium graminearum  

Microsoft Academic Search

The MIPS Fusarium graminearum Genome Database (FGDB) is a comprehensive genome database on one of the most devastating fungal plant pathogens of wheat and barley. FGDB provides information on two gene sets independently derived by automated annotation of the F.graminearum genome sequence. A complete manually revised gene set will be com- pleted within the near future. The initial results of

Ulrich Güldener; Gertrud Mannhaupt; Martin Münsterkötter; Dirk Haase; Matthias Oesterheld; Volker Stümpflen; Hans-werner Mewes; Gerhard Adam

2006-01-01

5

A Fungal Symbiont of Plant-Roots Modulates Mycotoxin Gene Expression in the Pathogen Fusarium sambucinum  

PubMed Central

Fusarium trichothecenes are fungal toxins that cause disease on infected plants and, more importantly, health problems for humans and animals that consume infected fruits or vegetables. Unfortunately, there are few methods for controlling mycotoxin production by fungal pathogens. In this study, we isolated and characterized sixteen Fusarium strains from naturally infected potato plants in the field. Pathogenicity tests were carried out in the greenhouse to evaluate the virulence of the strains on potato plants as well as their trichothecene production capacity, and the most aggressive strain was selected for further studies. This strain, identified as F. sambucinum, was used to determine if trichothecene gene expression was affected by the symbiotic Arbuscular mycorrhizal fungus (AMF) Glomus irregulare. AMF form symbioses with plant roots, in particular by improving their mineral nutrient uptake and protecting plants against soil-borne pathogens. We found that that G. irregulare significantly inhibits F. sambucinum growth. We also found, using RT-PCR assays to assess the relative expression of trichothecene genes, that in the presence of the AMF G. irregulare, F. sambucinum genes TRI5 and TRI6 were up-regulated, while TRI4, TRI13 and TRI101 were down-regulated. We conclude that AMF can modulate mycotoxin gene expression by a plant fungal pathogen. This previously undescribed effect may be an important mechanism for biological control and has fascinating implications for advancing our knowledge of plant-microbe interactions and controlling plant pathogens. PMID:21455305

Ismail, Youssef; McCormick, Susan; Hijri, Mohamed

2011-01-01

6

Factors influencing pathogenicity of Fusarium tumidum on gorse (Ulex europaeus)  

Microsoft Academic Search

Factors promoting pathogenicity of Fusarium tumidum on gorse (Ulex europaeus) were determined to develop a novel strategy for delivering this potential mycoherbicide using insects as vectors of inoculum. Fusarium tumidum sprayed as a suspension of 1×10 conidia mL on at least 50% of a gorse plant reduced shoot dry weight by 45% (P<0.05). A minimum of 910 viable conidia were

Emmanuel Yamoah; E. Eirian Jones; Graeme W. Bourdôt; David M. Suckling; Richard J. Weld; Alison Stewart

2008-01-01

7

Plant pathology (review) Fusarium wilt of peas (a review)  

E-print Network

Plant pathology (review) Fusarium wilt of peas (a review) JM Kraft US Department of Agriculture January 1995) Summary - Pea wilt was first described in 1925 and the pathogen identified as Fusarium discusses what little is known about seed transmission of the pea wilt pathogen. Résumé - Fusariose du pois

Paris-Sud XI, Université de

8

Role of ethylene in the protection of tomato plants against soil-borne fungal pathogens conferred by an endophytic Fusarium solani strain.  

PubMed

An endophytic fungal isolate (Fs-K), identified as a Fusarium solani strain, was obtained from root tissues of tomato plants grown on a compost which suppressed soil and foliar pathogens. Strain Fs-K was able to colonize root tissues and subsequently protect plants against the root pathogen Fusarium oxysporum f.sp. radicis-lycopersici (FORL), and elicit induced systemic resistance against the tomato foliar pathogen Septoria lycopersici. Interestingly, attenuated expression of certain pathogenesis-related genes, i.e. PR5 and PR7, was detected in tomato roots inoculated with strain Fs-K compared with non-inoculated plants. The expression pattern of PR genes was either not affected or aberrant in leaves. A genetic approach, using mutant tomato plant lines, was used to determine the role of ethylene and jasmonic acid in the plant's response to infection by the soil-borne pathogen F. oxysporum f.sp. radicis-lycopersici (FORL), in the presence or absence of isolate Fs-K. Mutant tomato lines Never ripe (Nr) and epinastic (epi1), both impaired in ethylene-mediated plant responses, inoculated with FORL are not protected by isolate Fs-K, indicating that the ethylene signalling pathway is required for the mode of action used by the endophyte to confer resistance. On the contrary, def1 mutants, affected in jasmonate biosynthesis, show reduced susceptibility to FORL, in the presence Fs-K, which suggests that jasmonic acid is not essential for the mediation of biocontrol activity of isolate Fs-K. PMID:18048373

Kavroulakis, Nektarios; Ntougias, Spyridon; Zervakis, Georgios I; Ehaliotis, Constantinos; Haralampidis, Kosmas; Papadopoulou, Kalliope K

2007-01-01

9

Plant Disease Lesson: Fusarium head blight (FHB) or scab  

NSDL National Science Digital Library

This plant disease lesson on Fusarium head blight (FHB) or scab (caused by the fungus Fusarium graminearum (anamorph) Gibberella zeae (teleomorph)) includes information on symptoms and signs, pathogen biology, disease cycle and epidemiology, disease management, and the significance of the disease. Selected references are listed and a glossary is also available for use with this resource.

David G. Schmale III (Cornell University;); Gary C. Bergstrom (Cornell University;)

2003-06-12

10

Antifungal activity of ZnO nanoparticles and their interactive effect with a biocontrol bacterium on growth antagonism of the plant pathogen Fusarium graminearum.  

PubMed

Fungal plant pathogens such as Fusarium graminearum cause severe global economic losses in cereals crops, and current control measures are limited. This work addresses the potential for ZnO nanoparticles (NPs) and biocontrol bacteria to be used in plant fungal control strategies. Growth of F. graminearum was significantly (p = 0.05) inhibited by inclusion of the NPs in a mung bean broth agar and in sand. Suspension in mung bean broth medium modified the surface charge, dissolution, and aggregation state of the ZnO NPs, in comparison to processes occurring in water suspension. The ZnO NPs were significantly more inhibitory to fungal growth than micro-sized particles of ZnO, although both types of particles released similar levels of soluble Zn, indicating size-dependent toxicity of the particles. Zn ions produced dose-dependent inhibition, noticeable at the level of soluble Zn released from NPs after seven-day suspension in medium; inhibitory levels caused acidification of the growth medium. Transfer of fungal inoculum after exposure to the ZnO NPs to fresh medium did not indicate adaptation to the stress because growth was still inhibited by the NPs. The ZnO NPs did not prevent metabolites from a biocontrol bacterium, Pseudomonas chlororaphis O6, from inhibiting Fusarium growth: no synergism was observed in the mung bean agar. Because other studies find that soil amendment with ZnO NPs required high doses for inhibition of plant growth, the findings of pathogen growth control reported in this paper open the possibility of using ZnO NP-based formulations to complement existing strategies for improving crop health in field settings. PMID:23933719

Dimkpa, Christian O; McLean, Joan E; Britt, David W; Anderson, Anne J

2013-12-01

11

Comparative genomics reveals mobile pathogenicity chromosomes in Fusarium  

SciTech Connect

Fusarium species are among the most important phytopathogenic and toxigenic fungi, having significant impact on crop production and animal health. Distinctively, members of the F. oxysporum species complex exhibit wide host range but discontinuously distributed host specificity, reflecting remarkable genetic adaptability. To understand the molecular underpinnings of diverse phenotypic traits and their evolution in Fusarium, we compared the genomes of three economically important and phylogenetically related, yet phenotypically diverse plant-pathogenic species, F. graminearum, F. verticillioides and F. oxysporum f. sp. lycopersici. Our analysis revealed greatly expanded lineage-specific (LS) genomic regions in F. oxysporum that include four entire chromosomes, accounting for more than one-quarter of the genome. LS regions are rich in transposons and genes with distinct evolutionary profiles but related to pathogenicity. Experimentally, we demonstrate for the first time the transfer of two LS chromosomes between strains of F. oxysporum, resulting in the conversion of a non-pathogenic strain into a pathogen. Transfer of LS chromosomes between otherwise genetically isolated strains explains the polyphyletic origin of host specificity and the emergence of new pathogenic lineages in the F. oxysporum species complex, putting the evolution of fungal pathogenicity into a new perspective.

Ma, Li Jun; van der Does, H. C.; Borkovich, Katherine A.; Coleman, Jeffrey J.; Daboussi, Marie-Jose; Di Pietro, Antonio; Dufresne, Marie; Freitag, Michael; Grabherr, Manfred; Henrissat, Bernard; Houterman, Petra M.; Kang, Seogchan; Shim, Won-Bo; Wolochuk, Charles; Xie, Xiaohui; Xu, Jin Rong; Antoniw, John; Baker, Scott E.; Bluhm, Burton H.; Breakspear, Andrew; Brown, Daren W.; Butchko, Robert A.; Chapman, Sinead; Coulson, Richard; Coutinho, Pedro M.; Danchin, Etienne G.; Diener, Andrew; Gale, Liane R.; Gardiner, Donald; Goff, Steven; Hammond-Kossack, Kim; Hilburn, Karen; Hua-Van, Aurelie; Jonkers, Wilfried; Kazan, Kemal; Kodira, Chinnappa D.; Koehrsen, Michael; Kumar, Lokesh; Lee, Yong Hwan; Li, Liande; Manners, John M.; Miranda-Saavedra, Diego; Mukherjee, Mala; Park, Gyungsoon; Park, Jongsun; Park, Sook Young; Proctor, Robert H.; Regev, Aviv; Ruiz-Roldan, M. C.; Sain, Divya; Sakthikumar, Sharadha; Sykes, Sean; Schwartz, David C.; Turgeon, Barbara G.; Wapinski, Ilan; Yoder, Olen; Young, Sarah; Zeng, Qiandong; Zhou, Shiguo; Galagan, James; Cuomo, Christina A.; Kistler, H. Corby; Rep, Martijn

2010-03-18

12

The Genome of the Generalist Plant Pathogen Fusarium avenaceum Is Enriched with Genes Involved in Redox, Signaling and Secondary Metabolism  

PubMed Central

Fusarium avenaceum is a fungus commonly isolated from soil and associated with a wide range of host plants. We present here three genome sequences of F. avenaceum, one isolated from barley in Finland and two from spring and winter wheat in Canada. The sizes of the three genomes range from 41.6–43.1 MB, with 13217–13445 predicted protein-coding genes. Whole-genome analysis showed that the three genomes are highly syntenic, and share>95% gene orthologs. Comparative analysis to other sequenced Fusaria shows that F. avenaceum has a very large potential for producing secondary metabolites, with between 75 and 80 key enzymes belonging to the polyketide, non-ribosomal peptide, terpene, alkaloid and indole-diterpene synthase classes. In addition to known metabolites from F. avenaceum, fuscofusarin and JM-47 were detected for the first time in this species. Many protein families are expanded in F. avenaceum, such as transcription factors, and proteins involved in redox reactions and signal transduction, suggesting evolutionary adaptation to a diverse and cosmopolitan ecology. We found that 20% of all predicted proteins were considered to be secreted, supporting a life in the extracellular space during interaction with plant hosts. PMID:25409087

Lysře, Erik; Harris, Linda J.; Walkowiak, Sean; Subramaniam, Rajagopal; Divon, Hege H.; Riiser, Even S.; Llorens, Carlos; Gabaldón, Toni; Kistler, H. Corby; Jonkers, Wilfried; Kolseth, Anna-Karin; Nielsen, Kristian F.; Thrane, Ulf; Frandsen, Rasmus J. N.

2014-01-01

13

Chromosome Complement of the Fungal Plant Pathogen Fusarium graminearum Based on Genetic and Physical Mapping and Cytological Observations  

Microsoft Academic Search

A genetic map of the filamentous fungus Fusarium graminearum (teleomorph: Gibberella zeae) was con- structed to both validate and augment the draft whole-genome sequence assembly of strain PH-1. A mapping population was created from a cross between mutants of the sequenced strain (PH-1, NRRL 31084, originally isolated from Michigan) and a field strain from Minnesota (00-676, NRRL 34097). A total

L. R. Gale; J. D. Bryant; S. Calvo; H. Giese; T. Katan; K. O'Donnell; H. Suga; M. Taga; T. R. Usgaard; T. J. Ward; H. C. Kistler

2005-01-01

14

Multilocus phylogenetic diversity of Fusarium avenaceum pathogenic on lisianthus.  

PubMed

Fusarium avenaceum is a globally distributed fungus commonly isolated from soil and a wide range of plants. Severe outbreaks of crown and stem rot of the flowering ornamental, lisianthus (Eustoma grandiflorum), have been attributed to F. avenaceum. We sequenced portions of the translation elongation factor 1-alpha (tef) and beta-tubulin (benA) protein coding genes as well as partial intergenic spacer (IGS) regions of the nuclear ribosomal genes in 37 Fusarium isolates obtained from lisianthus and other host plants. Isolates that were previously identified morphologically as F. acuminatum were included as an outgroup. Phylogenetic analyses of tef, benA, and IGS sequences showed that F. avenaceum isolates were an exclusive group with strong bootstrap support and no significant incongruence among gene genealogies. Isolates from lisianthus were scattered within this clade and did not form distinct groups based on host species or locality. Pathogenicity tests of F. avenaceum isolates obtained from several other hosts showed an ability to cause disease on lisianthus, suggesting that F. avenaceum may be pathogenic on lisianthus regardless of its phylogenetic origin. These findings have management implications and suggest that any host that supports F. avenaceum may serve as a source of inoculum for lisianthus growers. PMID:19271989

Nalim, F A; Elmer, W H; McGovern, R J; Geiser, D M

2009-04-01

15

Identification, pathogenicity and comparative virulence of Fusarium spp. associated with insect-damaged, diseased Centaurea spp. in Europe  

Microsoft Academic Search

Fusarium spp. isolated from insect-infested, diseased Centaurea diffusa and Centaurea maculosa in Europe were assessed for pathogenicity to North American plants of their respective original hosts: either C. diffusa or C. maculosa. Of the ten isolates of Fusarium spp. isolated from diseased Centaurea spp. in the Caucasus region of Russia and eastern Europe, all caused one or more disease symptoms

A. J. Caesar; G. Campobasso; G. TERRAGITTI

2002-01-01

16

Fusarium pathogenomics.  

PubMed

Fusarium is a genus of filamentous fungi that contains many agronomically important plant pathogens, mycotoxin producers, and opportunistic human pathogens. Comparative analyses have revealed that the Fusarium genome is compartmentalized into regions responsible for primary metabolism and reproduction (core genome), and pathogen virulence, host specialization, and possibly other functions (adaptive genome). Genes involved in virulence and host specialization are located on pathogenicity chromosomes within strains pathogenic to tomato (Fusarium oxysporum f. sp. lycopersici) and pea (Fusarium 'solani' f. sp. pisi). The experimental transfer of pathogenicity chromosomes from F. oxysporum f. sp. lycopersici into a nonpathogen transformed the latter into a tomato pathogen. Thus, horizontal transfer may explain the polyphyletic origins of host specificity within the genus. Additional genome-scale comparative and functional studies are needed to elucidate the evolution and diversity of pathogenicity mechanisms, which may help inform novel disease management strategies against fusarial pathogens. PMID:24024636

Ma, Li-Jun; Geiser, David M; Proctor, Robert H; Rooney, Alejandro P; O'Donnell, Kerry; Trail, Frances; Gardiner, Donald M; Manners, John M; Kazan, Kemal

2013-01-01

17

Plant defense response against Fusarium oxysporum and strategies to develop tolerant genotypes in banana.  

PubMed

Soil-borne fungal pathogen, Fusarium oxysporum causes major economic losses by inducing necrosis and wilting symptoms in many crop plants. Management of fusarium wilt is achieved mainly by the use of chemical fungicides which affect the soil health and their efficiency is often limited by pathogenic variability. Hence understanding the nature of interaction between pathogen and host may help to select and improve better cultivars. Current research evidences highlight the role of oxidative burst and antioxidant enzymes indicating that ROS act as an important signaling molecule in banana defense response against Fusarium oxysporum f.sp. cubense. The role of jasmonic acid signaling in plant defense against necrotrophic pathogens is well recognized. But recent studies show that the role of salicylic acid is complex and ambiguous against necrotrophic pathogens like Fusarium oxysporum, leading to many intriguing questions about its relationship between other signaling compounds. In case of banana, a major challenge is to identify specific receptors for effector proteins like SIX proteins and also the components of various signal transduction pathways. Significant progress has been made to uncover the role of defense genes but is limited to only model plants such as Arabidopsis and tomato. Keeping this in view, we review the host response, pathogen diversity, current understanding of biochemical and molecular changes that occur during host and pathogen interaction. Developing resistant cultivars through mutation, breeding, transgenic and cisgenic approaches have been discussed. This would help us to understand host defenses against Fusarium oxysporum and to formulate strategies to develop tolerant cultivars. PMID:24420701

Swarupa, V; Ravishankar, K V; Rekha, A

2014-04-01

18

Fusarium foetens, a new species pathogenic to begonia elatior hybrids (Begonia x hiemalis) and the sister taxon of the Fusarium oxysporum species complex.  

PubMed

A new disease recently was discovered in begonia elatior hybrid (Begonia × hiemalis) nurseries in The Netherlands. Diseased plants showed a combination of basal rot, vein yellowing and wilting and the base of collapsing plants was covered by unusually large masses of Fusarium macroconidia. A species of Fusarium was isolated consistently from the discolored veins of leaves and stems. It differed morphologically from F. begoniae, a known agent of begonia flower, leaf and stem blight. The Fusarium species resembled members of the F. oxysporum species complex in producing short monophialides on the aerial mycelium and abundant chlamydospores. Other phenotypic characters such as polyphialides formed occasionally in at least some strains, relatively long monophialides intermingled with the short monophialides formed on the aerial mycelium, distinct sporodochial conidiomata, and distinct pungent colony odor distinguished it from the F. oxysporum species complex. Phylogenetic analyses of partial sequences of the mitochondrial small subunit of the ribosomal DNA (mtSSU rDNA), nuclear translation elongation factor 1? (EF-1?) and ?-tubulin gene exons and introns indicate that the Fusarium species represents a sister group of the F. oxysporum species complex. Begonia × hiemalis cultivars Bazan, Bellona and Netja Dark proved to be highly susceptible to the new species. Inoculated plants developed tracheomycosis within 4 wk, and most died within 8 wk. The new taxon was not pathogenic to Euphorbia pulcherrima, Impatiens walleriana and Saintpaulia ionantha that commonly are grown in nurseries along with B. × hiemalis. Inoculated plants of Cyclamen persicum did not develop the disease but had discolored vessels from which the inoculated fungus was isolated. Given that the newly discovered begonia pathogen is distinct in pathogenicity, morphology and phylogeny from other fusaria, it is described here as a new species, Fusarium foetens. PMID:21148861

Schroers, H-J; Baayen, R P; Meffert, J P; de Gruyter, J; Hooftman, M; O'Donnell, K

2004-01-01

19

Phylogeny and pathogenicity of Fusarium spp. isolated from greenhouse melon soil in Liaoning Province.  

PubMed

Fungi of the Fusarium oxysporum are widely distributed around the world in all types of soils, and they are all anamorphic species. In order to investigate the relationships and differences among Fusarium spp., 25 Fusarium spp. were isolated from greenhouse melon soils in Liaoning Province, China. With these 25 strains, three positive control Fusarium strains were analyzed using universally primed PCR (UP-PCR). Seventy-three bands appeared after amplification using 6 primers, and 66 of these bands (90.4%) were polymorphic. All strains were clustered into eight groups, though 14 strains of F. oxysporum were clustered into a single group. We concluded that UP-PCR could reveal the genetic relationships and differences among Fusarium strains. Moreover, the UP-PCR results suggested that F. oxysporum is distinguishable from other Fusarium spp. Thus, UP-PCR is a useful method for Fusarium classification. The pathogenicity of 13 strains of F. oxysporum to muskmelon, cucumber and watermelon seedlings was studied by infecting the seedlings with a spore suspension after cutting the root. The results showed that the F. oxysporum strains were pathogenic to all three melon types, although the pathogenicity differed significantly among the 13 strains. In addition, all strains had the greatest pathogenicity toward watermelon. Since the factors affecting pathogenicity vary widely, they should be considered in future studies on Fusarium spp. The results of such studies may then yield an accurate description of the pathogenicity of Fusarium spp. PMID:25183948

Zhao, Baixia; Yan, Jianfang; Zhang, Shuo; Liu, Xian; Gao, Zenggui

2014-09-01

20

Phylogeny and pathogenicity of Fusarium spp. isolated from greenhouse melon soil in Liaoning Province  

PubMed Central

Fungi of the Fusarium oxysporum are widely distributed around the world in all types of soils, and they are all anamorphic species. In order to investigate the relationships and differences among Fusarium spp., 25 Fusarium spp. were isolated from greenhouse melon soils in Liaoning Province, China. With these 25 strains, three positive control Fusarium strains were analyzed using universally primed PCR (UP-PCR). Seventy-three bands appeared after amplification using 6 primers, and 66 of these bands (90.4%) were polymorphic. All strains were clustered into eight groups, though 14 strains of F. oxysporum were clustered into a single group. We concluded that UP-PCR could reveal the genetic relationships and differences among Fusarium strains. Moreover, the UP-PCR results suggested that F. oxysporum is distinguishable from other Fusarium spp. Thus, UP-PCR is a useful method for Fusarium classification. The pathogenicity of 13 strains of F. oxysporum to muskmelon, cucumber and watermelon seedlings was studied by infecting the seedlings with a spore suspension after cutting the root. The results showed that the F. oxysporum strains were pathogenic to all three melon types, although the pathogenicity differed significantly among the 13 strains. In addition, all strains had the greatest pathogenicity toward watermelon. Since the factors affecting pathogenicity vary widely, they should be considered in future studies on Fusarium spp. The results of such studies may then yield an accurate description of the pathogenicity of Fusarium spp. PMID:25183948

Zhao, Baixia; Yan, Jianfang; Zhang, Shuo; Liu, Xian; Gao, Zenggui

2013-01-01

21

Susceptibility of zinc-deficient wheat plants to colonization by Fusarium graminearum Schw. Group 1  

Microsoft Academic Search

Wheat plants were grown at three levels of zinc nutrition in potted soil under controlled conditions. The surface soil in half of the pots was inoculated with a thin layer of milled chaff colonized byFusarium graminearum Group 1. Forty days after sowing, the plants were assessed for dry matter production and the extent of colonization by the pathogen. The concentration

Denise H. Sparrow; Robin D. Graham

1988-01-01

22

Influence of Climatic Factors on Fusarium Species Pathogenic to Cereals  

Microsoft Academic Search

Fusarium head blight of small-grain cereals, ear rot of maize, seedling blight and foot rot of cereals are important diseases throughout the world. Fusarium graminearum, F. culmorum, F. poae, F. avenaceum and Microdochium nivale (formerly known as F. nivale) predominantly cause Fusarium diseases of small-grain cereals. Maize is predominantly attacked by F. graminearum, F. moniliforme, F. proliferatum and F. subglutinans.

F. M. Doohan; J. Brennan; B. M. Cooke

2003-01-01

23

[Biodegradation of agricultural plant residues by Fusarium oxysporum strains].  

PubMed

The cellulolytic and endoglucanase activity of Fusarium oxysporum strains isolated from soil and plants in the media with plant waste as carbon source has been studied. It was established that the majority of studied strains were able to hydrolyze the filter paper, husk of sunflower seeds, wheat straw and corn stalks. Cellulolytic activity depended on the strain of microscopic fungi, type of substrate and duration of cultivation. The maximum cellulase activity 1 U/ml and the concentration of reducing sugars -0.875 mg/ml were found in soil strain F. oxysporum 420 in the medium with corn stalks. Endoglucanase activity of plant pathogenic strains was higher than that of soil ones. PMID:25199344

Chepchak, T P; Kurchenko, I N; Iur'eva, E M

2014-01-01

24

Plant pathogen resistance  

DOEpatents

Azelaic acid or its derivatives or analogs induce a robust and a speedier defense response against pathogens in plants. Azelaic acid treatment alone does not induce many of the known defense-related genes but activates a plant's defense signaling upon pathogen exposure.

Greenberg, Jean T; Jung, Ho Won; Tschaplinski, Timothy

2012-11-27

25

THE PATHOGENICITY AND DNA POLYMORPHISM OF FUSARIUM OXYSPORUM ORIGINATING FROM DIANTHUS CARYOPHYLLUS, GYPSOPHILA SPP. AND SOIL  

Microsoft Academic Search

A number of Fusarium oxysporum pathogenic isolates originating from Dianthus caryophyllus, Gypsophila paniculata, G. repens and non-pathogenic strains obtained from soil was screened for pathogenicity and genetic variation. RAPD analysis con- ducted with arbitrary 10-mer primers gave 23 RAPD markers resulted from the DNA polymorphism. Clustering analysis based on RAPD fingerprint data revealed several distinct groups within F. oxysporum which

M. Werner; L. Irzykowska

26

REN1 is required for development of microconidia and macroconidia, but not of chlamydospores, in the plant pathogenic fungus Fusarium oxysporum.  

PubMed Central

The filamentous fungus Fusarium oxysporum is a soil-borne facultative parasite that causes economically important losses in a wide variety of crops. F. oxysporum exhibits filamentous growth on agar media and undergoes asexual development producing three kinds of spores: microconidia, macroconidia, and chlamydospores. Ellipsoidal microconidia and falcate macroconidia are formed from phialides by basipetal division; globose chlamydospores with thick walls are formed acrogenously from hyphae or by the modification of hyphal cells. Here we describe rensa, a conidiation mutant of F. oxysporum, obtained by restriction-enzyme-mediated integration mutagenesis. Molecular analysis of rensa identified the affected gene, REN1, which encodes a protein with similarity to MedA of Aspergillus nidulans and Acr1 of Magnaporthe grisea. MedA and Acr1 are presumed transcription regulators involved in conidiogenesis in these fungi. The rensa mutant and REN1-targeted strains lack normal conidiophores and phialides and form rod-shaped, conidium-like cells directly from hyphae by acropetal division. These mutants, however, exhibit normal vegetative growth and chlamydospore formation. Nuclear localization of Ren1 was verified using strains expressing the Ren1-green fluorescent protein fusions. These data strongly suggest that REN1 encodes a transcription regulator required for the correct differentiation of conidiogenesis cells for development of microconidia and macroconidia in F. oxysporum. PMID:15020411

Ohara, Toshiaki; Inoue, Iori; Namiki, Fumio; Kunoh, Hitoshi; Tsuge, Takashi

2004-01-01

27

The Fusarium Graminearum Genome Reveals a Link Between Localized Polymorphism and Pathogen Specialization  

SciTech Connect

We sequenced and annotated the genome of the filamentous fungus Fusarium graminearum, a major pathogen of cultivated cereals. Very few repetitive sequences were detected, and the process of repeat-induced point mutation, in which duplicated sequences are subject to extensive mutation, may partially account for the reduced repeat content and apparent low number of paralogous (ancestrally duplicated) genes. A second strain of F. graminearum contained more than 10,000 single-nucleotide polymorphisms, which were frequently located near telomeres and within other discrete chromosomal segments. Many highly polymorphic regions contained sets of genes implicated in plant-fungus interactions and were unusually divergent, with higher rates of recombination. These regions of genome innovation may result from selection due to interactions of F. graminearum with its plant hosts.

Cuomo, Christina A.; Guldener, Ulrich; Xu, Jin Rong; Trail, Frances; Turgeon, Barbara G.; Di Pietro, Antonio; Walton, Johnathan D.; Ma, Li Jun; Baker, Scott E.; Rep, Martijn; Adam, Gerhard; Antoniw, John; Baldwin, Thomas; Calvo, Sarah; Chang, Yueh Long; DeCaprio, David; Gale, Liane R.; Gnerre, Sante; Goswami, Rubella S.; Hammond-Kossack, Kim; Harris, Linda J.; Hilburn, Karen; Kennell, John C.; Kroken, Scott; Magnuson, Jon K.; Mannhaupt, Gertrud; Mauceli, Evan; Mewes, Hans Werner; Mitterbauer, Rudolf; Muehlbauer, Gary; Munsterkotter, Martin; Nelson, David; O'Donnell, Kerry; Ouellet, Therese; Qi, Weihong; Quesneville, Hadi; Roncero, M. Isabel; Seong, Kye Yong; Tetko, Igor V.; Urban, Martin; Waalwijk, Cees; Ward, Todd J.; Yao, Jiqiang; Birren, Bruce W.; Kistler, H. Corby

2007-09-07

28

Pathogenicity and In Planta Mycotoxin Accumulation Among Members of the Fusarium graminearum Species Complex on Wheat and Rice  

Microsoft Academic Search

Goswami, R. S., and Kistler, H. C. 2005. Pathogenicity and in planta mycotoxin accumulation among members of the Fusarium graminearum species complex on wheat and rice. Phytopathology 95:1397-1404. Fusarium head blight (FHB), or scab, is a destructive disease of small grains caused by members of the Fusarium graminearum species com- plex, comprised of at least nine distinct, cryptic species. Members

Rubella S. Goswami; H. Corby Kistler

2005-01-01

29

Antifungal properties of essential oils from Thai medical plants against rice pathogenic fungi  

Microsoft Academic Search

This in vitro study was aimed to evaluate the mycelium growth and spore germination inhibition properties of essential oils. Two Thai medicinal plants; Frankincense oil (Boswellia carteri Bird.) and Cassia oil (Acacia farnesiana Linn) were applied against 7 species of economically important rice pathogenic fungi; Alternaria brassicicola, Aspergillus flavus, Bipolaris oryzae, Fusarium moniliforme, Fusarium proliferatum, Pyricularia arisea and Rhizoctonia solani.

Apinya Piyo; Pitipong Thobunluepop

30

An adaptive evolutionary shift in Fusarium head blight pathogen populations is driving the rapid spread of more toxigenic Fusarium graminearum in North America  

Microsoft Academic Search

Analysis of Fusarium head blight (FHB) pathogen diversity revealed that 3ADON producing Fusarium graminearum are prevalent in North America and identified significant population structure associated with trichothecene chemotype differences (FST>0.285; P<0.001). In addition, we identified a trichothecene chemotype cline in Canada and documented a recent and significant shift in FHB pathogen composition by demonstrating that the 3ADON chemotype frequency in

Todd J. Ward; Randall M. Clear; Alejandro P. Rooney; Kerry O’Donnell; Don Gaba; Susan Patrick; David E. Starkey; Jeannie Gilbert; David M. Geiser; Tom W. Nowicki

2008-01-01

31

Identification of the main toxins isolated from Fusarium oxysporum f. sp. pisi race 2 and their relation with isolates' pathogenicity.  

PubMed

Fusarium oxysporum f. sp. pisi (Fop) is a pathogen of field pea inducing severe vascular wilt worldwide. Plant resistance to races 1, 5, and 6, producing wilt symptoms, is conferred by a single dominant gene, while resistance to race 2, which gives near-wilt symptoms, have been recently showed to be quantitative. Among the virulence factors reported to play a role in the infection process, toxin production is one of the best studied. Thus, five race 2 isolates have been investigated for toxin production in vitro and their relation to isolates' pathogenicity. All the isolates produced different amounts of fusaric and 9,10-dehydrofusaric acids. The content of the two toxins has been quantitated and correlated with the pathogenicity and aggressiveness of isolates on field pea. Results suggested that toxin production is an important determinant of Fop race 2 pathogenicity. PMID:24568659

Bani, Moustafa; Rispail, Nicolas; Evidente, Antonio; Rubiales, Diego; Cimmino, Alessio

2014-03-26

32

The Fusarium graminearum Genome Reveals a Link Between Localized Polymorphism and Pathogen Specialization  

Microsoft Academic Search

We sequenced and annotated the genome of the filamentous fungus Fusarium graminearum, a major pathogen of cultivated cereals. Very few repetitive sequences were detected, and the process of repeat-induced point mutation, in which duplicated sequences are subject to extensive mutation, may partially account for the reduced repeat content and apparent low number of paralogous (ancestrally duplicated) genes. A second strain

Christina A. Cuomo; Ulrich Güldener; Jin-Rong Xu; Frances Trail; B. Gillian Turgeon; Antonio Di Pietro; Jonathan D. Walton; Li-Jun Ma; Scott E. Baker; Martijn Rep; Gerhard Adam; John Antoniw; Thomas Baldwin; Sarah Calvo; Yueh-Long Chang; David DeCaprio; Liane R. Gale; Sante Gnerre; Rubella S. Goswami; Kim Hammond-Kosack; Linda J. Harris; Karen Hilburn; John C. Kennell; Scott Kroken; Jon K. Magnuson; Gertrud Mannhaupt; Evan Mauceli; Hans-Werner Mewes; Rudolf Mitterbauer; Gary Muehlbauer; Martin Münsterkötter; David Nelson; Kerry O'Donnell; Thérčse Ouellet; Weihong Qi; Hadi Quesneville; M. Isabel G. Roncero; Kye-Yong Seong; Igor V. Tetko; Martin Urban; Cees Waalwijk; Todd J. Ward; Jiqiang Yao; Bruce W. Birren; H. Corby Kistler

2007-01-01

33

Widespread Occurrence of Diverse Human Pathogenic Types of the Fungus Fusarium Detected in Plumbing Drains ? †  

PubMed Central

It has been proposed that plumbing systems might serve as a significant environmental reservoir of human-pathogenic isolates of Fusarium. We tested this hypothesis by performing the first extensive multilocus sequence typing (MLST) survey of plumbing drain-associated Fusarium isolates and comparing the diversity observed to the known diversity of clinical Fusarium isolates. We sampled 471 drains, mostly in bathroom sinks, from 131 buildings in the United States using a swabbing method. We found that 66% of sinks and 80% of buildings surveyed yielded at least one Fusarium culture. A total of 297 isolates of Fusarium collected were subjected to MLST to identify the phylogenetic species and sequence types (STs) of these isolates. Our survey revealed that the six most common STs in sinks were identical to the six most frequently associated with human infections. We speculate that the most prevalent STs, by virtue of their ability to form and grow in biofilms, are well adapted to plumbing systems. Six major Fusarium STs were frequently isolated from plumbing drains within a broad geographic area and were identical to STs frequently associated with human infections. PMID:21976755

Short, Dylan P. G.; O'Donnell, Kerry; Zhang, Ning; Juba, Jean H.; Geiser, David M.

2011-01-01

34

Galleria mellonella as model host for the trans-kingdom pathogen Fusarium oxysporum  

Microsoft Academic Search

Fusarium oxysporum, the causal agent of vascular wilt disease, affects a wide range of plant species and can produce disseminated infections in humans. F. oxysporum f. sp. lycopersici isolate FGSC 9935 causes disease both on tomato plants and immunodepressed mice, making it an ideal model for the comparative analysis of fungal virulence on plant and animal hosts. Here we tested

Gesabel Y. Navarro-Velasco; Rafael C. Prados-Rosales; Almudena Ortíz-Urquiza; Enrique Quesada-Moraga; Antonio Di Pietro

35

Development of a Selective Medium for the Fungal Pathogen Fusarium graminearum Using Toxoflavin Produced by the Bacterial Pathogen Burkholderia glumae  

PubMed Central

The ascomycete fungus Fusarium graminearum is a major causal agent for Fusarium head blight in cereals and produces mycotoxins such as trichothecenes and zearalenone. Isolation of the fungal strains from air or cereals can be hampered by various other airborne fungal pathogens and saprophytic fungi. In this study, we developed a selective medium specific to F. graminearum using toxoflavin produced by the bacterial pathogen Burkholderia glumae. F. graminearum was resistant to toxoflavin, while other fungi were sensitive to this toxin. Supplementing toxoflavin into medium enhanced the isolation of F. graminearum from rice grains by suppressing the growth of saprophytic fungal species. In addition, a medium with or without toxoflavin exposed to wheat fields for 1 h had 84% or 25%, respectively, of colonies identified as F. graminearum. This selection medium provides an efficient tool for isolating F. graminearum, and can be adopted by research groups working on genetics and disease forecasting. PMID:25288974

Jung, Boknam; Lee, Sehee; Ha, Jiran; Park, Jong-Chul; Han, Sung-Sook; Hwang, Ingyu; Lee, Yin-Won; Lee, Jungkwan

2013-01-01

36

Development of a Selective Medium for the Fungal Pathogen Fusarium graminearum Using Toxoflavin Produced by the Bacterial Pathogen Burkholderia glumae.  

PubMed

The ascomycete fungus Fusarium graminearum is a major causal agent for Fusarium head blight in cereals and produces mycotoxins such as trichothecenes and zearalenone. Isolation of the fungal strains from air or cereals can be hampered by various other airborne fungal pathogens and saprophytic fungi. In this study, we developed a selective medium specific to F. graminearum using toxoflavin produced by the bacterial pathogen Burkholderia glumae. F. graminearum was resistant to toxoflavin, while other fungi were sensitive to this toxin. Supplementing toxoflavin into medium enhanced the isolation of F. graminearum from rice grains by suppressing the growth of saprophytic fungal species. In addition, a medium with or without toxoflavin exposed to wheat fields for 1 h had 84% or 25%, respectively, of colonies identified as F. graminearum. This selection medium provides an efficient tool for isolating F. graminearum, and can be adopted by research groups working on genetics and disease forecasting. PMID:25288974

Jung, Boknam; Lee, Sehee; Ha, Jiran; Park, Jong-Chul; Han, Sung-Sook; Hwang, Ingyu; Lee, Yin-Won; Lee, Jungkwan

2013-12-01

37

Fungal microbiota from rain water and pathogenicity of Fusarium species isolated from atmospheric dust and rainfall dust.  

PubMed

In order to determine the presence of Fusarium spp. in atmospheric dust and rainfall dust, samples were collected during September 2007, and July, August, and October 2008. The results reveal the prevalence of airborne Fusarium species coming from the atmosphere of the South East coast of Spain. Five different Fusarium species were isolated from the settling dust: Fusarium oxysporum, F. solani, F. equiseti, F. dimerum, and F. proliferatum. Moreover, rainwater samples were obtained during significant rainfall events in January and February 2009. Using the dilution-plate method, 12 fungal genera were identified from these rainwater samples. Specific analyses of the rainwater revealed the presence of three species of Fusarium: F. oxysporum, F. proliferatum and F. equiseti. A total of 57 isolates of Fusarium spp. obtained from both rainwater and atmospheric rainfall dust sampling were inoculated onto melon (Cucumis melo L.) cv. Pińonet and tomato (Lycopersicon esculentum Mill.) cv. San Pedro. These species were chosen because they are the main herbaceous crops in Almeria province. The results presented in this work indicate strongly that spores or propagules of Fusarium are able to cross the continental barrier carried by winds from the Sahara (Africa) to crop or coastal lands in Europe. Results show differences in the pathogenicity of the isolates tested. Both hosts showed root rot when inoculated with different species of Fusarium, although fresh weight measurements did not bring any information about the pathogenicity. The findings presented above are strong indications that long-distance transmission of Fusarium propagules may occur. Diseases caused by species of Fusarium are common in these areas. They were in the past, and are still today, a problem for greenhouses crops in Almería, and many species have been listed as pathogens on agricultural crops in this region. Saharan air masses dominate the Mediterranean regions. The evidence of long distance dispersal of Fusarium spp. by atmospheric dust and rainwater together with their proved pathogenicity must be taken into account in epidemiological studies. PMID:20820862

Palmero, D; Rodríguez, J M; de Cara, M; Camacho, F; Iglesias, C; Tello, J C

2011-01-01

38

The Genome Sequence of the Fungal Pathogen Fusarium virguliforme  

E-print Network

, and Agricultural Systems, Southern Illinois University, Carbondale, Illinois, United States of America, 4 revealed that F. virguliforme was closely related to the pea pathogen, Nectria haematococca. Of the 14

Bhattacharyya, Madan Kumar

39

Incidence of Fusarium wilt of cotton as affected by pathogen propagule type, age and source  

E-print Network

on pathogen population dynamics DISCUSSION AND SUMMARY LITERATURE CITED Page Vl VI I IX 20 20 28 30 37 37 44 48 58 67 TABLE OF CONTENTS (Continued) APPENDIX A Effect of drying on inoculum propagule populations Introduction Materials... the inoculum age experiment 45 46 49 50 10 Effect of inoculum drying and method of population determination on the apparent number of colony forming units (cfu) of two different formac specialis of Fusarium oxysporum 81 11 Comparison of V-8-juice agar...

McEntee, James Philip

2012-06-07

40

The rhizosphere microbial community in a multiple parallel mineralization system suppresses the pathogenic fungus Fusarium oxysporum  

PubMed Central

The rhizosphere microbial community in a hydroponics system with multiple parallel mineralization (MPM) can potentially suppress root-borne diseases. This study focused on revealing the biological nature of the suppression against Fusarium wilt disease, which is caused by the fungus Fusarium oxysporum, and describing the factors that may influence the fungal pathogen in the MPM system. We demonstrated that the rhizosphere microbiota that developed in the MPM system could suppress Fusarium wilt disease under in vitro and greenhouse conditions. The microbiological characteristics of the MPM system were able to control the population dynamics of F. oxysporum, but did not eradicate the fungal pathogen. The roles of the microbiological agents underlying the disease suppression and the magnitude of the disease suppression in the MPM system appear to depend on the microbial density. F. oxysporum that survived in the MPM system formed chlamydospores when exposed to the rhizosphere microbiota. These results suggest that the microbiota suppresses proliferation of F. oxysporum by controlling the pathogen's morphogenesis and by developing an ecosystem that permits coexistence with F. oxysporum. PMID:24311557

Fujiwara, Kazuki; Iida, Yuichiro; Iwai, Takashi; Aoyama, Chihiro; Inukai, Ryuya; Ando, Akinori; Ogawa, Jun; Ohnishi, Jun; Terami, Fumihiro; Takano, Masao; Shinohara, Makoto

2013-01-01

41

The Genome Sequence of the Fungal Pathogen Fusarium virguliforme That Causes Sudden Death Syndrome in Soybean  

PubMed Central

Fusarium virguliforme causes sudden death syndrome (SDS) of soybean, a disease of serious concern throughout most of the soybean producing regions of the world. Despite the global importance, little is known about the pathogenesis mechanisms of F. virguliforme. Thus, we applied Next-Generation DNA Sequencing to reveal the draft F. virguliforme genome sequence and identified putative pathogenicity genes to facilitate discovering the mechanisms used by the pathogen to cause this disease. Methodology/Principal Findings We have generated the draft genome sequence of F. virguliforme by conducting whole-genome shotgun sequencing on a 454 GS-FLX Titanium sequencer. Initially, single-end reads of a 400-bp shotgun library were assembled using the PCAP program. Paired end sequences from 3 and 20 Kb DNA fragments and approximately 100 Kb inserts of 1,400 BAC clones were used to generate the assembled genome. The assembled genome sequence was 51 Mb. The N50 scaffold number was 11 with an N50 Scaffold length of 1,263 Kb. The AUGUSTUS gene prediction program predicted 14,845 putative genes, which were annotated with Pfam and GO databases. Gene distributions were uniform in all but one of the major scaffolds. Phylogenic analyses revealed that F. virguliforme was closely related to the pea pathogen, Nectria haematococca. Of the 14,845 F. virguliforme genes, 11,043 were conserved among five Fusarium species: F. virguliforme, F. graminearum, F. verticillioides, F. oxysporum and N. haematococca; and 1,332 F. virguliforme-specific genes, which may include pathogenicity genes. Additionally, searches for candidate F. virguliforme pathogenicity genes using gene sequences of the pathogen-host interaction database identified 358 genes. Conclusions The F. virguliforme genome sequence and putative pathogenicity genes presented here will facilitate identification of pathogenicity mechanisms involved in SDS development. Together, these resources will expedite our efforts towards discovering pathogenicity mechanisms in F. virguliforme. This will ultimately lead to improvement of SDS resistance in soybean. PMID:24454689

Srivastava, Subodh K.; Huang, Xiaoqiu; Brar, Hargeet K.; Fakhoury, Ahmad M.; Bluhm, Burton H.; Bhattacharyya, Madan K.

2014-01-01

42

Molecular Inversion Probe: A New Tool for Highly Specific Detection of Plant Pathogens  

PubMed Central

Highly specific detection methods, capable of reliably identifying plant pathogens are crucial in plant disease management strategies to reduce losses in agriculture by preventing the spread of diseases. We describe a novel molecular inversion probe (MIP) assay that can be potentially developed into a robust multiplex platform to detect and identify plant pathogens. A MIP has been designed for the plant pathogenic fungus Fusarium oxysporum f.sp. conglutinans and the proof of concept for the efficiency of this technology is provided. We demonstrate that this methodology can detect as little as 2.5 ng of pathogen DNA and is highly specific, being able to accurately differentiate Fusarium oxysporum f.sp. conglutinans from other fungal pathogens such as Botrytis cinerea and even pathogens of the same species such as Fusarium oxysporum f.sp. lycopersici. The MIP assay was able to detect the presence of the pathogen in infected Arabidopsis thaliana plants as soon as the tissues contained minimal amounts of pathogen. MIP methods are intrinsically highly multiplexable and future development of specific MIPs could lead to the establishment of a diagnostic method that could potentially screen infected plants for hundreds of pathogens in a single assay. PMID:25343255

Trau, Matt; Botella, Jose R.

2014-01-01

43

Mycotoxins biosynthesized by plant-derived Fusarium isolates.  

PubMed

There is little information on secondary metabolites produced by Fusaria infecting crop plants other than cereals. Many members of Fusarium genus have the ability to colonise perennial crops with only scarce infection or disease symptoms or with no symptoms at all while still being detectable. Even in case of such asymptomatic infection, significant mycotoxin contamination of the plant tissues is possible. The aim of this study was to characterise the spectrum of Fusarium species isolates obtained from different plant hosts (like asparagus, garlic, pineapple, banana, rhubarb, peppers, rice, maize, wheat, and oncidium) and evaluate their ability to biosynthesize the most common mycotoxins in vitro. Among the F.proliferatum isolates, up to 57 % of them biosynthesized fumonisins at very high mass fractions, amounting to above 1000 ?g g(-1), while other Fusarium species such as F. verticillioides, F. lactis, F. polyphialydicum, F. concentricum, F. temperatum, and F. fujikuroi formed fumonisins mostly at much lower level. Only F. ananatum and F. oxysporum did not produce these toxins. Co-occurrence of FBs with other mycotoxins [moniliformin (MON) and beauvericin (BEA)] was often observed and it was mainly F. proliferatum species that formed both mycotoxins (0.4 ?g g(-1) to 41.1 ?g g(-1) BEA and 0.1 ?g g(-1) to 158.5 ?g g(-1) MON). PMID:23334038

Wa?kiewicz, Agnieszka; St?pie?, ?ukasz

2012-12-01

44

Occurrence of plant parasitic nematodes and non?pathogenic species of Fusarium in tomato plants in Kenya and their role as mutualistic synergists for biological control of root?knot nematodes  

Microsoft Academic Search

The occurrence of plant parasitic nematodes and endophytic fungi in tomato plants was determined from different regions in Kenya. In areas with regular cultivation of tomatoes, the population densities of all species of nematodes, regardless of trophic group, were high. Meloidogyne incognita was the predominant plant parasitic nematode in the regions investigated. Apparently endophytic fungi were frequently isolated from tomato

J. Hallmann; R. A. Sikora

1994-01-01

45

A Putative Transcription Factor pcs1 Positively Regulates Both Conidiation and Sexual Reproduction in the Cereal Pathogen Fusarium graminearum.  

PubMed

The plant pathogen Fusarium graminearum causes Fusarium head blight in cereal crops and produces mycotoxins that are harmful to animals and humans. For the initiation and spread of disease, asexual and sexual reproduction is required. Therefore, studies on fungal reproduction contribute to the development of new methods to control and maintain the fungal population. Screening a previously generated transcription factor mutant collection, we identified one putative C2H2 zinc-finger transcription factor, pcs1, which is required for both sexual and asexual reproduction. Deleting pcs1 in F. graminearum resulted in a dramatic reduction in conidial production and a complete loss of sexual reproduction. The pathways and gene ontology of pcs1-dependent genes from microarray experiments showed that several G-protein related pathways, oxidase activity, ribosome biogenesis, and RNA binding and processing were highly enriched, suggesting that pcs1 is involved in several different biological processes. Further, overexpression of pcs1 increased conidial production and resulted in earlier maturation of ascospores compared to the wild-type strain. Additionally, the vegetative growth of the overexpression mutants was decreased in nutrient-rich conditions but was not different from the wild-type strain in nutrient-poor conditions. Overall, we discovered that the pcs1 transcription factor positively regulates both conidiation and sexual reproduction and confers nutrient condition-dependent vegetative growth. PMID:25289009

Jung, Boknam; Park, Jungwook; Son, Hokyoung; Lee, Yin-Won; Seo, Young-Su; Lee, Jungkwan

2014-09-01

46

A Putative Transcription Factor pcs1 Positively Regulates Both Conidiation and Sexual Reproduction in the Cereal Pathogen Fusarium graminearum  

PubMed Central

The plant pathogen Fusarium graminearum causes Fusarium head blight in cereal crops and produces mycotoxins that are harmful to animals and humans. For the initiation and spread of disease, asexual and sexual reproduction is required. Therefore, studies on fungal reproduction contribute to the development of new methods to control and maintain the fungal population. Screening a previously generated transcription factor mutant collection, we identified one putative C2H2 zinc-finger transcription factor, pcs1, which is required for both sexual and asexual reproduction. Deleting pcs1 in F. graminearum resulted in a dramatic reduction in conidial production and a complete loss of sexual reproduction. The pathways and gene ontology of pcs1-dependent genes from microarray experiments showed that several G-protein related pathways, oxidase activity, ribosome biogenesis, and RNA binding and processing were highly enriched, suggesting that pcs1 is involved in several different biological processes. Further, overexpression of pcs1 increased conidial production and resulted in earlier maturation of ascospores compared to the wild-type strain. Additionally, the vegetative growth of the overexpression mutants was decreased in nutrient-rich conditions but was not different from the wild-type strain in nutrient-poor conditions. Overall, we discovered that the pcs1 transcription factor positively regulates both conidiation and sexual reproduction and confers nutrient condition-dependent vegetative growth. PMID:25289009

Jung, Boknam; Park, Jungwook; Son, Hokyoung; Lee, Yin-Won; Seo, Young-Su; Lee, Jungkwan

2014-01-01

47

A Genetic and Biochemical Approach to Study Trichothecene Diversity in Fusarium sporotrichioides and Fusarium graminearum  

Microsoft Academic Search

The trichothecenes T-2 toxin and deoxynivalenol (DON) are natural fungal products that are toxic to both animals and plants. Their importance in the pathogenicity of Fusarium spp. on crop plants has inspired efforts to understand the genetic and biochemical mechanisms leading to trichothecene synthesis. In order to better understand T-2 toxin biosynthesis by Fusarium sporotrichioides and DON biosynthesis by F.

Daren W. Brown; Susan P. McCormick; Nancy J. Alexander; Robert H. Proctor; Anne E. Desjardins

2001-01-01

48

Fusarium Wilt in Cotton - a New Record in Australia  

Microsoft Academic Search

In March 1993 Fusarium oxysporum was consistently isolated from the vascular system of wilted cotton plants from the Brookstead\\/Cecil Plains area of the Darling Downs (Queensland). Pathogenicity studies and re-isolation from the apical region of inoculated seedlings indicated that it was a true vascular wilt pathogen and confirmed that it was Fusarium oxysporum fsp, vasinfectum. This appears to be the

JK Kochman

1995-01-01

49

Cerebroside elicitor confers resistance to fusarium disease in various plant species.  

PubMed

ABSTRACT In the rice blast fungus pathosystem, cerebroside, a compound categorized as a sphingolipid, was found in our previous study to be a non-racespecific elicitor, which elicits defense responses in rice. Here we describe that cerebroside C is produced in diverse strains of Fusarium oxysporum, a common soilborne agent of wilt disease affecting a wide range of plant species. In addition, some type of cerebroside elicitor involving cerebroside A, B, or C was detected in other soilborne phytopathogens, such as Pythium and Botrytis. Treatment of lettuce (Lactuca sativa), tomato (Lycopersicon esculentum), melon (Cucumis melo), and sweet potato (Ipomoea batatas) with cerebroside B resulted in resistance to infection by each pathogenic strain of F. oxysporum. Induction of pathogenesis-related genes and H(2)O(2) production by treatment with cerebroside B were observed in tomato root tissues. The cerebroside elicitor showed no antifungal activity against F. oxysporum in vitro, indicating that the cerebroside elicitor activates defense mechanisms to confer resistance to Fusarium disease. These results suggest that cerebroside functions as a non-race-specific elicitor in a wide range of plant-phytopathogenic fungus interactions. Additionally, cerebroside elicitor serves as a potential biologically derived control agent. PMID:18943100

Umemura, Kenji; Tanino, Shigeki; Nagatsuka, Tadako; Koga, Jinichiro; Iwata, Michiaki; Nagashima, Kenji; Amemiya, Yoshimiki

2004-08-01

50

Constitutive expression of the xylanase inhibitor TAXI-III delays Fusarium head blight symptoms in durum wheat transgenic plants.  

PubMed

Cereals contain xylanase inhibitor (XI) proteins which inhibit microbial xylanases and are considered part of the defense mechanisms to counteract microbial pathogens. Nevertheless, in planta evidence for this role has not been reported yet. Therefore, we produced a number of transgenic plants constitutively overexpressing TAXI-III, a member of the TAXI type XI that is induced by pathogen infection. Results showed that TAXI-III endows the transgenic wheat with new inhibition capacities. We also showed that TAXI-III is correctly secreted into the apoplast and possesses the expected inhibition parameters against microbial xylanases. The new inhibition properties of the transgenic plants correlate with a significant delay of Fusarium head blight disease symptoms caused by Fusarium graminearum but do not significantly influence leaf spot symptoms caused by Bipolaris sorokiniana. We showed that this contrasting result can be due to the different capacity of TAXI-III to inhibit the xylanase activity of these two fungal pathogens. These results provide, for the first time, clear evidence in planta that XI are involved in plant defense against fungal pathogens and show the potential to manipulate TAXI-III accumulation to improve wheat resistance against F. graminearum. PMID:23945000

Moscetti, Ilaria; Tundo, Silvio; Janni, Michela; Sella, Luca; Gazzetti, Katia; Tauzin, Alexandra; Giardina, Thierry; Masci, Stefania; Favaron, Francesco; D'Ovidio, Renato

2013-12-01

51

Pythium oligandrum in the control of Fusarium rot on some bulbous plants.  

PubMed

Pythium oligandrum was applied as tulip bulbs or gladiolus corms soak prior or after inoculation with formae speciales Fusarium oxysporum. The mycoparasite used before inoculation with pathogen suppressed the development of Fusarium rot. This effect was not observed, however, when P. oligandrum was used 24 hr after bulb inoculation. Soaking of forced tulip bulbs in oospore suspension of P. oligandrum may reduce Fusarium rot spread and increase number of flowers, but at conc. 2.5 x 10(3)-10(4)/cm3 caused inhibition of tulip root growth. PMID:12425035

Skrzypczak, C

2001-01-01

52

The Plant Cell, Vol. 10, 371382, March 1998 1998 American Society of Plant Physiologists Ethylene Regulates the Susceptible Response to Pathogen  

E-print Network

) and fungal (Fusarium oxysporum f sp lycopersici) pathogens. Bacterial spot disease symptoms were also reduced, there are only a limited number of cases in which phytotoxins have been demonstrated to directly control dis, bacterial and fungal pathogens generally do not evolve enough ethylene to be necrogenic in plant tissues

Klee, Harry J.

53

Evidence for a reversible drought induced shift in the species composition of mycotoxin producing Fusarium head blight pathogens isolated from symptomatic wheat heads.  

PubMed

Fusarium species are fungal plant pathogens producing toxic secondary metabolites such as deoxynivalenol (DON), 15-acetyl-deoxynivalenol (15AcDON) and nivalenol (NIV). In Luxembourg, the Fusarium species composition isolated from symptomatic winter wheat heads was dominated by Fusarium graminearum sensu stricto strains (genetic 15AcDON chemotype) between the years 2009 and 2012, except for 2011, when Fusarium culmorum strains (genetic NIV chemotype) dominated the pathogen complex. Previous reports indicated that F. graminearum sensu stricto (genetic 15AcDON chemotype) was also most frequently isolated from randomly sampled winter wheat kernels including symptomatic as well as asymptomatic kernels in 2007 and 2008. The annual precipitation (average of 10 weather stations scattered across the country) decreased continuously from 924.31mm in 2007 over 917.15mm in 2008, to 843.38mm in 2009, 736.24mm in 2010, and 575.09mm in 2011. In 2012, the annual precipitation increased again to 854.70mm. Hardly any precipitation was recorded around the time of wheat anthesis in the years 2010 and 2011, whereas precipitation levels >50mm within the week preceding anthesis plus the week post anthesis were observed in the other years. The shift to genetic NIV chemotype F. culmorum strains in 2011 was accompanied by a very minor elevation of average NIV contents (2.9ngg(-1)) in the grain. Our data suggest that high NIV levels in Luxembourgish winter wheat are at present rather unlikely, because the indigenous F. culmorum strains with the genetic NIV chemotype seem to be outcompeted under humid in vivo conditions by F. graminearum DON producing strains on the one hand and seem to be inhibited - even though to a lower extent than DON producing strains - under dry in vivo conditions on the other hand. PMID:24859190

Beyer, Marco; Pogoda, Friederike; Pallez, Marine; Lazic, Joëlle; Hoffmann, Lucien; Pasquali, Matias

2014-07-16

54

Antibody-mediated prevention of Fusarium mycotoxins in the field.  

PubMed

Fusarium mycotoxins directly accumulated in grains during the infection of wheat and other cereal crops by Fusarium head blight (FHB) pathogens are detrimental to humans and domesticated animals. Prevention of the mycotoxins via the development of FHB-resistant varieties has been a challenge due to the scarcity of natural resistance against FHB pathogens. Various antibodies specific to Fusarium fungi and mycotoxins are widely used in immunoassays and antibody-mediated resistance in planta against Fusarium pathogens has been demonstrated. Antibodies fused to antifungal proteins have been shown to confer a very significantly enhanced Fusarium resistance in transgenic plants. Thus, antibody fusions hold great promise as an effective tool for the prevention of mycotoxin contaminations in cereal grains. This review highlights the utilization of protective antibodies derived from phage display to increase endogenous resistance of wheat to FHB pathogens and consequently to reduce mycotoxins in field. The role played by Fusarium-specific antibody in the resistance is also discussed. PMID:19325726

Hu, Zu-Quan; Li, He-Ping; Zhang, Jing-Bo; Glinka, Elena; Liao, Yu-Cai

2008-10-01

55

In silico comparison of transcript abundances during Arabidopsis thaliana and Glycine max resistance to Fusarium virguliforme  

Microsoft Academic Search

BACKGROUND: Sudden death syndrome (SDS) of soybean (Glycine max L. Merr.) is an economically important disease, caused by the semi-biotrophic fungus Fusarium solani f. sp. glycines, recently renamed Fusarium virguliforme (Fv). Due to the complexity and length of the soybean-Fusarium interaction, the molecular mechanisms underlying plant resistance and susceptibility to the pathogen are not fully understood. F. virguliforme has a

Jiazheng Yuan; Mengxia Zhu; David A Lightfoot; M Javed Iqbal; Jack Y Yang; Khalid Meksem

2008-01-01

56

Biological Efficacy of Streptomyces sp. Strain BN1 against the Cereal Head Blight Pathogen Fusarium graminearum  

PubMed Central

Fusarium head blight (FHB) caused by the filamentous fungus Fusarium graminearum is one of the most severe diseases threatening the production of small grains. Infected grains are often contaminated with mycotoxins such as zearalenone and trichothecences. During survey of contamination by FHB in rice grains, we found a bacterial isolate, designated as BN1, antagonistic to F. graminearum. The strain BN1 had branching vegetative hyphae and spores, and its aerial hyphae often had long, straight filaments bearing spores. The 16S rRNA gene of BN1 had 100% sequence identity with those found in several Streptomyces species. Phylogenetic analysis of ITS regions showed that BN1 grouped with S. sampsonii with 77% bootstrap value, suggesting that BN1 was not a known Streptomyces species. In addition, the efficacy of the BN1 strain against F. graminearum strains was tested both in vitro and in vivo. Wheat seedling length was significantly decreased by F. graminearum infection. However, this effect was mitigated when wheat seeds were treated with BN1 spore suspension prior to F. graminearum infection. BN1 also significantly decreased FHB severity when it was sprayed onto wheat heads, whereas BN1 was not effective when wheat heads were point inoculated. These results suggest that spraying of BN1 spores onto wheat heads during the wheat flowering season can be efficient for plant protection. Mechanistic studies on the antagonistic effect of BN1 against F. graminearum remain to be analyzed. PMID:25288928

Jung, Boknam; Park, Sook-Young; Lee, Yin-Won; Lee, Jungkwan

2013-01-01

57

Biological Efficacy of Streptomyces sp. Strain BN1 against the Cereal Head Blight Pathogen Fusarium graminearum.  

PubMed

Fusarium head blight (FHB) caused by the filamentous fungus Fusarium graminearum is one of the most severe diseases threatening the production of small grains. Infected grains are often contaminated with mycotoxins such as zearalenone and trichothecences. During survey of contamination by FHB in rice grains, we found a bacterial isolate, designated as BN1, antagonistic to F. graminearum. The strain BN1 had branching vegetative hyphae and spores, and its aerial hyphae often had long, straight filaments bearing spores. The 16S rRNA gene of BN1 had 100% sequence identity with those found in several Streptomyces species. Phylogenetic analysis of ITS regions showed that BN1 grouped with S. sampsonii with 77% bootstrap value, suggesting that BN1 was not a known Streptomyces species. In addition, the efficacy of the BN1 strain against F. graminearum strains was tested both in vitro and in vivo. Wheat seedling length was significantly decreased by F. graminearum infection. However, this effect was mitigated when wheat seeds were treated with BN1 spore suspension prior to F. graminearum infection. BN1 also significantly decreased FHB severity when it was sprayed onto wheat heads, whereas BN1 was not effective when wheat heads were point inoculated. These results suggest that spraying of BN1 spores onto wheat heads during the wheat flowering season can be efficient for plant protection. Mechanistic studies on the antagonistic effect of BN1 against F. graminearum remain to be analyzed. PMID:25288928

Jung, Boknam; Park, Sook-Young; Lee, Yin-Won; Lee, Jungkwan

2013-03-01

58

Soil suppressiveness to fusarium disease: shifts in root microbiome associated with reduction of pathogen root colonization.  

PubMed

Soil suppressiveness to Fusarium disease was induced by incubating sandy soil with debris of wild rocket (WR; Diplotaxis tenuifolia) under field conditions. We studied microbial dynamics in the roots of cucumber seedlings following transplantation into WR-amended or nonamended soil, as influenced by inoculation with Fusarium oxysporum f. sp. radicis-cucumerinum. Disease symptoms initiated in nonamended soil 6 days after inoculation, compared with 14 days in WR-amended soil. Root infection by F. oxysporum f. sp. radicis-cucumerinum was quantified using real-time polymerase chain reaction (PCR). Target numbers were similar 3 days after inoculation for both WR-amended and nonamended soils, and were significantly lower (66%) 6 days after inoculation and transplanting into the suppressive (WR-amended) soil. This decrease in root colonization was correlated with a reduction in disease (60%) 21 days after inoculation and transplanting into the suppressive soil. Fungal community composition on cucumber roots was assessed using mass sequencing of fungal internal transcribed spacer gene fragments. Sequences related to F. oxysporum, Fusarium sp. 14005, Chaetomium sp. 15003, and an unclassified Ascomycota composed 96% of the total fungal sequences in all samples. The relative abundances of these major groups were highly affected by root inoculation with F. oxysporum f. sp. radicis-cucumerinum, with a 10-fold increase in F. oxysporum sequences, but were not affected by the WR amendment. Quantitative analysis and mass-sequencing methods indicated a qualitative shift in the root's bacterial community composition in suppressive soil, rather than a change in bacterial numbers. A sharp reduction in the size and root dominance of the Massilia population in suppressive soil was accompanied by a significant increase in the relative abundance of specific populations; namely, Rhizobium, Bacillus, Paenibacillus, and Streptomyces spp. Composition of the Streptomyces community shifted significantly, as determined by PCR denaturing gradient gel electrophoresis, resulting in an increase in the dominance of a specific population in suppressive soils after only 3 days. This shift was related mainly to the increase in Streptomyces humidus, a group previously described as antagonistic to phytopathogenic fungi. Thus, suitable soil amendment resulted in a shift in the root's bacterial communities, and infection by a virulent pathogen was contained by the root microbiome, leading to a reduced disease rate. PMID:22950737

Klein, Eyal; Ofek, Maya; Katan, Jaacov; Minz, Dror; Gamliel, Abraham

2013-01-01

59

Inhibitory Effect of Algal Extracts on Mycelial Growth of the Tomato-Wilt Pathogen, Fusarium oxysporum f. sp. lycopersici  

PubMed Central

The present study was undertaken to explore the inhibitory effect of cyanobacterial extracts of Nostoc commune FA-103 against the tomato-wilt pathogen, Fusarium oxysporum f. sp. lycopersici. In an optimal medium, cell growth, antifungal activity, and antifungal compound production could be increased 2.7-fold, 4.1-fold, and 13.4-fold, respectively. A crude algal extract had a similar effect as mancozeb at the recommended dose, both in laboratory and pot tests. In vitro and in vivo fungal growth, spore sporulation and fungal infection of wilt pathogen in tomato seeds were significantly inhibited by cyanobacterial extracts. Nostoc commune FA-103 extracts have potential for the suppression of Fusarium oxysporum f. sp. lycopersici. PMID:23997634

Kim, Jiyoung

2008-01-01

60

Signal perception in plant pathogen defense  

Microsoft Academic Search

Highly sensitive and specific recognition systems for microbial pathogens are essential for disease resistance in plants. Structurally diverse elicitors from various pathogens have been identified and shown to trigger plant defense mechanisms. Elicitor recognition by the plant is assumed to be mediated by receptors. Plant receptors for fungus-derived elicitors appear to reside preferentially in the plasma membrane, whereas viral and

T. Nürnberger

1999-01-01

61

Xylella Genomics and Bacterial Pathogenicity to Plants  

PubMed Central

Xylella fastidiosa, a pathogen of citrus, is the first plant pathogenic bacterium for which the complete genome sequence has been published. Inspection of the sequence reveals high relatedness to many genes of other pathogens, notably Xanthomonas campestris. Based on this, we suggest that Xylella possesses certain easily testable properties that contribute to pathogenicity. We also present some general considerations for deriving information on pathogenicity from bacterial genomics. PMID:11119303

Dow, J. M.

2000-01-01

62

Pathogenicity of two species of Fusarium on some cultivars of bean in greenhouse.  

PubMed

Twenty isolates of Fusarium oxysporum and F. solani were isolated from the infected roots of bean in different farms of east Azarbaijan and Tehran Provinces and their pathogenicity determined. Most isolates of the fungi were identified as F. oxysporun. They caused root rot, yellowing and wilting of bean in the field. In this test, the roots of 6 cultivars of bean seedlings soaked in suspension of the 7 isolates of the fungi (a1, Gogan, a2, Bilverdi, a3, Savojbolagh-Hashtgerd, a4, field of Agr. Coll. a5, Khomein, a6, Ramjin of F. oxysporum and a7 of F. solani of Varamin, Iran) for 5 minute (106 spores/ml.) then transplanted into the sterilized soil in 4 pots (as replication). For control (a8) the roots soaked in distilled water. The results showed that percentage average of necrotic roots and crowns of isolates al, a2, a3, a5, a6, a7 was %20.31 in group a, a4 was %43.52 in group b and a8 was %2.77 in group c after 3 weeks. The isolate a4 (from the field of Agricultural College, Karaj) was more infectious than the other because it caused wilting, yellowing the leaves and decreased the growth very soon, followed by a5 with %25.32 rate was more pathogenic. Bean cultivar Goli-Red was more tolerant with %10.02 than the others of 16.29 (Naz Red) to 25.15 percent of necrotic the roots & stems. PMID:16637191

Faraji, M; Okhovvat, S M

2005-01-01

63

Genetic analysis of growth, morphology and pathogenicity in the F(1) progeny of an interspecific cross between Fusarium circinatum and Fusarium subglutinans.  

PubMed

Fusarium circinatum and Fusarium subglutinans are two distinct species in the Gibberella fujikuroi species complex. A genetic linkage map produced from an interspecific cross between these species was used to identify quantitative trait loci (QTLs) associated with variation in mycelial growth and morphology of colony margins (CMs) in the 94 F(1) progeny. Mycelial growth was assessed by measuring culture size at 25°C and 30°C, while CM morphology was characterized in the parents and assessed in their F(1) progeny. In order to test the pathogenicity of the progeny, Pinus patula seedlings were inoculated and lesion lengths were measured after 3weeks. Seven putative QTLs were associated with mycelial growth, three for growth at 25°C and four at 30°C. One highly significant QTL (P<0.001) was present at both growth temperatures. For CM morphology, a QTL was identified at the same position (P<0.001) as the QTL responsible for growth at the two temperatures. The putative QTLs accounted for 45 and 41% of the total mycelial growth variation at 25°C and 30°C, respectively, and for 21% of the variation in CM morphology. Only one of the 94 F(1) progeny was pathogenic on P. patula seedlings. This observation could be explained by the genetic constitution of this F(1) isolate, namely that ?96% of its genome originated from the F. circinatum parent. This F(1) individual also grew significantly faster at 25°C than the F. circinatum parent (P<0.05), as well as more rapidly than the average growth for the remaining 93 F(1) progeny (P<0.05). However, no association was found between mycelial growth and pathogenicity at 25°C. The highly significant QTL associated with growth at two temperatures, suggests that this is a principal genomic region involved in mycelial growth at both temperatures, and that the same region is also responsible for CM morphology. PMID:21872187

De Vos, Lieschen; van der Nest, Magriet A; van der Merwe, Nicolaas A; Myburg, Alexander A; Wingfield, Michael J; Wingfield, Brenda D

2011-09-01

64

Suppression of maize root diseases caused by Macrophomina phaseolina, Fusarium moniliforme and Fusarium graminearum by plant growth promoting rhizobacteria.  

PubMed

A plant growth-promoting isolate of a fluorescent Pseudomonas sp. EM85 and two bacilli isolates MR-11(2) and MRF, isolated from maize rhizosphere, were found strongly antagonistic to Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina, causal agents of foot rots and wilting, collar rots/stalk rots and root rots and wilting, and charcoal rots of maize, respectively. Pseudomonas sp. EM85 produced antifungal antibiotics (Afa+), siderophore (Sid+), HCN (HCN+) and fluorescent pigments (Flu+) besides exhibiting plant growth promoting traits like nitrogen fixation, phosphate solubilization, and production of organic acids and IAA. While MR-11(2) produced siderophore (Sid+), antibiotics (Afa+) and antifungal volatiles (Afv+), MRF exhibited the production of antifungal antibiotics (Afa+) and siderophores (Sid+). Bacillus spp. MRF was also found to produce organic acids and IAA, solubilized tri-calcium phosphate and fixed nitrogen from the atmosphere. All three isolates suppressed the diseases caused by Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina in vitro. A Tn5:: lacZ induced isogenic mutant of the fluorescent Pseudomonas EM85, M23, along with the two bacilli were evaluated for in situ disease suppression of maize. Results indicated that combined application of the two bacilli significantly (P = 0.05) reduced the Macrophomina-induced charcoal rots of maize by 56.04%. Treatments with the MRF isolate of Bacillus spp. and Tn5:: lacZ mutant (M23) of fluorescent Pseudomonas sp. EM85 significantly reduced collar rots, root and foot rots, and wilting of maize caused by Fusarium moniliforme and F. graminearum (P = 0.05) compared to all other treatments. All these isolates were found very efficient in colonizing the rhizotic zones of maize after inoculation. Evaluation of the population dynamics of the fluorescent Pseudomonas sp. EM85 using the Tn5:: lacZ marker and of the Bacillus spp. MRF and MR-11(2) using an antibiotic resistance marker revealed that all the three isolates could proliferate successfully in the rhizosphere, rhizoplane and endorhizosphere of maize, both at 30 and 60 days after seeding. Four antifungal compounds from fluorescent Pseudomonas sp. EM85, one from Bacillus sp. MR-11(2) and three from Bacillus sp. MRF were isolated, purified and tested in vitro and in thin layer chromatography bioassays. All these compounds inhibited R. solani, M. phaseolina, F. moniliforme, F. graminearum and F. solani strongly. Results indicated that antifungal antibiotics and/or fluorescent pigment of fluorescent Pseudomonas sp. EM85, and antifungal antibiotics of the bacilli along with the successful colonization of all the isolates might be involved in the biological suppression of the maize root diseases. PMID:11716210

Pal, K K; Tilak, K V; Saxena, A K; Dey, R; Singh, C S

2001-01-01

65

The prevalence and impact of Fusarium head blight pathogens and mycotoxins on malting barley quality in UK.  

PubMed

Fusarium head blight (FHB) caused by Fusarium and Microdochium species can significantly affect the yield of barley grain as well as the quality and safety of malt and beer. The present study provides new knowledge on the impacts of the FHB pathogen complex on the malting and brewing quality parameters of naturally infected barley. Quantitative real-time PCR and liquid chromatography double mass spectrometry were used to quantify the predominant FHB pathogens and Fusarium mycotoxins, respectively, in commercially grown UK malting barley samples collected between 2007 and 2011. The predominant Fusarium species identified across the years were F. poae, F. tricinctum and F. avenaceum. Microdochium majus was the predominant Microdochium species in 2007, 2008, 2010 and 2011 whilst Microdochium nivale predominated in 2009. Deoxynivalenol and zearalenone quantified in samples collected between 2007 and 2009 were associated with F. graminearum and F. culmorum, whilst HT-2 and T-2, and nivalenol in samples collected between 2010 and 2011 correlated positively with F. langsethiae and F. poae, respectively. Analysis of the regional distribution and yearly variation in samples from 2010 to 2011 showed significant differences in the composition of the FHB species complex. In most regions (Scotland, the South and North of England) the harvest in 2010 had higher concentrations of Fusarium spp. than in 2011, although no significant difference was observed in the Midlands between the two years. Microdochium DNA was significantly higher in 2011 and in the North of England and Scotland compared to the South or Midlands regions. Pathogens of the FHB complex impacted negatively on grain yield and quality parameters. Thousand grain weight of malting barley was affected significantly by M. nivale and M. majus whilst specific weight correlated negatively with F. avenaceum and F. graminearum. To determine the impact of sub-acute infections of the identified Fusarium and Microdochium species on malting and brewing quality of naturally infected samples, selected malting barley cultivars (Optic, Quench and Tipple) were micromalted and subjected to malt and wort analysis of key quality parameters. F. poae and M. nivale decreased germinative energy and increased water sensitivity of barley. The fungal biomass of F. poae and F. langsethiae correlated with increased wort free amino nitrogen and with decreased extract of malt. DNA of M. nivale correlated with increased malt friability as well as decreased wort filtration volume. The findings of this study indicate that the impact of species such as the newly emerging F. langsethiae, as well as F. poae and the two non-toxigenic Microdochium species should be considered when evaluating the quality of malting barley. PMID:24727381

Nielsen, L K; Cook, D J; Edwards, S G; Ray, R V

2014-06-01

66

The prevalence and impact of Fusarium head blight pathogens and mycotoxins on malting barley quality in UK  

PubMed Central

Fusarium head blight (FHB) caused by Fusarium and Microdochium species can significantly affect the yield of barley grain as well as the quality and safety of malt and beer. The present study provides new knowledge on the impacts of the FHB pathogen complex on the malting and brewing quality parameters of naturally infected barley. Quantitative real-time PCR and liquid chromatography double mass spectrometry were used to quantify the predominant FHB pathogens and Fusarium mycotoxins, respectively, in commercially grown UK malting barley samples collected between 2007 and 2011. The predominant Fusarium species identified across the years were F. poae, F. tricinctum and F. avenaceum. Microdochium majus was the predominant Microdochium species in 2007, 2008, 2010 and 2011 whilst Microdochium nivale predominated in 2009. Deoxynivalenol and zearalenone quantified in samples collected between 2007 and 2009 were associated with F. graminearum and F. culmorum, whilst HT-2 and T-2, and nivalenol in samples collected between 2010 and 2011 correlated positively with F. langsethiae and F. poae, respectively. Analysis of the regional distribution and yearly variation in samples from 2010 to 2011 showed significant differences in the composition of the FHB species complex. In most regions (Scotland, the South and North of England) the harvest in 2010 had higher concentrations of Fusarium spp. than in 2011, although no significant difference was observed in the Midlands between the two years. Microdochium DNA was significantly higher in 2011 and in the North of England and Scotland compared to the South or Midlands regions. Pathogens of the FHB complex impacted negatively on grain yield and quality parameters. Thousand grain weight of malting barley was affected significantly by M. nivale and M. majus whilst specific weight correlated negatively with F. avenaceum and F. graminearum. To determine the impact of sub-acute infections of the identified Fusarium and Microdochium species on malting and brewing quality of naturally infected samples, selected malting barley cultivars (Optic, Quench and Tipple) were micromalted and subjected to malt and wort analysis of key quality parameters. F. poae and M. nivale decreased germinative energy and increased water sensitivity of barley. The fungal biomass of F. poae and F. langsethiae correlated with increased wort free amino nitrogen and with decreased extract of malt. DNA of M. nivale correlated with increased malt friability as well as decreased wort filtration volume. The findings of this study indicate that the impact of species such as the newly emerging F. langsethiae, as well as F. poae and the two non-toxigenic Microdochium species should be considered when evaluating the quality of malting barley. PMID:24727381

Nielsen, L.K.; Cook, D.J.; Edwards, S.G.; Ray, R.V.

2014-01-01

67

Chemosensitization of Plant Pathogenic Fungi to Agricultural Fungicides  

PubMed Central

A common consequence of using agricultural fungicides is the development of resistance by fungal pathogens, which undermines reliability of fungicidal effectiveness. A potentially new strategy to aid in overcoming or minimizing this problem is enhancement of pathogen sensitivity to fungicides, or “chemosensitization.” Chemosensitization can be accomplished by combining a commercial fungicide with a certain non- or marginally fungicidal substance at levels where, alone, neither compound would be effective. Chemosensitization decreases the probability of the pathogen developing resistance, reduces the toxic impact on the environment by lowering effective dosage levels of toxic fungicides, and improves efficacy of antifungal agents. The present study shows that the antifungal activity of azole and strobilurin fungicides can be significantly enhanced through their co-application with certain natural or synthetic products against several economically important plant pathogenic fungi. Quadris (azoxystrobin) combined with thymol at a non-fungitoxic concentration produced much higher growth inhibition of Bipolaris sorokiniana, Phoma glomerata, Alternaria sp. and Stagonospora nodorum than the fungicide alone. The effect of Dividend (difenoconazole) applied with thymol significantly enhanced antifungal activity against B. sorokiniana and S. nodorum. Folicur (tebuconazole) combined with 4-hydroxybenzaldehyde (4-HBA), 2,3-dihydroxybenzaldehyde or thymol significantly inhibited growth of Alternaria alternata, at a much greater level than the fungicide alone. In addition, co-application of Folicur and 4-HBA resulted in a similar enhancement of antifungal activity against Fusarium culmorum. Lastly, we discovered that metabolites in the culture liquid of Fusarium sambucinum biocontrol isolate FS-94 also had chemosensitizing activity, increasing S. nodorum sensitivity to Folicur and Dividend. PMID:22408641

Dzhavakhiya, Vitaly; Shcherbakova, Larisa; Semina, Yulia; Zhemchuzhina, Natalia; Campbell, Bruce

2012-01-01

68

Chemosensitization of plant pathogenic fungi to agricultural fungicides.  

PubMed

A common consequence of using agricultural fungicides is the development of resistance by fungal pathogens, which undermines reliability of fungicidal effectiveness. A potentially new strategy to aid in overcoming or minimizing this problem is enhancement of pathogen sensitivity to fungicides, or "chemosensitization." Chemosensitization can be accomplished by combining a commercial fungicide with a certain non- or marginally fungicidal substance at levels where, alone, neither compound would be effective. Chemosensitization decreases the probability of the pathogen developing resistance, reduces the toxic impact on the environment by lowering effective dosage levels of toxic fungicides, and improves efficacy of antifungal agents. The present study shows that the antifungal activity of azole and strobilurin fungicides can be significantly enhanced through their co-application with certain natural or synthetic products against several economically important plant pathogenic fungi. Quadris (azoxystrobin) combined with thymol at a non-fungitoxic concentration produced much higher growth inhibition of Bipolaris sorokiniana, Phoma glomerata, Alternaria sp. and Stagonospora nodorum than the fungicide alone. The effect of Dividend (difenoconazole) applied with thymol significantly enhanced antifungal activity against B. sorokiniana and S. nodorum. Folicur (tebuconazole) combined with 4-hydroxybenzaldehyde (4-HBA), 2,3-dihydroxybenzaldehyde or thymol significantly inhibited growth of Alternaria alternata, at a much greater level than the fungicide alone. In addition, co-application of Folicur and 4-HBA resulted in a similar enhancement of antifungal activity against Fusarium culmorum. Lastly, we discovered that metabolites in the culture liquid of Fusarium sambucinum biocontrol isolate FS-94 also had chemosensitizing activity, increasing S. nodorum sensitivity to Folicur and Dividend. PMID:22408641

Dzhavakhiya, Vitaly; Shcherbakova, Larisa; Semina, Yulia; Zhemchuzhina, Natalia; Campbell, Bruce

2012-01-01

69

Epigenetic control of effectors in plant pathogens  

PubMed Central

Plant pathogens display impressive versatility in adapting to host immune systems. Pathogen effector proteins facilitate disease but can become avirulence (Avr) factors when the host acquires discrete recognition capabilities that trigger immunity. The mechanisms that lead to changes to pathogen Avr factors that enable escape from host immunity are diverse, and include epigenetic switches that allow for reuse or recycling of effectors. This perspective outlines possibilities of how epigenetic control of Avr effector gene expression may have arisen and persisted in filamentous plant pathogens, and how it presents special problems for diagnosis and detection of specific pathogen strains or pathotypes.

Gijzen, Mark; Ishmael, Chelsea; Shrestha, Sirjana D.

2014-01-01

70

A protein from the mold Aspergillus giganteus is a potent inhibitor of fungal plant pathogens.  

PubMed

A purified preparation of antifungal protein (AFP) from Aspergillus giganteus exhibited potent antifungal activity against the phytopathogenic fungi Magnaporthe grisea and Fusarium moniliforme, as well as the oomycete pathogen Phytophthora infestans. Under conditions of total inhibition of fungal growth, no toxicity of AFP toward rice protoplasts was observed. Additionally, application of AFP on rice plants completely inhibited M. grisea growth. These results are discussed in relation to the potential of the afp gene to enhance crop protection against fungal pathogens in transgenic plants. PMID:11763131

Vila, L; Lacadena, V; Fontanet, P; Martinez del Pozo, A; San Segundo, B

2001-11-01

71

Recent advances in genes involved in secondary metabolite synthesis, hyphal development, energy metabolism and pathogenicity in Fusarium graminearum (teleomorph Gibberella zeae).  

PubMed

The ascomycete fungus, Fusarium graminearum (teleomorph Gibberella zeae), is the most common causal agent of Fusarium head blight (FHB), a devastating disease for cereal crops worldwide. F. graminearum produces ascospores (sexual spores) and conidia (asexual spores), which can serve as disease inocula of FHB. Meanwhile, Fusarium-infected grains are often contaminated with mycotoxins such as trichothecenes (TRIs), fumonisins, and zearalenones, among which TRIs are related to the pathogenicity of F. graminearum, and these toxins are hazardous to humans and livestock. In recent years, with the complete genome sequencing of F. graminearum, an increasing number of functional genes involved in the production of secondary metabolites, hyphal differentiation, sexual and asexual reproduction, virulence and pathogenicity have been identified from F. graminearum. In this review, the secondary metabolite synthesis, hyphal development and pathogenicity related genes in F. graminearum were thoroughly summarized, and the genes associated with secondary metabolites, sexual reproduction, energy metabolism, and pathogenicity were highlighted. PMID:24389085

Geng, Zongyi; Zhu, Wei; Su, Hao; Zhao, Yong; Zhang, Ke-Qin; Yang, Jinkui

2014-01-01

72

MYT3, A Myb-Like Transcription Factor, Affects Fungal Development and Pathogenicity of Fusarium graminearum  

PubMed Central

We previously characterized members of the Myb protein family, MYT1 and MYT2, in Fusarium graminearum. MYT1 and MYT2 are involved in female fertility and perithecium size, respectively. To expand knowledge of Myb proteins in F. graminearum, in this study, we characterized the functions of the MYT3 gene, which encodes a putative Myb-like transcription factor containing two Myb DNA-binding domains and is conserved in the subphylum Pezizomycotina of Ascomycota. MYT3 proteins were localized in nuclei during most developmental stages, suggesting the role of MYT3 as a transcriptional regulator. Deletion of MYT3 resulted in impairment of conidiation, germination, and vegetative growth compared to the wild type, whereas complementation of MYT3 restored the wild-type phenotype. Additionally, the ?myt3 strain grew poorly on nitrogen-limited media; however, the mutant grew robustly on minimal media supplemented with ammonium. Moreover, expression level of nitrate reductase gene in the ?myt3 strain was decreased in comparison to the wild type and complemented strain. On flowering wheat heads, the ?myt3 strain exhibited reduced pathogenicity, which corresponded with significant reductions in trichothecene production and transcript levels of trichothecene biosynthetic genes. When the mutant was selfed, mated as a female, or mated as a male for sexual development, perithecia were not observed on the cultures, indicating that the ?myt3 strain lost both male and female fertility. Taken together, these results demonstrate that MYT3 is required for pathogenesis and sexual development in F. graminearum, and will provide a robust foundation to establish the regulatory networks for all Myb-like proteins in F. graminearum. PMID:24722578

Son, Hokyoung; Choi, Gyung Ja; Kim, Jin-Cheol; Lee, Yin-Won

2014-01-01

73

Induction of Systemic Resistance of Benzothiadiazole and Humic Acid in Soybean Plants Against Fusarium Wilt Disease  

PubMed Central

The ability of benzothiadiazole (BTH) and/or humic acid (HA) used as seed soaking to induce systemic resistance against a pathogenic strain of Fusarium oxysporum was examined in four soybean cultivars under greenhouse conditions. Alone and in combination the inducers were able to protect soybean plants against damping-off and wilt diseases compared with check treatment. These results were confirmed under field conditions in two different locations (Minia and New Valley governorates). The tested treatments significantly reduced damping-off and wilt diseases and increased growth parameters, except the number of branches per plant and also increased seed yield. Application of BTH (0.25 g/L) + HA (4 g/L) was the most potent in this respect. Soybean seed soaking in BTH + HA produced the highest activities of the testes of oxidative enzymes followed by BTH in the four soybean cultivars. HA treatment resulted in the lowest increases of these oxidative enzymes. Similar results were obtained with total phenol but HA increased total phenol more than did BTH in all tested cultivars. PMID:22783118

Ismail, Mamdoh Ewis; Morsy, Kadry Mohamed

2011-01-01

74

Effect of azoxystrobin on activities of antioxidant enzymes and alternative oxidase in wheat head blight pathogens Fusarium graminearum and Microdochium nivale  

Microsoft Academic Search

Wheat head blight pathogens Fusarium graminearum and Microdochium nivale have distinct sensitivities to strobilurin fungicides, which inhibit activity of complex III in the mitochondrial electron\\u000a transport chain. When mycelia were cultured in medium with the strobilurin fungicide azoxystrobin (AZ), F. graminearum increased its oxygen-consumption, but M. nivale, which is more sensitive than Fusarium species to strobilurins, did not. There was

Isao Kaneko; Hideo Ishii

2009-01-01

75

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

PubMed Central

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

Anderson, Marilyn A.

2014-01-01

76

Plant growth-promoting rhizobacteria strain Bacillus amyloliquefaciens NJN-6-enriched bio-organic fertilizer suppressed Fusarium wilt and promoted the growth of banana plants.  

PubMed

Bacillus amyloliquefaciens strain NJN-6 is an important plant growth-promoting rhizobacteria (PGPR) which can produce secondary metabolites antagonistic to several soil-borne pathogens. In this study, the ability of a bio-organic fertilizer (BIO) containing NJN-6 strain to promote the growth and suppress Fusarium wilt of banana plants was evaluated in a pot experiment. The results showed that the application of BIO significantly decreased the incidence of Fusarium wilt and promoted the growth of banana plants compared to that for the organic fertilizer (OF). To determine the beneficial mechanism of the strain, the colonization of NJN-6 strain on banana roots was evaluated using scanning electron microscopy (SEM). The plant growth-promoting hormones indole-3-acetic acid (IAA) and gibberellin A3 (GA3), along with antifungal lipopeptides iturin A, were detected when the NJN-6 strain was incubated in both Landy medium with additional l-tryptophan and in root exudates of banana plants. In addition, some antifungal volatile organic compounds and iturin A were also detected in BIO. In summary, strain NJN-6 could colonize the roots of banana plants after the application of BIO and produced active compounds which were beneficial for the growth of banana plants. PMID:23541032

Yuan, Jun; Ruan, Yunze; Wang, Beibei; Zhang, Jian; Waseem, Raza; Huang, Qiwei; Shen, Qirong

2013-04-24

77

Phytophthora parasitica: a model oomycete plant pathogen  

PubMed Central

Oomycetes are eukaryotic microorganisms morphologically similar to but phylogenetically distant from true fungi. Most species in the genus Phytophthora of oomycetes are devastating plant pathogens, causing damages to both agricultural production and natural ecosystems. Tremendous progress has been achieved in recent years in diversity, evolution and lifestyles of oomycete plant pathogens, as well as on the understanding of genetic and molecular basis of oomycete-plant interactions. Phytophthora parasitica is a soilborne pathogen with a wide range of host plants and represents most species in the genus Phytophthora. In this review, we present some recent progress of P. parasitica research by highlighting important features that make it emerge as a model species of oomycete pathogens. The emerged model pathogen will facilitate improved understanding of oomycete biology and pathology that are crucial to the development of novel disease-control strategies and improved disease-control measures. PMID:24999436

Meng, Yuling; Zhang, Qiang; Ding, Wei; Shan, Weixing

2014-01-01

78

The Interaction of Human Enteric Pathogens with Plants  

PubMed Central

There are an increasing number of outbreaks of human pathogens related to fresh produce. Thus, the growth of human pathogens on plants should be explored. Human pathogens can survive under the harsh environments in plants, and can adhere and actively invade plants. Plant-associated microbiota or insects contribute to the survival and transmission of enteric pathogens in plants. Human enteric pathogens also trigger plant innate immunity, but some pathogens–such as Salmonella–can overcome this defense mechanism.

Lim, Jeong-A; Lee, Dong Hwan; Heu, Sunggi

2014-01-01

79

The fusarium mycotoxin deoxynivalenol can inhibit plant apoptosis-like programmed cell death.  

PubMed

The Fusarium genus of fungi is responsible for commercially devastating crop diseases and the contamination of cereals with harmful mycotoxins. Fusarium mycotoxins aid infection, establishment, and spread of the fungus within the host plant. We investigated the effects of the Fusarium mycotoxin deoxynivalenol (DON) on the viability of Arabidopsis cells. Although it is known to trigger apoptosis in animal cells, DON treatment at low concentrations surprisingly did not kill these cells. On the contrary, we found that DON inhibited apoptosis-like programmed cell death (PCD) in Arabidopsis cells subjected to abiotic stress treatment in a manner independent of mitochondrial cytochrome c release. This suggested that Fusarium may utilise mycotoxins to suppress plant apoptosis-like PCD. To test this, we infected Arabidopsis cells with a wild type and a DON-minus mutant strain of F. graminearum and found that only the DON producing strain could inhibit death induced by heat treatment. These results indicate that mycotoxins may be capable of disarming plant apoptosis-like PCD and thereby suggest a novel way that some fungi can influence plant cell fate. PMID:23922734

Diamond, Mark; Reape, Theresa J; Rocha, Olga; Doyle, Siamsa M; Kacprzyk, Joanna; Doohan, Fiona M; McCabe, Paul F

2013-01-01

80

BIOTRANSFORMATION OF 2,4,6-TRINITROTOLUENE (TNT) BY A PLANT-ASSOCIATED FUNGUS FUSARIUM OXYSPORUM  

EPA Science Inventory

The capability of a plant-associated fungus, Fusarium oxyvorum, to transform TNT in liquid cultures was investigated. TNT was transformed into 2-amino-4, 6-dinitrotoluene (2-A-DNT), 4-amino-2, 6-dinitrotoluene (4-A- DNT), and 2, 4-diamino-6-nitrotoluene (2, 4-DAT) via 2- and 4-hy...

81

Isolating fungal pathogens from a dynamic disease outbreak in a native plant population to establish plant-pathogen bioassays for the ecological model plant Nicotiana attenuata.  

PubMed

The wild tobacco species Nicotiana attenuata has been intensively used as a model plant to study its interaction with insect herbivores and pollinators in nature, however very little is known about its native pathogen community. We describe a fungal disease outbreak in a native N. attenuata population comprising 873 plants growing in an area of about 1500 m2. The population was divided into 14 subpopulations and disease symptom development in the subpopulations was monitored for 16 days, revealing a waxing and waning of visible disease symptoms with some diseased plants recovering fully. Native fungal N. attenuata pathogens were isolated from diseased plants, characterized genetically, chemotaxonomically and morphologically, revealing several isolates of the ascomycete genera Fusarium and Alternaria, that differed in the type and strength of the disease symptoms they caused in bioassays on either detached leaves or intact soil-grown plants. These isolates and the bioassays will empower the study of N. attenuata-pathogen interactions in a realistic ecological context. PMID:25036191

Schuck, Stefan; Weinhold, Arne; Luu, Van Thi; Baldwin, Ian T

2014-01-01

82

Isolating Fungal Pathogens from a Dynamic Disease Outbreak in a Native Plant Population to Establish Plant-Pathogen Bioassays for the Ecological Model Plant Nicotiana attenuata  

PubMed Central

The wild tobacco species Nicotiana attenuata has been intensively used as a model plant to study its interaction with insect herbivores and pollinators in nature, however very little is known about its native pathogen community. We describe a fungal disease outbreak in a native N. attenuata population comprising 873 plants growing in an area of about 1500 m2. The population was divided into 14 subpopulations and disease symptom development in the subpopulations was monitored for 16 days, revealing a waxing and waning of visible disease symptoms with some diseased plants recovering fully. Native fungal N. attenuata pathogens were isolated from diseased plants, characterized genetically, chemotaxonomically and morphologically, revealing several isolates of the ascomycete genera Fusarium and Alternaria, that differed in the type and strength of the disease symptoms they caused in bioassays on either detached leaves or intact soil-grown plants. These isolates and the bioassays will empower the study of N. attenuata-pathogen interactions in a realistic ecological context. PMID:25036191

Schuck, Stefan; Baldwin, Ian T.

2014-01-01

83

Variation in Pathogenicity Associated with the Genetic Diversity of Fusarium graminearum  

Microsoft Academic Search

We screened 188 isolates of Fusarium graminearum, which originated from northwest Europe, the USA and Nepal, for genetic diversity using a sequence-characterised amplified region polymorphism (SCAR). On the basis of this analysis, 42 of the 118 isolates were selected for random amplified polymorphic DNA (RAPD) analysis. Three groups were identified, two of which, A and B, contained the isolates from

J. P. Carter; H. N. Rezanoor; D. Holden; A. E. Desjardins; R. D. Plattner; P. Nicholson

2002-01-01

84

Deciphering the Cryptic Genome: Genome-wide Analyses of the Rice Pathogen Fusarium fujikuroi Reveal Complex Regulation of Secondary Metabolism and Novel Metabolites  

PubMed Central

The fungus Fusarium fujikuroi causes “bakanae” disease of rice due to its ability to produce gibberellins (GAs), but it is also known for producing harmful mycotoxins. However, the genetic capacity for the whole arsenal of natural compounds and their role in the fungus' interaction with rice remained unknown. Here, we present a high-quality genome sequence of F. fujikuroi that was assembled into 12 scaffolds corresponding to the 12 chromosomes described for the fungus. We used the genome sequence along with ChIP-seq, transcriptome, proteome, and HPLC-FTMS-based metabolome analyses to identify the potential secondary metabolite biosynthetic gene clusters and to examine their regulation in response to nitrogen availability and plant signals. The results indicate that expression of most but not all gene clusters correlate with proteome and ChIP-seq data. Comparison of the F. fujikuroi genome to those of six other fusaria revealed that only a small number of gene clusters are conserved among these species, thus providing new insights into the divergence of secondary metabolism in the genus Fusarium. Noteworthy, GA biosynthetic genes are present in some related species, but GA biosynthesis is limited to F. fujikuroi, suggesting that this provides a selective advantage during infection of the preferred host plant rice. Among the genome sequences analyzed, one cluster that includes a polyketide synthase gene (PKS19) and another that includes a non-ribosomal peptide synthetase gene (NRPS31) are unique to F. fujikuroi. The metabolites derived from these clusters were identified by HPLC-FTMS-based analyses of engineered F. fujikuroi strains overexpressing cluster genes. In planta expression studies suggest a specific role for the PKS19-derived product during rice infection. Thus, our results indicate that combined comparative genomics and genome-wide experimental analyses identified novel genes and secondary metabolites that contribute to the evolutionary success of F. fujikuroi as a rice pathogen. PMID:23825955

Studt, Lena; Niehaus, Eva-Maria; Espino, Jose J.; Huss, Kathleen; Michielse, Caroline B.; Albermann, Sabine; Wagner, Dominik; Bergner, Sonja V.; Connolly, Lanelle R.; Fischer, Andreas; Reuter, Gunter; Kleigrewe, Karin; Bald, Till; Wingfield, Brenda D.; Ophir, Ron; Freeman, Stanley; Hippler, Michael; Smith, Kristina M.; Brown, Daren W.; Proctor, Robert H.; Munsterkotter, Martin; Freitag, Michael; Humpf, Hans-Ulrich; Guldener, Ulrich; Tudzynski, Bettina

2013-01-01

85

[Successful treatment of Fusarium-associated keratitis with multiresistant pathogen and multimorbid patient].  

PubMed

A 75-year-old man (not a contact lens wearer) presented with Fusarium-associated hypopyon keratitis. After several weeks of empirical and subsequently targeted antimycotic treatment, no considerable improvement was observed. However, after sclerokeratoplasty (11.2?×?11.2 mm) combined with prolonged antimycotic therapy a good local result with relapse-free long-term follow-up was achieved. PMID:23774966

Alnawaiseh, M; Böhm, M R R; Idelevich, E A; Becker, K; Grewe, S; Grenzebach, U H; Eter, N

2014-03-01

86

EPCOT, NASA and plant pathogens in space.  

PubMed

Cooperative work between NASA and Walt Disney World's EPCOT Land Pavilion is described. Joint efforts include research about allelopathy in multi-species plant cropping in CELSS, LEDs as light sources in hydroponic systems, and the growth of plant pathogens in space. PMID:11540338

White, R

1996-01-01

87

Histone Acetylation in Fungal Pathogens of Plants  

PubMed Central

Acetylation of histone lysine residues occurs in different organisms ranging from yeast to plants and mammals for the regulation of diverse cellular processes. With the identification of enzymes that create or reverse this modification, our understanding on histone acetylation has expanded at an amazing pace during the last two decades. In fungal pathogens of plants, however, the importance of such modification has only just begun to be appreciated in the recent years and there is a dearth of information on how histone acetylation is implicated in fungal pathogenesis. This review covers the current status of research related to histone acetylation in plant pathogenic fungi and considers relevant findings in the interaction between fungal pathogens and host plants. We first describe the families of histone acetyltransferases and deacetylases. Then we provide the cases where histone acetylation was investigated in the context of fungal pathogenesis. Finally, future directions and perspectives in epigenetics of fungal pathogenesis are discussed. PMID:25288980

Jeon, Junhyun; Kwon, Seomun; Lee, Yong-Hwan

2014-01-01

88

Antifungal activity and mechanism of palladium-modified nitrogen-doped titanium oxide photocatalyst on agricultural pathogenic fungi Fusarium graminearum.  

PubMed

Fusarium graminearum is the pathogen for Fusarium head blight (FHB) on wheat, which could significantly reduce grain quality/yield and produce a variety of mycotoxins posing a potential safety concern to human foods. As an environmentally friendly alternative to the commonly used chemical fugicides, a highly effective photocatalytic disinfection of F. graminearum macroconidia under visible light illumination was demonstrated on a visible-light-activated palladium-modified nitrogen-doped titanium oxide (TiON/PdO) nanoparticle photocatalyst. Because of the opposite surface charges of the TiON/PdO nanoparticles and the F. graminearum macroconidium, the nanoparticles were strongly adsorbed onto the macroconidium surface, which is beneficial to the photocatalytic disinfection of these macroconidia. The photocatalytic disinfection mechanism of TiON/PdO nanoparticles on these macroconidia could be attributed to their cell wall/membrane damage caused by the attack from reactive oxygen species (ROSs) as demonstrated by the fluorescence/phase contrast microscopy observations, while a breakage of their cell structure was not necessary for their loss of viability. PMID:24175751

Zhang, Jingtao; Liu, Yang; Li, Qi; Zhang, Xiaoping; Shang, Jian Ku

2013-11-13

89

Isolation and characterization of soil Streptomyces species as potential biological control agents against fungal plant pathogens.  

PubMed

The use of antagonist microorganisms against fungal plant pathogens is an attractive and ecologically alternative to the use of chemical pesticides. Streptomyces are beneficial soil bacteria and potential candidates for biocontrol agents. This study reports the isolation, characterization and antagonist activity of soil streptomycetes from the Los Petenes Biosphere Reserve, a Natural protected area in Campeche, Mexico. The results showed morphological, physiological and biochemical characterization of six actinomycetes and their inhibitory activity against Curvularia sp., Aspergillus niger, Helminthosporium sp. and Fusarium sp. One isolate, identified as Streptomyces sp. CACIS-1.16CA showed the potential to inhibit additional pathogens as Alternaria sp., Phytophthora capsici, Colletotrichum sp. and Rhizoctonia sp. with percentages ranging from 47 to 90 %. This study identified a streptomycete strain with a broad antagonist activity that could be used for biocontrol of plant pathogenic fungi. PMID:24310522

Evangelista-Martínez, Zahaed

2014-05-01

90

Vesicle Trafficking in Plant Pathogen Defence  

Microsoft Academic Search

\\u000a Recent progress in our understanding of plant mechanisms has revealed important roles of vesicle trafficking in the cellular\\u000a processes of pathogen defence. While most of the existing knowledge regarding the mechanistic details related to vesicle trafficking\\u000a originates from non-plant systems, it is evident that most of these processes are also conserved in plants. Meanwhile, we\\u000a are beginning to understand the

91

Plant Pathogen Forensics: Capabilities, Needs, and Recommendations  

PubMed Central

A biological attack on U.S. crops, rangelands, or forests could reduce yield and quality, erode consumer confidence, affect economic health and the environment, and possibly impact human nutrition and international relations. Preparedness for a crop bioterror event requires a strong national security plan that includes steps for microbial forensics and criminal attribution. However, U.S. crop producers, consultants, and agricultural scientists have traditionally focused primarily on strategies for prevention and management of diseases introduced naturally or unintentionally rather than on responding appropriately to an intentional pathogen introduction. We assess currently available information, technologies, and resources that were developed originally to ensure plant health but also could be utilized for postintroduction plant pathogen forensics. Recommendations for prioritization of efforts and resource expenditures needed to enhance our plant pathogen forensics capabilities are presented. PMID:16760310

Fletcher, J.; Bender, C.; Budowle, B.; Cobb, W. T.; Gold, S. E.; Ishimaru, C. A.; Luster, D.; Melcher, U.; Murch, R.; Scherm, H.; Seem, R. C.; Sherwood, J. L.; Sobral, B. W.; Tolin, S. A.

2006-01-01

92

Genome and Transcriptome Analysis of the Fungal Pathogen Fusarium oxysporum f. sp. cubense Causing Banana Vascular Wilt Disease  

PubMed Central

Background The asexual fungus Fusarium oxysporum f. sp. cubense (Foc) causing vascular wilt disease is one of the most devastating pathogens of banana (Musa spp.). To understand the molecular underpinning of pathogenicity in Foc, the genomes and transcriptomes of two Foc isolates were sequenced. Methodology/Principal Findings Genome analysis revealed that the genome structures of race 1 and race 4 isolates were highly syntenic with those of F. oxysporum f. sp. lycopersici strain Fol4287. A large number of putative virulence associated genes were identified in both Foc genomes, including genes putatively involved in root attachment, cell degradation, detoxification of toxin, transport, secondary metabolites biosynthesis and signal transductions. Importantly, relative to the Foc race 1 isolate (Foc1), the Foc race 4 isolate (Foc4) has evolved with some expanded gene families of transporters and transcription factors for transport of toxins and nutrients that may facilitate its ability to adapt to host environments and contribute to pathogenicity to banana. Transcriptome analysis disclosed a significant difference in transcriptional responses between Foc1 and Foc4 at 48 h post inoculation to the banana ‘Brazil’ in comparison with the vegetative growth stage. Of particular note, more virulence-associated genes were up regulated in Foc4 than in Foc1. Several signaling pathways like the mitogen-activated protein kinase Fmk1 mediated invasion growth pathway, the FGA1-mediated G protein signaling pathway and a pathogenicity associated two-component system were activated in Foc4 rather than in Foc1. Together, these differences in gene content and transcription response between Foc1 and Foc4 might account for variation in their virulence during infection of the banana variety ‘Brazil’. Conclusions/Significance Foc genome sequences will facilitate us to identify pathogenicity mechanism involved in the banana vascular wilt disease development. These will thus advance us develop effective methods for managing the banana vascular wilt disease, including improvement of disease resistance in banana. PMID:24743270

Zeng, Huicai; Fan, Dingding; Zhu, Yabin; Feng, Yue; Wang, Guofen; Peng, Chunfang; Jiang, Xuanting; Zhou, Dajie; Ni, Peixiang; Liang, Changcong; Liu, Lei; Wang, Jun; Mao, Chao

2014-01-01

93

Identification of Fusarium from a patient with fungemia after multiple organ injury.  

PubMed

Fusarium is a filamentous fungus widely distributed in nature, which is an important opportunistic pathogen and could cause fusariosis both in plants and animals. In human, Fusarium could cause local and disseminated infections both in immunocompetent and immunocompromised patients. We describe here a case of a male patient suffered from multiple organ injury, whose blood fungal culture was positive. The isolate was confirmed as "Fusarium solani" according to the morphology of the fungus and the results of phenotypic and molecular identification. PMID:23703243

Kang, Yuli; Li, Li; Zhu, Junhao; Zhao, Ying; Zhang, Qiangqiang

2013-08-01

94

Microbial populations responsible for specific soil suppressiveness to plant pathogens.  

PubMed

Agricultural soils suppressive to soilborne plant pathogens occur worldwide, and for several of these soils the biological basis of suppressiveness has been described. Two classical types of suppressiveness are known. General suppression owes its activity to the total microbial biomass in soil and is not transferable between soils. Specific suppression owes its activity to the effects of individual or select groups of microorganisms and is transferable. The microbial basis of specific suppression to four diseases, Fusarium wilts, potato scab, apple replant disease, and take-all, is discussed. One of the best-described examples occurs in take-all decline soils. In Washington State, take-all decline results from the buildup of fluorescent Pseudomonas spp. that produce the antifungal metabolite 2,4-diacetylphloroglucinol. Producers of this metabolite may have a broader role in disease-suppressive soils worldwide. By coupling molecular technologies with traditional approaches used in plant pathology and microbiology, it is possible to dissect the microbial composition and complex interactions in suppressive soils. PMID:12147763

Weller, David M; Raaijmakers, Jos M; Gardener, Brian B McSpadden; Thomashow, Linda S

2002-01-01

95

Interaction between Alternaria alternata or Fusarium equiseti and Glomus mosseae and its effects on plant growth  

Microsoft Academic Search

The effect of inoculation with the saprophytic fungi Alternaria alternata or Fusarium equiseti on maize (Zea mays) and lettuce (Lactuca sativa) with or without arbuscular mycorrhizal (AM) colonization by Glomus mosseae was studied in a greenhouse trial. Plant dry weights of non-AM-inoculated maize and lettuce were unaffected by the presence\\u000a of A. alternata and F. equiseti. In contrast, A. alternata

C. B. McAllister; J. M. Garcia-Garrido; I. Garcia-Romera; A. Godeas; J. A. Ocampo

1997-01-01

96

Systemic expression of defense response genes in wheat spikes as a response to Fusarium graminearum infection  

Microsoft Academic Search

Wheat spikes infected by Fusarium graminearum result in Fusarium head blight, a devastating disease of wheat. The spikes respond to infection by inducing a set of defense response genes in infected spikelets much as has been shown in other plant-pathogen interactions. To determine whether defense response genes are expressed systemically within F. graminearum -inoculated wheat spikes, we examined transcript accumulation

Clara Pritsch; Carroll P. Vance; William R. Bushnell; David A. Somers; Thomas M. Hohn; Gary J. Muehlbauer

2001-01-01

97

Icebergs and species in populations of Fusarium  

Microsoft Academic Search

(Accepted for publication August 2001 and published electronically 22 October 2001) ''Why is the name of the pathogen I work on changing?'' is a common question raised by plant pathologists. Species in the genus Fusarium (and the authors of this article) often are the target for such questions. Species descriptions, even very thorough ones, usually rely on a limited set

John F. Leslie; Kurt A. Zeller; Brett A. Summerell

2001-01-01

98

Comparative analysis of twelve Dothideomycete plant pathogens  

SciTech Connect

The Dothideomycetes are one of the largest and most diverse groups of fungi. Many are plant pathogens and pose a serious threat to agricultural crops grown for biofuel, food or feed. Most Dothideomycetes have only a single host and related Dothideomycete species can have very diverse host plants. Twelve Dothideomycete genomes have currently been sequenced by the Joint Genome Institute and other sequencing centers. They can be accessed via Mycocosm which has tools for comparative analysis

Ohm, Robin; Aerts, Andrea; Salamov, Asaf; Goodwin, Stephen B.; Grigoriev, Igor

2011-03-11

99

Resistance to Bacterial Pathogens in Plants  

E-print Network

(yellowing). For example, wilt-causing bacteria clog the vascular tissue, preventing movement of water-surface-based surveillance system that detects conserved pathogen molecules and (3) an intracellular surveillance system system, plants have to rely solely on their innate immune system to defend themselves against invading

Innes, Roger

100

Integrated management strategies for tomato Fusarium wilt.  

PubMed

Fusarium wilt is caused by the fungal pathogens, Fusarium oxysporum or Fusarium solani. It is a devastating disease that affects many important food and vegetable crops and a major source of loss to farmers worldwide. Initial strategies developed to combat this devastating plant disease include the use of cultural, physical and chemical control. None of these strategies have been able to give the best results of completely ameliorating the situation except for the cultural method which is mainly preventive. A good knowledge of the nature, behaviour and environmental conditions of growth of the disease agent is very important to controlling the disease development in that case. Biological control has been shown to be an environmentally friendly alternative. It makes use of rhizospheric and endophytic microorganisms that can survive and compete favourably well with the Fusarium wilt pathogen. They include plant growth-promoting rhizobacteria (PGPR) such as Bacillus spp. and Pseudomonas spp. For PGPR to control or inhibit the growth of the Fusarium wilt pathogen, they make use of mechanisms such as indole acetic acid production, siderophore production, phosphate solublilization, systemic resistance induction and antifungal volatile production among others. PMID:24077535

Ajilogba, Caroline F; Babalola, Olubukola O

2013-01-01

101

Paleogene Radiation of a Plant Pathogenic Mushroom  

PubMed Central

Background The global movement and speciation of fungal plant pathogens is important, especially because of the economic losses they cause and the ease with which they are able to spread across large areas. Understanding the biogeography and origin of these plant pathogens can provide insights regarding their dispersal and current day distribution. We tested the hypothesis of a Gondwanan origin of the plant pathogenic mushroom genus Armillaria and the currently accepted premise that vicariance accounts for the extant distribution of the species. Methods The phylogeny of a selection of Armillaria species was reconstructed based on Maximum Parsimony (MP), Maximum Likelihood (ML) and Bayesian Inference (BI). A timeline was then placed on the divergence of lineages using a Bayesian relaxed molecular clock approach. Results Phylogenetic analyses of sequenced data for three combined nuclear regions provided strong support for three major geographically defined clades: Holarctic, South American-Australasian and African. Molecular dating placed the initial radiation of the genus at 54 million years ago within the Early Paleogene, postdating the tectonic break-up of Gondwana. Conclusions The distribution of extant Armillaria species is the result of ancient long-distance dispersal rather than vicariance due to continental drift. As these finding are contrary to most prior vicariance hypotheses for fungi, our results highlight the important role of long-distance dispersal in the radiation of fungal pathogens from the Southern Hemisphere. PMID:22216099

Coetzee, Martin P. A.; Bloomer, Paulette; Wingfield, Michael J.; Wingfield, Brenda D.

2011-01-01

102

Plant-pathogen interactions and elevated CO2: morphological changes in favour of pathogens  

Microsoft Academic Search

Crop losses caused by pests and weeds have been estimated at 42% worldwide, with plant pathogens responsible for almost $10 billion worth of damage in the USA in 1994 alone. Elevated carbon dioxide (ECO2) and associated climate change have the potential to accelerate plant pathogen evolution, which may, in turn, affect virulence. Plant- pathogen interactions under increasing CO2 concentrations have

Janice Ann Lake; Ruth Nicola Wade

2009-01-01

103

Mating, conidiation and pathogenicity of Fusarium graminearum , the main causal agent of the headblight disease of wheat, are regulated by the MAP kinase gpmk1  

Microsoft Academic Search

To date, only very little is known about the molecular infection mechanisms of the head-blight pathogen of wheat, Fusarium graminearum (teleomorph Gibberella zeae). Here, we report on the isolation and characterization of the Fus3\\/Pmk1 mitogen-activated protein kinase homologue Gpmk1 from F. graminearum. Disruption of the gpmk1 gene in F. graminearum results in mutants that are reduced in conidial production, are

Nicole J. Jenczmionka; Frank J. Maier; Anke P. Lösch; Wilhelm Schäfer

2003-01-01

104

Fusarium graminearum Gene Deletion Mutants Map1 and tri5 Reveal Similarities and Differences in the Pathogenicity Requirements to Cause Disease on Arabidopsis and Wheat Floral Tissue  

Microsoft Academic Search

The Ascomycete pathogen Fusarium graminearum can infect all cereal species and lower grain yield, quality and safety. The fungus can also cause disease on Arabidopsis thaliana. In this study, the disease-causing ability of two F. graminearum mutants was analysed to further explore the parallels between the wheat (Triticum aestivum) and Arabidopsis floral pathosystems. Wild-type F graminearum (strain PH-1) and two

Alayne Cuzick; Martin Urban; Kim Hammond-Kosack

2008-01-01

105

Salicylic acid is a modulator of catalase isozymes in chickpea plants infected with Fusarium oxysporum f. sp. ciceri.  

PubMed

The relationship between salicylic acid level catalases isoforms chickpea cv. ICCV-10 infected with Fusarium oxysporum f. sp. ciceri was investigated. Pathogen-treated chickpea plants showed high levels of SA compared with the control. Two isoforms of catalases in shoot extract (CAT-IS and CAT-IIS) and single isoform in root extract (CAT-R) were detected in chickpea. CAT-IS and CAT-R activities were inhibited in respective extracts treated with pathogen whereas, CAT-IIS activity was not inhibited. These isoforms were purified and their kinetic properties studied in the presence or absence of SA. The molecular mass determined by SDS-PAGE of CAT-IS, CAT-IIS and CAT-R was found to be 97, 40 and 66 kDa respectively. Kinetic studies indicated that Km and V(max) of CAT-IS were 0.2 mM and 300 U/mg, 0.53 mM and 180 U/mg for CAT-IIS and 0.25 mM and 280 U/mg for CAT-R, respectively. CAT-IS and CAT-R were found to be more sensitive to SA and 50% of their activities were inhibited at 6 and 4 ?M respectively, whereas CAT-IIS was insensitive to SA up to 100 ?M. Quenching of the intrinsic tryptophan fluorescence of purified catalases were used to quantitate SA binding; the estimated K(d) value for CAT-IS, CAT-IIS and CAT-R found to be 2.3 ?M, 3.1 mM and 2.8 ?M respectively. SA is a modulator of catalase isozymes activity, supports its role in establishment of SAR in chickpea plants infected with the pathogen. PMID:22245913

Gayatridevi, S; Jayalakshmi, S K; Sreeramulu, K

2012-03-01

106

Fusarium Solani: A Causative Agent of Skin and Nail Infections  

PubMed Central

Fusarium spp are non-dermatophytic hyaline moulds found as saprophytes and plant pathogens. Human infections are probably a result of various precipitating predisposing factors of impaired immune status. Immunocompetent individuals of late are also vulnerable to various unassuming saprophytic and plant pathogens. To stress the need to identify correctly and institute appropriate antifungal therapy in newly emerging human fungal infectious agents. Repeated mycological sampling of the skin and nails of the suspected fungal infection were processed as per the standard format including direct microscopy and fungal culture on Sabouraud's dextrose agar. The fungus was isolated as Fusarium solani. Fusarium is an important plant pathogen and soil saprophyte. Infection is acquired by direct inoculation or inhalation of spores. It is associated with a variety of diseases like keratitis, onychomycosis, eumycetoma, skin lesions and disseminated diseases. PMID:22837572

Kuruvilla, Thomas S; Dias, Meena

2012-01-01

107

How soil-borne pathogens may affect plant competition  

Microsoft Academic Search

A role for pathogens in plant competition has often been suggested, but examples are rare and, in the case of soil pathogens, virtually absent. In this paper we examine if and how soil-borne pathogens may play a role in plant competition. As a model, two successional plant species from coastal sand dunes were used: Ammophila arenaria (marram grass) and Festuca

Wim H. Van der Putten; Bas A. M. Peters

1997-01-01

108

Inhibitory effects of essential oils of medicinal plants from growth of plant pathogenic fungi.  

PubMed

Plant cells produce a vast amount of secondary metabolites. Production of some compounds is restricted to a single species. Some compounds are nearly always found only in certain specific plant organs and during a specific developmental period of the plant. Some secondary metabolites of plants serve as defensive compounds against invading microorganisms. Nowadays, it is attempted to substitute the biological and natural agents with chemically synthesized fungicides. In the present research, the antifungal activities of essential oils of seven medicinal plants on mycelial growth of three soilborne plant pathogenic fungi were investigated. The plants consisted of Zataria multiflora, Thymus carmanicus, Mentha pieperata, Satureja hortensis, Lavandual officinolis, Cuminum cyminum and Azadirachta indica. The first five plants are from the family Labiatae. Examined fungi, Fusarium oxysporum f.sp. lycopersici, Fusarium solani and Rhizoctonia solani are the causal agents of tomato root rot. Essential oils of Z. multiflora, T. carmanicus, M. pieperata, S. hortensis and C. cyminum were extracted by hydro-distillation method. Essential oils of L. officinalis and A. indica were extracted by vapor-distillation method. A completely randomized design with five replicates was used to examine the inhibitory impact of each concentration (300, 600 and 900 ppm) of each essential oil. Poisoned food assay using potato dextrose agar (PDA) medium was employed. Results showed that essential oils of A. indica, Z. multiflora, T. carmanicus and S. hortensis in 900 ppm at 12 days post-inoculation, when the control fungi completely covered the plates, prevented about 90% from mycelial growth of each of the fungi. While, the essential oils of M. pieperata, C. cyminum and L. officinalis in the same concentration and time prevented 54.86, 52.77 and 48.84%, respectively, from F. solani growth. These substances did not prevent from F. oxysporum f.sp. lycopersici and R. solani growth. Minimum inhibitory concentration (MIC) of essential oils of T. carmanicus, Z. multiflora and A. indica from R. solani and F. solani growth was 900 and 600 ppm, respectively. In addition, the MIC of essential oils of these plants and essential oil of S. hortensis from F. oxysporum f.sp. lycopersici growth was 900 ppm. The MIC of essential oils of M. pieperata, C. cyminum and L. officinalis from F. solani growth was 900 ppm. PMID:22702190

Panjehkeh, N; Jahani Hossein-Abadi, Z

2011-01-01

109

Plant pathogens as biocontrol agents of Cirsium arvense an overestimated approach? 1 Plant pathogens as biocontrol agents of  

E-print Network

Plant pathogens as biocontrol agents of Cirsium arvense ­ an overestimated approach? 1 Plant pathogens as biocontrol agents of Cirsium arvense ­ an overestimated approach? Esther Müller1 , Wolfgang: Müller E, Nentwig W (2011) Plant pathogens as biocontrol agents of Cirsium arvense ­ an overestimated

Richner, Heinz

110

Genome Sequence of Fusarium oxysporum f. sp. melonis Strain NRRL 26406, a Fungus Causing Wilt Disease on Melon  

PubMed Central

Horizontal chromosome transfer introduces host-specific pathogenicity among members of the Fusarium oxysporum species complex and is responsible for some of the most destructive and intractable plant diseases. This paper reports the genome sequence of F. oxysporum f. sp. melonis (NRRL 26406), a causal agent of Fusarium wilt disease on melon. PMID:25081257

Shea, Terrance; Young, Sarah; Zeng, Qiandong; Kistler, H. Corby

2014-01-01

111

Genome Sequence of Fusarium oxysporum f. sp. melonis Strain NRRL 26406, a Fungus Causing Wilt Disease on Melon.  

PubMed

Horizontal chromosome transfer introduces host-specific pathogenicity among members of the Fusarium oxysporum species complex and is responsible for some of the most destructive and intractable plant diseases. This paper reports the genome sequence of F. oxysporum f. sp. melonis (NRRL 26406), a causal agent of Fusarium wilt disease on melon. PMID:25081257

Ma, Li-Jun; Shea, Terrance; Young, Sarah; Zeng, Qiandong; Kistler, H Corby

2014-01-01

112

Plant pathogen population dynamics in potato fields.  

PubMed

Modern technologies incorporating Geographic Information Systems (GIS), Global Positioning Systems (GPS), remote sensing, and geostatistics provide unique opportunities to advance ecological understanding of pests across a landscape. Increased knowledge of the population dynamics of plant pathogens will promote management strategies, such as site-specific management, and cultural practices minimizing the introduction and impact of plant pathogens. The population dynamics of Alternaria solani, Verticillium dahliae, and Pratylenchus penetrans were investigated in commercial potato fields. A 0.5-ha diamond grid-sampling scheme was georeferenced, and all disease ratings and nematode samples were taken at these grid points. Percent disease severity was rated weekly, and P. penetrans densities were quantified 4 weeks after potato emergence. Spatial statistics and interpolation methods were used to identify the spatial distribution and population dynamics of each pathogen. Interpolated maps and aerial imagery identified A. solani intra-season progression across the fields as the potato crop matured. Late-season nitrogen application reduced A. solani severity. The spatial distributions of V. dahliae and P. penetrans were spatially correlated. PMID:19265932

Morgan, G D; Stevenson, W R; Macguidwin, A E; Kelling, K A; Binning, L K; Zhu, J

2002-09-01

113

Field performance of maize grown from Fusarium verticillioides -inoculated seed  

Microsoft Academic Search

Fusarium verticillioides is an important fungus occupying dual roles in the maize plant. The fungus functions as an endophyte, a fungal\\/host interaction beneficial to the growth of some plants. At other times, the fungus may function as a mycotoxin producing pathogen. The advantages and\\/or disadvantages of the endophytic relationship must be established in order to target appropriate sites for controlling

I. E. Yates; N. W. Widstrom; C. W. Bacon; A. Glenn; D. M. Hinton; D. Sparks; A. J. Jaworski

2005-01-01

114

Insights into Auxin Signaling in Plant-Pathogen Interactions  

PubMed Central

The phytohormone auxin has been known to be a regulator of plant growth and development ever since its discovery. Recent studies on plant–pathogen interactions identify auxin as a key character in pathogenesis and plant defense. Like plants, diverse pathogens possess the capacity to synthesize indole-3-acetic acid (IAA), the major form of auxin in plants. The emerging knowledge on auxin-signaling components, auxin metabolic processes, and indole-derived phytoalexins in plant responses to pathogen invasion has provided putative mechanisms of IAA in plant susceptibility and resistance to non-gall- or tumor-inducing pathogens. PMID:22639609

Fu, Jing; Wang, Shiping

2011-01-01

115

Infection of corn ears by Fusarium spp. induces the emission of volatile sesquiterpenes.  

PubMed

Infection of corn (Zea mays L.) ears with fungal pathogens of the Fusarium genus might result in yield losses and in the accumulation of mycotoxins. The aim of this study was to investigate whether volatile profiles could be used to identify Fusarium-infected corn ears. The volatiles released by corn ears infected by Fusarium graminearum, Fusarium verticillioides, and Fusarium subglutinans were studied. Volatile emission was recorded at 24 days postinoculation (dpi) and in a time series (from 4 to 24 dpi). Twenty-two volatiles were differentially emitted from Fusarium-infected versus healthy corn ears. These included C6-C8 compounds and sesquiterpenoids. All volatiles indicative of Fusarium infection were detectable as early as 4-8 dpi and continued to be produced to the final sampling time (early milk maturity stage). The induced emission of ?-macrocarpene and ?-bisabolene correlated with an increased transcript accumulation of corn terpene synthase 6/11 (tps6/11). Additionally, the modification of volatile profiles after Fusarium infection was accompanied by the induction of plant defense compounds such as zealexins and oxylipins. Together, these results reveal a broad metabolic response of the plant to pathogen attack. Volatile biomarkers of Fusarium infection are promising indicators for the early detection of fungal infection before disease symptoms become visible. PMID:24816267

Becker, Eva-Maria; Herrfurth, Cornelia; Irmisch, Sandra; Köllner, Tobias G; Feussner, Ivo; Karlovsky, Petr; Splivallo, Richard

2014-06-01

116

Phenylpropanoid pathway is potentiated by silicon in the roots of banana plants during the infection process of Fusarium oxysporum f. sp. cubense.  

PubMed

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense, is a disease that causes large reductions in banana yield worldwide. Considering the importance of silicon (Si) to potentiate the resistance of several plant species to pathogen infection, this study aimed to investigate, at the histochemical level, whether this element could enhance the production of phenolics on the roots of banana plants in response to F. oxysporum f. sp. cubense infection. Plants of cultivar Maçă, which is susceptible to F. oxysporum f. sp. cubense, were grown in plastic pots amended with 0 (-Si) or 0.39 g of Si (+Si) per kilogram of soil and inoculated with race 1 of F. oxysporum f. sp. cubense. The root Si concentration was increased by 35.6% for +Si plants in comparison to the -Si plants, which contributed to a 27% reduction in the symptoms of Fusarium wilt on roots. There was an absence of fluorescence for the root sections of the -Si plants treated with the Neu and Wilson's reagents. By contrast, for the root sections obtained from the +Si plants treated with Neu's reagent, strong yellow-orange fluorescence was observed in the phloem, and lemon-yellow fluorescence was observed in the sclerenchyma and metaxylem vessels, indicating the presence of flavonoids. For the root sections of the +Si plants treated with Wilson's reagent, orange-yellowish autofluorescence was more pronounced around the phloem vessels, and yellow fluorescence was more pronounced around the metaxylem vessels, also indicating the presence of flavonoids. Lignin was more densely deposited in the cortex of the roots of the +Si plants than for the -Si plants. Dopamine was barely detected in the roots of the -Si plants after using the lactic and glyoxylic acid stain, but was strongly suspected to occur on the phloem and metaxylem vessels of the roots of the +Si plants as confirmed by the intense orange-yellow fluorescence. The present study provides new evidence of the pivotal role of the phenylpropanoid pathway in the resistance of banana plants to F. oxysporum f. sp. cubense infection when supplied with Si. PMID:24350769

Fortunato, Alessandro Antônio; da Silva, Washington Luís; Rodrigues, Fabrício Ávila

2014-06-01

117

Strangers in the matrix: plant cell walls and pathogen susceptibility  

E-print Network

. Vicente2 , John M. Labavitch1 , Alan B. Bennett1 and Ann L.T. Powell1 1 Department of Plant Sciences the wall, a pathogen potentially reveals itself to the plant and activates responses, setting off events current information about how plant and pathogen CWDPs modify the plant wall and affect its functions

Labavitch, John

118

Maize plants infestation by Fusarium spp. and deoxynivalenol in genetically modified corn hybrid and traditional maize cultivars.  

PubMed

The objective of the performed investigations was to isolate pathogenic fungi from contaminated maize cobs, to assess the appearance of maize cob fusariosis and to determine grain contamination with deoxynivalenol in the cultivation of genetically modified maize containing a gene resistance against European corn borer (Ostrinia nubilalis Hbn) as well as selected non-modified cultivars. The plant material comprised the following genetically modified maize cultivar: DKC 3421 YG (MON 810) and non-modified cultivars obtained from Smolice Plant Breeding Ltd., IHAR Group: Junak (FAO 210-220), Prosna (FAO 220), SMH (FAO 230), Baca (FAO 220). Prior to harvesting, the occurrence of maize cob fusariosis was determined in the 89 (BBCH) developmental ripening stage. Microbiological assessment was carried out on grains selected from cobs characterized by various pathological symptoms. In 2008, a total of 133 isolates was obtained from the examined samples of infected maize plants, of which 51 isolates were species-identified, while in 2009, the total of 123 isolates were determined, of which 63 were species-identified. In both experimental years, the majority of isolates contained fungi from the Fusarium genus. The performed analysis of mean levels of cob contamination by fusarioses revealed that DKC 3421 YG (MON 810) and SMH (FAO 230) cultivars showed the smallest levels of contamination as well as the lowest percent of cob contamination per plant, while Junak (FAO 210-220) and Baca (FAO 220) cultivars were characterized by the highest degree of contamination. The lowest deoxynivalenol concentrations were determined in years 2008 and 2009 in the case of the DKC 3421 YG (MON 810) cultivar, whereas Prosna (FAO 220) cultivar was characterized by the highest deoxynivalenol concentration. PMID:22390066

Selwet, Marek

2011-01-01

119

Comparative Genomics Yields Insights into Niche Adaptation of Plant Vascular Wilt Pathogens  

PubMed Central

The vascular wilt fungi Verticillium dahliae and V. albo-atrum infect over 200 plant species, causing billions of dollars in annual crop losses. The characteristic wilt symptoms are a result of colonization and proliferation of the pathogens in the xylem vessels, which undergo fluctuations in osmolarity. To gain insights into the mechanisms that confer the organisms' pathogenicity and enable them to proliferate in the unique ecological niche of the plant vascular system, we sequenced the genomes of V. dahliae and V. albo-atrum and compared them to each other, and to the genome of Fusarium oxysporum, another fungal wilt pathogen. Our analyses identified a set of proteins that are shared among all three wilt pathogens, and present in few other fungal species. One of these is a homolog of a bacterial glucosyltransferase that synthesizes virulence-related osmoregulated periplasmic glucans in bacteria. Pathogenicity tests of the corresponding V. dahliae glucosyltransferase gene deletion mutants indicate that the gene is required for full virulence in the Australian tobacco species Nicotiana benthamiana. Compared to other fungi, the two sequenced Verticillium genomes encode more pectin-degrading enzymes and other carbohydrate-active enzymes, suggesting an extraordinary capacity to degrade plant pectin barricades. The high level of synteny between the two Verticillium assemblies highlighted four flexible genomic islands in V. dahliae that are enriched for transposable elements, and contain duplicated genes and genes that are important in signaling/transcriptional regulation and iron/lipid metabolism. Coupled with an enhanced capacity to degrade plant materials, these genomic islands may contribute to the expanded genetic diversity and virulence of V. dahliae, the primary causal agent of Verticillium wilts. Significantly, our study reveals insights into the genetic mechanisms of niche adaptation of fungal wilt pathogens, advances our understanding of the evolution and development of their pathogenesis, and sheds light on potential avenues for the development of novel disease management strategies to combat destructive wilt diseases. PMID:21829347

Klosterman, Steven J.; Subbarao, Krishna V.; Kang, Seogchan; Veronese, Paola; Gold, Scott E.; Thomma, Bart P. H. J.; Chen, Zehua; Henrissat, Bernard; Lee, Yong-Hwan; Park, Jongsun; Garcia-Pedrajas, Maria D.; Barbara, Dez J.; Anchieta, Amy; de Jonge, Ronnie; Santhanam, Parthasarathy; Maruthachalam, Karunakaran; Atallah, Zahi; Amyotte, Stefan G.; Paz, Zahi; Inderbitzin, Patrik; Hayes, Ryan J.; Heiman, David I.; Young, Sarah; Zeng, Qiandong; Engels, Reinhard; Galagan, James; Cuomo, Christina A.; Dobinson, Katherine F.; Ma, Li-Jun

2011-01-01

120

The AMT1 Arginine Methyltransferase Gene Is Important for Plant Infection and Normal Hyphal Growth in Fusarium graminearum  

PubMed Central

Arginine methylation of non-histone proteins by protein arginine methyltransferase (PRMT) has been shown to be important for various biological processes from yeast to human. Although PRMT genes are well conserved in fungi, none of them have been functionally characterized in plant pathogenic ascomycetes. In this study, we identified and characterized all of the four predicted PRMT genes in Fusarium graminearum, the causal agent of Fusarium head blight of wheat and barley. Whereas deletion of the other three PRMT genes had no obvious phenotypes, the ?amt1 mutant had pleiotropic defects. AMT1 is a predicted type I PRMT gene that is orthologous to HMT1 in Saccharomyces cerevisiae. The ?amt1 mutant was slightly reduced in vegetative growth but normal in asexual and sexual reproduction. It had increased sensitivities to oxidative and membrane stresses. DON mycotoxin production and virulence on flowering wheat heads also were reduced in the ?amt1 mutant. The introduction of the wild-type AMT1 allele fully complemented the defects of the ?amt1 mutant and Amt1-GFP fusion proteins mainly localized to the nucleus. Hrp1 and Nab2 are two hnRNPs in yeast that are methylated by Hmt1 for nuclear export. In F. graminearum, AMT1 is required for the nuclear export of FgHrp1 but not FgNab2, indicating that yeast and F. graminearum differ in the methylation and nucleo-cytoplasmic transport of hnRNP components. Because AMT2 also is a predicted type I PRMT with limited homology to yeast HMT1, we generated the ?amt1 ?amt2 double mutants. The ?amt1 single and ?amt1 ?amt2 double mutants had similar defects in all the phenotypes assayed, including reduced vegetative growth and virulence. Overall, data from this systematic analysis of PRMT genes suggest that AMT1, like its ortholog in yeast, is the predominant PRMT gene in F. graminearum and plays a role in hyphal growth, stress responses, and plant infection. PMID:22693618

Hou, Rui; Zhou, Xiaoying; Li, Guotian; Zhang, Shijie; Xu, Jin-Rong

2012-01-01

121

Fusarium infection in maize: Volatile induction of infected and neighboring uninfected plants has the potential to attract a pest cereal leaf beetle, Oulema melanopus  

Microsoft Academic Search

Fusarium infection of maize leaves and\\/or roots through the soil can stimulate the emission of volatile organic compounds (VOCs). It is also well known that VOC emission from maize plants can repel or attract pests. In our experiments, we studied VOC induction responses of Zea mays L. ssp. mays cv. ‘Prosna’ having Fusarium infection (mix of four species) in leaves

Dariusz Piesik; Grzegorz Lem?czyk; Agata Skoczek; Robert Lamparski; Jan Bocianowski; Karol Kotwica; Kevin J. Delaney

2011-01-01

122

Stacking of antimicrobial genes in potato transgenic plants confers increased resistance to bacterial and fungal pathogens.  

PubMed

Solanum tuberosum plants were transformed with three genetic constructions expressing the Nicotiana tabacum AP24 osmotine, Phyllomedusa sauvagii dermaseptin and Gallus gallus lysozyme, and with a double-transgene construction expressing the AP24 and lysozyme sequences. Re-transformation of dermaseptin-transformed plants with the AP24/lysozyme construction allowed selection of plants simultaneously expressing the three transgenes. Potato lines expressing individual transgenes or double- and triple-transgene combinations were assayed for resistance to Erwinia carotovora using whole-plant and tuber infection assays. Resistance levels for both infection tests compared consistently for most potato lines and allowed selection of highly resistant phenotypes. Higher resistance levels were found in lines carrying the dermaseptin and lysozyme sequences, indicating that theses proteins are the major contributors to antibacterial activity. Similar results were obtained in tuber infection tests conducted with Streptomyces scabies. Plant lines showing the higher resistance to bacterial infections were challenged with Phytophthora infestans, Rhizoctonia solani and Fusarium solani. Considerable levels of resistance to each of these pathogens were evidenced employing semi-quantitative tests based in detached-leaf inoculation, fungal growth inhibition and in vitro plant inoculation. On the basis of these results, we propose that stacking of these transgenes is a promising approach to achieve resistance to both bacterial and fungal pathogens. PMID:22115953

Rivero, Mercedes; Furman, Nicolás; Mencacci, Nicolás; Picca, Pablo; Toum, Laila; Lentz, Ezequiel; Bravo-Almonacid, Fernando; Mentaberry, Alejandro

2012-01-20

123

Fot 1 insertions in the Fusarium oxysporum f. sp. albedinis genome provide diagnostic PCR targets for detection of the date palm pathogen.  

PubMed

Populations of Fusarium oxysporum f. sp. albedinis, the causal agent of Bayoud disease of date palm, are derivatives of a single clonal lineage and exhibit very similar Fot 1 hybridization patterns. In order to develop a sensitive diagnostic tool for F. oxysporum f. sp. albedinis detection, we isolated several DNA clones containing a copy of the transposable element Fot 1 from a genomic library of the date palm pathogen. Regions flanking the insertion sites were sequenced, and these sequences were used to design PCR primers that amplify the DNA regions at several Fot 1 insertion sites. When tested on a large sample of Fusarium isolates, including 286 F. oxysporum f. sp. albedinis isolates, 17 other special forms, nonpathogenic F. oxysporum isolates from palm grove soils, and 8 other Fusarium species, the primer pair TL3-FOA28 allowed amplification of a 400-bp fragment found only in F. oxysporum f. sp. albedinis. Sequence analysis showed that one of the Fot 1 copies was truncated, lacking 182 bp at its 3' terminus. The primer pair BI03-FOA1 amplified a 204-bp fragment which overlapped the Fot 1 truncated copy and its 3' site of insertion in the F. oxysporum f. sp. albedinis genome and identified 95% of the isolates. The primer pairs BIO3-FOA1 and TL3-FOA28 used in PCR assays thus provide a useful diagnostic tool for F. oxysporum f. sp. albedinis isolates. PMID:9464402

Fernandez, D; Ouinten, M; Tantaoui, A; Geiger, J P; Daboussi, M J; Langin, T

1998-02-01

124

Preliminary Identification and Typing of Pathogenic and Toxigenic Fusarium Species Using Restriction Digestion of ITS1-5.8S rDNA-ITS2 Region  

PubMed Central

Background: Fusarium species are capable of causing a wide range of crop plants infections as well as uncommon human infections. Many species of the genus produce mycotoxins, which are responsible for acute or chronic diseases in animals and humans. Identification of Fusaria to the species level is necessary for biological, epidemiological, pathological, and toxicological purposes. In this study, we undertook a computer-based analysis of ITS1-5.8SrDNA-ITS2 in 192 GenBank sequences from 36 Fusarium species to achieve data for establishing a molecular method for specie-specific identification. Methods: Sequence data and 610 restriction enzymes were analyzed for choosing RFLP profiles, and subsequently designed and validated a PCR-restriction enzyme system for identification and typing of species. DNA extracted from 32 reference strains of 16 species were amplified using ITS1 and ITS4 universal primers followed by sequencing and restriction enzyme digestion of PCR products. Results: The following 3 restriction enzymes TasI, ItaI and CfoI provide the best discriminatory power. Using ITS1 and ITS4 primers a product of approximately 550bp was observed for all Fusarium strains, as expected regarding the sequence analyses. After RFLP of the PCR products, some species were definitely identified by the method and some strains had different patterns in same species. Conclusion: Our profile has potential not only for identification of species, but also for genotyping of strains. On the other hand, some Fusarium species were 100% identical in their ITS-5.8SrDNA-ITS2 sequences, therefore differentiation of these species is impossible regarding this target alone. ITS-PCR-RFLP method might be useful for preliminary differentiation and typing of most common Fusarium species. PMID:23113036

Mirhendi, H; Ghiasian, A; Vismer, HF; Asgary, MR; Jalalizand, N; Arendrup, MC; Makimura, K

2010-01-01

125

Prospects of molecular markers in Fusarium species diversity.  

PubMed

Recent developments in genomics have opened up for newer opportunities to study the diversity and classification of fungi. The genus Fusarium contains many plant pathogens that attack diverse agricultural crops. Fusarium spp. are not only pathogenic to plants but are also known as toxin producers that negatively affect animal and human health. The identification of Fusarium species still remains one of the most critical issues in fungal taxonomy, given that the number of species recognized in the genus has been constantly changing in the last century due to the different taxonomic systems. This review focuses of various molecular-based techniques employed to study the diversity of Fusarium species causing diseases in major food crops. An introduction of fusarial diseases and their mycotoxins and molecular-marker-based methods for detection introduce the concept of marker application. Various well-known molecular techniques such as random amplified polymorphic DNA, amplification fragment length polymorphism, etc. to more modern ones such as DNA microarrays, DNA barcoding, and pyrosequencing and their application form the core of the review. Target regions in the genome which can be potential candidates for generation of probes and their use in phylogeny of Fusarium spp. are also presented. The concluding part emphasizes the value of molecular markers for assessing genetic variability and reveals that molecular tools are indispensable for providing information not only of one Fusarium species but on whole fungal community. This will be of extreme value for diagnosticians and researchers concerned with fungal biology, ecology, and genetics. PMID:21494869

Chandra, Nayaka S; Wulff, E G; Udayashankar, A C; Nandini, B P; Niranjana, S R; Mortensen, C N; Prakash, H S

2011-06-01

126

Fungal control of pathogenic fungi isolated from wild plants in Taif Governorate, Saudia Arabia.  

PubMed

Twenty two plants were collected from Taif Governorate and identified as: Euphorbia glomerifera, Juniperus procera, Launaea mucronata, Capparis dcidua, Punica granatum, Opuntia ficus, Prunus persica, Eucalyptus globulus, Medicago sativa, Artemisia monosperma, Trichodesma calathiforme, Artemisia judaica, Foeniculum vulgare, Phagnalon sinaicum, Rumex dentatus, Asphodelus aestives, Pulicaria crispa, Launae sonchoides, Forsskaolea tenacissima, Arnebia hispidissima, Avena spp and Aerva lanata. Pathogenic fungi were isolated from some of these plants and identified as Alternaria alternate, Ulocladium botrytis, Cladosporium spp, Cephalosporium spp, Penicillium chrysogenum, Fusarium oxysporum and Humicola grisea. Four antagonistic isolates were tested, 2 from Gliocladium fungus and 2 from Trichoderma fungus. We found that all the four antagonistic isolates (G. deliquescens, G. virens, T. viride and T. hamatum) significantly inhibited the radial growth of the pathogenic fungi tested, with different ratios. The results indicated that the antibiotics produced by the antagonists were more effective than the fungus itself and differ with different fungi. Coating plant stems with antagonists or with antagonist extracts reduce the severity of the disease but not prevent it in all tested pathogens. PMID:18928069

Abou-Zeid, A M; Altalhi, A D; Abd El-Fattah, R I

2007-01-01

127

An inordinate fondness for Fusarium: phylogenetic diversity of fusaria cultivated by ambrosia beetles in the genus Euwallacea on avocado and other plant hosts.  

PubMed

Ambrosia beetle fungiculture represents one of the most ecologically and evolutionarily successful symbioses, as evidenced by the 11 independent origins and 3500 species of ambrosia beetles. Here we document the evolution of a clade within Fusarium associated with ambrosia beetles in the genus Euwallacea (Coleoptera: Scolytinae). Ambrosia Fusarium Clade (AFC) symbionts are unusual in that some are plant pathogens that cause significant damage in naďve natural and cultivated ecosystems, and currently threaten avocado production in the United States, Israel and Australia. Most AFC fusaria produce unusual clavate macroconidia that serve as a putative food source for their insect mutualists. AFC symbionts were abundant in the heads of four Euwallacea spp., which suggests that they are transported within and from the natal gallery in mandibular mycangia. In a four-locus phylogenetic analysis, the AFC was resolved in a strongly supported monophyletic group within the previously described Clade 3 of the Fusarium solani species complex (FSSC). Divergence-time estimates place the origin of the AFC in the early Miocene ?21.2 Mya, which coincides with the hypothesized adaptive radiation of the Xyleborini. Two strongly supported clades within the AFC (Clades A and B) were identified that include nine species lineages associated with ambrosia beetles, eight with Euwallacea spp. and one reportedly with Xyleborus ferrugineus, and two lineages with no known beetle association. More derived lineages within the AFC showed fixation of the clavate (club-shaped) macroconidial trait, while basal lineages showed a mix of clavate and more typical fusiform macroconidia. AFC lineages consisted mostly of genetically identical individuals associated with specific insect hosts in defined geographic locations, with at least three interspecific hybridization events inferred based on discordant placement in individual gene genealogies and detection of recombinant loci. Overall, these data are consistent with a strong evolutionary trend toward obligate symbiosis coupled with secondary contact and interspecific hybridization. PMID:23608321

Kasson, Matthew T; O'Donnell, Kerry; Rooney, Alejandro P; Sink, Stacy; Ploetz, Randy C; Ploetz, Jill N; Konkol, Joshua L; Carrillo, Daniel; Freeman, Stanley; Mendel, Zvi; Smith, Jason A; Black, Adam W; Hulcr, Jiri; Bateman, Craig; Stefkova, Kristyna; Campbell, Paul R; Geering, Andrew D W; Dann, Elizabeth K; Eskalen, Akif; Mohotti, Keerthi; Short, Dylan P G; Aoki, Takayuki; Fenstermacher, Kristi A; Davis, Donald D; Geiser, David M

2013-07-01

128

Controlling Plant Pathogens with Bacterial/Fungal Antagonist Combinations.  

National Technical Information Service (NTIS)

Fungal/bacterial antagonist combinations, a seed coated with one of the combinations and a plant protected from plant pathogens by one of the combinations. The invention is also a fungal/bacterial antagonist combination comprising a Trichoderma virens fun...

T. D. Johnson

2004-01-01

129

Unravelling the Microbiome of Eggs of the Endangered Sea Turtle Eretmochelys imbricata Identifies Bacteria with Activity against the Emerging Pathogen Fusarium falciforme  

PubMed Central

Habitat bioaugmentation and introduction of protective microbiota have been proposed as potential conservation strategies to rescue endangered mammals and amphibians from emerging diseases. For both strategies, insight into the microbiomes of the endangered species and their habitats is essential. Here, we sampled nests of the endangered sea turtle species Eretmochelys imbricata that were infected with the fungal pathogen Fusarium falciforme. Metagenomic analysis of the bacterial communities associated with the shells of the sea turtle eggs revealed approximately 16,664 operational taxonomic units, with Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes as the most dominant phyla. Subsequent isolation of Actinobacteria from the eggshells led to the identification of several genera (Streptomyces, Amycolaptosis, Micromomospora Plantactinospora and Solwaraspora) that inhibit hyphal growth of the pathogen F. falciforme. These bacterial genera constitute a first set of microbial indicators to evaluate the potential role of microbiota in conservation of endangered sea turtle species. PMID:24743166

Sarmiento-Ramirez, Jullie M.; van der Voort, Menno; Raaijmakers, Jos M.; Dieguez-Uribeondo, Javier

2014-01-01

130

RESPONSE OF PLANT PATHOGENS AND HERBIVORES TO A WARMING EXPERIMENT  

Microsoft Academic Search

Pathogens and herbivores can severely reduce host fitness, potentially leading to altered succession rates and changes in plant community composition. Thus, to predict vegetation dynamics under climate change, it is necessary to understand how plant path- ogens and herbivores will respond. Pathogens and herbivores are predicted to increase under climate warming because the amount of time available for growth and

Bitty A. Roy; Sabine Güsewell; John Harte

2004-01-01

131

Insights into Cross-Kingdom Plant Pathogenic Bacteria  

PubMed Central

Plant and human pathogens have evolved disease factors to successfully exploit their respective hosts. Phytopathogens utilize specific determinants that help to breach reinforced cell walls and manipulate plant physiology to facilitate the disease process, while human pathogens use determinants for exploiting mammalian physiology and overcoming highly developed adaptive immune responses. Emerging research, however, has highlighted the ability of seemingly dedicated human pathogens to cause plant disease, and specialized plant pathogens to cause human disease. Such microbes represent interesting systems for studying the evolution of cross-kingdom pathogenicity, and the benefits and tradeoffs of exploiting multiple hosts with drastically different morphologies and physiologies. This review will explore cross-kingdom pathogenicity, where plants and humans are common hosts. We illustrate that while cross-kingdom pathogenicity appears to be maintained, the directionality of host association (plant to human, or human to plant) is difficult to determine. Cross-kingdom human pathogens, and their potential plant reservoirs, have important implications for the emergence of infectious diseases. PMID:24710301

Kirzinger, Morgan W.B.; Nadarasah, Geetanchaly; Stavrinides, John

2011-01-01

132

Emerging infectious diseases of plants: pathogen pollution, climate change  

E-print Network

Emerging infectious diseases of plants: pathogen pollution, climate change and agrotechnology, Boston, MA 02115, USA Emerging infectious diseases (EIDs) pose threats to conservation and public health for the surveillance and control of plant EIDs. Emerging infectious diseases (EIDs) are caused by pathogens that: (i

Schweik, Charles M.

133

448 PHYTOPATHOLOGY Population Genetics of Soilborne Fungal Plant Pathogens  

E-print Network

448 PHYTOPATHOLOGY Symposium Population Genetics of Soilborne Fungal Plant Pathogens The Population of populations of plant pathogens is needed to implement effective control strate- gies (48). Research on the genetic structure of fungal populations has mushroomed, and review papers that summarize these studies

McDonald, Bruce

134

Currency notes and coins as a possible source of transmitting fungal pathogens of man and plants.  

PubMed

Currency (notes and coins) handling by people during transaction is one of the most mobile objects within the community, which has a potential of transmitting pathogens. A survey carried out recently in Nanded city (Maharashtra) revealed heavy contamination of currency notes and coins by important fungal pathogens of plants and man, i.e. Aspergillus niger (60.37%), A. flavus (3.98%), A.nidulans (0.2%), Penicillium citrinum (17.80%), Alternaria tenuis (0.20%), Curvularia pallescens (0.20%), Cladosporium cladosporioides (10.69%), Rhizopus stolonifer (1.04%), an unidentified Aspergillus species .1 (0.20%) and another unidentified Aspergillus species.2 (3.14%), Fusarium sp. (0.20%), Trichoderma viride (0.20%),white sterile mycelium (0.62%) and brown sterile mycelium (0.62%). The study highlights the importance of preventing and controlling fungal contamination of currency notes and coins in public health and plant protection. Currency notes or coins are rarely suspected as infection sources and often not quarantined at airport or seaport terminal. Possible transmission of pathogens or "alien", invasive species through currency across borders or across countries needs to be taken into consideration especially under circumstances of serious outbreak of important disease or when there is a threat of biological warfare. PMID:23505834

Wanule, Dinesh; Jalander, Vaghmare; Gachande, B D; Sirsikar, A N

2011-10-01

135

Tandem mass spectrometry for the detection of plant pathogenic fungi and the effects of database composition on protein inferences  

PubMed Central

LC-MS/MS has demonstrated potential for detecting plant pathogens. Unlike PCR or ELISA, LC-MS/MS does not require pathogen-specific reagents for the detection of pathogen-specific proteins and peptides. However, the MS/MS approach we and others have explored does require a protein sequence reference database and database-search software to interpret tandem mass spectra. To evaluate the limitations of database composition on pathogen identification, we analyzed proteins from cultured Ustilago maydis, Phytophthora sojae, Fusarium graminearum, and Rhizoctonia solani by LC-MS/MS. When the search database did not contain sequences for a target pathogen, or contained sequences to related pathogens, target pathogen spectra were reliably matched to protein sequences from nontarget organisms, giving an illusion that proteins from nontarget organisms were identified. Our analysis demonstrates that when database-search software is used as part of the identification process, a paradox exists whereby additional sequences needed to detect a wide variety of possible organisms may lead to more cross-species protein matches and misidentification of pathogens. PMID:17922518

Padliya, Neerav D.; Garrett, Wesley M.; Campbell, Kimberly B.; Tabb, David L.; Cooper, Bret

2010-01-01

136

Comparative analysis and characterization of the soybean sudden death syndrome pathogen Fusarium virguliforme in the northern United States  

Microsoft Academic Search

Sudden death syndrome (SDS), caused by Fusarium virguliforme, has occurred in several US states and Ontario since 1985 but is a new problem in the northern states, including Minnesota. The characteristics and distribution of F. virguliforme and SDS in Minnesota and other northern soybean production areas were unknown. In 2006 and 2007, SDS was confirmed in 21 counties from the

D. K. Malvick; K. E. Bussey

2008-01-01

137

Plant immunity: towards an integrated view of plant–pathogen interactions  

Microsoft Academic Search

Plants are engaged in a continuous co-evolutionary struggle for dominance with their pathogens. The outcomes of these interactions are of particular importance to human activities, as they can have dramatic effects on agricultural systems. The recent convergence of molecular studies of plant immunity and pathogen infection strategies is revealing an integrated picture of the plant–pathogen interaction from the perspective of

Peter N. Dodds; John P. Rathjen

2010-01-01

138

504 Plant Disease / Vol. 98 No. 4 Monitoring the Long-Distance Transport of Fusarium graminearum  

E-print Network

of tobacco blue mold (4), Phakopsora pachyrhizi, causal agent of Asian soybean rust (4,21), and Puccinia graminis f. sp. tritici, causal agent of wheat stem rust (40). The atmospheric transport of plant pathogens followed a nonsusceptible host (soybeans). Reduced-till or no-till systems are expected to result

Ross, Shane

139

In vitro antifugal activity of medicinal plant extract against Fusarium oxysporum f. sp. lycopersici race 3 the causal agent of tomato wilt.  

PubMed

Medicinal plant extracts of five plants; Adhatoda vasica, Eucalyptus globulus, Lantana camara, Nerium oleander and Ocimum basilicum collected from Cairo, Egypt were evaluated against Fusarium oxysporum f. sp. lycopersici race 3 in vitro conditions using water and certain organic solvents. The results revealed that cold distilled water extracts of O. basilicum and E. globulus were the most effective ones for inhibiting the growth of F. oxysporum f. sp. lycopersici. Butanolic and ethanolic extracts of the tested plants inhibited the pathogen growth to a higher extent than water extracts. Butanolic extract of O. basilicum completely inhibited the growth of F. oxysporum f. sp. lycopersici at concentrations 1.5 and 2.0% (v/v). Butanolic extracts (2.0%) of tested plants had a strong inhibitory effect on hydrolytic enzymes; ?-glucosidase, pectin lyase and protease of F. oxysporum f. sp. lycopersici. This study has confirmed that the application of plant extracts, especially from O. basilicum for controlling F. oxysporum f. sp. lycopersici is environmentally safe, cost effective and does not disturb ecological balance. Investigations are in progress to test the efficacy of O. basilicum extract under in vivo conditions. PMID:24561899

Isaac, G S; Abu-Tahon, M A

2014-03-01

140

Antifungal activity of nettle (Urtica dioica L.), colocynth (Citrullus colocynthis L. Schrad), oleander (Nerium oleander L.) and konar (Ziziphus spina-christi L.) extracts on plants pathogenic fungi.  

PubMed

Anti-mycotic activity of the ethanol extracts from Nettle (Urtica dioica L.), Colocynth (Citrullus colocynthis L. Schrad), Konar (Ziziphus spina-christi L.) and Oleander (Nerium oleander L.) floral parts were screened in vitro against four important plant pathogenic fungi viz.; Alternaria alternate, Fusarium oxysporum, Fusarium solani and Rizoctonia solani using agar dilution bioassay. Extracts showed antifungal activity against all the tested fungi. Among the plants, Nettle and Colocynth were the most effective against A. alternate and R. solani while Oleander possesses the best inhibition on F. oxysporum and F. solani. Konar was the most effective extract by reducing the growth of Rizoctonia solani than other fungi. These results showed that extracts could be considered suitable alternatives to chemical additives for the control of fungal diseases in plants. PMID:19579919

Hadizadeh, I; Peivastegan, B; Kolahi, M

2009-01-01

141

Transposition of the miniature inverted-repeat transposable element mimp1 in the wheat pathogen Fusarium culmorum.  

PubMed

High-throughput methods are needed for functional genomics analysis in Fusarium culmorum, the cause of crown and foot rot on wheat and a type B trichothecene producer. Our aim was to develop and test the efficacy of a double-component system based on the ability of the impala transposase to transactivate the miniature inverted-repeat transposable element mimp1 of Fusarium oxysporum. We report, for the first time, the application of a tagging system based on a heterologous transposon and of splinkerette-polymerase chain reaction to identify mimp1 flanking regions in the filamentous fungus F.?culmorum. Similar to previous observations in Fusarium graminearum, mimp1 transposes in F.?culmorum by a cut-and-paste mechanism into TA dinucleotides, which are duplicated on insertion. mimp1 was reinserted in open reading frames in 16.4% (i.e. 10 of 61) of the strains analysed, probably spanning throughout the entire genome of F.?culmorum. The effectiveness of the mimp1/impala double-component system for gene tagging in F.?culmorum was confirmed phenotypically for a putative aurofusarin gene. This system also allowed the identification of two genes putatively involved in oxidative stress-coping capabilities in F.?culmorum, as well as a sequence specific to this fungus, thus suggesting the valuable exploratory role of this tool. PMID:22897438

Spanu, Francesca; Pasquali, Matias; Scherm, Barbara; Balmas, Virgilio; Marcello, Angela; Ortu, Giuseppe; Dufresne, Marie; Hoffmann, Lucien; Daboussi, Marie-Josée; Migheli, Quirico

2012-12-01

142

The cuticle and plant defense to pathogens  

PubMed Central

The cuticle provides a physical barrier against water loss and protects against irradiation, xenobiotics, and pathogens. Components of the cuticle are perceived by invading fungi and activate developmental processes during pathogenesis. In addition, cuticle alterations of various types induce a syndrome of reactions that often results in resistance to necrotrophs. This article reviews the current knowledge on the role of the cuticle in relation to the perception of pathogens and activation of defenses. PMID:24982666

Serrano, Mario; Coluccia, Fania; Torres, Martha; L'Haridon, Floriane; Metraux, Jean-Pierre

2014-01-01

143

Plant pathogens and integrated defence responses to infection  

Microsoft Academic Search

Plants cannot move to escape environmental challenges. Biotic stresses result from a battery of potential pathogens: fungi, bacteria, nematodes and insects intercept the photosynthate produced by plants, and viruses use replication machinery at the host's expense. Plants, in turn, have evolved sophisticated mechanisms to perceive such attacks, and to translate that perception into an adaptive response. Here, we review the

Jeffery L. Dangl; Jonathan D. G. Jones

2001-01-01

144

Silicon and plant disease resistance against pathogenic fungi  

Microsoft Academic Search

Silicon (Si) is a bioactive element associated with beneficial effects on mechanical and physiological properties of plants. Silicon alleviates abiotic and biotic stresses, and increases the resistance of plants to pathogenic fungi. Several studies have suggested that Si activates plant defense mechanisms, yet the exact nature of the interaction between the element and biochemical pathways leading to resistance remains unclear.

James G. Menzies; Richard R. Bélanger

2005-01-01

145

Pseudomonas syringae manipulates systemic plant defenses against pathogens and herbivores  

E-print Network

Pseudomonas syringae manipulates systemic plant defenses against pathogens and herbivores Jianping highlight the complexity of defense signaling interactions among plants, patho- gens, and herbivores, and physiological defenses. Because defenses can be costly for plants in the absence of enemies (1), selection often

Pierce, Naomi E.

146

Synergy between pathogen release and resource availability in plant invasion  

PubMed Central

Why do some exotic plant species become invasive? Two common hypotheses, increased resource availability and enemy release, may more effectively explain invasion if they favor the same species, and therefore act in concert. This would be expected if plant species adapted to high levels of available resources in their native range are particularly susceptible to enemies, and therefore benefit most from a paucity of enemies in their new range. We tested this possibility by examining how resource adaptations influence pathogen richness and release among 243 European plant species naturalized in the United States. Plant species adapted to higher resource availability hosted more pathogen species in their native range. Plants from mesic environments hosted more fungi than plants from xeric environments, and plants from nitrogen-rich environments hosted more viruses than plants from nitrogen-poor environments. Furthermore, plants classified as competitors hosted more than 4 times as many fungi and viruses as did stress tolerators. Patterns of enemy release mirrored those of pathogen richness: competitors and species from mesic and nitrogen-rich environments were released from many pathogen species, while stress tolerators and species from xeric and nitrogen-poor environments were released from relatively few pathogen species. These results suggest that enemy release contributes most to invasion by fast-growing species adapted to resource-rich environments. Consequently, enemy release and increases in resource availability may act synergistically to favor exotic over native species. PMID:19416888

Blumenthal, Dana; Mitchell, Charles E.; Pysek, Petr; Jarosik, Vojtech

2009-01-01

147

Efficacy of Various Fungal and Bacterial Biocontrol Organisms for Control of Fusarium Wilt of Tomato  

Microsoft Academic Search

Larkin, R. P., and Fravel, D. R. 1998. Effi cacy of various fungal and bacterial biocontrol organ- isms for control of Fusarium wilt of tomato. Plant Dis. 82: 1022-1028. Numerous fungi and bacteria, including existing biocontrol strains with known activity against soilborne fungal pathogens as well as isolates collected from the roots and rhizosphere of to- mato plants growing in

Robert P. Larkin; Deborah R. Fravel

1998-01-01

148

Method of identifying plant pathogen tolerance  

DOEpatents

A process for identifying a plant having disease tolerance comprising administering to a plant an inhibitory amount of ethylene and screening for ethylene insensitivity, thereby identifying a disease tolerant plant, is described. Plants identified by the foregoing process are also described.

Ecker, Joseph R. (Erial, NJ); Staskawicz, Brian J. (Castro Valley, CA); Bent, Andrew F. (Piedmont, CA); Innes, Roger W. (Bloomington, IN)

1997-10-07

149

The effect of elevated atmospheric CO{sub 2} on interactions between plant roots, arbuscular-mycorrhizal and pathogenic fungi  

SciTech Connect

Of all effects of elevated atmospheric CO{sub 2} on plants and ecosystems, the least is known about plant rhizosphere responses. Rhizosphere fungi are fed primarily by root-derived substrates, and fulfill functions such as immobilization, decomposition, pathogeneity, and improvement of plant nutrition. This study describes the effect of elevated CO{sub 2} on the interaction between the pathogen Fusarium solani and the AM fungus Glomus intraradices in the rhizosphere of Artemisia tridentata. We measured intraradical infection and extraradical growth by the two fungi under elevated and ambient CO{sub 2} concentrations. We found a strong interaction between the two fungi. Root infection by and extraradical hyphal length of solani did not differ significantly between CO{sub 2} treatments in the presence of G. intraradices. In the absence of G. intraradices, however, infection by F. solani and its extraradical hyphal length increased under elevated CO{sub 2}. Our results indicate that pathogenic fungi do respond to elevated CO{sub 2} by increased hyphal growth and root infection (potential response), but also show that mycorrhizal fungi can profit more from the new conditions and serve to suppress the pathogen.

Rillig, M.C.; Klironomos, J.N.; Allen, M.F. [San Diego State Univ., CA (United States)] [and others

1995-09-01

150

Sphingolipid C-9 Methyltransferases Are Important for Growth and Virulence but Not for Sensitivity to Antifungal Plant Defensins in Fusarium graminearum? †  

PubMed Central

The C-9-methylated glucosylceramides (GlcCers) are sphingolipids unique to fungi. They play important roles in fungal growth and pathogenesis, and they act as receptors for some antifungal plant defensins. We have identified two genes, FgMT1 and FgMT2, that each encode a putative sphingolipid C-9 methyltransferase (C-9-MT) in the fungal pathogen Fusarium graminearum and complement a Pichia pastoris C-9-MT-null mutant. The ?Fgmt1 mutant produced C-9-methylated GlcCer like the wild-type strain, PH-1, whereas the ?Fgmt2 mutant produced 65 to 75% nonmethylated and 25 to 35% methylated GlcCer. No ?Fgmt1?Fgmt2 double-knockout mutant producing only nonmethylated GlcCer could be recovered, suggesting that perhaps C-9-MTs are essential in this pathogen. This is in contrast to the nonessential nature of this enzyme in the unicellular fungus P. pastoris. The ?Fgmt2 mutant exhibited severe growth defects and produced abnormal conidia, while the ?Fgmt1 mutant grew like the wild-type strain, PH-1, under the conditions tested. The ?Fgmt2 mutant also exhibited drastically reduced disease symptoms in wheat and much-delayed disease symptoms in Arabidopsis thaliana. Surprisingly, the ?Fgmt2 mutant was less virulent on different host plants tested than the previously characterized ?Fggcs1 mutant, which lacks GlcCer synthase activity and produces no GlcCer at all. Moreover, the ?Fgmt1 and ?Fgmt2 mutants, as well as the P. pastoris strain in which the C-9-MT gene was deleted, retained sensitivity to the antifungal plant defensins MsDef1 and RsAFP2, indicating that the C-9 methyl group is not a critical structural feature of the GlcCer receptor required for the antifungal action of plant defensins. PMID:19028992

Ramamoorthy, Vellaisamy; Cahoon, Edgar B.; Thokala, Mercy; Kaur, Jagdeep; Li, Jia; Shah, Dilip M.

2009-01-01

151

Molecular battles between plant and pathogenic bacteria in the phyllosphere  

PubMed Central

The phyllosphere, i.e., the aerial parts of the plant, provides one of the most important niches for microbial colonization. This niche supports the survival and, often, proliferation of microbes such as fungi and bacteria with diverse lifestyles including epiphytes, saprophytes, and pathogens. Although most microbes may complete the life cycle on the leaf surface, pathogens must enter the leaf and multiply aggressively in the leaf interior. Natural surface openings, such as stomata, are important entry sites for bacteria. Stomata are known for their vital role in water transpiration and gas exchange between the plant and the environment that is essential for plant growth. Recent studies have shown that stomata can also play an active role in limiting bacterial invasion of both human and plant pathogenic bacteria as part of the plant innate immune system. As counter-defense, plant pathogens such as Pseudomonas syringae pv. tomato (Pst) DC3000 use the virulence factor coronatine to suppress stomata-based defense. A novel and crucial early battleground in host-pathogen interaction in the phyllosphere has been discovered with broad implications in the study of bacterial pathogenesis, host immunity, and molecular ecology of bacterial diseases. PMID:20602017

Baker, C.M.; Chitrakar, R.; Obulareddy, N.; Panchal, S.; Williams, P.; Melotto, M.

2011-01-01

152

The Adenylyl Cyclase Plays a Regulatory Role in the Morphogenetic Switch from Vegetative to Pathogenic Lifestyle of Fusarium graminearum on Wheat  

PubMed Central

Cyclic 3?,5?-adenosine monophosphate (cAMP) is a nucleotide derived from adenosine triphosphate that acts as a second messenger throughout all kingdoms. Intracellular cAMP levels are synthesized by a membrane-bound protein, the adenylyl cyclase. In order to analyze the function of this gene and the importance of cAMP in the life cycle of the cereal pathogen Fusarium graminearum, the adenylyl cyclase gene (FGSG_01234) was deleted by gene replacement (?Fgac1). The ?Fgac1 mutant displayed a drastically reduced growth on agar medium which could be rescued by a cAMP analogon. Furthermore, the ?Fgac1 mutant was unable to produce perithecia on detached wheat nodes. However, artificial conditions like carrot agar allowed perithecia development. Pathogenicity towards wheat was drastically reduced in ?Fgac1 compared to the wild type. Point-inoculated spikelets showed only small lesions but no typical head blight disease symptoms. Fluorescence microscopy using dsRed-expressing strains revealed that the ?Fgac1 strain was unable to develop any complex infection structures like lobate appressoria and infection cushions. Instead, hyphal anastomosis occurs frequently. Scanning electron microscopy demonstrated the lack of fungal penetration. Hence, the formation of compound appressoria seems to be essential for infection of wheat. Hyphae on flower leaves produced huge amounts of new conidia, thereby circumventing the infection cycle. This abundant sporulation on wheat epidermis was not observed in wild type. Intriguingly, the Fgac1 deletion mutant was able to infect maize cobs as wild type, indicating that cAMP signaling is not important for maize infection. The ?Fgac1 mutant was unable to produce the mycotoxin deoxynivalenol both in vitro and during wheat infection. In this study, we show that cAMP signaling controls important cellular processes such as development of infection structures, pathogenicity, secondary metabolite production and sexual reproduction. For the first time, we show that cAMP regulates the switch from vegetative to pathogenic lifestyle of F. graminearum on wheat. PMID:24603887

Bormann, Jorg; Boenisch, Marike Johanne; Bruckner, Elena; Firat, Demet; Schafer, Wilhelm

2014-01-01

153

How Do Filamentous Pathogens Deliver Effector Proteins into Plant Cells?  

PubMed Central

Fungal and oomycete plant parasites are among the most devastating pathogens of food crops. These microbes secrete effector proteins inside plant cells to manipulate host processes and facilitate colonization. How these effectors reach the host cytoplasm remains an unclear and debated area of plant research. In this article, we examine recent conflicting findings that have generated discussion in the field. We also highlight promising approaches based on studies of both parasite and host during infection. Ultimately, this knowledge may inform future broad spectrum strategies for protecting crops from such pathogens. PMID:24586116

Petre, Benjamin; Kamoun, Sophien

2014-01-01

154

Clonality, recombination, and hybridization in the plumbing-inhabiting human pathogen Fusarium keratoplasticum inferred from multilocus sequence typing  

PubMed Central

Background Recent work has shown that Fusarium species and genotypes most commonly associated with human infections, particularly of the cornea (mycotic keratitis), are the same as those most commonly isolated from plumbing systems. The species most dominant in plumbing biofilms is Fusarium keratoplasticum, a cosmopolitan fungus known almost exclusively from animal infections and biofilms. To better understand its diversity and population dynamics, we developed and utilized a nine-locus sequence-based typing system to make inferences about clonality, recombination, population structure, species boundaries and hybridization. Results High levels of genetic diversity and evidence for recombination and clonality were detected among 75 clinical and 156 environmental isolates of Fusarium keratoplasticum. The multilocus sequence typing system (MLST) resolved 111 unique nine-locus sequence types (STs). The single locus bifactorial determinants of mating compatibility (mating types MAT1-1 and MAT1-2), were found in a ratio of 70:30. All but one of the 49 isolates of the most common ST (FSSC 2d-2) came from human infections, mostly of the cornea, and from biofilms associated with contact lenses and plumbing surfaces. Significant levels of phylogenetic incongruence were found among loci. Putative clonal relationships among genotypes were estimated, showing a mixture of large clonal complexes and unrelated singletons. Discordance between the nuclear ribosomal rRNA and other gene genealogies is consistent with introgression of ribosomal RNA alleles of phylogenetic species FSSC 9 into F. keratoplasticum. No significant population subdivision based on clinical versus non-clinical sources was found. Conclusions Incongruent phylogenetic trees and the presence of both mating types within otherwise identical STs were observed, providing evidence for sexuality in F. keratoplasticum. Cryptic speciation suggested in a published three-locus MLST system was not supported with the addition of new loci, but evidence of introgression of ribosomal RNA genes from another strongly supported phylogenetic species (FSSC 9), also known from plumbing systems and human infections, was detected in two isolates. Overall, F. keratoplasticum is a diverse and geographically unstructured species with a mixed clonal and recombinant life history. PMID:24766947

2014-01-01

155

Ultrastructural and Cytochemical Aspects of the Interaction Between the Mycoparasite Pythium oligandrum and Soilborne Plant Pathogens.  

PubMed

ABSTRACT The interaction between the oomycete Pythium oligandrum and various soilborne oomycete and fungal plant pathogens (P. ultimum, P. aphanidermatum, Fusarium oxysporum f. sp. radicis-lycopersici, Verticillium albo-atrum, Rhizoctonia solani, and Phytophthora megasperma) was studied by light and electron microscopy in order to assess the relative contribution of mycoparasitism and antibiosis in the antagonistic process. Scanning electron microscope investigations of the interaction regions showed that structural alterations of all pathogenic fungi and oomycetes (except for Phytophthora megasperma) occurred soon after contact with the antagonist. Light and transmission electron microscope studies of the interaction region between the antagonist and P. ultimum revealed that intimate contact between both partners preceded a sequence of degradation events including aggregation of host cytoplasm and penetration of altered host hyphae. Localization of the host wall cellulose component showed that cellulose was altered at potential penetration sites. A similar scheme of events was observed during the interaction between P. oligandrum and F. oxysporum f. sp. radicis-lycopersici, with the exception that complete loss of host protoplasm was associated with antagonist invasion. The interaction between P. oligandrum and R. solani resulted in an abnormal deposition of a wall-like material at potential penetration sites for the antagonist. However, the antagonist displayed the ability to circumvent this barrier and penetrate host hyphae by locally altering the chitin component of the host hyphal wall. Interestingly, antagonist cells also showed extensive alteration as evidenced by the frequent occurrence of empty hyphal shells. In the case of Phytophthora megasperma, hyphal interactions did not occur, but hyphae of the plant pathogen were damaged severely. At least two distinct mechanisms appear to be involved in the process of oomycete and fungal attack by P. oligandrum: (i) mycoparasitism, mediated by intimate hyphal interactions, and (ii) antibiosis, with alteration of the host hyphae prior to contact with the antagonist. However, the possibility that the antagonistic process may rely on the dual action of antibiotics and hydrolytic enzymes is discussed. PMID:18944723

Benhamou, N; Rey, P; Picard, K; Tirilly, Y

1999-06-01

156

Brassinosteroid enhances resistance to fusarium diseases of barley.  

PubMed

Fusarium pathogens are among the most damaging pathogens of cereals. These pathogens have the ability to attack the roots, seedlings, and flowering heads of barley and wheat plants with disease, resulting in yield loss and head blight disease and also resulting in the contamination of grain with mycotoxins harmful to human and animal health. There is increasing evidence that brassinosteroid (BR) hormones play an important role in plant defense against both biotic and abiotic stress agents and this study set out to determine if and how BR might affect Fusarium diseases of barley. Application of the epibrassinolide (epiBL) to heads of 'Lux' barley reduced the severity of Fusarium head blight (FHB) caused by Fusarium culmorum by 86% and reduced the FHB-associated loss in grain weight by 33%. Growth of plants in soil amended with epiBL resulted in a 28 and 35% reduction in Fusarium seedling blight (FSB) symptoms on the Lux and 'Akashinriki' barley, respectively. Microarray analysis was used to determine whether growth in epiBL-amended soil changed the transcriptional profile in stem base tissue during the early stages of FSB development. At 24 and 48 h post F. culmorum inoculation, there were 146 epiBL-responsive transcripts, the majority being from the 48-h time point (n = 118). Real-time reverse-transcription polymerase chain reaction analysis validated the results for eight transcripts, including five defense genes. The results of gene expression studies show that chromatin remodeling, hormonal signaling, photosynthesis, and pathogenesis-related genes are activated in plants as a result of growth in epiBL. PMID:23777406

Ali, Shahin S; Kumar, G B Sunil; Khan, Mojibur; Doohan, Fiona M

2013-12-01

157

Pathogenic amoebae in power-plant cooling lakes. Final report  

SciTech Connect

Cooling waters and associated algae and sediments from four northern and four southern/western electric power plants were tested for the presence of pathogenic amoebae. Unheated control waters and algae/sediments from four northern and five southern/western sites were also tested. When comparing results from the test versus control sites, a significantly higher proportion (P less than or equal to 0.05) of the samples from the test sites were positive for thermophilic amoeba, thermophilic Naegleria and pathogenic Naegleria. The difference in number of samples positive for thermophilic Naegleria between heated and unheated waters, however, was attributable predominantly to the northern waters and algae/sediments. While two of four northern test sites yielded pathogenic Naegleria, seven of the eight isolates were obtained from one site. Seasonality effects relative to the isolation of the pathogen were also noted at this site. One pathogen was isolated from a southwestern test site. Pathogens were not isolated from any control sites. Some of the pathogenic isolates were analyzed serologically and classified as pathogenic Naegleria fowleri. Salinity, pH, conductivity, and bacteriological profiles did not obviously correlate with the presence or absence of pathogenic Naegleria. While thermal addition was significantly associated with the presence of thermophilic Naegleria (P less than or equal to 0.05), the data implicate other as yet undefined parameters associated with the presence of the pathogenic thermophile. Until further delineation of these parameters is effected, generalizations cannot be made concerning the effect of thermal impact on the growth of pathogenic amoeba in a particular cooling system.

Tyndall, R.L.; Willaert, E.; Stevens, A.R.

1981-06-01

158

Nucleic Acid Transport in Plant-Pathogen Interactions  

Microsoft Academic Search

\\u000a Transport of nucleic acid molecules is central to many plant-pathogen interactions. Nucleic acids are transported between\\u000a cells when plant viruses move their genomes from the infected into adjacent uninfected cells through plant intercellular connections,\\u000a the plasmodesmata. DNA and RNA molecules are also transported from the host cell cytoplasm into the nucleus during many viral\\u000a infections. In addition, nuclear import of

Robert Lartey; Vitaly Citovsky

159

Arabidopsis GOLDEN2-LIKE (GLK) transcription factors activate jasmonic acid (JA)-dependent disease susceptibility to the biotrophic pathogen Hyaloperonospora arabidopsidis, as well as JA-independent plant immunity against the necrotrophic pathogen Botrytis cinerea.  

PubMed

Arabidopsis thaliana GOLDEN2-LIKE (GLK1 and 2) transcription factors regulate chloroplast development in a redundant manner. Overexpression of AtGLK1 (35S:AtGLK1) in Arabidopsis also confers resistance to the cereal pathogen Fusarium graminearum. To further elucidate the role of GLK transcription factors in plant defence, the Arabidopsis glk1 glk2 double-mutant and 35S:AtGLK1 plants were challenged with the virulent oomycete pathogen Hyaloperonospora arabidopsidis (Hpa) Noco2. Compared with Col-0, glk1 glk2 plants were highly resistant to Hpa Noco2, whereas 35S:AtGLK1 plants showed enhanced susceptibility to this pathogen. Genetic studies suggested that AtGLK-mediated plant defence to Hpa Noco2 was partially dependent on salicylic acid (SA) accumulation, but independent of the SA signalling protein NONEXPRESSOR OF PATHOGENESIS-RELATED 1 (NPR1). Pretreatment with jasmonic acid (JA) dramatically reversed Hpa Noco2 resistance in the glk1 glk2 double mutant, but only marginally affected the 35S:AtGLK1 plants. In addition, overexpression of AtGLK1 in the JA signalling mutant coi1-16 did not increase susceptibility to Hpa Noco2. Together, our GLK gain-of-function and loss-of-function experiments suggest that GLK acts upstream of JA signalling in disease susceptibility to Hpa Noco2. In contrast, glk1 glk2 plants were more susceptible to the necrotrophic fungal pathogen Botrytis cinerea, whereas 35S:AtGLK1 plants exhibited heightened resistance which could be maintained in the absence of JA signalling. Together, the data reveal that AtGLK1 is involved in JA-dependent susceptibility to the biotrophic pathogen Hpa Noco2 and in JA-independent resistance to the necrotrophic pathogen B. cinerea. PMID:24393452

Murmu, Jhadeswar; Wilton, Michael; Allard, Ghislaine; Pandeya, Radhey; Desveaux, Darrell; Singh, Jas; Subramaniam, Rajagopal

2014-02-01

160

Involvement of Type IV Pili in Pathogenicity of Plant Pathogenic Bacteria  

PubMed Central

Type IV pili (T4P) are hair-like appendages found on the surface of a wide range of bacteria belonging to the ?-, ?-, and ?-Proteobacteria, Cyanobacteria and Firmicutes. They constitute an efficient device for a particular type of bacterial surface motility, named twitching, and are involved in several other bacterial activities and functions, including surface adherence, colonization, biofilm formation, genetic material uptake and virulence. Tens of genes are involved in T4P synthesis and regulation, with the majority of them being generally named pil/fim genes. Despite the multiple functionality of T4P and their well-established role in pathogenicity of animal pathogenic bacteria, relatively little attention has been given to the role of T4P in plant pathogenic bacteria. Only in recent years studies have begun to examine with more attention the relevance of these surface appendages for virulence of plant bacterial pathogens. The aim of this review is to summarize the current knowledge about T4P genetic machinery and its role in the interactions between phytopathogenic bacteria and their plant hosts. PMID:24710288

Burdman, Saul; Bahar, Ofir; Parker, Jennifer K.; De La Fuente, Leonardo

2011-01-01

161

Involvement of Type IV Pili in Pathogenicity of Plant Pathogenic Bacteria.  

PubMed

Type IV pili (T4P) are hair-like appendages found on the surface of a wide range of bacteria belonging to the ?-, ?-, and ?-Proteobacteria, Cyanobacteria and Firmicutes. They constitute an efficient device for a particular type of bacterial surface motility, named twitching, and are involved in several other bacterial activities and functions, including surface adherence, colonization, biofilm formation, genetic material uptake and virulence. Tens of genes are involved in T4P synthesis and regulation, with the majority of them being generally named pil/fim genes. Despite the multiple functionality of T4P and their well-established role in pathogenicity of animal pathogenic bacteria, relatively little attention has been given to the role of T4P in plant pathogenic bacteria. Only in recent years studies have begun to examine with more attention the relevance of these surface appendages for virulence of plant bacterial pathogens. The aim of this review is to summarize the current knowledge about T4P genetic machinery and its role in the interactions between phytopathogenic bacteria and their plant hosts. PMID:24710288

Burdman, Saul; Bahar, Ofir; Parker, Jennifer K; De La Fuente, Leonardo

2011-01-01

162

A Genetic Map of Gibberellafijikuroi Mating Population A (Fusarium moniliforme)  

Microsoft Academic Search

We constructed a recombination-based map of the fungal plant pathogen Gibberellafujikuroi mating population A (asexual stage Fusarium moniliforme). The map is based on the segregation of 142 restriction fragment length polymorphism (RFLP) markers, two auxotrophic genes (argl, nicl), mating type (matA+\\/matA-), female sterility (stel), spore-killer (Sk), and a gene governing the production of the mycotoxin fumonisin B1 (fuml) among 121

Jin-rong Xu; John F. Leslie

1996-01-01

163

Pseudomonas syringae manipulates systemic plant defenses against pathogens and herbivores  

Microsoft Academic Search

Many pathogens are virulent because they specifically interfere with host defense responses and therefore can proliferate. Here, we report that virulent strains of the bacterial phytopathogen Pseudomonas syringae induce systemic susceptibility to secondary P. syringae infection in the host plant Arabidopsis thaliana. This systemic induced susceptibility (SIS) is in direct contrast to the well studied avirulence\\/R gene-dependent resistance response known

Jianping Cui; Adam K. Bahrami; Elizabeth G. Pringle; Gustavo Hernandez-Guzman; Carol L. Bender; Naomi E. Pierce; Frederick M. Ausubel

2005-01-01

164

Subcutaneous infection caused by Corynespora cassiicola, a plant pathogen.  

PubMed

We describe a 69-year-old female farmer with diabetes mellitus who developed subcutaneous infection due to a plant pathogen, Corynespora cassiicola. The organism was identified based on characteristic morphotypes and confirmed by sequence analysis of the internal transcribed spacer (ITS) regions. The patient was treated successfully with amphotericin B therapy. PMID:19925826

Huang, Hong-Kai; Liu, Chun-Eng; Liou, Jia-Hung; Hsiue, Han-Chung; Hsiao, Cheng-Hsiang; Hsueh, Po-Ren

2010-02-01

165

The effectiveness of plant essential oils on the growth of Botrytis cinerea, Fusarium sp. and Clavibacter michiganensis subsp. michiganensis  

Microsoft Academic Search

Oregano, thyme, dictamnus, marjoram, lavender, rosemary, sage and pennyroyal essential oils were tested for their effectiveness against Botrytis cinerea, Fusarium sp. (Fusarium solani var. coeruleum), and Clavibacter michiganensis subsp. michiganensis on artificial growth media. The chemical composition of the oils was determined by gas chromatography-mass spectrometry (GC-MS). The growth of Botrytis cinerea, Fusarium sp. and Clavibacter michiganensis subsp. michiganensis was

Dimitra J Daferera; Basil N Ziogas; Moschos G Polissiou

2003-01-01

166

The role of MADS-box transcription factors in secondary metabolism and sexual development in the maize pathogen Fusarium verticillioides.  

PubMed

MADS-box transcription factors (TFs) regulate functionally diverse gene targets in eukaryotes. In select ascomycetes, MADS-box TFs have been shown to play a role in virulence, and vegetative and sexual development. Here, we characterized Fusarium verticillioides MADS-box TFs, Mads1 and Mads2, in terms of their roles in secondary metabolism and sexual mating. Sequence analyses showed that MADS1 and MADS2 encode TFs with a SRF-type dimerization domain and a MEF2-type dimerization domain, respectively. The MADS1 and MADS2 knockout mutants (Fmt1 and Fmt2 strains, respectively) exhibited decreased vegetative growth and FB1 production when compared to the wild-type. Fmt1 showed reduced expression of 14 polyketide synthase (PKS) genes present in the organism, whereas Fmt2 did not display a change in PKS gene expression. Significantly, the deletion of MADS1 and MADS2 in the MAT1-2 genotype (Fmt4 and Fmt5 strains, respectively) led to strains that failed to produce perithecia and ascospores when crossed with the MAT1-1 wild-type strain. Notably, deletion of either gene did not have an effect on the ability of the fungus to colonize maize stalk or kernels. FB1 production and PKS expression data suggest that Mads1 is a broad regulator of secondary metabolism in F. verticillioides, and may target regulons upstream of Mads2 to influence FB1 production. In addition, MADS-box TFs in F. verticillioides play a critical role in the perithecia development. PMID:23985144

Ortiz, Carlos S; Shim, Won-Bo

2013-11-01

167

Dermatitis and systemic mycosis in lined seahorses Hippocampus erectus associated with a marine-adapted Fusarium solani species complex pathogen.  

PubMed

During a 4 mo epizootic, 100% of 152 lined seahorses Hippocampus erectus in 3 separate groups died while in quarantine following shipment to a public aquarium. Twelve animals with skin depigmentation and ulceration were received by the Aquatic Pathology Service, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA, for diagnostic evaluation. Microscopically, lesions in 11 seahorses included multifocal epithelial necrosis and ulceration associated with 2 to 7 µm diameter, branching, septate fungal hyphae, typically accompanied by deeper infiltration into underlying skeletal muscle. Angioinvasion, with vascular thrombosis and tissue infarction, was a prominent feature in multiple animals. Fungal invasion of one or more internal organs was observed in 4 animals. Hyphae appeared to course freely through tissues and elicited little or no inflammatory response. Fusariosis has been reported sporadically in fish and other aquatic organisms, but identification has often been limited to the genus level based solely on morphologic features. Morphologic characteristics of the fungus isolated from this case were consistent with the Fusarium solani species complex (FSSC), which includes over 50 members that can only be identified definitively using DNA sequence data. A 3-locus typing scheme identified the isolate as a distinct species/haplotype, designated FSSC 12-a, belonging to a specific lineage that appears adapted to aquatic environments and disease in marine animals. Empirical treatment with itraconazole failed to stop mortalities, and subsequent in vitro antifungal susceptibility data explained a lack of clinical efficacy for this agent. Effective treatment in human medicine has similarly been limited by poor susceptibility to several classes of antifungal compounds. PMID:23047188

Salter, Caroline E; O'Donnell, Kerry; Sutton, Deanna A; Marancik, David P; Knowles, Susan; Clauss, Tonya M; Berliner, Aimee L; Camus, Alvin C

2012-10-10

168

Reviewmpp_804 614..629 Top 10 plant pathogenic bacteria in molecular plant pathology  

E-print Network

plant bacteriologists, if not all, feel that their particular microbe should appear in any listReviewmpp_804 614..629 Top 10 plant pathogenic bacteria in molecular plant pathology JOHN MANSFIELD, Laboratoire des Interactions Plantes-Microorganismes (LIPM), UMR 441-2594, F-31326 Castanet Tolosan, France 3

Citovsky, Vitaly

169

Clemson University Plant Problem Clinic, Nematode Assay Lab and Molecular Plant Pathogen Detection Lab  

E-print Network

PDIS, the database and reporting system used by the Plant Problem Clinic. Dr. Paula Agudelo and herClemson University Plant Problem Clinic, Nematode Assay Lab and Molecular Plant Pathogen Detection Lab Annual Report for 2012 The Plant Problem Clinic serves the people of South Carolina

Stuart, Steven J.

170

Apoplastic effectors secreted by two unrelated eukaryotic plant pathogens target the tomato defense protease Rcr3  

Microsoft Academic Search

Current models of plant-pathogen interactions stipulate that pathogens secrete effector proteins that disable plant defense components known as virulence targets. Occasionally, the perturbations caused by these effectors trigger innate immunity via plant disease resistance proteins as described by the ``guard hypothesis.'' This model is nicely illustrated by the interaction between the fungal plant pathogen Cladosporium fulvum and tomato. C. fulvum

Jing Song; Joe Win; Miaoying Tian; Sebastian Schornack; Farnusch Kaschani; Muhammad Ilyas; Sophien Kamoun

2009-01-01

171

Pathogen and biological contamination management in plant tissue culture: phytopathogens, vitro pathogens, and vitro pests.  

PubMed

The ability to establish and grow plant cell, organ, and tissue cultures has been widely exploited for basic and applied research, and for the commercial production of plants (micro-propagation). Regardless of whether the application is for research or commerce, it is essential that the cultures be established in vitro free of biological contamination and be maintained as aseptic cultures during manipulation, growth, and storage. The risks from microbial contamination are spurious experimental results due to the effects of latent contaminants or losses of valuable experimental or commercial cultures. Much of the emphasis in culture contamination management historically focussed on the elimination of phytopathogens and the maintenance of cultures free from laboratory contamination by environmental bacteria, fungi (collectively referred to as "vitro pathogens", i.e. pathogens or environmental micro-organisms which cause culture losses), and micro-arthropods ("vitro pests"). Microbial contamination of plant tissue cultures is due to the high nutrient availability in the almost universally used Murashige and Skoog (Physiol Plant 15:473-497, 1962) basal medium or variants of it. In recent years, it has been shown that many plants, especially perennials, are at least locally endophytically colonized intercellularly by bacteria. The latter, and intracellular pathogenic bacteria and viruses/viroids, may pass latently into culture and be spread horizontally and vertically in cultures. Growth of some potentially cultivable endophytes may be suppressed by the high salt and sugar content of the Murashige and Skoog basal medium and suboptimal temperatures for their growth in plant tissue growth rooms. The management of contamination in tissue culture involves three stages: disease screening (syn. disease indexing) of the stock plants with disease and endophyte elimination where detected; establishment and pathogen and contaminant screening of established initial cultures; observation, random sampling, and culture screening for micro-organism in multiplication and stored cultures. The increasing accessibility of both broad-spectrum and specific molecular diagnostics has resulted in advances in multiple pathogen and latent contaminant detection. The hazard analysis critical control point management strategy for tissue culture laboratories is underpinned by staff training in aseptic technique and good laboratory practice. PMID:22610620

Cassells, Alan C

2012-01-01

172

Population Dynamics and Identification of Endophytic Bacteria Antagonistic Toward Plant-Pathogenic Fungi in Cotton Root  

Microsoft Academic Search

The antagonistic potentials of endophytic bacteria isolated from the roots of six cotton cultivars at different developmental\\u000a stages were determined in vitro toward three pathogens: Verticillium dahliae Kleb V107 and V396 and Fusarium oxysporum f.sp. vasinfectum (F108). The populations of antagonistic endophytic bacteria (AEB) toward V107, V396, and F108 at the flowering and maturation\\u000a stages were significantly higher than those

Chun-Hong Li; Ming-Wen Zhao; Can-Ming Tang; Shun-Peng Li

2010-01-01

173

In vitro assessments of diverse plant pathogenic fungi treated with a novel growth control agent  

Microsoft Academic Search

The efficacy of an agent with an iodine-based active ingredient (a.i.) was evaluated for controlling the growth of fungi pathogenic to many different food crops. Even though iodine is a necessary mineral for mammals and is an approved food additive, interest in using iodine-based agrochemicals for fungal control is recent. Fusarium verticillioides (synonym=F. moniliforme J. Sheld) sensitivity to the iodine-base

Ida E. Yates; Judy W. Arnold; Charles W. Bacon; Dorothy M. Hinton

2004-01-01

174

Evaluation of Fusarium head blight in barley infected by Fusarium graminearum.  

PubMed

Fusarium head blight, which is primarily caused by Fusarium graminearum, is a devastating disease in the barley field. A real-time PCR protocol was developed to evaluate the growth of this pathogen in the host plant tissues. All four strains harbored the gene encoding ATP-BINDING CASSETTE TRANSPORTER (FgABC; FGSG_00541) as a single copy within their genomes. Our Southern blot result was identical with the genomic data for F. graminearum strain PH-1. Based on the crossing point (CP) values obtained in our TaqMan real-time PCR analysis, two standard curves describing the relationship among the CP value, FgABC copy number, and amount of fungal DNA were constructed. Chronological enumeration of fungal growth was coincided with the symptom development. PMID:23990309

Kang, Woo-Ri; Hwang, Duk-Ju; Bae, Shin-Chul; Lee, Theresa; Kim, Soonok; Ahn, Il-Pyung

2013-08-01

175

Genetic variation of aggressiveness in individual field populations of Fusarium graminearum and Fusarium culmorum tested on young plants of winter rye  

Microsoft Academic Search

Fusarium graminearum andF. culmorum are capable of infecting winter cereals at all growth stages. From natural field epidemics of wheat head blight and rye foot rot, three fungal populations were collected with 21, 38 and 54 isolates, respectively; their aggressiveness was analyzed in comparison to collections ofF. graminearum (25 isolates) andF. culmorum (70 isolates) that represent a wide range of

Thomas Miedaner; Angela G. Schilling

1996-01-01

176

Natural Competence and Recombination in the Plant Pathogen Xylella fastidiosa ?  

PubMed Central

Homologous recombination is one of many forces contributing to the diversity, adaptation, and emergence of pathogens. For naturally competent bacteria, transformation is one possible route for the acquisition of novel genetic material. This study demonstrates that Xylella fastidiosa, a generalist bacterial plant pathogen responsible for many emerging plant diseases, is naturally competent and able to homologously recombine exogenous DNA into its genome. Several factors that affect transformation and recombination efficiencies, such as nutrient availability, growth stage, and methylation of transforming DNA, were identified. Recombination was observed in at least one out of every 106 cells when exogenous plasmid DNA was supplied and one out of every 107 cells when different strains were grown together in vitro. Based on previous genomic studies and experimental data presented here, there is mounting evidence that recombination can occur at relatively high rates and could play a large role in shaping the genetic diversity of X. fastidiosa. PMID:21666009

Kung, Stephanie H.; Almeida, Rodrigo P. P.

2011-01-01

177

Regulation by light in Fusarium.  

PubMed

The genus Fusarium stands out as research model for pathogenesis and secondary metabolism. Light stimulates the production of some Fusarium metabolites, such as the carotenoids, and in many species it influences the production of asexual spores and sexual fruiting bodies. As found in other fungi with well-known photoresponses, the Fusarium genomes contain several genes for photoreceptors, among them a set of White Collar (WC) proteins, a cryptochrome, a photolyase, a phytochrome and two presumably photoactive opsins. The mutation of the opsin genes produced no apparent phenotypic alterations, but the loss of the only WC-1 orthologous protein eliminated the photoinduced expression of the photolyase and opsin genes. In contrast to other carotenogenic species, lack of the WC photoreceptor did not impede the light-induced accumulation of carotenoids, but produced alterations in conidiation, animal pathogenicity and nitrogen-regulated secondary metabolism. The regulation and functional role of other Fusarium photoreceptors is currently under investigation. PMID:20460165

Avalos, Javier; Estrada, Alejandro F

2010-11-01

178

Oligandrin, the elicitin-like protein produced by the mycoparasite Pythium oligandrum , induces systemic resistance to Fusarium crown and root rot in tomato plants  

Microsoft Academic Search

Oligandrin, the elicitin-like protein produced by the mycoparasite Pythium oligandrum, crab shell chitosan and crude glucans, isolated from P. oligandrum cell walls were applied to decapitated tomato plants and evaluated for their potential to induce defence mechanisms in root tissues infected by Fusarium oxysporum f. sp. radicis-lycopersici. A significant decrease in disease incidence was monitored in oligandrin- and chitosan-treated plants

Nicole Benhamou; Richard R Bélanger; Patrice Rey; Yves Tirilly

2001-01-01

179

Genome sequence of the necrotrophic plant pathogen Pythium ultimum reveals original pathogenicity mechanisms and effector repertoire  

PubMed Central

Background Pythium ultimum is a ubiquitous oomycete plant pathogen responsible for a variety of diseases on a broad range of crop and ornamental species. Results The P. ultimum genome (42.8 Mb) encodes 15,290 genes and has extensive sequence similarity and synteny with related Phytophthora species, including the potato blight pathogen Phytophthora infestans. Whole transcriptome sequencing revealed expression of 86% of genes, with detectable differential expression of suites of genes under abiotic stress and in the presence of a host. The predicted proteome includes a large repertoire of proteins involved in plant pathogen interactions, although, surprisingly, the P. ultimum genome does not encode any classical RXLR effectors and relatively few Crinkler genes in comparison to related phytopathogenic oomycetes. A lower number of enzymes involved in carbohydrate metabolism were present compared to Phytophthora species, with the notable absence of cutinases, suggesting a significant difference in virulence mechanisms between P. ultimum and more host-specific oomycete species. Although we observed a high degree of orthology with Phytophthora genomes, there were novel features of the P. ultimum proteome, including an expansion of genes involved in proteolysis and genes unique to Pythium. We identified a small gene family of cadherins, proteins involved in cell adhesion, the first report of these in a genome outside the metazoans. Conclusions Access to the P. ultimum genome has revealed not only core pathogenic mechanisms within the oomycetes but also lineage-specific genes associated with the alternative virulence and lifestyles found within the pythiaceous lineages compared to the Peronosporaceae. PMID:20626842

2010-01-01

180

Advances in Bacteriophage-Mediated Control of Plant Pathogens  

PubMed Central

There is continuing pressure to maximise food production given a growing global human population. Bacterial pathogens that infect important agricultural plants (phytopathogens) can reduce plant growth and the subsequent crop yield. Currently, phytopathogens are controlled through management programmes, which can include the application of antibiotics and copper sprays. However, the emergence of resistant bacteria and the desire to reduce usage of toxic products that accumulate in the environment mean there is a need to develop alternative control agents. An attractive option is the use of specific bacteriophages (phages), viruses that specifically kill bacteria, providing a more targeted approach. Typically, phages that target the phytopathogen are isolated and characterised to determine that they have features required for biocontrol. In addition, suitable formulation and delivery to affected plants are necessary to ensure the phages survive in the environment and do not have a deleterious effect on the plant or target beneficial bacteria. Phages have been isolated for different phytopathogens and have been used successfully in a number of trials and commercially. In this paper, we address recent progress in phage-mediated control of plant pathogens and overcoming the challenges, including those posed by CRISPR/Cas and abortive infection resistance systems. PMID:22934116

Frampton, Rebekah A.; Pitman, Andrew R.; Fineran, Peter C.

2012-01-01

181

Communication between filamentous pathogens and plants at the biotrophic interface.  

PubMed

Fungi and oomycetes that colonize living plant tissue form extensive interfaces with plant cells in which the cytoplasm of the microorganism is closely aligned with the host cytoplasm for an extended distance. In all cases, specialized biotrophic hyphae function to hijack host cellular processes across an interfacial zone consisting of a hyphal plasma membrane, a specialized interfacial matrix, and a plant-derived membrane. The interface is the site of active secretion by both players. This cross talk at the interface determines the winner in adversarial relationships and establishes the partnership in mutualistic relationships. Fungi and oomycetes secrete many specialized effector proteins for controlling the host, and they can stimulate remarkable cellular reorganization even in distant plant cells. Breakthroughs in live-cell imaging of fungal and oomycete encounter sites, including live-cell imaging of pathogens secreting fluorescently labeled effector proteins, have led to recent progress in understanding communication across the interface. PMID:23750888

Yi, Mihwa; Valent, Barbara

2013-01-01

182

Tobraviruses--plant pathogens and tools for biotechnology.  

PubMed

The tobraviruses, Tobacco rattle virus (TRV), Pea early-browning virus (PEBV) and Pepper ringspot virus (PepRSV), are positive-strand RNA viruses with rod-shaped virus particles that are transmitted between plants by trichodorid nematodes. As a group, these viruses infect many plant species, with TRV having the widest host range. Recent studies have begun to dissect the interaction of TRV with potato, currently the most commercially important crop disease caused by any of the tobraviruses. As well as being successful plant pathogens, these viruses have become widely used as vectors for expression in plants of nonviral proteins or, more frequently, as initiators of virus-induced gene silencing (VIGS). Precisely why tobraviruses should be so effective as VIGS vectors is not known; however, molecular studies of the mode of action of the tobravirus silencing suppressor protein are shedding some light on this process. PMID:20618713

Macfarlane, Stuart A

2010-07-01

183

A wilt of passion fruit (Passiflora edulis f. edulis Sims) caused by Fusarium solani and Phytophthora nicotianae var. parasitica  

Microsoft Academic Search

A wilt of purple passion fruit (Passiflora edulis f. edulis Sims) is widespread in Zimbabwe. Fusarium solani was consistently isolated from discoloured vascular tissue of plants obtained from several farms. All isolates of the fungus were pathogenic. The possible role of Phytophthora nicotianae var. parasitica in the wilt disease was investigated because it was frequently isolated from the stem base

D. L. Cole; T. R. Hedges; T. Ndowora

1992-01-01

184

Salmonella colonization activates the plant immune system and benefits from association with plant pathogenic bacteria.  

PubMed

Despite increasing incidences of human salmonellosis caused by consumption of contaminated vegetables, relatively little is known about how the plant immune system responds to and may inhibit Salmonella colonization. Here we show that Salmonella Typhimurium activates the plant immune system primarily due to its recognition of the flg22 region in Salmonella flagellin. Several previously identified plant genes that play a role in immunity were found to affect the host response to Salmonella. The Salmonella flg22 (Seflg22) peptide induced the immune response in leaves which effectively restricted the growth of Salmonella as well as the plant pathogenic bacterium, Pseudomonas syringae pv. tomato. Induction of immune responses by Seflg22 was dependent on the plant FLS2 receptor. Salmonella multiplied poorly on plant tissues similar to other bacteria which are non-pathogenic to plants. However, Salmonella populations increased significantly when co-inoculated with P. syringae pv. tomato but not when co-inoculated with a type III secretion system mutant of this pathogen. Our results suggest that Salmonella benefits from the immune-suppressing effects of plant pathogenic bacteria, and this growth enhancement may increase the risk of salmonellosis. PMID:23517029

Meng, Fanhong; Altier, Craig; Martin, Gregory B

2013-09-01

185

Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper  

PubMed Central

Background and Aims Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots. Methods Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen. Key Results Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant. Conclusions The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks. PMID:22437662

Lee, Boyoung; Lee, Soohyun; Ryu, Choong-Min

2012-01-01

186

Associations of planting date, drought stress, and insects with Fusarium ear rot and fumonisin B1 contamination in California maize  

Microsoft Academic Search

Fusarium ear rot, caused by Fusarium verticillioides, is one of the most common diseases of maize, causing yield and quality reductions and contamination of grain by fumonisins and other mycotoxins. Drought stress and various insects have been implicated as factors affecting disease severity. Field studies were conducted to evaluate the interactions and relative influences of drought stress, insect infestation, and

M. W. Parsons; G. P. Munkvold

2010-01-01

187

Effects of Varying Environmental Conditions on Biological Control of Fusarium Wilt of Tomato by Nonpathogenic Fusarium spp.  

PubMed

ABSTRACT The influence of varying environmental and cropping conditions including temperature, light, soil type, pathogen isolate and race, and cultivar of tomato on biological control of Fusarium wilt of tomato by isolates of nonpathogenic Fusarium oxysporum (CS-20 and CS-24) and F. solani (CS-1) was evaluated in greenhouse and growth chamber experiments. Liquid spore suspensions (10(6)/ml) of the biocontrol isolates were applied to soilless potting mix at the time of tomato seeding, and the seedlings were transplanted into pathogen-infested field soil 2 weeks later. Temperature regimes ranging from 22 to 32 degrees C significantly affected disease development and plant physiological parameters. Biocontrol isolate CS-20 significantly reduced disease at all temperature regimes tested, yielding reductions of disease incidence of 59 to 100% relative to pathogen control treatments. Isolates CS-24 and CS-1 reduced disease incidence in the greenhouse and at high temperatures, but were less effective at the optimum temperature for disease development (27 degrees C). Growing plants under shade (50% of full light) versus full light affected some plant growth parameters, but did not affect the efficacy of biocontrol of any of the three bio-control isolates. Isolate CS-20 effectively reduced disease incidence (56 to 79% reduction) in four different field soils varying in texture (sandy to clayey) and organic matter content (0 to 3.2%). Isolate CS-1 reduced disease in the sandy and loamy soils (49 to 66% reduction), but was not effective in a heavy clay soil. Both CS-1 and CS-20 were equally effective against all three races of the pathogen, as well as multiple isolates of each race (48 to 66% reduction in disease incidence). Both isolates, CS-1 and CS-20, were equally effective in reducing disease incidence (66 to 80% reduction) by pathogenic races 1, 2, and 3 on eight different tomato cultivars containing varying levels of inherent resistance to Fusarium wilt (susceptible, resistant to race 1, or resistant to races 1 and 2). These results demonstrate that both these Fusarium isolates, and particularly CS-20, can effectively reduce Fusarium wilt disease of tomato under a variety of environmental conditions and have potential for further development. PMID:18944240

Larkin, Robert P; Fravel, Deborah R

2002-11-01

188

Plant defenses against parasitic plants show similarities to those induced by herbivores and pathogens  

PubMed Central

Herbivores and pathogens come quickly to mind when one thinks of the biotic challenges faced by plants. Important but less appreciated enemies are parasitic plants, which can have important consequences for the fitness and survival of their hosts. Our knowledge of plant perception, signaling and response to herbivores and pathogens has expanded rapidly in recent years, but information is generally lacking for parasitic species. In a recent paper we reported that some of the same defense responses induced by herbivores and pathogens—notably increases in jasmonic acid (JA), salicylic acid (SA), and a hypersensitive-like response (HLR)—also occur in tomato plants upon attack by the parasitic plant Cuscuta pentagona (field dodder). Parasitism induced a distinct pattern of JA and SA accumulation, and growth trials using genetically-altered tomato hosts suggested that both JA and SA govern effective defenses against the parasite, though the extent of the response varied with host plant age. Here we discuss similarities between the induced responses we observed in response to Cuscuta parasitism to those previously described for herbivores and pathogens and present new data showing that trichomes should be added to the list of plant defenses that act against multiple enemies and across kingdoms. PMID:20495380

Runyon, Justin B; Mescher, Mark C

2010-01-01

189

Plant defenses against parasitic plants show similarities to those induced by herbivores and pathogens.  

PubMed

Herbivores and pathogens come quickly to mind when one thinks of the biotic challenges faced by plants. Important but less appreciated enemies are parasitic plants, which can have important consequences for the fitness and survival of their hosts. Our knowledge of plant perception, signaling, and response to herbivores and pathogens has expanded rapidly in recent years, but information is generally lacking for parasitic species. In a recent paper we reported that some of the same defense responses induced by herbivores and pathogens--notably increases in jasmonic acid (JA), salicylic acid (SA), and a hypersensitive-like response (HLR)--also occur in tomato plants upon attack by the parasitic plant Cuscuta pentagona (field dodder). Parasitism induced a distinct pattern of JA and SA accumulation, and growth trials using genetically-altered tomato hosts suggested that both JA and SA govern effective defenses against the parasite, though the extent of the response varied with host plant age. Here we discuss similarities between the induced responses we observed in response to Cuscuta parasitism to those previously described for herbivores and pathogens and present new data showing that trichomes should be added to the list of plant defenses that act against multiple enemies and across Kingdoms. PMID:20495380

Runyon, Justin B; Mescher, Mark C; De Moraes, Consuelo M

2010-08-01

190

Proteomic approaches to study plant-pathogen interactions.  

PubMed

The analysis of plant proteomes has drastically expanded in the last few years. Mass spectrometry technology, stains, software and progress in bioinformatics have made identification of proteins relatively easy. The assignment of proteins to particular organelles and the development of better algorithms to predict sub-cellular localization are examples of how proteomic studies are contributing to plant biology. Protein phosphorylation and degradation are also known to occur during plant defense signaling cascades. Despite the great potential to give contributions to the study of plant-pathogen interactions, only recently has the proteomic approach begun to be applied to this field. Biological variation and complexity in a situation involving two organisms in intimate contact are intrinsic challenges in this area, however, for proteomics studies yet, there is no substitute for in planta studies with pathogens, and ways to address these problems are discussed. Protein identification depends not only on mass spectrometry, but also on the existence of complete genome sequence databases for comparison. Although the number of completely sequenced genomes is constantly growing, only four plants have their genomes completely sequenced. Additionally, there are already a number of pathosystems where both partners in the interaction have genomes fully sequenced and where functional genomics tools are available. It is thus to be expected that great progress in understanding the biology of these pathosystems will be made over the next few years. Cheaper sequencing technologies should make protein identification in non-model species easier and the bottleneck in proteomic research should shift from unambiguous protein identification to determination of protein function. PMID:20005547

Quirino, B F; Candido, E S; Campos, P F; Franco, O L; Krüger, R H

2010-03-01

191

Disrupting the Transmission of a Vector-Borne Plant Pathogen  

PubMed Central

Approaches to control vector-borne diseases rarely focus on the interface between vector and microbial pathogen, but strategies aimed at disrupting the interactions required for transmission may lead to reductions in disease spread. We tested if the vector transmission of the plant-pathogenic bacterium Xylella fastidiosa was affected by three groups of molecules: lectins, carbohydrates, and antibodies. Although not comprehensively characterized, it is known that X. fastidiosa adhesins bind to carbohydrates, and that these interactions are important for initial cell attachment to vectors, which is required for bacterial transmission from host to host. Lectins with affinity to substrates expected to occur on the cuticular surface of vectors colonized by X. fastidiosa, such as wheat germ agglutinin, resulted in statistically significant reductions in transmission rate, as did carbohydrates with N-acetylglucosamine residues. Presumably, lectins bound to receptors on the vector required for cell adhesion/colonization, while carbohydrate-saturated adhesins on X. fastidiosa's cell surface. Furthermore, antibodies against X. fastidiosa whole cells, gum, and afimbrial adhesins also resulted in transmission blockage. However, no treatment resulted in the complete abolishment of transmission, suggesting that this is a complex biological process. This work illustrates the potential to block the transmission of vector-borne pathogens without directly affecting either organism. PMID:22101059

Rashed, Arash; Almeida, Rodrigo P. P.

2012-01-01

192

Biocontrol of vascular wilt and corm rot of gladiolus caused by Fusarium oxysporum f. sp. gladioli using plant growth promoting rhizobacterial mixture  

Microsoft Academic Search

Talc-based formulations of plant growth promoting rhizobacterial strain S2BC-2 (Bacillus atrophaeus) and strain mixture, S2BC-2 + TEPF-Sungal (Burkholderia cepacia), inhibitory to the growth of Fusarium oxysporum f. sp. gladioli (FOG), were developed for corm dressing and soil application in gladiolus. In comparison to the individual strain, the strain mixture recorded maximum spike and corm production of 100 and 150%, respectively with less

Veerubommu Shanmugam; Nandina Kanoujia; Markandey Singh; Sukhjinder Singh; Ramdeen Prasad

2011-01-01

193

Influence of Soil Fumigation on the Fusarium-Root-knot Nematode Disease Complex of Cotton in California.  

PubMed

For control of the root-knot nematode, Meloidogyne incognita, and the pathogenic wilt fungus, Fusarium oxysporum, on cotton, soil fumigants were applied in the field at conventional and higher rates. Conventional rates suppressed Fusarium wilt but higher rates gave quicker early growth, better stands, less stand loss over the season, a lower percentage of plants infected with wilt, fewer plants with vascular discoloration, and fewer nematodes. The best treatment about doubled the yields of untreated controls in one experiment and quadrupled them in another. PMID:19305846

Jorgenson, E C; Hyer, A H; Garber, R H; Smith, S N

1978-07-01

194

Production of dragon's blood in Dracaena cochinchinensis plants by inoculation of Fusarium proliferatum.  

PubMed

Dragon's blood is a traditional medicine widely used in the world from ancient times. However, little is known about its formation mechanism. This work aimed to gain some insights into its formation mechanism and to control its production. The results demonstrate that wounding plus causal fungal infection and keeping the wound moist are essential for efficient dragon's blood formation in Dracaena cochinchinensis. Two fungal isolates YM-266 and YM-71213 of Fusarium proliferatum increased the yield of dragon's blood in D. cochinchinensis trees by 2.7- and 3.3-times compared to that of the control (wounding alone and keeping the wound moist), respectively. The fungal induced dragon's blood had almost identical chemical constituents to that of the natural dragon's blood with a higher loureirins a and b content as analyzed by TLC and HPLC. In addition, the induced dragon's blood had similar antimicrobial activity and similar or higher antioxidant activity than that of the natural dragon's blood. The novel biological technology developed here for the production of dragon's blood is safe, repeatable, practical, and feasible for the farmers, enabling the production of dragon's blood in a sustainable way without destroying the endangered trees and environment. PMID:21421373

Wang, Xing-Hong; Zhang, Changhe; Yang, Ling-Ling; Gomes-Laranjo, José

2011-02-01

195

Endogenous Methyl Salicylate in Pathogen-Inoculated Tobacco Plants1  

PubMed Central

The tobacco (Nicotiana tabacum) cultivar Xanthi-nc (genotype NN) produces high levels of salicylic acid (SA) after inoculation with the tobacco mosaic virus (TMV). Gaseous methyl salicylate (MeSA), a major volatile produced in TMV-inoculated tobacco plants, was recently shown to be an airborne defense signal. Using an assay developed to measure the MeSA present in tissue, we have shown that in TMV-inoculated tobacco plants the level of MeSA increases dramatically, paralleling increases in SA. MeSA accumulation was also observed in upper, noninoculated leaves. In TMV-inoculated tobacco shifted from 32 to 24°C, the MeSA concentration increased from nondetectable levels to 2318 ng/g fresh weight 12 h after the temperature shift, but subsequently decreased with the onset of the hypersensitive response. Similar results were observed in plants inoculated with Pseudomonas syringae pathovar phaseolicola, in which MeSA levels were highest just before the hypersensitive response-induced tissue desiccation. Transgenic NahG plants unable to accumulate SA also did not accumulate MeSA after TMV inoculation, and did not show increased resistance to TMV following MeSA treatment. Based on the spatial and temporal kinetics of its accumulation, we conclude that tissue MeSA may play a role similar to that of volatile MeSA in the pathogen-induced defense response.

Seskar, Mirjana; Shulaev, Vladimir; Raskin, Ilya

1998-01-01

196

Effects of Arbuscular Mycorrhizal Colonization on Microbial Community in Rhizosphere Soil and Fusarium Wilt Disease in Tomato  

Microsoft Academic Search

Fusarium wilt is caused by soil-borne pathogen Fusarium oxysporum. Tomato (Lycopersicon esculentum Mill.) is susceptible to Fusarium oxysporum f. sp. lycopersici race 1 and was infected with wilt disease. A pot experiment was conducted to investigate effects of inoculating arbuscular mycorrhizal (AM) fungus (Glomus etunicatium) on the microbial community in the rhizosphere soil and Fusarium wilt in tomato (cv. Oogatafukuju).

Lixuan Ren; Yunsheng Lou; Kazunori Sakamoto; Kazuyuki Inubushi; Yoshimiki Amemiya; Qirong Shen; Guohua Xu

2010-01-01

197

Dioecy, hermaphrodites and pathogen load in plants Alex Williams, Janis Antonovics and Jens Rolff  

E-print Network

657 Dioecy, hermaphrodites and pathogen load in plants Alex Williams, Janis Antonovics and Jens Rolff A. Williams and J. Rolff (jor@sheffield.ac.uk), Dept of Animal and Plant Sciences, Univ in animals and to a much lesser degree in plants. Here, we investigated the incidence of fungal pathogens

Antonovics, Janis

198

N-acyl-homoserine lactones-producing bacteria protect plants against plant and human pathogens.  

PubMed

The implementation of beneficial microorganisms for plant protection has a long history. Many rhizobia bacteria are able to influence the immune system of host plants by inducing resistance towards pathogenic microorganisms. In this report, we present a translational approach in which we demonstrate the resistance-inducing effect of Ensifer meliloti (Sinorhizobium meliloti) on crop plants that have a significant impact on the worldwide economy and on human nutrition. Ensifer meliloti is usually associated with root nodulation in legumes and nitrogen fixation. Here, we suggest that the ability of S.?meliloti to induce resistance depends on the production of the quorum-sensing molecule, oxo-C14-HSL. The capacity to enhanced resistance provides a possibility to the use these beneficial bacteria in agriculture. Using the Arabidopsis-Salmonella model, we also demonstrate that the application of N-acyl-homoserine lactones-producing bacteria could be a successful strategy to prevent plant-originated infections with human pathogens. PMID:25234390

Hernández-Reyes, Casandra; Schenk, Sebastian T; Neumann, Christina; Kogel, Karl-Heinz; Schikora, Adam

2014-11-01

199

Plant Antimicrobial Agents and Their Effects on Plant and Human Pathogens  

PubMed Central

To protect themselves, plants accumulate an armoury of antimicrobial secondary metabolites. Some metabolites represent constitutive chemical barriers to microbial attack (phytoanticipins) and others inducible antimicrobials (phytoalexins). They are extensively studied as promising plant and human disease-controlling agents. This review discusses the bioactivity of several phytoalexins and phytoanticipins defending plants against fungal and bacterial aggressors and those with antibacterial activities against pathogens affecting humans such as Pseudomonas aeruginosa and Staphylococcus aureus involved in respiratory infections of cystic fibrosis patients. The utility of plant products as “antibiotic potentiators” and “virulence attenuators” is also described as well as some biotechnological applications in phytoprotection. PMID:20111686

Gonzalez-Lamothe, Rocio; Mitchell, Gabriel; Gattuso, Mariza; Diarra, Moussa S.; Malouin, Francois; Bouarab, Kamal

2009-01-01

200

Roles of Plant Hormones in Plant Resistance and Susceptibility to Pathogens  

Microsoft Academic Search

Plants and animals trigger an innate immune response upon perception of pathogen-associated molecular patterns (PAMPs) such\\u000a as flagellin. In Arabidopsis, flagellin perception elevates resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000), although the molecular mechanisms involved remain elusive. A flagellin-derived peptide transiently enhances the\\u000a accumulation of a plant microRNA that directs degradation of mRNA for TIR1, an F-box auxin

Lionel Navarro; Rajendra Bari; Alexandre Seilaniantz; Adnane Nemri; Jonathan D. G. Jones

201

Fungal development of the plant pathogen Ustilago maydis.  

PubMed

The maize pathogen Ustilago maydis has to undergo various morphological transitions for the completion of its sexual life cycle. For example, haploid cells respond to pheromone by forming conjugation tubes that fuse at their tips. The resulting dikaryon grows filamentously, expanding rapidly at the apex and inserting retraction septa at the basal pole. In this review, we present progress on the underlying mechanisms regulating such defined developmental programmes. The key findings of the postgenomic era are as follows: (1) endosomes function not only during receptor recycling, but also as multifunctional transport platforms; (2) a new transcriptional master regulator for pathogenicity is part of an intricate transcriptional network; (3) determinants for uniparental mitochondrial inheritance are encoded at the a2 mating-type locus; (4) microtubule-dependent mRNA transport is important in determining the axis of polarity; and (5) a battery of fungal effectors encoded in gene clusters is crucial for plant infection. Importantly, most processes are tightly controlled at the transcriptional, post-transcriptional and post-translational levels, resulting in a complex regulatory network. This intricate system is crucial for the timing of the correct order of developmental phases. Thus, new insights from all layers of regulation have substantially advanced our understanding of fungal development. PMID:21729109

Vollmeister, Evelyn; Schipper, Kerstin; Baumann, Sebastian; Haag, Carl; Pohlmann, Thomas; Stock, Janpeter; Feldbrügge, Michael

2012-01-01

202

Biopesticidal value of selected essential oils against pathogenic fungus, termites, and nematodes  

Microsoft Academic Search

The biopesticidal potential of six plant-derived essential oils (mint [Mentha arvensis], ajwain [Carum capticum], lemongrass [Cymbopogon citrates], clove [Eugenia caryophyllata], cedarwood [Cedrus deodara], and eucalyptus [Eucalyptus globulas]) was evaluated against Odontotermes obesus (termites), Fusarium oxysporum (plant pathogenic fungi), and Meloidogyne incognita (nematodes). In the case of termites, a “no-choice” bioassay revealed that the mint oil gave the best results (100%

Aditi Gupta; Satyawati Sharma; S. N. Naik

2011-01-01

203

Controls on pathogen species richness in plants introduced and native ranges: roles of residence  

E-print Network

LETTER Controls on pathogen species richness in plantsĂ? introduced and native ranges: roles,4 Emily E. Puckett1 and Petr Pysek3,4 Abstract Introduced species escape many pathogens and other enemies, raising three questions. How quickly do introduced hosts accumulate pathogen species? What factors control

KratochvĂ­l, Lukas

204

In vitro: Response of plant growth regulators and antimalformins on conidia germination of Fusarium mangiferae and incidence of mango malformation.  

PubMed

Mango malformation is the most important and threatening disease of recent times, primarily because of persistent lacuna in complete understanding of its nature. Diverse Fusarium spp, including F. mangiferae, were found to be associated with the disease. Here, F. mangiferae from mango cv Dashehri was morphologically characterized. Typically, oval-shaped microconidia without septum and crescent-shaped macroconidia with 3-septate were more often observed, whereas not a single chlamydospore was detected. The length and width of micro- and macro-conidia were 7.5, 55, 3.2, and 3.5, respectively. The plant growth regulators such as NAA, GA3, BAP and ethrel were found to induce in vitro germination of conidia of F. mangiferae after 12 h. In contrast, antimalformin silver nitrate (AgNO3) inhibits conidial germination in vitro and none of conidia was germinated beyond 500 ppm, however antimalformin glutathione was highly effective in stimulating conidial germination of F. mangiferae in vitro at > 1000 ppm after 24 h. We observed that the response of F. mangiferae to germinate the conidia in vitro under influence of plant growth regulators and antimalformins is not coincided with earlier findings of reduced disease incidence by exogenous application of these compounds. The present findings do not authenticate the involvement of F. mangiferae in the disease, however hormonal imbalance, most probably ethylene, might be responsible for deformed functional morphology of panicle. Further, a signal transduction mechanism of stress-stimulated ethylene imbalance causing physio-morphological changes in reproductive organs of mango flower and thereby failure of fertilization and fruit set, which needs to be investigated. PMID:24505497

Ansari, Mohammad Wahid; Tula, Suresh; Shukla, Alok; Pant, Ramesh Chandra; Tuteja, Narendra

2013-11-01

205

Whole-Genome Shotgun Sequence of Bacillus mojavensis Strain RRC101, an Endophytic Bacterium Antagonistic to the Mycotoxigenic Endophytic Fungus Fusarium verticillioides  

PubMed Central

Here, we report the whole-genome shotgun sequence of Bacillus mojavensis strain RRC101, isolated from a maize kernel. This strain is antagonistic to the mycotoxigenic plant pathogen Fusarium verticillioides and grows within maize tissue, suggesting potential as an endophytic biocontrol agent. PMID:25359909

Blacutt, A. A.; Meinersmann, R. J.; Bacon, C. W.

2014-01-01

206

Indigenous Arbuscular Mycorrhizal Fungal Assemblages Protect Grassland Host Plants from Pathogens  

PubMed Central

Plant roots can establish associations with neutral, beneficial and pathogenic groups of soil organisms. Although it has been recognized from the study of individual isolates that these associations are individually important for plant growth, little is known about interactions of whole assemblages of beneficial and pathogenic microorganisms associating with plants. We investigated the influence of an interaction between local arbuscular mycorrhizal (AM) fungal and pathogenic/saprobic microbial assemblages on the growth of two different plant species from semi-arid grasslands in NE Germany (Mallnow near Berlin). In a greenhouse experiment each plant species was grown for six months in either sterile soil or in sterile soil with one of three different treatments: 1) an AM fungal spore fraction isolated from field soil from Mallnow; 2) a soil pathogen/saprobe fraction consisting of a microbial community prepared with field soil from Mallnow and; 3) the combined AM fungal and pathogen/saprobe fractions. While both plant species grew significantly larger in the presence of AM fungi, they responded negatively to the pathogen/saprobe treatment. For both plant species, we found evidence of pathogen protection effects provided by the AM fungal assemblages. These results indicate that interactions between assemblages of beneficial and pathogenic microorganisms can influence the growth of host plants, but that the magnitude of these effects is plant species-specific. PMID:22110635

Wehner, Jeannine; Antunes, Pedro M.; Powell, Jeff R.; Caruso, Tancredi; Rillig, Matthias C.

2011-01-01

207

A second polycaprolactone depolymerase from Fusarium , a lipase distinct from cutinase  

Microsoft Academic Search

Polycaprolactone (PCL), a synthetic polyester with applications in biodegradable plastics, is degraded by a variety of microorganisms,\\u000a including fungal phytopathogens. These pathogens secrete cutinase, which hydrolyzes cutin, the polyester structural component\\u000a of plant cuticle, releasing ?-hydroxy fatty acids that induce cutinase synthesis. Our laboratory previously reported that\\u000a growth of Fusarium solani on PCL requires cutinase, which is active as a

C. A. Murphy; J. A. Cameron; S. J. Huang; R. T. Vinopal

1998-01-01

208

Extracellular Chitinases of Fluorescent Pseudomonads Antifungal to Fusarium oxysporum f. sp. dianthi Causing Carnation Wilt  

Microsoft Academic Search

Vascular wilt of carnation caused by Fusarium oxysporum f. sp. dianthi (Prill. & Delacr.) W. C. Synder & H.N. Hans inflicts substantial yield and quality loss to the crop. Mycolytic enzymes such\\u000a as chitinases are antifungal and contribute significantly to the antagonistic activity of fluorescent pseudomonads belonging\\u000a to plant-growth-promoting rhizobacteria. Fluorescent pseudomonads antagonistic to the vascular wilt pathogen were studied

Naosekpam Singh Ajit; Rajni Verma; V. Shanmugam

2006-01-01

209

Extracellular xylanases from two pathogenic races of Fusarium oxysporum f. sp. ciceris: enzyme production in culture and purification and characterization of a major isoform as an alkaline endo-beta-(1,4)-xylanase of low molecular weight.  

PubMed

Fusarium oxysporum f. sp. ciceris, the causal agent of Fusarium wilt of chickpea, comprises eight pathogenic races and two pathotypes. Races 0 and 5, representative of the least virulent yellowing pathotype and the most virulent wilt pathotype, respectively, produced extracellular xylanases when grown on minimal medium supplemented with either 1% commercial birchwood xylan or 0.3% chickpea cell walls. The pattern of extracellular proteins analysed by denaturing polyacrylamide gel electrophoresis in the two media presented some minor but distinctive differences between fungal races. By preparative isoelectrofocusing, the xylanase activity in cell wall-culture filtrates could be resolved into basic and neutral fractions with pI values around to 10 and 8, respectively, whereas the xylan-culture filtrates contained an additional acidic fraction of pI around 4. A common major xylanase was purified 7-fold to homogeneity by cation-exchange chromatography and chromatofocusing. The purified xylanase has a molecular weight of 21.6 kDa, optimum pH and temperature of 5.5 and 55 degrees C, respectively, pI in the range of 8.2 to 9.0, and Km and Vmax values of 2.24 mg ml(-1) (birchwood xylan as substrate) and 1200 nkat mg(-1) protein (72 U mg(-1) protein), respectively. The enzyme has an endo mode of action, hydrolysing xylan to xylobiose and higher short-chain xylooligosaccharides without forming free xylose. PMID:15928976

Jorge, Inmaculada; de la Rosa, Olga; Navas-Cortés, Juan A; Jiménez-Díaz, Rafael M; Tena, Manuel

2005-07-01

210

Survey and Evaluation of Plant Pathogens of Alligatorweed (Alternanthera philoxeroides (Mart.) Griseb.).  

National Technical Information Service (NTIS)

Plant pathogens may offer a means for the biological control of alligatorweed (Alternanthera philoxeroides), an emersed aquatic plant infesting waterways in many areas of the southeastern United States. Three diseases of alligatorweed were found during su...

H. R. Hill

1972-01-01

211

NPS6, Encoding a Nonribosomal Peptide Synthetase Involved in Siderophore-Mediated Iron Metabolism, Is a Conserved Virulence Determinant of Plant Pathogenic Ascomycetes[W  

PubMed Central

NPS6, encoding a nonribosomal peptide synthetase, is a virulence determinant in the maize (Zea mays) pathogen Cochliobolus heterostrophus and is involved in tolerance to H2O2. Deletion of NPS6 orthologs in the rice (Oryza sativa) pathogen, Cochliobolus miyabeanus, the wheat (Triticum aestivum) pathogen, Fusarium graminearum, and the Arabidopsis thaliana pathogen, Alternaria brassicicola, resulted in reduced virulence and hypersensitivity to H2O2. Introduction of the NPS6 ortholog from the saprobe Neurospora crassa to the ?nps6 strain of C. heterostrophus restored wild-type virulence to maize and tolerance to H2O2, demonstrating functional conservation in filamentous ascomycete phytopathogens and saprobes. Increased sensitivity to iron depletion was identified as a conserved phenotype of ?nps6 strains. Exogenous application of iron enhanced the virulence of ?nps6 strains of C. heterostrophus, C. miyabeanus, F. graminearum, and A. brassicicola to each host. NPS6 is responsible for the biosynthesis of extracellular siderophores by C. heterostrophus, F. graminearum, and A. brassicicola. Application of the extracellular siderophore of A. brassicicola restored wild-type virulence of the ?Abnps6 strain to Arabidopsis. It is proposed that the role of extracellular siderophores in fungal virulence to plants is to supply an essential nutrient, iron, to their producers in planta and not to act as phytotoxins, depriving their hosts of iron. PMID:17056706

Oide, Shinichi; Moeder, Wolfgang; Krasnoff, Stuart; Gibson, Donna; Haas, Hubertus; Yoshioka, Keiko; Turgeon, B. Gillian

2006-01-01

212

Effect of acidic electrolyzed water on the viability of bacterial and fungal plant pathogens and on bacterial spot disease of tomato.  

PubMed

Acidic electrolyzed water (AEW), known to have germicidal activity, was obtained after electrolysis of 0.045% aqueous solution of sodium chloride. Freshly prepared AEW (pH 2.3-2.6, oxidation-reduction potential 1007-1025 mV, and free active chlorine concentration 27-35 ppm) was tested in vitro and (or) on tomato foliage and seed surfaces for its effects on the viability of plant pathogen propagules that could be potential seed contaminants. Foliar sprays of AEW were tested against bacterial spot disease of tomato under greenhouse and field conditions. The viability of propagules of Xanthomonas campestris pv. vesicatoria (bacterial spot pathogen), Streptomyces scabies (potato scab pathogen), and Fusarium oxysporum f.sp. lycopersici (root rot pathogen) was significantly reduced 4-8 log units within 2 min of exposure to AEW. Immersion of tomato seed from infected fruit in AEW for 1 and 3 min significantly reduced the populations of X. campestris pv. vesicatoria from the surface of the seed without affecting seed germination. Foliar sprays of AEW reduced X. campestris pv. vesicatoria populations and leaf spot severity on tomato foliage in the greenhouse. In the field, multiple sprays of AEW consistently reduced bacterial spot severity on tomato foliage. Disease incidence and severity was also reduced on fruit, but only in 2003. Fruit yield was either enhanced or not affected by the AEW sprays. These results indicate a potential use of AEW as a seed surface disinfectant or contact bactericide. PMID:17110959

Abbasi, P A; Lazarovits, G

2006-10-01

213

The Relationship Between Pathogen-induced Systemic Resistance (ISR) and Multigenic (horizontal) Resistance in Plants  

Microsoft Academic Search

Plants have developed mechanisms to successfully co-exist in the presence of pathogenic organisms. Some interactions between plants and pathogens are based on recognition of specific elicitor molecules from avirulent pathogen races (avr gene products), which is described in the gene-for-gene resistance theory. Another type of resistance, multigenic (horizontal) resistance, is a less well-studied phenomenon that depends upon multiple genes in

Sadik Tuzun

2001-01-01

214

Biological Control of Plant Pathogens: Research, Commercialization, and Application in the USA  

NSDL National Science Digital Library

This article describes the current status of research, commercial development, and application of biocontrol strategies targeted at plant pathogens. Also included is a description of future prospects for using biological control to limit the damage of plant pathogens in both conventional and organic agriculture.

Brian B. McSpadden Gardener (The Ohio State University-OARDC;); Deborah R. Fravel (USDA, ARS;)

2002-05-10

215

Development of recombinant antibody technology for application in plant pathogen diagnosis  

Microsoft Academic Search

This thesis describes the applicability of the novel phage display technique to select plant-pathogen-specific monoclonal antibodies (MAbs) from combinatorial antibody libraries. The retrieved MAbs are so specific that they can be used as diagnostic tools in sensitive immunoassays for the detection and identification of plant pathogens. Testing results, obtained from laboratories that have applied these recombinant MAbs, are discussed in

R. A. Griep

1999-01-01

216

Genome-Wide Identification of Transcriptional Start Sites in the Plant Pathogen Pseudomonas syringae pv. tomato  

E-print Network

syringae pv. tomato str. DC3000 Melanie J. Filiatrault1,2 *, Paul V. Stodghill1,2 , Christopher R. Myers3 identified 59-ends of transcripts for the plant pathogen Pseudomonas syringae pv. tomato str. DC3000-Wide Identification of Transcriptional Start Sites in the Plant Pathogen Pseudomonas syringae pv. tomato str. DC3000

Myers, Chris

217

Soil fungal pathogens and the relationship between plant diversity and productivity  

E-print Network

LETTER Soil fungal pathogens and the relationship between plant diversity and productivity John L whether suppression of plant productivity by soil fungal pathogens might also drive a positive diversity treatment. In control (non-fungicide treated) assemblages there was a strong positive relationship between

Cleveland, Cory

218

The broad host range pathogen Pseudomonas aeruginosa strain PA14 carries two pathogenicity islands harboring plant and animal virulence genes  

PubMed Central

The ubiquitous bacterium Pseudomonas aeruginosa is the quintessential opportunistic pathogen. Certain isolates infect a broad range of host organisms, from plants to humans. The pathogenic promiscuity of particular variants may reflect an increased virulence gene repertoire beyond the core P. aeruginosa genome. We have identified and characterized two P. aeruginosa pathogenicity islands (PAPI-1 and PAPI-2) in the genome of PA14, a highly virulent clinical isolate. The 108-kb PAPI-1 and 11-kb PAPI-2, which are absent from the less virulent reference strain PAO1, exhibit highly modular structures, revealing their complex derivations from a wide array of bacterial species and mobile elements. Most of the genes within these islands that are homologous to known genes occur in other human and plant bacterial pathogens. For example, PAPI-1 carries a complete gene cluster predicted to encode a type IV group B pilus, a well known adhesin absent from strain PAO1. However, >80% of the PAPI-1 DNA sequence is unique, and 75 of its 115 predicted ORF products are unrelated to any known proteins or functional domains. Significantly, many PAPI-1 ORFs also occur in several P. aeruginosa cystic fibrosis isolates. Twenty-three PAPI ORFs were mutated, and 19 were found to be necessary for full plant or animal virulence, with 11 required for both. The large set of “extra” virulence functions encoded by both PAPIs may contribute to the increased promiscuity of highly virulent P. aeruginosa strains, by directing additional pathogenic functions. PMID:14983043

He, Jianxin; Baldini, Regina L.; Deziel, Eric; Saucier, Maude; Zhang, Qunhao; Liberati, Nicole T.; Lee, Daniel; Urbach, Jonathan; Goodman, Howard M.; Rahme, Laurence G.

2004-01-01

219

Mycotoxigenic Fusarium and Deoxynivalenol Production Repress Chitinase Gene Expression in the Biocontrol Agent Trichoderma atroviride P1  

PubMed Central

Mycotoxin contamination associated with head blight of wheat and other grains caused by Fusarium culmorum and F. graminearum is a chronic threat to crop, human, and animal health throughout the world. One of the most important toxins in terms of human exposure is deoxynivalenol (DON) (formerly called vomitoxin), an inhibitor of protein synthesis with a broad spectrum of toxigenicity against animals. Certain Fusarium toxins have additional antimicrobial activity, and the phytotoxin fusaric acid has recently been shown to modulate fungus-bacterium interactions that affect plant health (Duffy and Défago, Phytopathology 87:1250-1257, 1997). The potential impact of DON on Fusarium competition with other microorganisms has not been described previously. Any competitive advantage conferred by DON would complicate efforts to control Fusarium during its saprophytic growth on crop residues that are left after harvest and constitute the primary inoculum reservoir for outbreaks in subsequent plantings. We examined the effect of the DON mycotoxin on ecological interactions between pathogenic Fusarium and Trichoderma atroviride strain P1, a competitor fungus with biocontrol activity against a wide range of plant diseases. Expression of the Trichoderma chitinase genes, ech42 and nag1, which contribute to biocontrol activity, was monitored in vitro and on crop residues of two maize cultivars by using goxA reporter gene fusions. We found that DON-producing F. culmorum and F. graminearum strains repressed expression of nag1-gox. DON-negative wild-type Fusarium strains and a DON-negative mutant with an insertional disruption in the tricothecene biosynthetic gene, tri5, had no effect on antagonist gene expression. The role of DON as the principal repressor above other pathogen factors was confirmed. Exposure of Trichoderma to synthetic DON or to a non-DON-producing Fusarium mutant resulted in the same level of nag1-gox repression as the level observed with DON-producing Fusarium. DON repression was specific for nag1-gox and had no effect, either positive or negative, on expression of another key chitinase gene, ech42. This is the first demonstration that a target pathogen down-regulates genes in a fungal biocontrol agent, and our results provide evidence that mycotoxins have a novel ecological function as factors in Fusarium competitiveness. PMID:12788701

Lutz, Matthias P.; Feichtinger, Georg; Defago, Genevieve; Duffy, Brion

2003-01-01

220

Identification of a Chitinase-modifying Protein from Fusarium verticillioides  

PubMed Central

Chitinase-modifying proteins (cmps) are proteases secreted by fungal pathogens that truncate the plant class IV chitinases ChitA and ChitB during maize ear rot. cmp activity has been characterized for Bipolaris zeicola and Stenocarpella maydis, but the identities of the proteases are not known. Here, we report that cmps are secreted by multiple species from the genus Fusarium, that cmp from Fusarium verticillioides (Fv-cmp) is a fungalysin metalloprotease, and that it cleaves within a sequence that is conserved in class IV chitinases. Protein extracts from Fusarium cultures were found to truncate ChitA and ChitB in vitro. Based on this activity, Fv-cmp was purified from F. verticillioides. N-terminal sequencing of truncated ChitA and MALDI-TOF-MS analysis of reaction products showed that Fv-cmp is an endoprotease that cleaves a peptide bond on the C-terminal side of the lectin domain. The N-terminal sequence of purified Fv-cmp was determined and compared with a set of predicted proteins, resulting in its identification as a zinc metalloprotease of the fungalysin family. Recombinant Fv-cmp also truncated ChitA, confirming its identity, but had reduced activity, suggesting that the recombinant protease did not mature efficiently from its propeptide-containing precursor. This is the first report of a fungalysin that targets a nonstructural host protein and the first to implicate this class of virulence-related proteases in plant disease. PMID:21878653

Naumann, Todd A.; Wicklow, Donald T.; Price, Neil P. J.

2011-01-01

221

Toxicity of abiotic stressors to Fusarium species: differences in hydrogen peroxide and fungicide tolerance.  

PubMed

Stress sensitivity of three related phytopathogenic Fusarium species (Fusarium graminearum, Fusarium oxysporum and Fusarium verticillioides) to different oxidative, osmotic, cell wall, membrane, fungicide stressors and an antifungal protein (PAF) were studied in vitro. The most prominent and significant differences were found in oxidative stress tolerance: all the three F. graminearum strains showed much higher sensitivity to hydrogen peroxide and, to a lesser extent, to menadione than the other two species. High sensitivity of F. verticillioides strains was also detectable to an azole drug, Ketoconazole. Surprisingly, no or limited differences were observed in response to other oxidative, osmotic and cell wall stressors. These results indicate that fungal oxidative stress response and especially the response to hydrogen peroxide (this compound is involved in a wide range of plant-fungus interactions) might be modified on niche-specific manner in these phylogenetically related Fusarium species depending on their pathogenic strategy. Supporting the increased hydrogen peroxide sensitivity of F. graminearum, genome-wide analysis of stress signal transduction pathways revealed the absence one CatC-type catalase gene in F. graminearum in comparison to the other two species. PMID:24939687

Nagygyörgy, Emese D; Kovács, Barbara; Leiter, Eva; Miskei, Márton; Pócsi, István; Hornok, László; Adám, Attila L

2014-06-01

222

The Nuclear Protein Sge1 of Fusarium oxysporum Is Required for Parasitic Growth  

PubMed Central

Dimorphism or morphogenic conversion is exploited by several pathogenic fungi and is required for tissue invasion and/or survival in the host. We have identified a homolog of a master regulator of this morphological switch in the plant pathogenic fungus Fusarium oxysporum f. sp. lycopersici. This non-dimorphic fungus causes vascular wilt disease in tomato by penetrating the plant roots and colonizing the vascular tissue. Gene knock-out and complementation studies established that the gene for this putative regulator, SGE1 (SIX Gene Expression 1), is essential for pathogenicity. In addition, microscopic analysis using fluorescent proteins revealed that Sge1 is localized in the nucleus, is not required for root colonization and penetration, but is required for parasitic growth. Furthermore, Sge1 is required for expression of genes encoding effectors that are secreted during infection. We propose that Sge1 is required in F. oxysporum and other non-dimorphic (plant) pathogenic fungi for parasitic growth. PMID:19851506

Reijnen, Linda; Manders, Erik M. M.; Boas, Sonja; Olivain, Chantal; Alabouvette, Claude; Rep, Martijn

2009-01-01

223

Volatiles modulate the development of plant pathogenic rust fungi.  

PubMed

Rust fungi are obligate biotrophic pathogens that differentiate a series of specialized cells to establish infection. One of these cells, the haustorium, which serves to absorb nutrients from living host cells, normally develops only in planta. Here, we show that the rust fungus Uromyces fabae (Pers.) Schroet. stimulates volatile emission of its host, broad bean (Vicia faba L.). Volatiles were identified and shown to be perceived by the fungus in in vitro assays that excluded the host. Three of them, nonanal, decanal, and hexenyl acetate promoted the development of haustoria on artificial membranes. In contrast, the terpenoid farnesyl acetate suppressed this differentiation. In assays using whole plants, farnesyl acetate reduced rust disease not only on broad bean but also on several cereals and legumes including soybean. This natural substance was effective against all rusts tested when directly applied to the host. This demonstrated that farnesyl acetate may serve as a powerful novel tool to combat rust fungi including Phakopsora pachyrhizi that currently threatens the production of soybeans world-wide. PMID:16775700

Mendgen, Kurt; Wirsel, Stefan G R; Jux, Andreas; Hoffmann, Jochen; Boland, Wilhelm

2006-11-01

224

Isolate Identity Determines Plant Tolerance to Pathogen Attack in Assembled Mycorrhizal Communities  

PubMed Central

Arbuscular mycorrhizal fungi (AMF) are widespread soil microorganisms that associate mutualistically with plant hosts. AMF receive photosynthates from the host in return for various benefits. One of such benefits is in the form of enhanced pathogen tolerance. However, this aspect of the symbiosis has been understudied compared to effects on plant growth and its ability to acquire nutrients. While it is known that increased AMF species richness positively correlates with plant productivity, the relationship between AMF diversity and host responses to pathogen attack remains obscure. The objective of this study was to test whether AMF isolates can differentially attenuate the deleterious effects of a root pathogen on plant growth, whether the richest assemblage of AMF isolates provides the most tolerance against the pathogen, and whether AMF-induced changes to root architecture serve as a mechanism for improved plant disease tolerance. In a growth chamber study, we exposed the plant oxeye daisy (Leucanthemum vulgare) to all combinations of three AMF isolates and to the plant root pathogen Rhizoctonia solani. We found that the pathogen caused an 81% reduction in shoot and a 70% reduction in root biomass. AMF significantly reduced the highly deleterious effect of the pathogen. Mycorrhizal plants infected with the pathogen produced 91% more dry shoot biomass and 72% more dry root biomass relative to plants solely infected with R. solani. AMF isolate identity was a better predictor of AMF-mediated host tolerance to the pathogen than AMF richness. However, the enhanced tolerance response did not result from AMF-mediated changes to root architecture. Our data indicate that AMF communities can play a major role in alleviating host pathogen attack but this depends primarily on the capacity of individual AMF isolates to provide this benefit. PMID:23620744

Lewandowski, Thaddeus J.; Dunfield, Kari E.; Antunes, Pedro M.

2013-01-01

225

Phytophagous Arthropods and a Pathogen Sharing a Host Plant: Evidence for Indirect Plant-Mediated Interactions  

PubMed Central

In ecological systems, indirect interactions between plant pathogens and phytophagous arthropods can arise when infestation by a first attacker alters the common host plant so that although a second attacker could be spatially or temporally separated from the first one, the former could be affected. The induction of plant defense reactions leading to the production of secondary metabolites is thought to have an important role since it involves antagonistic and/or synergistic cross-talks that may determine the outcome of such interactions. We carried out experiments under controlled conditions on young rose plants in order to assess the impact of these indirect interactions on life history traits of three pests: the necrotrophic fungus Botrytis cinerea Pers.: Fr. (Helotiales: Sclerotiniaceae), the aphid Rhodobium porosum Sanderson (Hemiptera: Aphididae) and the thrips Frankliniella occidentalis Pergande (Thysanoptera: Thripidae). Our results indicated (i) a bi-directional negative interaction between B. cinerea and R. porosum, which is conveyed by decreased aphid growth rate and reduced fungal lesion area, as well as (ii) an indirect negative effect of B. cinerea on insect behavior. No indirect effect was observed between thrips and aphids. This research highlights several complex interactions that may be involved in structuring herbivore and plant pathogen communities within natural and managed ecosystems. PMID:21611161

Mouttet, Raphaelle; Bearez, Philippe; Thomas, Cecile; Desneux, Nicolas

2011-01-01

226

Root Rot of Balloon Flower (Platycodon grandiflorum) Caused by Fusarium solani and Fusarium oxysporum  

PubMed Central

Balloon flower (Platycodon grandiflorum) is a kind of mountain herbs whose roots have restorative properties and the cultivating acreage of balloon flower has been steadily increasing in Korea. More frequent rain and high amount of rainfalls as a result of climate changes predisposed balloon flower to the outbreaks of root rot at high-density cultivation area in recent years. Root crowns were usually discolored into brown to blackish brown at first and the infected plants showed slight wilting symptom at early infection stage. Severely infected roots were entirely rotted and whole plants eventually died at late infection stage. The overall disease severities of root rot of balloon flower were quite variable according to the surveyed fields in Jeonnam, Gyeongnam and Jeju Provinces, which ranged from 0.1% to 40%. The root rot occurred more severely at the paddy or clay soils than the sandy soils and their severities were much higher at lowland than upland in the same localty. The disease increased with aging of the balloon flower. The causal fungi were identified as Fusarium solani and F. oxysporum on the basis of their mycological characteristics. The optimum temperature ranges of their mycelial growths was found to be 24°C. The pathogenic characters of F. solani and F. oxysporum treated by artificial wounding inoculation on healthy roots of balloon flower revealed that F. solani was more virulent than F. oxysporum. This study identified the causal agents of root rot of balloon flower as Fusarium solani and F. oxysporum, probably for the first time.

Jeon, Chi Sung; Kim, Gyoung Hee; Son, Kyeong In; Hur, Jae-Seoun; Jeon, Kwon-Seok; Yoon, Jun-Hyuck; Koh, Young Jin

2013-01-01

227

Endophytic fungal entomopathogens with activity against plant pathogens: ecology and evolution  

Microsoft Academic Search

Dual biological control, of both insect pests and plant pathogens, has been reported for the fungal entomopathogens, Beauveria bassiana (Bals.-Criv.) Vuill. (Ascomycota: Hypocreales) and Lecanicillium spp. (Ascomycota: Hypocreales). However, the primary mechanisms of plant disease suppression are different for these fungi.\\u000a Beauveria spp. produce an array of bioactive metabolites, and have been reported to limit growth of fungal plant pathogens

Bonnie H. OwnleyKimberly; Kimberly D. Gwinn; Fernando E. Vega

2010-01-01

228

Endophytic fungal entomopathogens with activity against plant pathogens: ecology and evolution  

Microsoft Academic Search

\\u000a Dual biological control, of both insect pests and plant pathogens, has been reported for the fungal entomopathogens, Beauveria bassiana (Bals.-Criv.) Vuill. (Ascomycota: Hypocreales) and Lecanicillium spp. (Ascomycota: Hypocreales). However, the primary mechanisms of plant disease suppression are different for these fungi.\\u000a Beauveria spp. produce an array of bioactive metabolites, and have been reported to limit growth of fungal plant pathogens

Bonnie H. OwnleyKimberly; Kimberly D. Gwinn; Fernando E. Vega

229

Exserohilum rostratum: Characterization of a Cross-Kingdom Pathogen of Plants and Humans  

PubMed Central

Pathogen host shifts represent a major source of new infectious diseases. There are several examples of cross-genus host jumps that have caused catastrophic epidemics in animal and plant species worldwide. Cross-kingdom jumps are rare, and are often associated with nosocomial infections. Here we provide an example of human-mediated cross-kingdom jumping of Exserohilum rostratum isolated from a patient who had received a corticosteroid injection and died of fungal meningitis in a Florida hospital in 2012. The clinical isolate of E. rostratum was compared with two plant pathogenic isolates of E. rostratum and an isolate of the closely related genus Bipolaris in terms of morphology, phylogeny, and pathogenicity on one C3 grass, Gulf annual rye grass (Lolium multiflorum), and two C4 grasses, Japanese stilt grass (Microstegium vimineum) and bahia grass (Paspalum notatum). Colony growth and color, as well as conidia shape and size were the same for the clinical and plant isolates of E. rostratum, while these characteristics differed slightly for the Bipolaris sp. isolate. The plant pathogenic and clinical isolates of E. rostratum were indistinguishable based on morphology and ITS and 28S rDNA sequence analysis. The clinical isolate was as pathogenic to all grass species tested as the plant pathogenic strains that were originally isolated from plant hosts. The clinical isolate induced more severe symptoms on stilt grass than on rye grass, while this was the reverse for the plant isolates of E. rostratum. The phylogenetic similarity between the clinical and plant-associated E. rostratum isolates and the ability of the clinical isolate to infect plants suggests that a plant pathogenic strain of E. rostratum contaminated the corticosteroid injection fluid and was able to cause systemic disease in the affected patient. This is the first proof that a clinical isolate of E. rostratum is also an effective plant pathogen. PMID:25285444

Sharma, Kalpana; Goss, Erica M.; Dickstein, Ellen R.; Smith, Matthew E.; Johnson, Judith A.; Southwick, Frederick S.; van Bruggen, Ariena H. C.

2014-01-01

230

Exserohilum rostratum: Characterization of a Cross-Kingdom Pathogen of Plants and Humans.  

PubMed

Pathogen host shifts represent a major source of new infectious diseases. There are several examples of cross-genus host jumps that have caused catastrophic epidemics in animal and plant species worldwide. Cross-kingdom jumps are rare, and are often associated with nosocomial infections. Here we provide an example of human-mediated cross-kingdom jumping of Exserohilum rostratum isolated from a patient who had received a corticosteroid injection and died of fungal meningitis in a Florida hospital in 2012. The clinical isolate of E. rostratum was compared with two plant pathogenic isolates of E. rostratum and an isolate of the closely related genus Bipolaris in terms of morphology, phylogeny, and pathogenicity on one C3 grass, Gulf annual rye grass (Lolium multiflorum), and two C4 grasses, Japanese stilt grass (Microstegium vimineum) and bahia grass (Paspalum notatum). Colony growth and color, as well as conidia shape and size were the same for the clinical and plant isolates of E. rostratum, while these characteristics differed slightly for the Bipolaris sp. isolate. The plant pathogenic and clinical isolates of E. rostratum were indistinguishable based on morphology and ITS and 28S rDNA sequence analysis. The clinical isolate was as pathogenic to all grass species tested as the plant pathogenic strains that were originally isolated from plant hosts. The clinical isolate induced more severe symptoms on stilt grass than on rye grass, while this was the reverse for the plant isolates of E. rostratum. The phylogenetic similarity between the clinical and plant-associated E. rostratum isolates and the ability of the clinical isolate to infect plants suggests that a plant pathogenic strain of E. rostratum contaminated the corticosteroid injection fluid and was able to cause systemic disease in the affected patient. This is the first proof that a clinical isolate of E. rostratum is also an effective plant pathogen. PMID:25285444

Sharma, Kalpana; Goss, Erica M; Dickstein, Ellen R; Smith, Matthew E; Johnson, Judith A; Southwick, Frederick S; van Bruggen, Ariena H C

2014-01-01

231

A critical role of autophagy in plant resistance to necrotrophic fungal pathogens.  

PubMed

Autophagy is a pathway for degradation of cytoplasmic components. In plants, autophagy plays an important role in nutrient recycling during nitrogen or carbon starvation, and in responses to abiotic stress. Autophagy also regulates age- and immunity-related programmed cell death, which is important in plant defense against biotrophic pathogens. Here we show that autophagy plays a critical role in plant resistance to necrotrophic pathogens. ATG18a, a critical autophagy protein in Arabidopsis, interacts with WRKY33, a transcription factor that is required for resistance to necrotrophic pathogens. Expression of autophagy genes and formation of autophagosomes are induced in Arabidopsis by the necrotrophic fungal pathogen Botrytis cinerea. Induction of ATG18a and autophagy by B. cinerea was compromised in the wrky33 mutant, which is highly susceptible to necrotrophic pathogens. Arabidopsis mutants defective in autophagy exhibit enhanced susceptibility to the necrotrophic fungal pathogens B. cinerea and Alternaria brassicicola based on increased pathogen growth in the mutants. The hypersusceptibility of the autophagy mutants was associated with reduced expression of the jasmonate-regulated PFD1.2 gene, accelerated development of senescence-like chlorotic symptoms, and increased protein degradation in infected plant tissues. These results strongly suggest that autophagy cooperates with jasmonate- and WRKY33-mediated signaling pathways in the regulation of plant defense responses to necrotrophic pathogens. PMID:21395886

Lai, Zhibing; Wang, Fei; Zheng, Zuyu; Fan, Baofang; Chen, Zhixiang

2011-06-01

232

Phenotypic Variation in the Plant Pathogenic Bacterium Acidovorax citrulli  

PubMed Central

Acidovorax citrulli causes bacterial fruit blotch (BFB) of cucurbits, a disease that threatens the cucurbit industry worldwide. Despite the economic importance of BFB, little is known about pathogenicity and fitness strategies of the bacterium. We have observed the phenomenon of phenotypic variation in A. citrulli. Here we report the characterization of phenotypic variants (PVs) of two strains, M6 and 7a1, isolated from melon and watermelon, respectively. Phenotypic variation was observed following growth in rich medium, as well as upon isolation of bacteria from inoculated plants or exposure to several stresses, including heat, salt and acidic conditions. When grown on nutrient agar, all PV colonies possessed a translucent appearance, in contrast to parental strain colonies that were opaque. After 72 h, PV colonies were bigger than parental colonies, and had a fuzzy appearance relative to parental strain colonies that are relatively smooth. A. citrulli colonies are generally surrounded by haloes detectable by the naked eye. These haloes are formed by type IV pilus (T4P)-mediated twitching motility that occurs at the edge of the colony. No twitching haloes could be detected around colonies of both M6 and 7a1 PVs, and microscopy observations confirmed that indeed the PVs did not perform twitching motility. In agreement with these results, transmission electron microscopy revealed that M6 and 7a1 PVs do not produce T4P under tested conditions. PVs also differed from their parental strain in swimming motility and biofilm formation, and interestingly, all assessed variants were less virulent than their corresponding parental strains in seed transmission assays. Slight alterations could be detected in some DNA fingerprinting profiles of 7a1 variants relative to the parental strain, while no differences at all could be seen among M6 variants and parental strain, suggesting that, at least in the latter, phenotypic variation is mediated by slight genetic and/or epigenetic alterations. PMID:24023830

Shrestha, Ram Kumar; Rosenberg, Tally; Makarovsky, Daria; Eckshtain-Levi, Noam; Zelinger, Einat; Kopelowitz, June; Sikorski, Johannes; Burdman, Saul

2013-01-01

233

Phenotypic variation in the plant pathogenic bacterium Acidovorax citrulli.  

PubMed

Acidovorax citrulli causes bacterial fruit blotch (BFB) of cucurbits, a disease that threatens the cucurbit industry worldwide. Despite the economic importance of BFB, little is known about pathogenicity and fitness strategies of the bacterium. We have observed the phenomenon of phenotypic variation in A. citrulli. Here we report the characterization of phenotypic variants (PVs) of two strains, M6 and 7a1, isolated from melon and watermelon, respectively. Phenotypic variation was observed following growth in rich medium, as well as upon isolation of bacteria from inoculated plants or exposure to several stresses, including heat, salt and acidic conditions. When grown on nutrient agar, all PV colonies possessed a translucent appearance, in contrast to parental strain colonies that were opaque. After 72 h, PV colonies were bigger than parental colonies, and had a fuzzy appearance relative to parental strain colonies that are relatively smooth. A. citrulli colonies are generally surrounded by haloes detectable by the naked eye. These haloes are formed by type IV pilus (T4P)-mediated twitching motility that occurs at the edge of the colony. No twitching haloes could be detected around colonies of both M6 and 7a1 PVs, and microscopy observations confirmed that indeed the PVs did not perform twitching motility. In agreement with these results, transmission electron microscopy revealed that M6 and 7a1 PVs do not produce T4P under tested conditions. PVs also differed from their parental strain in swimming motility and biofilm formation, and interestingly, all assessed variants were less virulent than their corresponding parental strains in seed transmission assays. Slight alterations could be detected in some DNA fingerprinting profiles of 7a1 variants relative to the parental strain, while no differences at all could be seen among M6 variants and parental strain, suggesting that, at least in the latter, phenotypic variation is mediated by slight genetic and/or epigenetic alterations. PMID:24023830

Shrestha, Ram Kumar; Rosenberg, Tally; Makarovsky, Daria; Eckshtain-Levi, Noam; Zelinger, Einat; Kopelowitz, June; Sikorski, Johannes; Burdman, Saul

2013-01-01

234

RNA silencing suppression by plant pathogens: defence, counter-defence and counter-counter-defence.  

PubMed

RNA silencing is a central regulator of gene expression in most eukaryotes and acts both at the transcriptional level through DNA methylation and at the post-transcriptional level through direct mRNA interference mediated by small RNAs. In plants and invertebrates, the same pathways also function directly in host defence against viruses by targeting viral RNA for degradation. Successful viruses have consequently evolved diverse mechanisms to avoid silencing, most notably through the expression of viral suppressors of RNA silencing. RNA silencing suppressors have also been recently identified in plant pathogenic bacteria and oomycetes, suggesting that disruption of host silencing is a general virulence strategy across several kingdoms of plant pathogens. There is also increasing evidence that plants have evolved specific defences against RNA-silencing suppression by pathogens, providing yet another illustration of the never-ending molecular arms race between plant pathogens and their hosts. PMID:24129510

Pumplin, Nathan; Voinnet, Olivier

2013-11-01

235

Combating Pathogenic Microorganisms Using Plant-Derived Antimicrobials: A Minireview of the Mechanistic Basis  

PubMed Central

The emergence of antibiotic resistance in pathogenic bacteria has led to renewed interest in exploring the potential of plant-derived antimicrobials (PDAs) as an alternative therapeutic strategy to combat microbial infections. Historically, plant extracts have been used as a safe, effective, and natural remedy for ailments and diseases in traditional medicine. Extensive research in the last two decades has identified a plethora of PDAs with a wide spectrum of activity against a variety of fungal and bacterial pathogens causing infections in humans and animals. Active components of many plant extracts have been characterized and are commercially available; however, research delineating the mechanistic basis of their antimicrobial action is scanty. This review highlights the potential of various plant-derived compounds to control pathogenic bacteria, especially the diverse effects exerted by plant compounds on various virulence factors that are critical for pathogenicity inside the host. In addition, the potential effect of PDAs on gut microbiota is discussed. PMID:25298964

Upadhyaya, Indu; Kollanoor-Johny, Anup

2014-01-01

236

Upscaled CTAB-Based DNA Extraction and Real-Time PCR Assays for Fusarium culmorum and F. graminearum DNA in Plant Material with Reduced Sampling Error  

PubMed Central

Fusarium graminearum Schwabe (Gibberella zeae Schwein. Petch.) and F. culmorum W.G. Smith are major mycotoxin producers in small-grain cereals afflicted with Fusarium head blight (FHB). Real-time PCR (qPCR) is the method of choice for species-specific, quantitative estimation of fungal biomass in plant tissue. We demonstrated that increasing the amount of plant material used for DNA extraction to 0.5–1.0 g considerably reduced sampling error and improved the reproducibility of DNA yield. The costs of DNA extraction at different scales and with different methods (commercial kits versus cetyltrimethylammonium bromide-based protocol) and qPCR systems (doubly labeled hybridization probes versus SYBR Green) were compared. A cost-effective protocol for the quantification of F. graminearum and F. culmorum DNA in wheat grain and maize stalk debris based on DNA extraction from 0.5–1.0 g material and real-time PCR with SYBR Green fluorescence detection was developed. PMID:19330077

Brandfass, Christoph; Karlovsky, Petr

2008-01-01

237

The role of effectors in nonhost resistance to filamentous plant pathogens  

PubMed Central

In nature, most plants are resistant to a wide range of phytopathogens. However, mechanisms contributing to this so-called nonhost resistance (NHR) are poorly understood. Besides constitutive defenses, plants have developed two layers of inducible defense systems. Plant innate immunity relies on recognition of conserved pathogen-associated molecular patterns (PAMPs). In compatible interactions, pathogenicity effector molecules secreted by the invader can suppress host defense responses and facilitate the infection process. Additionally, plants have evolved pathogen-specific resistance mechanisms based on recognition of these effectors, which causes secondary defense responses. The current effector-driven hypothesis is that NHR in plants that are distantly related to the host plant is triggered by PAMP recognition that cannot be efficiently suppressed by the pathogen, whereas in more closely related species, nonhost recognition of effectors would play a crucial role. In this review we give an overview of current knowledge of the role of effector molecules in host and NHR and place these findings in the context of the model. We focus on examples from filamentous pathogens (fungi and oomycetes), discuss their implications for the field of plant-pathogen interactions and relevance in plant breeding strategies for development of durable resistance in crops.

Stam, Remco; Mantelin, Sophie; McLellan, Hazel; Thilliez, Gaëtan

2014-01-01

238

Fatal breakthrough infection with Fusarium andiyazi: new multi-resistant aetiological agent cross-reacting with Aspergillus galactomannan enzyme immunoassay.  

PubMed

Disseminated infections caused by members of the Fusarium fujikuroi species complex (FFSC) occur regularly in immunocompromised patients. Here, we present the first human case caused by FFSC-member Fusarium andiyazi. Fever, respiratory symptoms and abnormal computerised tomography findings developed in a 65-year-old man with acute myelogenous leukaemia who was under posaconazole prophylaxis during his remission-induction chemotherapy. During the course of infection, two consecutive blood galactomannan values were found to be positive, and two blood cultures yielded strains resembling Fusarium species, according to morphological appearance. The aetiological agent proved to be F. andiyazi based on multilocus sequence typing. The sequencing of the internal transcribed spacer region did not resolve the closely related members of the FFSC, but additional data on partial sequence of transcription elongation factor 1 alpha subunit did. A detailed morphological study confirmed the identification of F. andiyazi, which had previously only been reported as a plant pathogen affecting various food crops. PMID:24612042

Kebabc?, Nesrin; van Diepeningen, Anne D; Ener, Beyza; Ersal, Tuba; Meijer, Martin; Al-Hatmi, Abdullah M S; Ozkocaman, Vildan; Ursava?, Ahmet; Cetino?lu, Ezgi D; Akal?n, Halis

2014-04-01

239

The Effect of Nitrogen on Disease Development and Gene Expression in Bacterial and Fungal Plant Pathogens  

Microsoft Academic Search

Successful colonisation of plants by pathogens requires efficient utilisation of nutrient resources available in host tissues. Several bacterial and fungal genes are specifically induced during pathogenesis and under nitrogen-limiting conditions in vitro. This suggests that a nitrogen-limiting environment may be one of the cues for disease symptom development during growth of the pathogens in planta. Here we review recent literature

Sandor S. Snoeijers; Alejandro Pérez-García; Matthieu H. A. J. Joosten

2000-01-01

240

Cytochemical Labeling for Fungal and Host Components in Plant Tissues Inoculated with Fungal Wilt Pathogens  

NASA Astrophysics Data System (ADS)

Antibodies to detect pectin in present investigations attached to distinct fibrils in vessel lumina. In carnation infected with an isolate of Fusarium oxysporum f.sp., labeling of pathogen cells also occurred; in a resistant cultivar (cv.), it was coincident with proximate pectin fibrils and linked to altered fungal walls, which was the opposite in the susceptible cv., indicating that hindrance of pathogen ability to degrade pectin may be related to resistance. Labeling of the fungus in culture was nil, except in media containing pectin, showing that pectin is not native to the pathogen. Labeling of fungal walls for cellulose in elm (inoculated with Ophiostoma novo-ulmi) and carnation also occurred, linked to adsorbed host wall components. The chitin probe often attached to dispersed matter, in vessel lumina, traceable to irregularly labeled fungal cells and host wall degradation products. With an anti-horseradish peroxidase probe, host and fungal walls were equally labeled, and with a glucosidase, differences of labeling between these walls were observed, depending on pH of the test solution. Fungal extracellular matter and filamentous structures, present in fungal walls, predominantly in another elm isolate (Phaeotheca dimorphospora), did not label with any of the probes used. However, in cultures of this fungus, extracellular material labeled, even at a distance from the colony margin, with an anti-fimbriae probe.

Ouellette, G. B.; Baayen, R. P.; Chamberland, H.; Simard, M.; Rioux, D.; Charest, P. M.

2004-08-01

241

Complex interactions between a plant pathogen and insect parasitoid via the shared vector-host: consequences for host plant infection  

Microsoft Academic Search

Plant viruses modify the development of their aphid vectors by inducing physiological changes in the shared host plant. The\\u000a performance of hymenopterous parasitoids exploiting these aphids can also be modified by the presence of the plant pathogen.\\u000a We used laboratory and glasshouse microcosms containing beans (Vicia faba) as the host plant to examine the interactions between a plant virus (pea

Simon Hodge; Glen Powell

2008-01-01

242

1268 Plant Disease /Vol. 97 No. 10 Integrated Control of Potato Pathogens  

E-print Network

, produce, or sell planting material for vegetative fruit and vegetable crops to farm- ers. The exception domain. Seed potato production in Wisconsin is an example of produc- tion and certification of planting1268 Plant Disease /Vol. 97 No. 10 Integrated Control of Potato Pathogens Through Seed Potato

Scharer, John E.

243

Biofilm formation by enteric pathogens and its role in plant colonization and persistence.  

PubMed

The significant increase in foodborne outbreaks caused by contaminated fresh produce, such as alfalfa sprouts, lettuce, melons, tomatoes and spinach, during the last 30 years stimulated investigation of the mechanisms of persistence of human pathogens on plants. Emerging evidence suggests that Salmonella enterica and Escherichia coli, which cause the vast majority of fresh produce outbreaks, are able to adhere to and to form biofilms on plants leading to persistence and resistance to disinfection treatments, which subsequently can cause human infections and major outbreaks. In this review, we present the current knowledge about host, bacterial and environmental factors that affect the attachment to plant tissue and the process of biofilm formation by S.?enterica and E.?coli, and discuss how biofilm formation assists in persistence of pathogens on the plants. Mechanisms used by S.?enterica and E.?coli to adhere and persist on abiotic surfaces and mammalian cells are partially similar and also used by plant pathogens and symbionts. For example, amyloid curli fimbriae, part of the extracellular matrix of biofilms, frequently contribute to adherence and are upregulated upon adherence and colonization of plant material. Also the major exopolysaccharide of the biofilm matrix, cellulose, is an adherence factor not only of S.?enterica and E.?coli, but also of plant symbionts and pathogens. Plants, on the other hand, respond to colonization by enteric pathogens with a variety of defence mechanisms, some of which can effectively inhibit biofilm formation. Consequently, plant compounds might be investigated for promising novel antibiofilm strategies. PMID:25351039

Yaron, Sima; Römling, Ute

2014-11-01

244

Emergence and evolution of Arsenophonus bacteria as insect-vectored plant pathogens.  

PubMed

Arsenophonus bacteria are among the most biologically diverse and widespread endosymbionts of arthropods. Notably, two species, Phlomobacter fragariae and Arsenophonus phytopathogenicus, have been characterized as phloem-restricted plant pathogens that are obligatorily transmitted by and hosted in planthoppers of the family Cixiidae (Hemiptera: Auchenorrhyncha). Here, I review the current understanding on the lifestyle transition, evolution, host interaction, and infection cycles of these emerging plant pathogens. PMID:24444593

Bressan, Alberto

2014-03-01

245

CANNABIS CLINIC Fusarium Wilt  

Microsoft Academic Search

Fusarium wilt is caused by two closely-related fungi, Fusarium oxysporum f. sp. vasinfectum and Fusarium oxysporum f. sp. cannabis. The disease was first described on hemp in Eastern Europe about 50 years ago, but is now found throughout the Northern hemisphere. Greenhouse studies demonstrated that all cultivars of Cannabis that were tested are susceptible. Signs and symptoms, life history of

John M. McPartland; Karl W. Hillig

2004-01-01

246

Development of a Fusarium graminearum Affymetrix GeneChip for profiling fungal gene expression in vitro and in planta  

Microsoft Academic Search

Recently the genome sequences of several filamentous fungi have become available, providing the opportunity for large-scale functional analysis including genome-wide expression analysis. We report the design and validation of the first Affymetrix GeneChip microarray based on the entire genome of a filamentous fungus, the ascomycetous plant pathogen Fusarium graminearum. To maximize the likelihood of representing all putative genes (?14,000) on

Ulrich Güldener; Kye-Yong Seong; Jayanand Boddu; Seungho Cho; Frances Trail; Jin-Rong Xu; Gerhard Adam; Hans-Werner Mewes; Gary J. Muehlbauer; H. Corby Kistler

2006-01-01

247

Comparative analysis of 87,000 expressed sequence tags from the fumonisin-producing fungus Fusarium verticillioides  

Microsoft Academic Search

Fusarium verticillioides (teleomorph Gibberella moniliformis) is a pathogen of maize worldwide and produces fumonisins, a family of mycotoxins that have been associated with several animal diseases as well as cancer in humans. In this study, we sought to identify fungal genes that affect fumonisin production and\\/or the plant–fungal interaction. We generated over 87,000 expressed sequence tags from nine different cDNA

Daren W. Brown; Foo Cheung; Robert H. Proctor; Robert A. E. Butchko; Li Zheng; Yuandan Lee; Teresa Utterback; Shannon Smith; Tamara Feldblyum; Anthony E. Glenn; Ronald D. Plattner; David F. Kendra; Christopher D. Town; Catherine A. Whitelaw

2005-01-01

248

The evolutionary strategies of plant defenses have a dynamic impact on the adaptations and interactions of vectors and pathogens.  

PubMed

Plants have evolved and diversified to reduce the damages imposed by infectious pathogens and herbivorous insects. Living in a sedentary lifestyle, plants are constantly adapting to their environment. They employ various strategies to increase performance and fitness. Thus, plants developed cost-effective strategies to defend against specific insects and pathogens. Plant defense, however, imposes selective pressure on insects and pathogens. This selective pressure provides incentives for pathogens and insects to diversify and develop strategies to counter plant defense. This results in an evolutionary arms race among plants, pathogens and insects. The ever-changing adaptations and physiological alterations among these organisms make studying plant-vector-pathogen interactions a challenging and fascinating field. Studying plant defense and plant protection requires knowledge of the relationship among organisms and the adaptive strategies each organism utilize. Therefore, this review focuses on the integral parts of plant-vector-pathogen interactions in order to understand the factors that affect plant defense and disease development. The review addresses plant-vector-pathogen co-evolution, plant defense strategies, specificity of plant defenses and plant-vector-pathogen interactions. Improving the comprehension of these factors will provide a multi-dimensional perspective for the future research in pest and disease management. PMID:23955882

Huot, Ordom Brian; Nachappa, Punya; Tamborindeguy, Cecilia

2013-06-01

249

A proteomic approach provides new insights into the control of soil-borne plant pathogens by Bacillus species.  

PubMed

Beneficial microorganisms (also known as biopesticides) are considered to be one of the most promising methods for more rational and safe crop management practices. We used Bacillus strains EU07, QST713 and FZB24, and investigated their inhibitory effect on Fusarium. Bacterial cell cultures, cell-free supernatants and volatiles displayed varying degrees of suppressive effect. Proteomic analysis of secreted proteins from EU07 and FZB24 revealed the presence of lytic enzymes, cellulases, proteases, 1,4-?-glucanase and hydrolases, all of which contribute to degradation of the pathogen cell wall. Further proteomic investigations showed that proteins involved in metabolism, protein folding, protein degradation, translation, recognition and signal transduction cascade play an important role in the control of Fusarium oxysporum. Our findings provide new knowledge on the mechanism of action of Bacillus species and insight into biocontrol mechanisms. PMID:23301041

Baysal, Omür; Lai, Duo; Xu, Han-Hong; Siragusa, Mirko; Cal??kan, Mikail; Carimi, Francesco; da Silva, Jaime A Teixeira; Tör, Mahmut

2013-01-01

250

A Proteomic Approach Provides New Insights into the Control of Soil-Borne Plant Pathogens by Bacillus Species  

PubMed Central

Beneficial microorganisms (also known as biopesticides) are considered to be one of the most promising methods for more rational and safe crop management practices. We used Bacillus strains EU07, QST713 and FZB24, and investigated their inhibitory effect on Fusarium. Bacterial cell cultures, cell-free supernatants and volatiles displayed varying degrees of suppressive effect. Proteomic analysis of secreted proteins from EU07 and FZB24 revealed the presence of lytic enzymes, cellulases, proteases, 1,4-?-glucanase and hydrolases, all of which contribute to degradation of the pathogen cell wall. Further proteomic investigations showed that proteins involved in metabolism, protein folding, protein degradation, translation, recognition and signal transduction cascade play an important role in the control of Fusarium oxysporum. Our findings provide new knowledge on the mechanism of action of Bacillus species and insight into biocontrol mechanisms. PMID:23301041

Xu, Han-Hong; Siragusa, Mirko; Cal?skan, Mikail; Carimi, Francesco; da Silva, Jaime A. Teixeira.; Tor, Mahmut

2013-01-01

251

Avoidance and suppression of plant defenses by herbivores and pathogens  

Microsoft Academic Search

Plants are nutritious and hence herbivores and phytopathogens have specialized to attack and consume them. In turn, plants have evolved adaptations to detect and withstand these attacks. Such adaptations we call ‘defenses’ and they can operate either directly between the plant and the plant consumer or indirectly i.e. when taking effect via other organisms such as predators and parasitoids of

Juan M. Alba; Joris J. Glas; Bernardus C. J. Schimmel; Merijn R. Kant

2011-01-01

252

Very long chain fatty acid and lipid signaling in the response of plants to pathogens.  

PubMed

Recent findings indicate that lipid signaling is essential for plant resistance to pathogens. Besides oxylipins and unsaturated fatty acids known to play important signaling functions during plant-pathogen interactions, the very long chain fatty acid (VLCFA) biosynthesis pathway has been recently associated to plant defense through different aspects. VLCFAs are indeed required for the biosynthesis of the plant cuticle and the generation of sphingolipids. Elucidation of the roles of these lipids in biotic stress responses is the result of the use of genetic approaches together with the identification of the genes/proteins involved in their biosynthesis. This review focuses on recent observations which revealed the complex function of the cuticle and cuticle-derived signals, and the key role of sphingolipids as bioactive molecules involved in signal transduction and cell death regulation during plant-pathogen interactions. PMID:19649180

Raffaele, Sylvain; Leger, Amandine; Roby, Dominique

2009-02-01

253

Impact of the UPR on the virulence of the plant fungal pathogen A. brassicicola  

PubMed Central

The fungal genus Alternaria contains many destructive plant pathogens, including Alternaria brassicicola, which causes black spot disease on a wide range of Brassicaceae plants and which is routinely used as a model necrotrophic pathogen in studies with Arabidopsis thaliana. During host infection, many fungal proteins that are critical for disease progression are processed in the endoplasmic reticulum (ER)/Golgi system and secreted in planta. The unfolded protein response (UPR) is an essential part of ER protein quality control that ensures efficient maturation of secreted and membrane-bound proteins in eukaryotes. This review highlights the importance of the UPR signaling pathway with respect to the ability of A. brassicicola to efficiently accomplish key steps of its pathogenic life cycle. Understanding the pathogenicity mechanisms that fungi uses during infection is crucial for the development of new antifungal therapies. Therefore the UPR pathway has emerged as a promising drug target for plant disease control. PMID:24189567

Guillemette, Thomas; Calmes, Benoit; Simoneau, Philippe

2014-01-01

254

Researchers Discover Mechanism of Plant Resistance to Pathogens  

NSF Publications Database

... plants have an effective and sophisticated immune system. Their first line of defense is a thick ... of immune systems in plants and animals, bacterial flagellin can also trigger innate immune response ...

255

Ecology and Human Pathogenicity of Plant-Associated Bacteria  

Microsoft Academic Search

\\u000a Plant species and organs are colonised by diverse bacterial communities, which fulfil important functions for their host.\\u000a Plant-associated bacteria have a great potential in diverse areas of biotechnology, e.g. as biological control agents (BCAs)\\u000a in plant protection. Although many of them have a positive interaction with their host plants, they can interact with other\\u000a eukaryotic hosts like humans in a

Gabriele Berg; Christin Zachow; Massimiliano Cardinale; Henry Müller

256

A rapid method for isolation of total DNA from pathogenic filamentous plant fungi.  

PubMed

DNA isolation from some fungal organisms of agronomic importance is difficult because they have cell walls or capsules that are relatively unsusceptible to lysis. We have developed a fast DNA isolation protocol for Fusarium oxysporum, which causes fusarium wilt disease in more than 100 plant species, and for Pyrenochaeta terrestris, which causes pink root in onions. This protocol was based on the sodium dodecyl sulfate/phenol method, without beta-mercaptoethanol and without maceration in liquid nitrogen; it uses phenol/chloroform extraction to remove proteins and co-precipitated polysaccharides. The A(260/280) absorbance ratios of isolated DNA were around 1.9, suggesting that the DNA fraction was pure and may be used for further analysis. Additionally, the A(260/230) values were higher than 1.8, suggesting negligible contamination by polysaccharides. The DNA isolated by this protocol is of sufficient quality for molecular applications; this technique could be applied to other organisms that have similar substances that hinder DNA extraction. PMID:20198572

González-Mendoza, D; Argumedo-Delira, R; Morales-Trejo, A; Pulido-Herrera, A; Cervantes-Díaz, L; Grimaldo-Juarez, O; Alarcón, A

2010-01-01

257

Modified Primers for the Identification of Nonpathogenic Fusarium oxysporum Isolates That Have Biological Control Potential against Fusarium Wilt of Cucumber in Taiwan  

PubMed Central

Previous investigations demonstrated that Fusarium oxysporum (Fo), which is not pathogenic to cucumbers, could serve as a biological control agent for managing Fusarium wilt of cucumber caused by Fo f. sp. cucumerinum (Foc) in Taiwan. However, thus far it has not been possible to separate the populations of pathogenic Fo from the nonpathogenic isolates that have biological control potential through their morphological characteristics. Although these two populations can be distinguished from one another using a bioassay, the work is laborious and time-consuming. In this study, a fragment of the intergenic spacer (IGS) region of ribosomal DNA from an Fo biological control agent, Fo366, was PCR-amplified with published general primers, FIGS11/FIGS12 and sequenced. A new primer, NPIGS-R, which was designed based on the IGS sequence, was paired with the FIGS11 primer. These primers were then evaluated for their specificity to amplify DNA from nonpathogenic Fo isolates that have biological control potential. The results showed that the modified primer pair, FIGS11/NPIGS-R, amplified a 500-bp DNA fragment from five of seven nonpathogenic Fo isolates. These five Fo isolates delayed symptom development of cucumber Fusarium wilt in greenhouse bioassay tests. Seventy-seven Fo isolates were obtained from the soil and plant tissues and then subjected to amplification using the modified primer pair; six samples showed positive amplification. These six isolates did not cause symptoms on cucumber seedlings when grown in peat moss infested with the isolates and delayed disease development when the same plants were subsequently inoculated with a virulent isolate of Foc. Therefore, the modified primer pair may prove useful for the identification of Fo isolates that are nonpathogenic to cucumber which can potentially act as biocontrol agents for Fusarium wilt of cucumber. PMID:23762289

Wang, Chaojen; Lin, Yisheng; Lin, Yinghong; Chung, Wenhsin

2013-01-01

258

Non-streptomycete actinomycetes as biocontrol agents of soil-borne fungal plant pathogens and as plant growth promoters  

Microsoft Academic Search

Among soil microorganisms, bacteria and fungi and to a lesser extent actinomycetes, have received considerable attention as biocontrol agents of soil-borne fungal plant pathogens and as plant growth promoters. Within actinomycetes, Streptomyces spp. have been investigated predominantly, mainly because of their dominance on, and the ease of isolation from, dilution plates and because of the commercial interest shown on the

Khaled A. El-Tarabily; Krishnapillai Sivasithamparam

2006-01-01

259

UC Davis Policies and Practices for Work with Transgenic Plants and Plant Pathogens 1 | P a g e  

E-print Network

viable materials, after removing gloves, and before leaving the laboratory. 3. Eating, drinking contamination or soiling of street clothes and dissemination of plant material or plant pathogens outside Containment of fruit and seed Watering Staking and trimming #12;UC Davis Policies and Practices for Work

Ferrara, Katherine W.

260

Phaeohyphomycosis caused by a plant pathogen, Corynespora cassiicola.  

PubMed

We report a case of subcutaneous phaeohyphomycosis caused by Corynespora cassiicola. Molecular identification of this pathogen on grasses confirms that it may be involved in human infection, as previously reported once in pre-molecular literature. In vitro antifungal susceptibility data of the strain are provided. The patient was successfully treated with oral terbinafine with topical povidone iodine in accordance with the results obtained through in vitro susceptibility testing. PMID:21281061

Lv, Gui X; Ge, Yi P; Shen, Yong N; Li, Min; Zhang, X; Chen, Hao; Deng, S; de Hoog, G Sybren; Liu, Wei D

2011-08-01

261

Ethylene-dependent salicylic acid regulates an expanded cell death response to a plant pathogen  

E-print Network

Ethylene-dependent salicylic acid regulates an expanded cell death response to a plant pathogen@gnv.ifas.uÂŻ.edu). Summary The molecular events associated with susceptible plant responses to disease-causing organisms stress. Because the metabolic cost of producing a battery of gene products is high, defense responses

Klee, Harry J.

262

Harpins, multifunctional proteins secreted by gram-negative plant-pathogenic bacteria.  

PubMed

Harpins are glycine-rich and heat-stable proteins that are secreted through type III secretion system in gram-negative plant-pathogenic bacteria. Many studies show that these proteins are mostly targeted to the extracellular space of plant tissues, unlike bacterial effector proteins that act inside the plant cells. Over the two decades since the first harpin of pathogen origin, HrpN of Erwinia amylovora, was reported in 1992 as a cell-free elicitor of hypersensitive response (HR), diverse functional aspects of harpins have been determined. Some harpins were shown to have virulence activity, probably because of their involvement in the translocation of effector proteins into plant cytoplasm. Based on this function, harpins are now considered to be translocators. Their abilities of pore formation in the artificial membrane, binding to lipid components, and oligomerization are consistent with this idea. When harpins are applied to plants directly or expressed in plant cells, these proteins trigger diverse beneficial responses such as induction of defense responses against diverse pathogens and insects and enhancement of plant growth. Therefore, in this review, we will summarize the functions of harpins as virulence factors (or translocators) of bacterial pathogens, elicitors of HR and immune responses, and plant growth enhancers. PMID:23745678

Choi, Min-Seon; Kim, Wooki; Lee, Chanhui; Oh, Chang-Sik

2013-10-01

263

Arbuscular mycorrhizal fungal spore-associated bacteria affect mycorrhizal colonization, plant growth and potato pathogens  

Microsoft Academic Search

Arbuscular mycorrhizal (AM) fungi and their bacterial associates are essential living components of the soil microbiota. From a total of 385 bacteria previously isolated from spores of AM fungi (AMB), 10 were selected based on ability to inhibit growth of plant pathogens. Effects of these isolates on AM fungal colonization, plant growth in potato (Solanum tuberosum L.) and inhibition of

Dharam Parkash Bharadwaj; Per-Olof Lundquist; Sadhna Alström

2008-01-01

264

Affinity Purification and Characterization of a Cutinase from the Fungal Plant Pathogen Monilinia fructicola (Wint.) Honey  

E-print Network

Affinity Purification and Characterization of a Cutinase from the Fungal Plant Pathogen Monilinia plant patho- gen Monilinia fructicola and to serve as an effective affinity ligand for the purification-Sepharose. Buffer containing 0.5% Triton X-100 also selectively eluted cutinases from the affin- ity column. Two

Hammock, Bruce D.

265

The role of the secondary cell wall in plant resistance to pathogens  

PubMed Central

Plant resistance to pathogens relies on a complex network of constitutive and inducible defensive barriers. The plant cell wall is one of the barriers that pathogens need to overcome to successfully colonize plant tissues. The traditional view of the plant cell wall as a passive barrier has evolved to a concept that considers the wall as a dynamic structure that regulates both constitutive and inducible defense mechanisms, and as a source of signaling molecules that trigger immune responses. The secondary cell walls of plants also represent a carbon-neutral feedstock (lignocellulosic biomass) for the production of biofuels and biomaterials. Therefore, engineering plants with improved secondary cell wall characteristics is an interesting strategy to ease the processing of lignocellulosic biomass in the biorefinery. However, modification of the integrity of the cell wall by impairment of proteins required for its biosynthesis or remodeling may impact the plants resistance to pathogens. This review summarizes our understanding of the role of the plant cell wall in pathogen resistance with a focus on the contribution of lignin to this biological process. PMID:25161657

Miedes, Eva; Vanholme, Ruben; Boerjan, Wout; Molina, Antonio

2014-01-01

266

Antimicrobial activities of extracts from tropical Atlantic marine plants against marine pathogens and saprophytes  

Microsoft Academic Search

Studies investigating disease resistance in marine plants have indicated that secondary metabolites may have important defensive functions against harmful marine microorganisms. The goal of this study was to systematically screen extracts from marine plants for antimicrobial effects against marine pathogens and saprophytes. Lipophilic and hydrophilic extracts from species of 49 marine algae and 3 seagrasses collected in the tropical Atlantic

Sebastian Engel; Melany P. Puglisi; Paul R. Jensen; William Fenical

2006-01-01

267

Incursion preparedness: anticipating the arrival of an economically important plant pathogen Xylella fastidiosa Wells (Proteobacteria  

E-print Network

interceptions of H. vitripennis and the potential for X. fastidiosa to be moved in live plant material or within live vectors indicate the need for rapid detection of an incursion in areas considered at high riskIncursion preparedness: anticipating the arrival of an economically important plant pathogen

Hoddle, Mark S.

268

Plant-in-chip: Microfluidic system for studying root growth and pathogenic interactions in Arabidopsis  

NASA Astrophysics Data System (ADS)

We report a microfluidic platform for the hydroponic growth of Arabidopsis plants with high-resolution visualization of root development and root-pathogen interactions. The platform comprises a set of parallel microchannels with individual input/output ports where 1-day old germinated seedlings are initially placed. Under optimum conditions, a root system grows in each microchannel and its images are recorded over a 198-h period. Different concentrations of plant growth media show different root growth characteristics. Later, the developed roots are inoculated with two plant pathogens (nematodes and zoospores) and their physicochemical interactions with the live root systems are observed.

Parashar, Archana; Pandey, Santosh

2011-06-01

269

UBL1 of Fusarium verticillioides links the N-end rule pathway to extracellular sensing and plant pathogenesis.  

PubMed

Fusarium verticillioides produces fumonisin mycotoxins during colonization of maize. Currently, molecular mechanisms underlying responsiveness of F.verticillioides to extracellular cues during pathogenesis are poorly understood. In this study, insertional mutants were created and screened to identify genes involved in responses to extracellular starch. In one mutant, the restriction enzyme-mediated integration cassette disrupted a gene (UBL1) encoding a UBR-Box/RING domain E3 ubiquitin ligase involved in the N-end rule pathway. Disruption of UBL1 in F.verticillioides (?ubl1) influenced conidiation, hyphal morphology, pigmentation and amylolysis. Disruption of UBL1 also impaired kernel colonization, but the ratio of fumonisin B1 per unit growth was not significantly reduced. The inability of a ?ubl1 mutant to recognize an N-end rule degron confirmed involvement of UBL1 in the N-end rule pathway. Additionally, Ubl1 physically interacted with two G protein ? subunits of F.verticillioides, thus implicating UBL1 in G protein-mediated sensing of the external environment. Furthermore, deletion of the UBL1 orthologue in F.graminearum reduced virulence on wheat and maize, thus indicating that UBL1 has a broader role in virulence among Fusarium species. This study provides the first linkage between the N-end rule pathway and fungal pathogenesis, and illustrates a new mechanism through which fungi respond to the external environment. PMID:24237664

Ridenour, John B; Smith, Jonathon E; Hirsch, Robert L; Horevaj, Peter; Kim, Hun; Sharma, Sandeep; Bluhm, Burton H

2014-07-01

270

Plants and pathogens: putting infection strategies and defence mechanisms on the map.  

PubMed

All plant organs are vulnerable to colonisation and molecular manipulation by microbes. When this interaction allows proliferation of the microbe at the expense of the host, the microbe can be described as a pathogen. In our attempts to understand the full nature of the interactions that occur between a potential pathogen and its host, various aspects of the molecular mechanisms of infection and defence have begun to be characterised. There is significant variation in these mechanisms. While previous research has examined plant-pathogen interactions with whole plant/organ resolution, the specificity of infection strategies and changes in both gene expression and protein localisation of immune receptors upon infection suggest there is much to be gained from examination of plant-microbe interactions at the cellular level. PMID:22981427

Faulkner, Christine; Robatzek, Silke

2012-12-01

271

Cloning and expression analysis of NhL1, a gene encoding an extracellular lipase from the fungal pea pathogen Nectria haematococca MP VI (Fusarium solani f. sp. pisi) that is expressed in planta.  

PubMed

The filamentous fungus Nectria haematococca (anamorph Fusarium solani f. sp. pisi) resides in soil, and attacks pea seedlings in the area of the underground epicotyl and upper tap root, causing foot rot disease. We detected lipase activity during in vitro growth of N. haematococca. Subsequently, a lipase gene was cloned and functionally characterised by heterologous expression in Saccharomyces cerevisiae. The full-length cDNA of 1152 bp was cloned using a 3' RACE-PCR approach coupled with cDNA library screening. The genomic clone, comprising an ORF of 999 bp interrupted by two introns of 56 and 64 bp, was isolated from a newly constructed lambda phage library. Analysis of the deduced protein sequence revealed the presence of a typical signal peptide at the N-terminus, and of the three conserved amino acids forming the active site of lipases. The lipase of N. haematococca has a low degree of similarity to the lipases from Humicola lanuginosa (37.2%), Rhizomucor miehei (21.6%), Rhizopus delemar (23.1%), Rhizopus niveus (25.9%), and to mono- and diacylglycerol lipase from Penicillium camembertii (30.8%), and very high similarity (94.6%) to a lipase from Fusarium heterosporum. The lipase from N. haematococca shows maximal activity at 37 degrees C and pH 8.0. Based on Southern analysis, the lipase clone represents a single-copy gene in N. haematococca. Expression analysis was performed by RT-PCR. In vitro, the lipase gene shows a low basal expression, but is highly inducible by lipase substrates, and repressed by glucose. During plant infection, transcripts of this fungal lipase gene were detected 4, 8, and 10 days after infection. PMID:11361331

Nasser Eddine, A; Hannemann, F; Schäfer, W

2001-04-01

272

Dominance relationships of bean pathogens at Lake Balaton.  

PubMed

Dominance relationships of different bean pathogens were examined during 1999-2000 in small plot trials at Lake Balaton in Hungary. In 1999 the dominant pathogen species were Xanthomonas campestris pv. phaseoli. The main cause of the stock decay was due to the infection of Fusarium spp. Bean plants were infected also by Alternaria, Colletotrichum, Macrophomina and Sclerotinia, species part from viruses. Among of thirty-eight examined bean cultivars and genotypes the variety "Díszbab" and the genotype 513 were the most resistant. In 2000 Macrophomina phaseolina and Fusarium spp. caused epidemics. Most of the observed plants died early. The most healthy species and branches were the SC-34-1 and cv. Díszbab. PMID:12425043

Balázs, A; Budai, P; Kadlicskó, S; Kovács, J

2001-01-01

273

Grassland fires may favor native over introduced plants by reducing pathogen loads.  

PubMed

Grasslands have been lost and degraded in the United States since Euro-American settlement due to agriculture, development, introduced invasive species, and changes in fire regimes. Fire is frequently used in prairie restoration to control invasion by trees and shrubs, but may have additional consequences. For example, fire might reduce damage by herbivore and pathogen enemies by eliminating litter, which harbors eggs and spores. Less obviously, fire might influence enemy loads differently for native and introduced plant hosts. We used a controlled burn in a Willamette Valley (Oregon) prairie to examine these questions. We expected that, without fire, introduced host plants should have less damage than native host plants because the introduced species are likely to have left many of their enemies behind when they were transported to their new range (the enemy release hypothesis, or ERH). If the ERH holds, then fire, which should temporarily reduce enemies on all species, should give an advantage to the natives because they should see greater total reduction in damage by enemies. Prior to the burn, we censused herbivore and pathogen attack on eight plant species (five of nonnative origin: Bromus hordaceous, Cynosuros echinatus, Galium divaricatum, Schedonorus arundinaceus (= Festuca arundinacea), and Sherardia arvensis; and three natives: Danthonia californica, Epilobium minutum, and Lomatium nudicale). The same plots were monitored for two years post-fire. Prior to the burn, native plants had more kinds of damage and more pathogen damage than introduced plants, consistent with the ERH. Fire reduced pathogen damage relative to the controls more for the native than the introduced species, but the effects on herbivory were negligible. Pathogen attack was correlated with plant reproductive fitness, whereas herbivory was not. These results suggest that fire may be useful for promoting some native plants in prairies due to its negative effects on their pathogens. PMID:25163122

Roy, Bitty A; Hudson, Kenneth; Visser, Matt; Johnson, Bart R

2014-07-01

274

The ascomycete Verticillium longisporum is a hybrid and a plant pathogen with an expanded host range.  

PubMed

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

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

2011-01-01

275

Life histories of hosts and pathogens predict patterns in tropical fungal plant diseases.  

PubMed

Plant pathogens affect the fitness of their hosts and maintain biodiversity. However, we lack theories to predict the type and intensity of infections in wild plants. Here we demonstrate using fungal pathogens of tropical plants that an examination of the life histories of hosts and pathogens can reveal general patterns in their interactions. Fungal infections were more commonly reported for light-demanding than for shade-tolerant species and for evergreen rather than for deciduous hosts. Both patterns are consistent with classical defence theory, which predicts lower resistance in fast-growing species and suggests that the deciduous habit can reduce enemy populations. In our literature survey, necrotrophs were found mainly to infect shade-tolerant woody species whereas biotrophs dominated in light-demanding herbaceous hosts. Far-red signalling and its inhibitory effects on jasmonic acid signalling are likely to explain this phenomenon. Multiple changes between the necrotrophic and the symptomless endophytic lifestyle at the ecological and evolutionary scale indicate that endophytes should be considered when trying to understand large-scale patterns in the fungal infections of plants. Combining knowledge about the molecular mechanisms of pathogen resistance with classical defence theory enables the formulation of testable predictions concerning general patterns in the infections of wild plants by fungal pathogens. PMID:24171899

García-Guzmán, Graciela; Heil, Martin

2014-03-01

276

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

PubMed Central

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

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

2011-01-01

277

Reaction of glucosinolate-myrosinase defence system in Brassica plants to pathogenicity factor of Sclerotinia sclerotiorum  

Microsoft Academic Search

The glucosinolate-myrosinase defence system, specific to Brassicales plants, produces toxic volatile compounds during mechanical\\u000a injury or pathogen attack. The reaction of this system to oxalic acid, known as a pathogenicity factor of Sclerotinia sclerotiorum, is not fully understood. The hydrolysis of glucosinolates was studied at varying conditions in the presence of oxalic acid\\u000a in the substrate. In a bioassay, colonies

Siamak Rahmanpour; David Backhouse; Heather M. Nonhebel

2010-01-01

278

Genes from mycoparasitic fungi as a source for improving plant resistance to fungal pathogens.  

PubMed

Disease resistance in transgenic plants has been improved, for the first time, by the insertion of a gene from a biocontrol fungus. The gene encoding a strongly antifungal endochitinase from the mycoparasitic fungus Trichoderma harzianum was transferred to tobacco and potato. High expression levels of the fungal gene were obtained in different plant tissues, which had no visible effect on plant growth and development. Substantial differences in endochitinase activity were detected among transformants. Selected transgenic lines were highly tolerant or completely resistant to the foliar pathogens Alternaria alternata, A. solani, Botrytis cinerea, and the soilborne pathogen Rhizoctonia solani. The high level and the broad spectrum of resistance obtained with a single chitinase gene from Trichoderma overcome the limited efficacy of transgenic expression in plants of chitinase genes from plants and bacteria. These results demonstrate a rich source of genes from biocontrol fungi that can be used to control diseases in plants. PMID:9653105

Lorito, M; Woo, S L; Garcia, I; Colucci, G; Harman, G E; Pintor-Toro, J A; Filippone, E; Muccifora, S; Lawrence, C B; Zoina, A; Tuzun, S; Scala, F; Fernandez, I G

1998-07-01

279

Wound-induced pectin methylesterases enhance banana (Musa spp. AAA) susceptibility to Fusarium oxysporum f. sp. cubense  

PubMed Central

Recent studies suggest that plant pectin methylesterases (PMEs) are directly involved in plant defence besides their roles in plant development. However, the molecular mechanisms of PME action on pectins are not well understood. In order to understand how PMEs modify pectins during banana (Musa spp.)–Fusarium interaction, the expression and enzyme activities of PMEs in two banana cultivars, highly resistant or susceptible to Fusarium, were compared with each other. Furthermore, the spatial distribution of PMEs and their effect on pectin methylesterification of 10 individual homogalacturonan (HG) epitopes with different degrees of methylesterification (DMs) were also examined. The results showed that, before pathogen treatment, the resistant cultivar displayed higher PME activity than the susceptible cultivar, corresponding well to the lower level of pectin DM. A significant increase in PME expression and activity and a decrease in pectin DM were observed in the susceptible cultivar but not in the resistant cultivar when plants were wounded, which was necessary for successful infection. With the increase of PME in the wounded susceptible cultivar, the JIM5 antigen (low methyestrified HGs) increased. Forty-eight hours after pathogen infection, the PME activity and expression in the susceptible cultivar were higher than those in the resistant cultivar, while the DM was lower. In conclusion, the resistant and the susceptible cultivars differ significantly in their response to wounding. Increased PMEs and thereafter decreased DMs acompanied by increased low methylesterified HGs in the root vascular cylinder appear to play a key role in determination of banana susceptibility to Fusarium. PMID:23580752

Xu, Chunxiang

2013-01-01

280

Experimental Evolution of a Plant Pathogen into a Legume Symbiont  

PubMed Central

Rhizobia are phylogenetically disparate ?- and ?-proteobacteria that have achieved the environmentally essential function of fixing atmospheric nitrogen in symbiosis with legumes. Ample evidence indicates that horizontal transfer of symbiotic plasmids/islands has played a crucial role in rhizobia evolution. However, adaptive mechanisms that allow the recipient genomes to express symbiotic traits are unknown. Here, we report on the experimental evolution of a pathogenic Ralstonia solanacearum chimera carrying the symbiotic plasmid of the rhizobium Cupriavidus taiwanensis into Mimosa nodulating and infecting symbionts. Two types of adaptive mutations in the hrpG-controlled virulence pathway of R. solanacearum were identified that are crucial for the transition from pathogenicity towards mutualism. Inactivation of the hrcV structural gene of the type III secretion system allowed nodulation and early infection to take place, whereas inactivation of the master virulence regulator hrpG allowed intracellular infection of nodule cells. Our findings predict that natural selection of adaptive changes in the legume environment following horizontal transfer has been a major driving force in rhizobia evolution and diversification and show the potential of experimental evolution to decipher the mechanisms leading to symbiosis. PMID:20084095

Cruveiller, Stephane; Chane-Woon-Ming, Beatrice; Gris, Carine; Timmers, Ton; Poinsot, Verena; Gilbert, Luz B.; Heeb, Philipp; Medigue, Claudine; Batut, Jacques; Masson-Boivin, Catherine

2010-01-01

281

Endophytic Fusarium spp. from Roots of Lawn Grass (Axonopus compressus)  

PubMed Central

Fungal endophytes are found inside host plants but do not produce any noticeable disease symptoms in their host. In the present study, endophytic Fusarium species were isolated from roots of lawn grass (Axonopus compressus). A total of 51 isolates were recovered from 100 root segments. Two Fusarium species, F. oxysporum (53%) and F. solani (47%), were identified based on macroconidia and conidiogenous cell morphology. The detection of endophytic F. oxysporum and F. solani in the roots of lawn grass contributes to the knowledge of both the distribution of the two Fusarium species and the importance of roots as endophytic niches for Fusarium species. PMID:24575251

Zakaria, Latiffah; Ning, Chua Harn

2013-01-01

282

Antibacterial activity of some medicinal plants against selected human pathogenic bacteria.  

PubMed

Medicinal plants are traditionally used for the treatment of human infections. The present study was undertaken to investigate Bergenia ciliata, Jasminum officinale, and Santalum album for their potential activity against human bacterial pathogens. B. ciliata, J. officinale, and S. album extracts were prepared in cold and hot water. The activity of plant extracts and selected antibiotics was evaluated against five bacterial pathogens including Staphylococcus aureus, Bacillus subtilis, Proteus vulgaris, Pseudomonas aeruginosa, and Escherichia coli using agar well diffusion method. Among the three medicinal plants, B. ciliata extracts displayed potential activity against bacterial pathogens. Cold water extract of Bergenia ciliate showed the highest activity against B. subtilis, which is comparable with a zone of inhibition exhibited by ceftriaxone and erythromycin. J. officinale and S. album extracts demonstrated variable antibacterial activity. Further studies are needed to explore the novel antibacterial bioactive molecules. PMID:24294497

Khan, Usman Ali; Rahman, Hazir; Niaz, Zeeshan; Qasim, Muhammad; Khan, Jafar; Tayyaba; Rehman, Bushra

2013-12-01

283

Molecular variability among isolates of Fusarium oxysporum associated with root rot disease of Agave tequilana.  

PubMed

In this study, 115 isolates of Fusarium oxysporum from roots of Agave tequilana Weber cv azul plants and soil in commercial plantations in western Mexico were characterized using morphological and molecular methods. Genetic analyses of monosporic isolates included restriction enzyme analysis of rDNA (ARDRA) using HaeIII and HinfI, and genetic diversity was determined using Box-PCR molecular markers. Box-PCR analysis generated 14 groups. The groups correlated highly with the geographic location of the isolate and sample type. These results demonstrate the usefulness of ARDRA and Box-PCR techniques in the molecular characterization of the Fusarium genus for the discrimination of pathogenic isolates. PMID:23315087

Vega-Ramos, Karla L; Uvalle-Bueno, J Xavier; Gómez-Leyva, Juan F

2013-04-01

284

Advanced backcross QTL mapping of resistance to Fusarium head blight and plant morphological traits in a Triticum macha × T. aestivum population.  

PubMed

While many reports on genetic analysis of Fusarium head blight (FHB) resistance in bread wheat have been published during the past decade, only limited information is available on FHB resistance derived from wheat relatives. In this contribution, we report on the genetic analysis of FHB resistance derived from Triticum macha (Georgian spelt wheat). As the origin of T. macha is in the Caucasian region, it is supposed that its FHB resistance differs from other well-investigated resistance sources. To introduce valuable alleles from the landrace T. macha into a modern genetic background, we adopted an advanced backcross QTL mapping scheme. A backcross-derived recombinant-inbred line population of 321 BC(2)F(3) lines was developed from a cross of T. macha with the Austrian winter wheat cultivar Furore. The population was evaluated for Fusarium resistance in seven field experiments during four seasons using artificial inoculations. A total of 300 lines of the population were genetically fingerprinted using SSR and AFLP markers. The resulting linkage map covered 33 linkage groups with 560 markers. Five novel FHB-resistance QTL, all descending from T. macha, were found on four chromosomes (2A, 2B, 5A, 5B). Several QTL for morphological and developmental traits were mapped in the same population, which partly overlapped with FHB-resistance QTL. Only the 2BL FHB-resistance QTL co-located with a plant height QTL. The largest-effect FHB-resistance QTL in this population mapped at the spelt-type locus on chromosome 5A and was associated with the wild-type allele q, but it is unclear whether q has a pleiotropic effect on FHB resistance or is closely linked to a nearby resistance QTL. PMID:21479934

Buerstmayr, Maria; Lemmens, Marc; Steiner, Barbara; Buerstmayr, Hermann

2011-07-01

285

Airborne signalling by methyl salicylate in plant pathogen resistance  

Microsoft Academic Search

Methyl salicylate, a volatile liquid, also known as oil of winter-green, is made by a number of plants1-9. Here we show that methyl salicylate is a major volatile compound produced by tobacco plants inoculated with tobacco mosaic virus. Methyl salicylate is synthesized from salicylic acid, a non-volatile chemical signal required for the establishment of acquired resistance10 and local and systemic

Vladimir Shulaev; Paul Silverman; Ilya Raskin

1997-01-01

286

Metabolic environments and genomic features associated with pathogenic and mutualistic interactions between bacteria and plants.  

PubMed

Genomic characteristics discriminating parasitic and mutualistic relationship of bacterial symbionts with plants are poorly understood. This study comparatively analyzed the genomes of 54 mutualists and pathogens to discover genomic markers associated with the different phenotypes. Using metabolic network models, we predict external environments associated with free-living and symbiotic lifestyles and quantify dependences of symbionts on the host in terms of the consumed metabolites. We show that specific differences between the phenotypes are pronounced at the levels of metabolic enzymes, especially carbohydrate active, and protein functions. Overall, biosynthetic functions are enriched and more diverse in plant mutualists whereas processes and functions involved in degradation and host invasion are enriched and more diverse in pathogens. A distinctive characteristic of plant pathogens is a putative novel secretion system with a circadian rhythm regulator. A specific marker of plant mutualists is the co-residence of genes encoding nitrogenase and ribulose bisphosphate carboxylase/oxygenase (RuBisCO). We predict that RuBisCO is likely used in a putative metabolic pathway to supplement carbon obtained heterotrophically with low-cost assimilation of carbon from CO2. We validate results of the comparative analysis by predicting correct phenotype, pathogenic or mutualistic, for 20 symbionts in an independent set of 30 pathogens, mutualists, and commensals. PMID:24580106

Karpinets, Tatiana V; Park, Byung H; Syed, Mustafa H; Klotz, Martin G; Uberbacher, Edward C

2014-07-01

287

A role for a menthone reductase in resistance against microbial pathogens in plants.  

PubMed

Plants elaborate a vast array of enzymes that synthesize defensive secondary metabolites in response to pathogen attack. Here, we isolated the pathogen-responsive CaMNR1 [menthone: (+)-(3S)-neomenthol reductase] gene, a member of the short-chain dehydrogenase/reductase (SDR) superfamily, from pepper (Capsicum annuum) plants. Gas chromatography-mass spectrometry analysis revealed that purified CaMNR1 and its ortholog AtSDR1 from Arabidopsis (Arabidopsis thaliana) catalyze a menthone reduction with reduced nicotinamide adenine dinucleotide phosphate as a cofactor to produce neomenthol with antimicrobial activity. CaMNR1 and AtSDR1 also possess a significant catalytic activity for neomenthol oxidation. We examined the cellular function of the CaMNR1 gene by virus-induced gene silencing and ectopic overexpression in pepper and Arabidopsis plants, respectively. CaMNR1-silenced pepper plants were significantly more susceptible to Xanthomonas campestris pv vesicatoria and Colletotrichum coccodes infection and expressed lower levels of salicylic acid-responsive CaBPR1 and CaPR10 and jasmonic acid-responsive CaDEF1. CaMNR1-overexpressing Arabidopsis plants exhibited enhanced resistance to the hemibiotrophic pathogen Pseudomonas syringae pv tomato DC3000 and the biotrophic pathogen Hyaloperonospora parasitica isolate Noco2, accompanied by the induction of AtPR1 and AtPDF1.2. In contrast, mutation in the CaMNR1 ortholog AtSDR1 significantly enhanced susceptibility to both pathogens. Together, these results indicate that the novel menthone reductase gene CaMNR1 and its ortholog AtSDR1 positively regulate plant defenses against a broad spectrum of pathogens. PMID:18599651

Choi, Hyong Woo; Lee, Byung Gil; Kim, Nak Hyun; Park, Yong; Lim, Chae Woo; Song, Hyun Kyu; Hwang, Byung Kook

2008-09-01

288

Colonization of plants by human pathogenic bacteria in the course of organic vegetable production.  

PubMed

In recent years, increasing numbers of outbreaks caused by the consumption of vegetables contaminated with human pathogenic bacteria were reported. The application of organic fertilizers during vegetable production is one of the possible reasons for contamination with those pathogens. In this study laboratory experiments in axenic and soil systems following common practices in organic farming were conducted to identify the minimal dose needed for bacterial colonization of plants and to identify possible factors like bacterial species or serovariation, plant species or organic fertilizer types used, influencing the success of plant colonization by human pathogenic bacteria. Spinach and corn salad were chosen as model plants and were inoculated with different concentrations of Salmonella enterica sv. Weltevreden, Listeria monocytogenes sv. 4b and EGD-E sv. 1/2a either directly (axenic system) or via agricultural soil amended with spiked organic fertilizers (soil system). In addition to PCR- and culture-based detection methods, fluorescence in situ hybridization (FISH) was applied in order to localize bacteria on or in plant tissues. Our results demonstrate that shoots were colonized by the pathogenic bacteria at inoculation doses as low as 4 × 10 CFU/ml in the axenic system or 4 × 10(5) CFU/g in the soil system. In addition, plant species dependent effects were observed. Spinach was colonized more often and at lower inoculation doses compared to corn salad. Differential colonization sites on roots, depending on the plant species could be detected using FISH-CLSM analysis. Furthermore, the transfer of pathogenic bacteria to plants via organic fertilizers was observed more often and at lower initial inoculation doses when fertilization was performed with inoculated slurry compared to inoculated manure. Finally, it could be shown that by introducing a simple washing step, the bacterial contamination was reduced in most cases or even was removed completely in some cases. PMID:24829562

Hofmann, Andreas; Fischer, Doreen; Hartmann, Anton; Schmid, Michael

2014-01-01

289

Disease induction by human microbial pathogens in plant-model systems: potential, problems and prospects.  

PubMed

Relatively simple eukaryotic model organisms such as the genetic model weed plant Arabidopsis thaliana possess an innate immune system that shares important similarities with its mammalian counterpart. In fact, some human pathogens infect Arabidopsis and cause overt disease with human symptomology. In such cases, decisive elements of the plant's immune system are likely to be targeted by the same microbial factors that are necessary for causing disease in humans. These similarities can be exploited to identify elementary microbial pathogenicity factors and their corresponding targets in a green host. This circumvents important cost aspects that often frustrate studies in humans or animal models and, in addition, results in facile ethical clearance. PMID:17275738

van Baarlen, Peter; van Belkum, Alex; Thomma, Bart P H J

2007-02-01

290

[Features of interaction bacterial strains Micrococcus luteus LBK1 from plants varieties/hybrids cucumber and sweet pepper and with fungus Fusarium oxysporum Scelecht].  

PubMed

The article presents the results of studying the impact of bacterial strain M. luteus LBK1, stimulating the growth and development of plant varieties/hybrids of cucumber and sweet pepper on the intensity of sporulation of the fungus F. oxysporum Scelecht--fusariose rot pathogen. PMID:24800513

Parfeniuk, A; Sterlikova, O; Beznosko, I; Krut', V

2014-01-01

291

Root Rot of Balloon Flower (Platycodon grandiflorum) Caused by Fusarium solani and Fusarium oxysporum.  

PubMed

Balloon flower (Platycodon grandiflorum) is a kind of mountain herbs whose roots have restorative properties and the cultivating acreage of balloon flower has been steadily increasing in Korea. More frequent rain and high amount of rainfalls as a result of climate changes predisposed balloon flower to the outbreaks of root rot at high-density cultivation area in recent years. Root crowns were usually discolored into brown to blackish brown at first and the infected plants showed slight wilting symptom at early infection stage. Severely infected roots were entirely rotted and whole plants eventually died at late infection stage. The overall disease severities of root rot of balloon flower were quite variable according to the surveyed fields in Jeonnam, Gyeongnam and Jeju Provinces, which ranged from 0.1% to 40%. The root rot occurred more severely at the paddy or clay soils than the sandy soils and their severities were much higher at lowland than upland in the same localty. The disease increased with aging of the balloon flower. The causal fungi were identified as Fusarium solani and F. oxysporum on the basis of their mycological characteristics. The optimum temperature ranges of their mycelial growths was found to be 24°C. The pathogenic characters of F. solani and F. oxysporum treated by artificial wounding inoculation on healthy roots of balloon flower revealed that F. solani was more virulent than F. oxysporum. This study identified the causal agents of root rot of balloon flower as Fusarium solani and F. oxysporum, probably for the first time. PMID:25288973

Jeon, Chi Sung; Kim, Gyoung Hee; Son, Kyeong In; Hur, Jae-Seoun; Jeon, Kwon-Seok; Yoon, Jun-Hyuck; Koh, Young Jin

2013-12-01

292

Intercropping with aerobic rice suppressed Fusarium wilt in watermelon  

Microsoft Academic Search

Watermelon is susceptible to Fusarium wilt in successively mono-cropped soil. Pot experiments were carried out to investigate the effect of intercropping with aerobic rice on Fusarium wilt in watermelon. The tested soil was classified as a loam soil, previously planted with watermelon and collected from Hexian county, Anhui province, China. The results obtained are listed as follows: (1) 66.7% of

Lixuan Ren; Shiming Su; Xingming Yang; Yangchun Xu; Qiwei Huang; Qirong Shen

2008-01-01

293

When plants encounter pathogens, resistance mechanisms are activated  

E-print Network

is required for the induction of SAR. Application of salicylic acid or its synthetic analogs [2,6-dichloroisonicotinic acid (INA) or benzo (1,2,3)thiadiazole-7-carbo- thioic acid S-methyl ester (BTH)] to plants that express salicylate hydroxylase, whichisencodedbythebacterialnahG gene,canneitheraccumulatesalicylic acid

Delaney, Terrence

294

Polypyrrole nanoribbon based chemiresistive immunosensors for viral plant pathogen detection  

E-print Network

of cucumber mosaic virus (CMV). The sensitivity of the nano-immunosensors was enhanced by reducing Cucumber mosaic virus (CMV), the plant virus genus Cucumovi- rus (family Bromoviridae), is commonly found viruses, effective treatments have not been reported to prevent and/or eliminate CMV infection. Due

Chen, Wilfred

295

SGT1 positively regulates the process of plant cell death during both compatible and incompatible plant-pathogen interactions.  

PubMed

SGT1 (suppressor of G2 allele of Skp1), an interactor of SCF (Skp1-Cullin-F-box) ubiquitin ligase complexes that mediate protein degradation, plays an important role at both G1-S and G2-M cell cycle transitions in yeast, and is highly conserved throughout eukaryotes. Plant SGT1 is required for both resistance (R) gene-mediated disease resistance and nonhost resistance to certain pathogens. Using virus-induced gene silencing (VIGS) in Nicotiana benthamiana, we demonstrate that SGT1 positively regulates the process of cell death during both host and nonhost interactions with various pathovars of Pseudomonas syringae. Silencing of NbSGT1 in N. benthamiana plants delays the induction of hypersensitive response (HR)-mediated cell death against nonhost pathogens and the development of disease-associated cell death caused by the host pathogen P. syringae pv. tabaci. Our results further demonstrate that NbSGT1 is required for Erwinia carotovora- and Sclerotinia sclerotiorum-induced disease-associated cell death. Overexpression of NbSGT1 in N. benthamiana accelerates the development of HR during R gene-mediated disease resistance and nonhost resistance. Our data also indicate that SGT1 is required for pathogen-induced cell death, but is not always necessary for the restriction of bacterial multiplication in planta. Therefore, we conclude that SGT1 is an essential component affecting the process of cell death during both compatible and incompatible plant-pathogen interactions. PMID:20695999

Wang, Keri; Uppalapati, Srinivasa Rao; Zhu, Xiaohong; Dinesh-Kumar, Savithramma P; Mysore, Kirankumar S

2010-09-01

296

Fusarium pathogenesis investigated using Galleria mellonella as a heterologous host  

PubMed Central

Members of the fungal genus Fusarium are capable of manifesting in a multitude of clinical infections, most commonly in immunocompromised patients. In order to better understand the interaction between the fungus and host, we have developed the larvae of the greater wax moth, Galleria mellonella, as a heterologous host for fusaria. When conidia are injected into the hemocoel of this Lepidopteran system, both clinical and environmental isolates of the fungus are able to kill the larvae at 37°C, although killing occurs more rapidly when incubated at 30°C. This killing was dependent on several other factors besides temperature, including the Fusarium strain, the number of conidia injected, and the conidia morphology, where macroconidia are more virulent than their microconidia counterpart. There was a correlation in the killing rate of Fusarium spp. when evaluated in G. mellonella and a murine model. In vivo studies indicated G. mellonella hemocytes were capable of initially phagocytosing both conidial morphologies. The G. mellonella system was also used to evaluate antifungal agents, and amphotericin B was able to confer a significant increase in survival to Fusarium infected-larvae. The G. mellonella-Fusarium pathogenicity system revealed that virulence of Fusarium spp. is similar, regardless of the origin of the isolate, and that mammalian endothermy is a major deterrent for Fusarium infection and therefore provides a suitable alternative to mammalian models to investigate the interaction between the host and this increasingly important fungal pathogen. PMID:22115447

Coleman, Jeffrey J.; Muhammed, Maged; Kasperkovitz, Pia V.; Vyas, Jatin M.; Mylonakis, Eleftherios

2011-01-01

297

Role of Cereal Secondary Metabolites Involved in Mediating the Outcome of Plant-Pathogen Interactions  

PubMed Central

Cereal crops such as wheat, rice and barley underpin the staple diet for human consumption globally. A multitude of threats to stable and secure yields of these crops exist including from losses caused by pathogens, particularly fungal. Plants have evolved complex mechanisms to resist pathogens including programmed cell death responses, the release of pathogenicity-related proteins and oxidative bursts. Another such mechanism is the synthesis and release of secondary metabolites toxic to potential pathogens. Several classes of these compounds have been identified and their anti-fungal properties demonstrated. However the lack of suitable analytical techniques has hampered the progress of identifying and exploiting more of these novel metabolites. In this review, we summarise the role of the secondary metabolites in cereal crop diseases and briefly touch on the analytical techniques that hold the key to unlocking their potential in reducing yield losses. PMID:24957244

Du Fall, Lauren A.; Solomon, Peter S.

2011-01-01

298

A Domain-Centric Analysis of Oomycete Plant Pathogen Genomes Reveals Unique Protein Organization1[W][OA  

PubMed Central

Oomycetes comprise a diverse group of organisms that morphologically resemble fungi but belong to the stramenopile lineage within the supergroup of chromalveolates. Recent studies have shown that plant pathogenic oomycetes have expanded gene families that are possibly linked to their pathogenic lifestyle. We analyzed the protein domain organization of 67 eukaryotic species including four oomycete and five fungal plant pathogens. We detected 246 expanded domains in fungal and oomycete plant pathogens. The analysis of genes differentially expressed during infection revealed a significant enrichment of genes encoding expanded domains as well as signal peptides linking a substantial part of these genes to pathogenicity. Overrepresentation and clustering of domain abundance profiles revealed domains that might have important roles in host-pathogen interactions but, as yet, have not been linked to pathogenicity. The number of distinct domain combinations (bigrams) in oomycetes was significantly higher than in fungi. We identified 773 oomycete-specific bigrams, with the majority composed of domains common to eukaryotes. The analyses enabled us to link domain content to biological processes such as host-pathogen interaction, nutrient uptake, or suppression and elicitation of plant immune responses. Taken together, this study represents a comprehensive overview of the domain repertoire of fungal and oomycete plant pathogens and points to novel features like domain expansion and species-specific bigram types that could, at least partially, explain why oomycetes are such remarkable plant pathogens. PMID:21119047

Seidl, Michael F.; Van den Ackerveken, Guido; Govers, Francine; Snel, Berend

2011-01-01

299

Onychomycosis by Fusarium oxysporum probably acquired in utero  

PubMed Central

Fusarium oxysporum has been described as a pathogen causing onychomycosis, its incidence has been increasing in immunocompetent and disseminated infection can occur in immunosuppressed individuals. We describe the first case of congenital onychomycosis in a child caused by Fusarium oxysporum. The infection being acquired in utero was proven by molecular methods with the identification of the fungus both in the nail and placenta, most probably as an ascending contamination/infection in a HIV-positive, immunosuppressed mother. PMID:25383318

Carvalho, Vania O.; Vicente, Vania A.; Werner, Betina; Gomes, Renata R.; Fornari, Gheniffer; Herkert, Patricia F.; Rodrigues, Cristina O.; Abagge, Kerstin T.; Robl, Renata; Camina, Ricardo H

2014-01-01

300

Host-plant-mediated effects of Nadefensin on herbivore and pathogen resistance in Nicotiana attenuata  

PubMed Central

Background The adage from Shakespeare, "troubles, not as single spies, but in battalions come," holds true for Nicotiana attenuata, which is commonly attacked by both pathogens (Pseudomonas spp.) and herbivores (Manduca sexta) in its native habitats. Defense responses targeted against the pathogens can directly or indirectly influence the responses against the herbivores. Nadefensin is an effective induced defense gene against the bacterial pathogen Pseudomonas syringae pv tomato (PST DC3000), which is also elicited by attack from M. sexta larvae, but whether this defense protein influences M. sexta's growth and whether M. sexta-induced Nadefensin directly or indirectly influences PST DC3000 resistance are unknown. Results M. sexta larvae consumed less on WT and on Nadefensin-silenced N. attenuata plants that had previously been infected with PST DC3000 than on uninfected plants. WT plants infected with PST DC3000 showed enhanced resistance to PST DC3000 and decreased leaf consumption by M. sexta larvae, but larval mass gain was unaffected. PST DC3000-infected Nadefensin-silenced plants were less resistant to subsequent PST DC3000 challenge, and on these plants, M. sexta larvae consumed less and gained less mass. WT and Nadefensin-silenced plants previously damaged by M. sexta larvae were better able to resist subsequent PST DC3000 challenges than were undamaged plants. Conclusion These results demonstrate that Na-defensin directly mediates defense against PST DC3000 and indirectly against M. sexta in N. attenuata. In plants that were previously infected with PST DC3000, the altered leaf chemistry in PST DC3000-resistant WT plants and PST DC3000-susceptible Nadefensin-silenced plants differentially reduced M. sexta's leaf consumption and mass gain. In plants that were previously damaged by M. sexta, the combined effect of the altered host plant chemistry and a broad spectrum of anti-herbivore induced metabolomic responses was more effective than Nadefensin alone in resisting PST DC3000. PMID:18950524

Rayapuram, Cbgowda; Baldwin, Ian T

2008-01-01

301

Endogenous Methyl Salicylate in Pathogen-Inoculated Tobacco Plants1  

Microsoft Academic Search

The tobacco (Nicotiana tabacum) cultivar Xanthi-nc (genotype NN) produces high levels of salicylic acid (SA) after inoculation with the tobacco mosaic virus (TMV). Gaseous methyl salicylate (MeSA), a major volatile produced in TMV-inoculated tobacco plants, was recently shown to be an airborne defense signal. Using an assay developed to measure the MeSA present in tissue, we have shown that in

Mirjana Seskar; Vladimir Shulaev; Ilya Raskin

1998-01-01

302

Reactive Oxygen Species in Plant–Pathogen Interactions  

Microsoft Academic Search

Reactive oxygen species (ROS), superoxide, hydrogen peroxide and nitric oxide are produced at all levels of resistance reactions\\u000a in plants. In basal resistance, they are linked to papilla formation and the assembly of barriers. In the hypersensitive response,\\u000a they may be linked to programmed cell death, and in systemic acquired resistance, they interact with salicylate in signalling.\\u000a Despite this importance,

G. Paul Bolwell; Arsalan Daudi

303

Ctf1, a transcriptional activator of cutinase and lipase genes in Fusarium oxysporum is dispensable for virulence.  

PubMed

Cutinolytic enzymes are secreted by fungal pathogens attacking the aerial parts of the plant, to facilitate penetration of the outermost cuticular barrier of the host. The role of cutinases in soil-borne root pathogens has not been studied thus far. Here we report the characterization of the zinc finger transcription factor Ctf1 from the vascular wilt fungus Fusarium oxysporum, a functional orthologue of CTF1alpha that controls expression of cutinase genes and virulence in the pea stem pathogen Fusarium solani f. sp. pisi. Mutants carrying a Deltactf1 loss-of-function allele grown on inducing substrates failed to activate extracellular cutinolytic activity and expression of the cut1 and lip1 genes, encoding a putative cutinase and lipase, respectively, whereas strains harbouring a ctf1(C) allele in which the ctf1 coding region was fused to the strong constitutive Aspergillus nidulans gpdA promoter showed increased induction of cutinase activity and gene expression. These results suggest that F. oxysporum Ctf1 mediates expression of genes involved in fatty acid hydrolysis. However, expression of lip1 during root infection was not dependent on Ctf1, and virulence of the ctf1 mutants on tomato plants and fruits was indistinguishable from that of the wild-type. Thus, in contrast to the stem pathogen F. solani, Ctf1 is not essential for virulence in the root pathogen F. oxysporum. PMID:18705871

Rocha, Ana Lilia Martínez; Di Pietro, Antonio; Ruiz-Roldán, Carmen; Roncero, M Isabel G

2008-05-01

304

The effects of fungicides on non-target mites can be mediated by plant pathogens.  

PubMed

Field tests are useful for the evaluation of the pesticides' impact in realistic use situations. However, the distinction between the direct and indirect effects of a pesticide is not always possible in field, with consequences on the conclusions about pesticides toxicity. Generalist predatory mites belonging to the Phytoseiidae family are widely considered as non-target organisms in pesticide side-effect evaluations. Plant pathogens of several cultivated plants can be of importance as food resources for various phytoseiids. Pesticides with fungicidal activity may have a direct impact on phytoseiids, but they can also have an indirect effect reducing food availability for predatory mites. Here, we present the results of field experiments performed on grapevine, where we investigate whether the availability of the plant pathogen grape downy mildew has an effect on fungicides impact on the predatory mites Typhlodromus pyri Scheuten and Amblyseius andersoni (Chant). In these experiments we used fungicides characterized by differential selectivity to predatory mites in laboratory: copper compounds, folpet, and mancozeb. Results indicated that the abundance of predatory mites was associated with the plant pathogen foliar symptoms presence. The presence of predatory mites was different among treatments in response of the toxicological traits of a pesticide (direct effects), but also as consequences of differential plant pathogen availability induced by fungicide applications (indirect effects). During the investigation, the variable plant pathogen spread on untreated control determined contrasting results on pesticides effect. We segregated the direct effects from the indirect food resource-mediated effects including a non-toxic reference in the experimental protocols. PMID:20172588

Pozzebon, Alberto; Borgo, Michele; Duso, Carlo

2010-03-01

305

Plant pathogens as agroterrorist weapons: assessment of the threat for European agriculture and forestry  

Microsoft Academic Search

Malevolent use of plant pathogens in an act of agroterrorism represents a potential threat for European agriculture and forestry.\\u000a We investigated the risk of agroterrorism sensu lato, which is raising debates among the community of plant pathologists. In the absence of a previous unambiguous definition\\u000a of agroterrorism we characterized the risk for Europe by taking into account the multiplicity of

Frédéric Suffert; Émilie Latxague; Ivan Sache

2009-01-01

306

The evolution of species concepts and species recognition criteria in plant pathogenic fungi  

Microsoft Academic Search

In this paper, we review historical and contemporary species concepts and species recognition criteria for plant pathogenic\\u000a fungi. Previous incongruent and unstable classification based on subjective and changing criteria have led to some confusion,\\u000a especially amongst plant pathologists. The goal of systematics is to provide an informative and robust framework that stands\\u000a the test of time. The taxonomic histories of

Lei Cai; Tatiana Giraud; Ning Zhang; Dominik Begerow; Guohong Cai; Roger G. Shivas

307

Interactions Between the Mycoparasite Pythium oligandrum and Sclerotia of the Plant Pathogen Sclerotinia sclerotiorum  

Microsoft Academic Search

Pythium oligandrum Drechsler is a mycoparasite which parasitizes hyphae of many fungal species. A detailed study of the interactions between P. oligandrum and the sclerotia of the plant pathogen Sclerotinia sclerotiorum (Lib.) de Bary is presented. Pythium oligandrum was present in Danish soils at concentrations between 4 and 26 cfu g-1 soil. An increase in the natural population of P.

A. Mette Madsen; Eigil de Neergaard

1999-01-01

308

Sequencing of K60, Type Strain of the Major Plant Pathogen Ralstonia solanacearum  

PubMed Central

Ralstonia solanacearum is a widespread and destructive plant pathogen. We present the genome of the type strain, K60 (phylotype IIA, sequevar 7). Sequevar 7 strains cause ongoing tomato bacterial wilt outbreaks in the southeastern United States. K60 generally resembles R. solanacearum CFBP2957, a Caribbean tomato isolate, but has almost 360 unique genes. PMID:22535929

Remenant, Benoît; Babujee, Lavanya; Lajus, Aurélie; Médigue, Claudine; Prior, Philippe

2012-01-01

309

Seaweed Polysaccharides and Derived Oligosaccharides Stimulate Defense Responses and Protection Against Pathogens in Plants  

PubMed Central

Plants interact with the environment by sensing “non-self” molecules called elicitors derived from pathogens or other sources. These molecules bind to specific receptors located in the plasma membrane and trigger defense responses leading to protection against pathogens. In particular, it has been shown that cell wall and storage polysaccharides from green, brown and red seaweeds (marine macroalgae) corresponding to ulvans, alginates, fucans, laminarin and carrageenans can trigger defense responses in plants enhancing protection against pathogens. In addition, oligosaccharides obtained by depolymerization of seaweed polysaccharides also induce protection against viral, fungal and bacterial infections in plants. In particular, most seaweed polysaccharides and derived oligosaccharides trigger an initial oxidative burst at local level and the activation of salicylic (SA), jasmonic acid (JA) and/or ethylene signaling pathways at systemic level. The activation of these signaling pathways leads to an increased expression of genes encoding: (i) Pathogenesis-Related (PR) proteins with antifungal and antibacterial activities; (ii) defense enzymes such as pheylalanine ammonia lyase (PAL) and lipoxygenase (LOX) which determine accumulation of phenylpropanoid compounds (PPCs) and oxylipins with antiviral, antifugal and antibacterial activities and iii) enzymes involved in synthesis of terpenes, terpenoids and/or alkaloids having antimicrobial activities. Thus, seaweed polysaccharides and their derived oligosaccharides induced the accumulation of proteins and compounds with antimicrobial activities that determine, at least in part, the enhanced protection against pathogens in plants. PMID:22363237

Vera, Jeannette; Castro, Jorge; Gonzalez, Alberto; Moenne, Alejandra

2011-01-01

310

Climate change – impact on crop growth and food production, and plant pathogens  

Microsoft Academic Search

Climates are changing worldwide at rates not seen previously in geological time. This affects food production itself and the growth and reproduction of plant pathogens which reduce crop yield and quality. There is a need to develop an understanding of the implications and impacts of climate change on natural biodiversity, artificial landscapes as well as production agriculture (defined here as

Geoffrey Richard Dixon

2012-01-01

311

Oxalic Acid, a Pathogenicity Factor for Sclerotinia sclerotiorum, Suppresses the Oxidative Burst of the Host Plant  

Microsoft Academic Search

Effective pathogenesis by the fungus Sclerotinia sclerotiorum requires the secretion of oxalic acid. Studies were con- ducted to determine whether oxalate aids pathogen compatibility by modulating the oxidative burst of the host plant. Inoculation of tobacco leaves with an oxalate-deficient nonpathogenic mutant of S. sclerotiorum induced measurable oxidant biosynthesis, but inoculation with an oxalate-secreting strain did not. Oxalate inhibited production

Stephen G. Cessna; Valerie E. Sears; Martin B. Dickman; Philip S. Low

2000-01-01

312

Draft Genome Sequence of Pseudomonas chlororaphis YL-1, a Biocontrol Strain Suppressing Plant Microbial Pathogens  

PubMed Central

Pseudomonas chlororaphis YL-1 was isolated from soybean root tips and showed a broad range of antagonistic activities to microbial plant pathogens. Here, we report the high-quality draft genome sequence of YL-1, which consists of a chromosome with an estimated size of 6.8 Mb with a G+C value of 63.09%. PMID:24482513

Lu, Shi-En; Baird, Sonya M.; Qiao, Junqing; Du, Yan

2014-01-01

313

Seaweed polysaccharides and derived oligosaccharides stimulate defense responses and protection against pathogens in plants.  

PubMed

Plants interact with the environment by sensing "non-self" molecules called elicitors derived from pathogens or other sources. These molecules bind to specific receptors located in the plasma membrane and trigger defense responses leading to protection against pathogens. In particular, it has been shown that cell wall and storage polysaccharides from green, brown and red seaweeds (marine macroalgae) corresponding to ulvans, alginates, fucans, laminarin and carrageenans can trigger defense responses in plants enhancing protection against pathogens. In addition, oligosaccharides obtained by depolymerization of seaweed polysaccharides also induce protection against viral, fungal and bacterial infections in plants. In particular, most seaweed polysaccharides and derived oligosaccharides trigger an initial oxidative burst at local level and the activation of salicylic (SA), jasmonic acid (JA) and/or ethylene signaling pathways at systemic level. The activation of these signaling pathways leads to an increased expression of genes encoding: (i) Pathogenesis-Related (PR) proteins with antifungal and antibacterial activities; (ii) defense enzymes such as pheylalanine ammonia lyase (PAL) and lipoxygenase (LOX) which determine accumulation of phenylpropanoid compounds (PPCs) and oxylipins with antiviral, antifugal and antibacterial activities and iii) enzymes involved in synthesis of terpenes, terpenoids and/or alkaloids having antimicrobial activities. Thus, seaweed polysaccharides and their derived oligosaccharides induced the accumulation of proteins and compounds with antimicrobial activities that determine, at least in part, the enhanced protection against pathogens in plants. PMID:22363237

Vera, Jeannette; Castro, Jorge; Gonzalez, Alberto; Moenne, Alejandra

2011-12-01

314

Inhibition of Fungal and Bacterial Plant Pathogens In Vitro and In Planta with Ultrashort Cationic Lipopeptides?  

PubMed Central

Plant diseases constitute an emerging threat to global food security. Many of the currently available antimicrobial agents for agriculture are highly toxic and nonbiodegradable and cause extended environmental pollution. Moreover, an increasing number of phytopathogens develop resistance to them. Recently, we have reported on a new family of ultrashort antimicrobial lipopeptides which are composed of only four amino acids linked to fatty acids (A. Makovitzki, D. Avrahami, and Y. Shai, Proc. Natl. Acad. Sci. USA 103:15997-16002, 2006). Here, we investigated the activities in vitro and in planta and the modes of action of these short lipopeptides against plant-pathogenic bacteria and fungi. They act rapidly, at low micromolar concentrations, on the membranes of the microorganisms via a lytic mechanism. In vitro microscopic analysis revealed wide-scale damage to the microorganism's membrane, in addition to inhibition of pathogen growth. In planta potent antifungal activity was demonstrated on cucumber fruits and leaves infected with the pathogen Botrytis cinerea as well as on corn leaves infected with Cochliobolus heterostrophus. Similarly, treatment with the lipopeptides of Arabidopsis leaves infected with the bacterial leaf pathogen Pseudomonas syringae efficiently and rapidly reduced the number of bacteria. Importantly, in contrast to what occurred with many native lipopeptides, no toxicity was observed on the plant tissues. These data suggest that the ultrashort lipopeptides could serve as native-like antimicrobial agents economically feasible for use in plant protection. PMID:17720828

Makovitzki, Arik; Viterbo, Ada; Brotman, Yariv; Chet, Ilan; Shai, Yechiel

2007-01-01

315

Antibacterial activity of plant extracts from Brazil against fish pathogenic bacteria  

PubMed Central

The aim of this work was to evaluate the antibacterial activity of Brazilian plants extracts against fish pathogenic bacteria. Forty six methanolic extracts were screened to identify their antibacterial properties against Streptococcus agalactiae, Flavobacterium columnare and Aeromonas hydrophila. Thirty one extracts showed antibacterial activity. PMID:24031303

Castro, S.B.R.; Leal, C.A.G.; Freire, F.R.; Carvalho, D.A.; Oliveira, D.F.; Figueiredo, H.C.P.

2008-01-01

316

Antifungal activity in vitro of Aloe vera pulp and liquid fraction against plant pathogenic fungi  

Microsoft Academic Search

The leaf pulp of Aloe vera, designated as the gel, and the bitter, yellow liquid fraction have been tested against pathogens (bacteria and fungi) affecting human and plants. However, their activity for fungal control in commercial industrial crops has not been determined. The objectives of this study were to evaluate the inhibitory effect of Aloe pulp and liquid fraction on

D. Jasso de Rodr??guez; D. Hernández-Castillo; R. Rodr??guez-Garc??a; J. L. Angulo-Sánchez

2005-01-01

317

Fungal Control of Pathogenic Fungi Isolated From Some Wild Plants in Taif Governorate, Saudi Arabia  

Microsoft Academic Search

Twenty two plants were collected from Taif Governorate and identified as: Aerva lanata, Arnebia hispidissima, Artemisia judaica, Artemisia monosperma, Asphodelus aestives, Avena barbata, Capparis dcidua, Eucalyptus globulus, Euphorbia glomerifera, Foeniculum vulgare, Forsskaolea tenacissima, Juniperus procera, Launaea mucronata, Launaea sonchoides, Medicago sativa, Opuntia ficus, Phagnalon sinaicum, Prunus persica, Pulicaria crispa, Punica granatum, Rumex dentatus and Trichodesma calathiforme. Pathogenic fungi were isolated

Abd El-Fattah

318

New species of Fusarium associated with dieback of Spartina alterniflora in Atlantic salt marshes.  

PubMed

Sudden vegetation dieback (SVD) is the loss of smooth cordgrass (Spartina alterniflora) along intertidal creeks in salt marshes of the Atlantic and Gulf states. The underlying cause of SVD remains unclear, but earlier work suggested a contributing role for Fusarium spp. in Louisiana. This report investigated whether these or other Fusarium species were associated with S. alterniflora dieback in mid- to north-Atlantic states. Isolations from seven SVD sites yielded 192 isolates of Fusarium spp., with more than 75% isolated from aboveground tissue. Most isolates (88%) fell into two undescribed morphospecies (MS) distinguished from each other by macroconidial shape, phialide ontogeny and growth rates. Pathogenicity tests on wound-inoculated S. alterniflora stems and seedling roots revealed that isolates in MS1 were more virulent than those in MS2 but no single isolate caused plant mortality. No matches to known species of Fusarium were revealed by DNA sequence queries of translation elongation factor 1-? (tef1) sequences. A phylogenetic analysis of partial sequences of three genes, ?-tubulin (?-tub), calmodulin (cal) and tef1, was conducted on representative isolates from MS1 (n = 20) and MS2 (n = 18); it provided strong evidence that the MS1 isolates form a clade that represents a heretofore undescribed species, which we designate Fusarium palustre sp. nov. Isolates from the more variable MS2 clustered with the F. incarnatum-equiseti species complex as F. cf. incarnatum. Although a strong association exists between both species and declining S. alterniflora in SVD sites, neither appears to play a primary causal role in SVD. However, our findings suggest that F. palustre might play an important secondary role in the ecological disruption of the salt marshes. PMID:21471289

Elmer, Wade H; Marra, Robert E

2011-01-01

319

A plant pathogen reduces the enemy-free space of an insect herbivore on a shared host plant.  

PubMed Central

An important mechanism in stabilizing tightly linked host-parasitoid and prey-predator interactions is the presence of refuges that protect organisms from their natural enemies. However, the presence and quality of refuges can be strongly affected by the environment. We show that infection of the host plant Silene latifolia by its specialist fungal plant pathogen Microbotryum violaceum dramatically alters the enemy-free space of a herbivore, the specialist noctuid seed predator Hadena bicruris, on their shared host plant. The pathogen arrests the development of seed capsules that serve as refuges for the herbivore's offspring against the specialist parasitoid Microplitis tristis, a major source of mortality of H. bicruris in the field. Pathogen infection resulted both in lower host-plant food quality, causing reduced adult emergence, and in twofold higher rates of parasitism of the herbivore. We interpret the strong oviposition preference of H. bicruris for uninfected plants in the field as an adaptive response, positioning offspring on refuge-rich, high-quality hosts. To our knowledge, this is the first demonstration that plant-inhabiting micro-organisms can affect higher trophic interactions through alteration of host refuge quality. We speculate that such interference can potentially destabilize tightly linked multitrophic interactions. PMID:12427312

Biere, Arjen; Elzinga, Jelmer A; Honders, Sonja C; Harvey, Jeffrey A

2002-01-01

320

Callose-mediated resistance to pathogenic intruders in plant defense-related papillae  

PubMed Central

Plants are exposed to a wide range of potential pathogens, which derive from diverse phyla. Therefore, plants have developed successful defense mechanisms during co-evolution with different pathogens. Besides many specialized defense mechanisms, the plant cell wall represents a first line of defense. It is actively reinforced through the deposition of cell wall appositions, so-called papillae, at sites of interaction with intruding microbial pathogens. The papilla is a complex structure that is formed between the plasma membrane and the inside of the plant cell wall. Even though the specific biochemical composition of papillae can vary between different plant species, some classes of compounds are commonly found which include phenolics, reactive oxygen species, cell wall proteins, and cell wall polymers. Among these polymers, the (1,3)-?-glucan callose is one of the most abundant and ubiquitous components. Whereas the function of most compounds could be directly linked with cell wall reinforcement or an anti-microbial effect, the role of callose has remained unclear. An evaluation of recent studies revealed that the timing of the different papilla-forming transport processes is a key factor for successful plant defense. PMID:24808903

Voigt, Christian A.

2014-01-01

321

Disseminated Fusarium originating from toenail paronychia in a neutropenic patient  

PubMed Central

Fusarium is a saprophytic organism that is found widely distributed in soil, subterranean and aerial plants, plant debris and other organic substrates. The organism can cause local tissue infections in immunocompetent patients such as onychomycosis, bone and joint infections, or sinusitis. Since the first case of disseminated Fusarium was described, the incidence of disseminated disease has increased significantly, particularly affecting those immunocompromised with hematological malignancies. We report here a 38 year-old hospitalized male with newly diagnosed acute myelogenous leukemia (AML) who developed disseminated Fusarium infection, originating from a toenail paronychia, in the setting of neutropenia. Pathological diagnosis of Fusarium is difficult because the septate hyphae of Fusarium are difficult to distinguish from Aspergillus, which has a more favorable outcome. Cultures of potential sources of infection, as well as tissue cultures, are essential in identifying the organism and initiating early aggressive therapy. PMID:20486458

Bourgeois, Greg P.; Cafardi, Jennifer A.; Sellheyer, Klaus; Andea, Aleodor A.

2010-01-01

322

Comparative analysis of the XopD type III secretion (T3S) effector family in plant pathogenic bacteria  

E-print Network

to promote bacterial growth (Bonas et al., 1991). Xcv uses the T3S system to translocate approximately 35 proteases con- served amongst animal and plant pathogenic bacteria (Staskaw- icz et al., 2001). MembersComparative analysis of the XopD type III secretion (T3S) effector family in plant pathogenic

Mudgettt, Mary Beth

323

Apoplastic effectors secreted by two unrelated eukaryotic plant pathogens target the tomato defense protease Rcr3.  

PubMed

Current models of plant-pathogen interactions stipulate that pathogens secrete effector proteins that disable plant defense components known as virulence targets. Occasionally, the perturbations caused by these effectors trigger innate immunity via plant disease resistance proteins as described by the "guard hypothesis." This model is nicely illustrated by the interaction between the fungal plant pathogen Cladosporium fulvum and tomato. C. fulvum secretes a protease inhibitor Avr2 that targets the tomato cysteine protease Rcr3(pim). In plants that carry the resistance protein Cf2, Rcr3(pim) is required for resistance to C. fulvum strains expressing Avr2, thus fulfilling one of the predictions of the guard hypothesis. Another prediction of the guard hypothesis has not yet been tested. Considering that virulence targets are important components of defense, different effectors from unrelated pathogens are expected to evolve to disable the same host target. In this study we confirm this prediction using a different pathogen of tomato, the oomycete Phytophthora infestans that is distantly related to fungi such as C. fulvum. This pathogen secretes an array of protease inhibitors including EPIC1 and EPIC2B that inhibit tomato cysteine proteases. Here we show that, similar to Avr2, EPIC1 and EPIC2B bind and inhibit Rcr3(pim). However, unlike Avr2, EPIC1 and EPIC2B do not trigger hypersensitive cell death or defenses on Cf-2/Rcr3(pim) tomato. We also found that the rcr3-3 mutant of tomato that carries a premature stop codon in the Rcr3 gene exhibits enhanced susceptibility to P. infestans, suggesting a role for Rcr3(pim) in defense. In conclusion, our findings fulfill a key prediction of the guard hypothesis and suggest that the effectors Avr2, EPIC1, and EPIC2B secreted by two unrelated pathogens of tomato target the same defense protease Rcr3(pim). In contrast to C. fulvum, P. infestans appears to have evolved stealthy effectors that carry inhibitory activity without triggering plant innate immunity. PMID:19171904

Song, Jing; Win, Joe; Tian, Miaoying; Schornack, Sebastian; Kaschani, Farnusch; Ilyas, Muhammad; van der Hoorn, Renier A L; Kamoun, Sophien

2009-02-01

324

Interaction of Fusarium oxysporum f. sp. ciceri and Meloidogyne javanica on Cicer arietinum.  

PubMed

Interaction of Meloidogyne javanica and Fusarium oxysporum f. sp. ciceri was studied on Fusarium wilt-susceptible (JG 62 and K 850) and resistant (JG 74 and Avrodhi) chickpea cultivars. In greenhouse experiments, inoculation of M. javanica juveniles prior to F. oxysporum f. sp. ciceri caused greater wilt incidence in susceptible cultivars and induced vascular discoloration in roots of resistant cultivars. Nematode reproduction was greatest (P = 0.05) at 25 degrees C. Number of galls and percentage of root area galled increased when the temperature was increased from 15 degrees C to 25 degrees C. Wilt incidence was greater at 20 degrees C than at 25 degrees C. Chlorosis of leaves and vascular discoloration of plants did not occur at 15 degrees C. The nematode enhanced the wilt incidence in wilt-susceptible cultivars only at 25 degrees C. Interaction between the two pathogens on shoot and root weights was significant only at 20 degrees C, and F. o. ciceri suppressed the nematode density at this temperature. Wilt incidence was greater in clayey (48% clay) than in loamy sand (85% sand) soils. The nematode caused greater plant damage on loamy sand than on clayey soil. Fusarium wilt resistance in Avrodhi and JG 74 was stable in the presence of M. javanica across temperatures and soil types. PMID:19274140

Maheswari, T U; Sharma, S B; Reddy, D D; Haware, M P

1997-03-01

325

Biological control of plant pathogens: advantages and limitations seen through the case study of Pythium oligandrum.  

PubMed

The management of certain plant beneficial microorganisms [biological control agents (BCAs)] seems to be a promising and environmental friendly method to control plant pathogens. However, applications are still limited because of the lack of consistency of BCAs when they are applied in the field. In the present paper, the advantages and limitations of BCAs are seen through the example of Pythium oligandrum, an oomycete that has received much attention in the last decade. The biological control exerted by P. oligandrum is the result of a complex process, which includes direct effects through the control of pathogens and/or indirect effects mediated by P. oligandrum, i.e. induction of resistance and growth promotion. P. oligandrum antagonism is a multifaceted and target fungus-dependent process. Interestingly, it does not seem to disrupt microflora biodiversity on the roots. P. oligandrum has an atypical relationship with the plant because it rapidly penetrates into the root tissues but it cannot stay alive in planta. After root colonisation, because of the elicitation by P. oligandrum of the plant-defence system, plants are protected from a range of pathogens. The management of BCAs, here P. oligandrum, is discussed with regard to its interactions with the incredibly complex agrosystems. PMID:23695856

Gerbore, J; Benhamou, N; Vallance, J; Le Floch, G; Grizard, D; Regnault-Roger, C; Rey, P

2014-04-01

326

Temporal and spatial scaling of the genetic structure of a vector-borne plant pathogen.  

PubMed

The ecology of plant pathogens of perennial crops is affected by the long-lived nature of their immobile hosts. In addition, changes to the genetic structure of pathogen populations may affect disease epidemiology and management practices; examples include local adaptation of more fit genotypes or introduction of novel genotypes from geographically distant areas via human movement of infected plant material or insect vectors. We studied the genetic structure of Xylella fastidiosa populations causing disease in sweet orange plants in Brazil at multiple scales using fast-evolving molecular markers (simple-sequence DNA repeats). Results show that populations of X. fastidiosa were regionally isolated, and that isolation was maintained for populations analyzed a decade apart from each other. However, despite such geographic isolation, local populations present in year 2000 were largely replaced by novel genotypes in 2009 but not as a result of migration. At a smaller spatial scale (individual trees), results suggest that isolates within plants originated from a shared common ancestor. In summary, new insights on the ecology of this economically important plant pathogen were obtained by sampling populations at different spatial scales and two different time points. PMID:24397266

Coletta-Filho, Helvécio D; Francisco, Carolina S; Almeida, Rodrigo P P

2014-02-01

327

A hyperparasite affects the population dynamics of a wild plant pathogen.  

PubMed

Assessing the impact of natural enemies of plant and animal pathogens on their host's population dynamics is needed to determine the role of hyperparasites in affecting disease dynamics, and their potential for use in efficient control strategies of pathogens. Here, we focus on the long-term study describing metapopulation dynamics of an obligate pathogen, the powdery mildew (Podosphaera plantaginis) naturally infecting its wild host plant (Plantago lanceolata) in the fragmented landscape of the Ĺland archipelago (southwest Finland). Regionally, the pathogen persists through a balance of extinctions and colonizations, yet factors affecting extinction rates remain poorly understood. Mycoparasites of the genus Ampelomyces appear as good candidates for testing the role of a hyperparasite, i.e. a parasite of other parasites, in the regulation of their fungal hosts' population dynamics. For this purpose, we first designed a quantitative PCR assay for detection of Ampelomyces spp. in field-collected samples. This newly developed molecular test was then applied to a large-scale sampling within the Ĺland archipelago, revealing that Ampelomyces is a widespread hyperparasite in this system, with high variability in prevalence among populations. We found that the hyperparasite was more common on leaves where multiple powdery mildew strains coexist, a pattern that may be attributed to differential exposure. Moreover, the prevalence of Ampelomyces at the plant level negatively affected the overwinter survival of its fungal host. We conclude that this hyperparasite may likely impact on its host population dynamics and argue for increased focus on the role of hyperparasites in disease dynamics. PMID:25204419

Tollenaere, C; Pernechele, B; Mäkinen, H S; Parratt, S R; Németh, M Z; Kovács, G M; Kiss, L; Tack, A J M; Laine, A-L

2014-12-01

328

Chemical Diversity and Defence Metabolism: How Plants Cope with Pathogens and Ozone Pollution  

PubMed Central

Chemical defences represent a main trait of the plant innate immune system. Besides regulating the relationship between plants and their ecosystems, phytochemicals are involved both in resistance against pathogens and in tolerance towards abiotic stresses, such as atmospheric pollution. Plant defence metabolites arise from the main secondary metabolic routes, the phenylpropanoid, the isoprenoid and the alkaloid pathways. In plants, antibiotic compounds can be both preformed (phytoanticipins) and inducible (phytoalexins), the former including saponins, cyanogenic glycosides and glucosinolates. Chronic exposure to tropospheric ozone (O3) stimulates the carbon fluxes from the primary to the secondary metabolic pathways to a great extent, inducing a shift of the available resources in favour of the synthesis of secondary products. In some cases, the plant defence responses against pathogens and environmental pollutants may overlap, leading to the unspecific synthesis of similar molecules, such as phenylpropanoids. Exposure to ozone can also modify the pattern of biogenic volatile organic compounds (BVOC), emitted from plant in response to herbivore feeding, thus altering the tritrophic interaction among plant, phytophagy and their natural enemies. Finally, the synthesis of ethylene and polyamines can be regulated by ozone at level of S-adenosylmethionine (SAM), the biosynthetic precursor of both classes of hormones, which can, therefore, mutually inhibit their own biosynthesis with consequence on plant phenotype. PMID:20111684

Iriti, Marcello; Faoro, Franco

2009-01-01

329

Genome-wide expression profiling shows transcriptional reprogramming in Fusarium graminearum by Fusarium graminearum virus 1-DK21 infection  

PubMed Central

Background Fusarium graminearum virus 1 strain-DK21 (FgV1-DK21) is a mycovirus that confers hypovirulence to F. graminearum, which is the primary phytopathogenic fungus that causes Fusarium head blight (FHB) disease in many cereals. Understanding the interaction between mycoviruses and plant pathogenic fungi is necessary for preventing damage caused by F. graminearum. Therefore, we investigated important cellular regulatory processes in a host containing FgV1-DK21 as compared to an uninfected parent using a transcriptional approach. Results Using a 3?-tiling microarray covering all known F. graminearum genes, we carried out genome-wide expression analyses of F. graminearum at two different time points. At the early point of growth of an infected strain as compared to an uninfected strain, genes associated with protein synthesis, including ribosome assembly, nucleolus, and ribosomal RNA processing, were significantly up-regulated. In addition, genes required for transcription and signal transduction, including fungal-specific transcription factors and cAMP signaling, respectively, were actively up-regulated. In contrast, genes involved in various metabolic pathways, particularly in producing carboxylic acids, aromatic amino acids, nitrogen compounds, and polyamines, showed dramatic down-regulation at the early time point. Moreover, genes associated with transport systems localizing to transmembranes were down-regulated at both time points. Conclusion This is the first report of global change in the prominent cellular pathways in the Fusarium host containing FgV1-DK21. The significant increase in transcripts for transcription and translation machinery in fungal host cells seems to be related to virus replication. In addition, significant down-regulation of genes required for metabolism and transporting systems in a fungal host containing the virus appears to be related to the host defense mechanism and fungal virulence. Taken together, our data aid in the understanding of how FgV1-DK21 regulates the transcriptional reprogramming of F. graminearum. PMID:22559730

2012-01-01

330

Methylobacterium-Induced Endophyte Community Changes Correspond with Protection of Plants against Pathogen Attack  

PubMed Central

Plant inoculation with endophytic bacteria that normally live inside the plant without harming the host is a highly promising approach for biological disease control. The mechanism of resistance induction by beneficial bacteria is poorly understood, because pathways are only partly known and systemic responses are typically not seen. The innate endophytic community structures change in response to external factors such as inoculation, and bacterial endophytes can exhibit direct or indirect antagonism towards pathogens. Earlier we showed that resistance induction by an endophytic Methylobacterium sp. in potato towards Pectobacterium atrosepticum was dependent on the density of the inoculum, whereas the bacterium itself had no antagonistic activity. To elucidate the role of innate endophyte communities in plant responses, we studied community changes in both in vitro and greenhouse experiments using various combinations of plants, endophyte inoculants, and pathogens. Induction of resistance was studied in several potato (Solanum tuberosum L.) cultivars by Methylobacterium sp. IMBG290 against the pathogens P. atrosepticum, Phytophthora infestans and Pseudomonas syringae pv. tomato DC3000, and in pine (Pinus sylvestris L.) by M. extorquens DSM13060 against Gremmeniella abietina. The capacities of the inoculated endophytic Methylobacterium spp. strains to induce resistance were dependent on the plant cultivar, pathogen, and on the density of Methylobacterium spp. inoculum. Composition of the endophyte community changed in response to inoculation in shoot tissues and correlated with resistance or susceptibility to the disease. Our results demonstrate that endophytic Methylobacterium spp. strains have varying effects on plant disease resistance, which can be modulated through the endophyte community of the host. PMID:23056459

Ardanov, Pavlo; Sessitsch, Angela; Haggman, Hely; Kozyrovska, Natalia; Pirttila, Anna Maria

2012-01-01

331

Tools to kill: Genome of one of the most destructive plant pathogenic fungi Macrophomina phaseolina  

PubMed Central

Background Macrophomina phaseolina is one of the most destructive necrotrophic fungal pathogens that infect more than 500 plant species throughout the world. It can grow rapidly in infected plants and subsequently produces a large amount of sclerotia that plugs the vessels, resulting in wilting of the plant. Results We sequenced and assembled ~49?Mb into 15 super-scaffolds covering 92.83% of the M. phaseolina genome. We predict 14,249 open reading frames (ORFs) of which 9,934 are validated by the transcriptome. This phytopathogen has an abundance of secreted oxidases, peroxidases, and hydrolytic enzymes for degrading cell wall polysaccharides and lignocelluloses to penetrate into the host tissue. To overcome the host plant defense response, M. phaseolina encodes a significant number of P450s, MFS type membrane transporters, glycosidases, transposases, and secondary metabolites in comparison to all sequenced ascomycete species. A strikingly distinct set of carbohydrate esterases (CE) are present in M. phaseolina, with the CE9 and CE10 families remarkably higher than any other fungi. The phenotypic microarray data indicates that M. phaseolina can adapt to a wide range of osmotic and pH environments. As a broad host range pathogen, M. phaseolina possesses a large number of pathogen-host interaction genes including those for adhesion, signal transduction, cell wall breakdown, purine biosynthesis, and potent mycotoxin patulin. Conclusions The M. phaseolina genome provides a framework of the infection process at the cytological and molecular level which uses a diverse arsenal of enzymatic and toxin tools to destroy the host plants. Further understanding of the M. phaseolina genome-based plant-pathogen interactions will be instrumental in designing rational strategies for disease control, essential to ensuring global agricultural crop production and security. PMID:22992219

2012-01-01

332

Presence of pathogenic amoebae in power plant cooling waters. Final report, October 15, 1977-September 30, 1979. [Naegleria fowleri  

SciTech Connect

Cooling-water-associated algae and sediments from five northern and five southern or western electric power plants were tested for the presence of pathogenic amoebae. In addition, water algae and sediments from five northern and five southern/western sites not associated with power plants were tested. There was a significant correlation at northern power plants between the presence of thermophilic, pathogenic amoebae in cooling waters and thermal additions. Presence of the pathogenic did not correlate with salinity, pH, conductivity, or a variety of various chemical components of the cooling waters. Selected pathogenic isolates were tested serologically and were classified as Naegleria fowleri. Although thermal additions were shown to be contributing factor in predisposing cooling waters to the growth of pathogenic amoebae, the data suggest the involvement of other currently undefined parameters associated with the presence of the pathogenic amoebae. 35 refs., 21 tabs.

Tyndall, R.L.; Willaert, E.; Stevens, A.R.

1981-03-01

333

Multihost Experimental Evolution of the Pathogen Ralstonia solanacearum Unveils Genes Involved in Adaptation to Plants.  

PubMed

Ralstonia solanacearum, the causal agent of a lethal bacterial wilt plant disease, infects an unusually wide range of hosts. These hosts can further be split into plants where R. solanacearum is known to cause disease (original hosts) and those where this bacterium can grow asymptomatically (distant hosts). Moreover, this pathogen is able to adapt to many plants as supported by field observations reporting emergence of strains with enlarged pathogenic properties. To investigate the genetic bases of host adaptation, we conducted evolution experiments by serial passages of a single clone of the pathogen on three original and two distant hosts over 300 bacterial generations and then analyzed the whole-genome of nine evolved clones. Phenotypic analysis of the evolved clones showed that the pathogen can increase its fitness on both original and distant hosts although the magnitude of fitness increase was greater on distant hosts. Only few genomic modifications were detected in evolved clones compared with the ancestor but parallel evolutionary changes in two genes were observed in independent evolved populations. Independent mutations in the regulatory gene efpR were selected for in three populations evolved on beans, a distant host. Reverse genetic approaches confirmed that these mutations were associated with fitness gain on bean plants. This work provides a first step toward understanding the within-host evolutionary dynamics of R. solanacearum during infection and identifying bacterial genes subjected to in planta selection. The discovery of EfpR as a determinant conditioning host adaptation of the pathogen illustrates how experimental evolution coupled with whole-genome sequencing is a potent tool to identify novel molecular players involved in central life-history traits. PMID:25086002

Guidot, Alice; Jiang, Wei; Ferdy, Jean-Baptiste; Thébaud, Christophe; Barberis, Patrick; Gouzy, Jérôme; Genin, Stéphane

2014-11-01

334

PCR detection assays for the trichothecene-producing species Fusarium graminearum, Fusarium culmorum, Fusarium poae, Fusarium equiseti and Fusarium sporotrichioides  

Microsoft Academic Search

Contamination of small-grain cereals with the fungal species Fusarium graminearum, F. culmorum, F. poae, F. sporotrichioides and F. equiseti is an important source of trichothecenes, Zearalenone and other mycotoxins which cause serious diseases in human and animals. Additionally, these species contribute to Fusarium Head Blight, a disease which produces important losses in cereal yield. Early detection and control of these

Miguel Jurado; Covadonga Vázquez; Belén Patińo; M. Teresa González-Jaén

2005-01-01

335

Effects of endogenous signals and Fusarium oxysporum on the mechanism regulating genistein synthesis and accumulation in yellow lupine and their impact on plant cell cytoskeleton.  

PubMed

The aim of the study was to examine cross-talk interactions of soluble sugars (sucrose, glucose and fructose) and infection caused by Fusarium oxysporum f.sp. lupini on the synthesis of genistein in embryo axes of Lupinus luteus L.cv. Juno. Genistein is a free aglycone, highly reactive and with the potential to inhibit fungal infection and development of plant diseases. As signal molecules, sugars strongly stimulated accumulation of isoflavones, including genistein, and the expression of the isoflavonoid biosynthetic genes. Infection significantly enhanced the synthesis of genistein and other isoflavone aglycones in cells of embryo axes of yellow lupine with high endogenous sugar levels. The activity of ?-glucosidase, the enzyme that releases free aglycones from their glucoside bindings, was higher in the infected tissues than in the control ones. At the same time, a very strong generation of the superoxide anion radical was observed in tissues with high sugar contents already in the initial stage of infection. During later stages after inoculation, a strong generation of semiquinone radicals was observed, which level was relatively higher in tissues deficient in sugars than in those with high sugar levels. Observations of actin and tubulin cytoskeletons in cells of infected embryo axes cultured on the medium with sucrose, as well as the medium without sugar, showed significant differences in their organization. PMID:25178062

Formela, Magda; Samardakiewicz, S?awomir; Marczak, ?ukasz; Nowak, Witold; Naro?na, Dorota; Bednarski, Waldemar; Kasprowicz-Malu?ki, Anna; Morkunas, Iwona

2014-01-01

336

Induced resistance enzymes in wild plants-do `early birds' escape from pathogen attack?  

NASA Astrophysics Data System (ADS)

Systemic acquired resistance (SAR) of plants to pathogens is a well-defined phenomenon. The underlying signalling pathways and its application in crop protection are intensively studied. However, most studies are conducted on crop plants or on Arabidopsis as a model plant. The taxonomic distribution of this phenomenon and its dependence on life history are thus largely unknown. We quantified activities of three classes of resistance-related enzymes in 18 plant species to investigate whether plants with varying life histories differ in their investment in disease resistance. Enzyme activities were quantified in untreated plants, and in plants induced with BION, a chemical resistance elicitor. All species showed constitutive activities of chitinase, peroxidase, or glucanase. However, constitutive chitinase activities varied by 30 times, and peroxidase by 50 times, among species. Several species did not respond to the induction treatment, while enzyme activities in other species increased more than threefold after BION application. Plant species differ dramatically in the presence and inducibility of resistance enzymes. This variation could be related to life history: While all resistance enzymes were significantly induced in larger perennial plants that flower during summer, spring geophytes hardly showed inducible resistance. These plants grow in an environment that is characterised by a low-pathogen pressure, and thus may simply ‘escape’ from infection. Our study presents the first comparative data set on resistance-related enzymes in noncultivated plants. The current view on SAR—narrowed by the concentration on cultivated crops—is not sufficient to understand the ecological and evolutionary relevance of this widespread plant trait.

Heil, Martin; Ploss, Kerstin

2006-09-01

337

Characterization of a novel plant growth-promoting bacteria strain Delftia tsuruhatensis HR4 both as a diazotroph and a potential biocontrol agent against various plant pathogens  

Microsoft Academic Search

A novel, plant growth-promoting bacterium Delftia tsuruhatensis, strain HR4, was isolated from the rhizoplane of rice (Oryza sativa L., cv. Yueguang) in North China. In vitro antagonistic assay showed this strain could suppress the growth of various plant pathogens effectively, especially the three main rice pathogens (Xanthomonas oryzae pv. oryzae, Rhizoctonia solani and Pyricularia oryzae Cavara). Treated with strain HR4

Jigang Han; Lei Sun; Xiuzhu Dong; Zhengqiu Cai; Xiaolu Sun; Hailian Yang; Yunshan Wang; Wei Song

2005-01-01

338

Interaction between Meloidogyne incognita and Agrobacterium tumefaciens or Fusarium oxysporum f. sp. lycopersici on Tomato.  

PubMed

Agrobacterium tumefaciens stimulated and Fusarium oxysporum f. sp. lycopersici inhibited development and reproduction of Meloidogyne incognita when applied to the opposite split root of tomato, Lycopersicon esculentum cv. Tropic, plants. The lowest rate of nematode reproduction occurred after 2,000 juveniles were applied and the fungus was present in the opposite split root. The effects of all three pathogens alone on the growth of roots and shoots of tomato plants were evident, but M. incognita had a greater effect alone than did either of the other pathogens. The length of split roots was reduced by the infection of M. incognita and A. tumefaciens or F. oxysporum f. sp. lycopersici. The number of galls induced by nematodes on roots was higher where the bacterium was applied and lower where the fungus was applied to the opposite split root. PMID:19283119

El-Sherif, A G; Elwakil, M A

1991-04-01

339

Stem-cell-triggered immunity safeguards cytokinin enriched plant shoot apexes from pathogen infection  

PubMed Central

Intricate mechanisms discriminate between friends and foes in plants. Plant organs deploy overlapping and distinct protection strategies. Despite vulnerability to a plethora of pathogens, the growing tips of plants grow bacteria free. The shoot apical meristem (SAM) is among three stem cells niches, a self-renewable reservoir for the future organogenesis of leaf, stem, and flowers. How plants safeguard this high value growth target from infections was not known until now. Recent reports find the stem cell secreted 12-amino acid peptide CLV3p (CLAVATA3 peptide) is perceived by FLS2 (FLAGELLIN SENSING 2) receptor and activates the transcription of immunity and defense marker genes. No infection in the SAM of wild type plants and bacterial infection in clv3 and fls2 mutants illustrate this natural protection against infections. Cytokinins (CKs) are enriched in the SAM and regulate meristem activities by their involvement in stem cell signaling networks. Auxin mediates plant susceptibility to pathogen infections while CKs boost plant immunity. Here, in addition to the stem-cell-triggered immunity we also highlight a potential link between CK signaling and CLV3p mediated immune response in the SAM.

Naseem, Muhammad; Srivastava, Mugdha; Dandekar, Thomas

2014-01-01

340

Volatiles produced by soil-borne endophytic bacteria increase plant pathogen resistance and affect tritrophic interactions  

PubMed Central

Volatile organic compounds (VOCs) released by soil microorganisms influence plant growth and pathogen resistance. Yet, very little is known about their influence on herbivores and higher trophic levels. We studied the origin and role of a major bacterial VOC, 2,3-butanediol (2,3-BD), on plant growth, pathogen and herbivore resistance, and the attraction of natural enemies in maize. One of the major contributors to 2,3-BD in the headspace of soil-grown maize seedlings was identified as Enterobacter aerogenes, an endophytic bacterium that colonizes the plants. The production of 2,3-BD by E. aerogenes rendered maize plants more resistant against the Northern corn leaf blight fungus Setosphaeria turcica. On the contrary, E. aerogenes-inoculated plants were less resistant against the caterpillar Spodoptera littoralis. The effect of 2,3-BD on the attraction of the parasitoid Cotesia marginiventris was more variable: 2,3-BD application to the headspace of the plants had no effect on the parasitoids, but application to the soil increased parasitoid attraction. Furthermore, inoculation of seeds with E. aerogenes decreased plant attractiveness, whereas inoculation of soil with a total extract of soil microbes increased parasitoid attraction, suggesting that the effect of 2,3-BD on the parasitoid is indirect and depends on the composition of the microbial community. PMID:24127750

Ton, Jurriaan; Brandenburg, Anna; Karlen, Danielle; Zopfi, Jakob; Turlings, Ted C. J.

2014-01-01

341

Stem-cell-triggered immunity safeguards cytokinin enriched plant shoot apexes from pathogen infection.  

PubMed

Intricate mechanisms discriminate between friends and foes in plants. Plant organs deploy overlapping and distinct protection strategies. Despite vulnerability to a plethora of pathogens, the growing tips of plants grow bacteria free. The shoot apical meristem (SAM) is among three stem cells niches, a self-renewable reservoir for the future organogenesis of leaf, stem, and flowers. How plants safeguard this high value growth target from infections was not known until now. Recent reports find the stem cell secreted 12-amino acid peptide CLV3p (CLAVATA3 peptide) is perceived by FLS2 (FLAGELLIN SENSING 2) receptor and activates the transcription of immunity and defense marker genes. No infection in the SAM of wild type plants and bacterial infection in clv3 and fls2 mutants illustrate this natural protection against infections. Cytokinins (CKs) are enriched in the SAM and regulate meristem activities by their involvement in stem cell signaling networks. Auxin mediates plant susceptibility to pathogen infections while CKs boost plant immunity. Here, in addition to the stem-cell-triggered immunity we also highlight a potential link between CK signaling and CLV3p mediated immune response in the SAM. PMID:25400652

Naseem, Muhammad; Srivastava, Mugdha; Dandekar, Thomas

2014-01-01

342

Green leaf volatiles: a plant's multifunctional weapon against herbivores and pathogens.  

PubMed

Plants cannot avoid being attacked by an almost infinite number of microorganisms and insects. Consequently, they arm themselves with molecular weapons against their attackers. Plant defense responses are the result of a complex signaling network, in which the hormones jasmonic acid (JA), salicylic acid (SA) and ethylene (ET) are the usual suspects under the magnifying glass when researchers investigate host-pest interactions. However, Green Leaf Volatiles (GLVs), C? molecules, which are very quickly produced and/or emitted upon herbivory or pathogen infection by almost every green plant, also play an important role in plant defenses. GLVs are semiochemicals used by insects to find their food or their conspecifics. They have also been reported to be fundamental in indirect defenses and to have a direct effect on pests, but these are not the only roles of GLVs. These volatiles, being probably one of the fastest weapons exploited, are also able to directly elicit or prime plant defense responses. Moreover, GLVs, via crosstalk with phytohormones, mostly JA, can influence the outcome of the plant's defense response against pathogens. For all these reasons GLVs should be considered as co-protagonists in the play between plants and their attackers. PMID:23999587

Scala, Alessandra; Allmann, Silke; Mirabella, Rossana; Haring, Michel A; Schuurink, Robert C

2013-01-01

343

Volatiles produced by soil-borne endophytic bacteria increase plant pathogen resistance and affect tritrophic interactions.  

PubMed

Volatile organic compounds (VOCs) released by soil microorganisms influence plant growth and pathogen resistance. Yet, very little is known about their influence on herbivores and higher trophic levels. We studied the origin and role of a major bacterial VOC, 2,3-butanediol (2,3-BD), on plant growth, pathogen and herbivore resistance, and the attraction of natural enemies in maize. One of the major contributors to 2,3-BD in the headspace of soil-grown maize seedlings was identified as Enterobacter aerogenes, an endophytic bacterium that colonizes the plants. The production of 2,3-BD by E.?aerogenes rendered maize plants more resistant against the Northern corn leaf blight fungus Setosphaeria turcica. On the contrary, E.?aerogenes-inoculated plants were less resistant against the caterpillar Spodoptera littoralis. The effect of 2,3-BD on the attraction of the parasitoid Cotesia marginiventris was more variable: 2,3-BD application to the headspace of the plants had no effect on the parasitoids, but application to the soil increased parasitoid attraction. Furthermore, inoculation of seeds with E.?aerogenes decreased plant attractiveness, whereas inoculation of soil with a total extract of soil microbes increased parasitoid attraction, suggesting that the effect of 2,3-BD on the parasitoid is indirect and depends on the composition of the microbial community. PMID:24127750

D'Alessandro, Marco; Erb, Matthias; Ton, Jurriaan; Brandenburg, Anna; Karlen, Danielle; Zopfi, Jakob; Turlings, Ted C J

2014-04-01

344

Influence of Soil Copper Pollution and Fusarium culmorum on the Heavy Metal Content in Wheat  

Microsoft Academic Search

BOGOEVA, I., E. BONCHEVA, R. STEFANOVA and B. BLAJEV, 2007. Influence of soil copper pollution and Fusarium culmorum on the heavy metal content in wheat. Bulg. J. Agric. Sci., 13: 333-339 A greenhouse experiment in pots was carried out in order to assess the effect of combination of stress factors - copper pollution and Fusarium culmorum pathogen on the bioavailability

I. BOGOEVA; E. BONCHEVA

345

Cytological aspects of compost-mediated induced resistance against fusarium crown and root rot in tomato.  

PubMed

ABSTRACT The potential of a pulp and paper mill residues compost for the control of crown and root rot of greenhouse-grown tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici was ultrastructurally investigated. Peat moss amended with compost substantially reduced disease-associated symptoms. Addition of Pythium oligandrum to either peat moss alone or peat moss amended with compost resulted in a considerable reduction in disease incidence compared with controls grown in peat moss alone. Histological and cytological observations of root samples from Fusarium-inoculated plants revealed that the beneficial effect of compost in reducing disease symptoms is associated with increased plant resistance to fungal colonization. One of the most prominent facets of compost-mediated induced resistance concerned the formation of physical barriers at sites of attempted fungal penetration. These structures, likely laid down to prevent pathogen ingress toward the vascular elements, included callose-enriched wall appositions and osmiophilic deposits around the sites of potential pathogen ingress. Invading hyphae, coated by the osmiophilic material, showed marked cellular disorganization. The use of the wheat germ agglutinin-ovomucoid-gold complex provided evidence that the wall-bound chitin was altered in severely damaged hyphae. A substantial increase in the extent and magnitude of the cellular changes induced by compost was observed when P. oligandrum was supplied to the potting substrate. This finding corroborates the current concept that amendment of composts with specific antagonists may be a valuable option for amplifying their beneficial properties in terms of plant disease suppression. PMID:18942956

Pharand, Benoît; Carisse, Odile; Benhamou, Nicole

2002-04-01

346

Functional characterization and gene expression profiling of superoxide dismutase from plant pathogenic phytoplasma.  

PubMed

The rapid production of huge amounts of reactive oxygen species (ROS) is one of the responses of animal and plant cells induced under stress conditions, such as pathogenic bacterial infection. To protect against the cytotoxic ROS, it is important for pathogenic bacteria to inactivate ROS by employing their antioxidant enzymes like superoxide dismutase (SOD). Here, we cloned and characterized the sodA gene from the plant pathogenic bacterium, 'Candidatus Phytoplasma asteris' OY-W strain. This is the first description of gene expression and antioxidant enzymatic activity of SOD from a phytoplasma. We also demonstrated the sodA gene product (OY-SOD) functions as Mn-type SOD. Since other Mollicutes bacteria such as mycoplasmas do not possess sodA probably due to reductive evolution, it is intriguing that phytoplasmas possess sodA despite their lack of many metabolic genes, suggesting that OY-SOD may play an important role in the phytoplasma colonization of plants and insects. Moreover, Western blot analysis and real-time PCR revealed that OY-SOD is expressed when the phytoplasma is grown in both plant and insect hosts, suggesting it is functioning in both hosts. Possible role of SOD in protection against damage by host-derived ROS is discussed. PMID:22982017

Miura, Chihiro; Sugawara, Kyoko; Neriya, Yutaro; Minato, Nami; Keima, Takuya; Himeno, Misako; Maejima, Kensaku; Komatsu, Ken; Yamaji, Yasuyuki; Oshima, Kenro; Namba, Shigetou

2012-12-01

347

Cereal crop volatile organic compound induction after mechanical injury, beetle herbivory (Oulema spp.), or fungal infection (Fusarium spp.).  

PubMed

Herbivory, mechanical injury or pathogen infestation to vegetative tissues can induce volatile organic compounds (VOCs) production, which can provide defensive functions to injured and uninjured plants. In our studies with 'McNeal' wheat, 'Otana' oat, and 'Harrington' barley, plants that were mechanically injured, attacked by either of two Oulema spp. (melanopus or cyanella) beetles, or infected by one of the three Fusarium spp. (graminearum, avenaceum, or culmorum), had significant VOC induction compared to undamaged plants. Mechanical injury to the main stem or one leaf caused the induction of one green leaf volatile (GLV) - (Z)-3-hexenol, and three terpenes (?-linalool, ?-caryophyllene, and ?-pinene) with all three grasses; wheat and barley also showed ?-linalool oxide induction. The blend of induced VOCs after Fusarium spp. infestation or Oulema spp. herbivory was dominated by GLVs ((Z)-3-hexenal, (E)-2-hexenal, (E)-2-hexenol, (Z)-3-hexenyl acetate, and 1-hexenyl acetate) and ?-linalool and ?-caryophyllene; beetle herbivory also induced (E)-?-farnesene. Different ratios of individual VOCs were induced between the two Oulema spp. for each cereal grass and different ratios across the three cereals for each beetle species. Also, different ratios of individual VOCs were induced between the three Fusarium spp. for each cereal grass and different ratios across the three cereals for each fungal pathogen species. Our results are preliminary since we could not simultaneously measure VOC induction from controls with each of the ten different injury treatments for each of the three cereals. However, the comparison of mechanical injury, insect herbivory, and fungal infection has not been previously examined with VOC responses from three different plant species within the same family. Also, our work suggests large qualitative and quantitative overlap of VOC induction from plants of all three cereals having beetle herbivory injury when compared to infection injury from necrotrophic fungal pathogens. PMID:21208684

Piesik, Dariusz; Pa?ka, Dariusz; Delaney, Kevin J; Skoczek, Agata; Lamparski, Robert; Weaver, David K

2011-06-15

348

Plant Pathology (2002) 51, 225230 2002 BSPP 225  

E-print Network

than in npFo-untreated plants after Foa inocula- tion. Antifungal activity (inhibition of fungal spore). The disease is particularly difficult to control because the crop is perennial, the pathogen is soil- borne, 1998; Larkin & Fravel, 1999; Bao & Lazarovits, 2001). Biological control of Fusarium crown and root rot

Hsiang, Tom

349

Biocontrol of Fusarium wilt disease in cucumber with improvement of growth and mineral uptake using some antagonistic formulations.  

PubMed

Fusarium wilt disease in Cucumber (Cucumis sativus L.) is widespread, responsible for serious economic losses. Amongst totally 15 isolates of Fusarium spp., obtained from different localities of Sohag governorate, Egypt, only the identified isolates as F. oxysporum were pathogenic on cucumber Denmark Beta-Alpha cv. and caused wilt symptoms. Totally 22 isolates of Trichoderma spp., B. subtilis and Pseudomonas spp., were obtained from rhizosphere of cucumber and some available commercial formulations and then tested for antagonistic activity against F. oxysporum (FO5) in vitro. The highest inhibitory effect on growth of FO5 was observed by isolate Trichodex of T. harzianum (89.29%) followed by Th4 of T. harzianum, Serenade and MBI 600 of B. subtilis, PS3 of Pseudomonas spp., and Treico and Tv2 of T. viride. Pot experiments were performed to investigate the effects of formulated antagonists as seed treatment on Fusarium wilt incidence, growth and mineral uptake of cucumber. Results showed that all tested formulations significantly reduced percent of wilted plants and disease severity, and improved plant growth by increasing length of shoot and root, fresh and dry weight of shoot and root system, and number of leaves and flowers per plant compared with untreated control. They also significantly increased nutrient contents of plant shoot including N, P, K, Ca, Fe, Mn, Cu, and Zn. Magnesium content in shoot slightly not significantly increased. Formulation of Trichodex was the most effective ones followed by Serenade, Th4 and PS3. PMID:23878960

Moharam, Moustafa H A; Negim, Osama O

2012-01-01

350

A soybean cyst nematode resistance gene points to a new mechanism of plant resistance to pathogens.  

PubMed

Soybean (Glycine max (L.) Merr.) is an important crop that provides a sustainable source of protein and oil worldwide. Soybean cyst nematode (Heterodera glycines Ichinohe) is a microscopic roundworm that feeds on the roots of soybean and is a major constraint to soybean production. This nematode causes more than US$1 billion in yield losses annually in the United States alone, making it the most economically important pathogen on soybean. Although planting of resistant cultivars forms the core management strategy for this pathogen, nothing is known about the nature of resistance. Moreover, the increase in virulent populations of this parasite on most known resistance sources necessitates the development of novel approaches for control. Here we report the map-based cloning of a gene at the Rhg4 (for resistance to Heterodera glycines 4) locus, a major quantitative trait locus contributing to resistance to this pathogen. Mutation analysis, gene silencing and transgenic complementation confirm that the gene confers resistance. The gene encodes a serine hydroxymethyltransferase, an enzyme that is ubiquitous in nature and structurally conserved across kingdoms. The enzyme is responsible for interconversion of serine and glycine and is essential for cellular one-carbon metabolism. Alleles of Rhg4 conferring resistance or susceptibility differ by two genetic polymorphisms that alter a key regulatory property of the enzyme. Our discovery reveals an unprecedented plant resistance mechanism against a pathogen. The mechanistic knowledge of the resistance gene can be readily exploited to improve nematode resistance of soybean, an increasingly important global crop. PMID:23235880

Liu, Shiming; Kandoth, Pramod K; Warren, Samantha D; Yeckel, Greg; Heinz, Robert; Alden, John; Yang, Chunling; Jamai, Aziz; El-Mellouki, Tarik; Juvale, Parijat S; Hill, John; Baum, Thomas J; Cianzio, Silvia; Whitham, Steven A; Korkin, Dmitry; Mitchum, Melissa G; Meksem, Khalid

2012-12-13

351

Genome Sequencing of the Plant Pathogen Taphrina deformans, the Causal Agent of Peach Leaf Curl  

PubMed Central

ABSTRACT Taphrina deformans is a fungus responsible for peach leaf curl, an important plant disease. It is phylogenetically assigned to the Taphrinomycotina subphylum, which includes the fission yeast and the mammalian pathogens of the genus Pneumocystis. We describe here the genome of T. deformans in the light of its dual plant-saprophytic/plant-parasitic lifestyle. The 13.3-Mb genome contains few identifiable repeated elements (ca. 1.5%) and a relatively high GC content (49.5%). A total of 5,735 protein-coding genes were identified, among which 83% share similarities with other fungi. Adaptation to the plant host seems reflected in the genome, since the genome carries genes involved in plant cell wall degradation (e.g., cellulases and cutinases), secondary metabolism, the hallmark glyoxylate cycle, detoxification, and sterol biosynthesis, as well as genes involved in the biosynthesis of plant hormones. Genes involved in lipid metabolism may play a role in its virulence. Several locus candidates for putative MAT cassettes and sex-related genes akin to those of Schizosaccharomyces pombe were identified. A mating-type-switching mechanism similar to that found in ascomycetous yeasts could be in effect. Taken together, the findings are consistent with the alternate saprophytic and parasitic-pathogenic lifestyles of T. deformans. PMID:23631913

Cisse, Ousmane H.; Almeida, Joao M. G. C. F.; Fonseca, Alvaro; Kumar, Ajay Anand; Salojarvi, Jarkko; Overmyer, Kirk; Hauser, Philippe M.; Pagni, Marco

2013-01-01

352

Pathogenic and Nonpathogenic Lifestyles in Colletotrichum acutatum from Strawberry and Other Plants.  

PubMed

ABSTRACT Anthracnose is one of the major fungal diseases of strawberry occurring worldwide. In Israel, the disease is caused primarily by the species Colletotrichum acutatum. The pathogen causes black spot on fruit, root necrosis, and crown rot resulting in mortality of transplants in the field. The host range and specificity of C. acutatum from strawberry was examined on pepper, eggplant, tomato, bean, and strawberry under greenhouse conditions. The fungus was recovered from all plant species over a 3-month period but caused disease symptoms only on strawberry. Epiphytic and endophytic (colonization) fungal growth in the different plant species was confirmed by reisolation from leaf tissues and by polymerase chain reaction (PCR)-specific primer amplification. C. acutatum was also isolated from healthy looking, asymptomatic plants of the weed genera Vicia and Conyza. Isolates that were recovered from the weeds caused disease symptoms on strawberry and were positively identified as C. acutatum by PCR. The habitation of a large number of plant species, including weeds, by C. acutatum suggests that, although it causes disease only on strawberry and anemone in Israel, this fungus can persist on many other plant species. Therefore, plants that are not considered hosts of C. acutatum may serve as a potential inoculum source for strawberry infection and permit survival of the pathogen between seasons. PMID:18944126

Freeman, S; Horowitz, S; Sharon, A

2001-10-01

353

Morphological characteristics and pathogenicity of fungi associated with Roselle (Hibiscus Sabdariffa) diseases in Penang, Malaysia.  

PubMed

Roselle, or Jamaica sorrel (Hibiscus sabdariffa) is a popular vegetable in many tropical regions, cultivated for its leaves, seeds, stems and calyces which, the dried calyces are used to prepare tea, syrup, jams and jellies and as beverages. The main objectives of this study were to identify and characterise fungal pathogens associated with Roselle diseases based on their morphological and cultural characteristics and to determine the pathogenicity of four fungi infecting Roselle seedlings, namely Phoma exigua, Fusarium nygamai, Fusarium tgcq and Rhizoctonia solani in Penang. A total of 200 fungal isolates were obtained from 90 samples of symptomatic Roselle tissues. The isolates were identified based on cultural and morphological characteristics, as well as their pathogenicity. The fungal pathogen most frequently isolated was P. exigua (present in 45% of the samples), followed by F. nygamai (25%), Rhizoctonia solani (19%) and F. camptoceras (11%). Pathogenicity tests showed that P. exigua, F. nygamai, F. camptoceras and R. solani were able to infect both wounded and unwounded seedlings with different degrees of severity as indicated by the Disease severity (DS). R. solani was the most pathogenic fungus affecting both wounded and unwounded Roselle seedlings, followed by P. exigua that was highly pathogenic on wounded seedlings. F. nygamai was less pathogenic while the least pathogenic fungus was F. camptoceras, infecting only the unwounded seedlings but, surprisingly, not the wounded plants. PMID:21839160

Eslaminejad, Touba; Zakaria, Maziah

2011-11-01

354

Antifungal Activity of Paenibacillus kribbensis Strain T-9 Isolated from Soils against Several Plant Pathogenic Fungi  

PubMed Central

The bacterial strain T-9, which shows strong antifungal activity, is isolated from the soils of Samcheok, Gangwondo and identified as Paenibacillus kribbensis according to morphological and taxonomic characteristics and 16S rRNA gene sequence analysis. The P. kribbensis strain T-9 strongly inhibits the growth of various phytopathogenic fungi including Botrytis cinerea, Colletotricum acutatum, Fusarium oxysporum f. sp. radicis-lycopersici, Magnaporthe oryzae, Phytophthora capsici, Rhizoctonia solani, and Sclerotium cepivorum in vitro. Also, the P. kribbensis strain T-9 exhibited similar or better control effects to plant diseases than in fungicide treatment through in vivo assays. In the 2-year greenhouse experiments, P. kribbensis strain T-9 was highly effective against clubroot. In the 2-year field trials, the P. kribbensis strain T-9 was less effective than the fungicide, but reduced clubroot on Chinese cabbage when compared to the control. The above-described results indicate that the strain T-9 may have the potential as an antagonist to control various phytopathogenic fungi. PMID:25288992

Xu, Sheng Jun; Hong, Sae Jin; Choi, Woobong; Kim, Byung Sup

2014-01-01

355

Genetic Conversion of a Fungal Plant Pathogen to a Nonpathogenic, Endophytic Mutualist  

Microsoft Academic Search

The filamentous fungal ascomycete Colletotrichum magna causes anthracnose in cucurbit plants. Isolation of a nonpathogenic mutant of this species (path-1) resulted in maintained wild-type levels of in vitro sporulation, spore adhesion, appressorial formation, and infection. Path-1 grew throughout host tissues as an endophyte and retained the wild-type host range, which indicates that the genetics involved in pathogenicity and host specificity

Stanley Freeman; Rusty J. Rodriguez

1993-01-01

356

Antimicrobial activities of extracts from Indo-Pacific marine plants against marine pathogens and saprophytes  

Microsoft Academic Search

This study is the second of two surveys designed to systematically screen extracts from marine plants for antimicrobial effects\\u000a against ecologically relevant marine microorganisms, and to compare results on a geographical basis. In the preceding survey,\\u000a extracts from tropical Atlantic marine algae and seagrasses were screened in growth inhibition assays against the pathogenic\\u000a fungus Lindra thalassiae, the saprophytic fungus Dendryphiella

Melany P. Puglisi; Sebastian Engel; Paul R. Jensen; William Fenical

2007-01-01

357

Does biopolymers composition in seeds contribute to the flax resistance against the Fusarium infection?  

PubMed

Over the last decades, the cultivation of fibrous flax declined heavily. There are number of reasons for that fact; one of them is flax susceptibility to the pathogen infection. Damages caused mainly by fungi from genus Fusarium lead to the significant losses when cultivating flax, which in turn discourage farmers to grow flax. Therefore, to launch the new products from flax with attractive properties there is a need to obtain new flax varieties with increased resistance to pathogens. In order to obtain the better quality of flax fiber, we previously generated flax with reduced pectin or lignin level (cell wall polymers). The modifications altered also plants' resistance to the Fusarium infection. Undoubtedly, the plant defense system is complex, however, in this article we aimed to investigate the composition of modified flax seeds and to correlate it with the observed changes in the flax resistance to the pathogen attack. In particular, we evaluated the content and composition of carbohydrates (cell wall polymers: pectin, cellulose, hemicelluloses and mucilage), and phenylpropanoid compounds (lignin, lignans, phenolics). From the obtained results we concluded that the observed changes in the vulnerability to pathogens putatively correlate with the antioxidant potential of phenylpropanoids accumulated in seeds, seco-isolariciresinol and coumaric acid diglycosides in particular, and with pectin level as a carbon source for pathogens. Surprisingly, relatively less important for the resistance was the physical barrier, including lignin and cellulose amount and cellulose structure. Certainly, the hypothesis should be verified on a larger number of genotypes. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:992-1004, 2014. PMID:25080398

Zeitoun, Ahmed M; Preisner, Marta; Kulma, Anna; Dymi?ska, Lucyna; Hanuza, Jerzy; Starzycki, Michal; Szopa, Jan

2014-09-01

358

Biological control of fusarium wilt of cucumber by chitinolytic bacteria.  

PubMed

ABSTRACT Two chitinolytic bacterial strains, Paenibacillus sp. 300 and Streptomyces sp. 385, suppressed Fusarium wilt of cucumber (Cucumis sativus) caused by Fusarium oxysporum f. sp. cucumerinum in nonsterile, soilless potting medium. A mixture of the two strains in a ratio of 1:1 or 4:1 gave significantly (P < 0.05) better control of the disease than each of the strains used individually or than mixtures in other ratios. Several formulations were tested, and a zeolite-based, chitosan-amended formulation (ZAC) provided the best protection against the disease. Dose-response studies indicated that the threshold dose of 6 g of formulation per kilogram of potting medium was required for significant (P < 0.001) suppression of the disease. This dose was optimum for maintaining high rhizosphere population densities of chitinolytic bacteria (log 8.1 to log 9.3 CFU/g dry weight of potting medium), which were required for the control of Fusarium wilt. The ZAC formulation was suppressive when added to pathogen-infested medium 15 days before planting cucumber seeds. The formulation also provided good control when stored for 6 months at room temperature or at 4 degrees C. Chitinase and beta-1,3-glucanase enzymes were produced when the strains were grown in the presence of colloidal chitin as the sole carbon source. Partial purification of the chitinases, followed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and activity staining, revealed the presence of five bands with molecular masses of 65, 62, 59, 55, and 52 kDa in the case of Paenibacillus sp. 300; and three bands with molecular masses of 52, 38, and 33 kDa in the case of Streptomyces sp. 385. Incubation of cell walls of F. oxysporum f. sp. cucumerinum with partially purified enzyme fractions led to the release of N-acetyl-D-glucosamine (NAGA). NAGA content was considerably greater when pooled enzyme fractions (64 to 67) from Paenibacillus sp. were used, because they contained high beta-1,3-glucanase activity in addition to chitinase activity. Suppression of Fusarium wilt of cucumber by a combination of these two bacteria may involve the action of these hydrolytic enzymes. PMID:18944809

Singh, P P; Shin, Y C; Park, C S; Chung, Y R

1999-01-01

359

Enniatin Production by Fusarium Strains and Its Effect on Potato Tuber Tissue  

PubMed Central

Several Fusarium strains produce the cyclohexadepsipeptide enniatin, a host-nonspecific phytotoxin. Enniatins are synthesized by the 347-kDa multifunctional enzyme enniatin synthetase. In the present study, 36 Fusarium strains derived from a wide range of host plants were characterized with respect to enniatin production in different media. Thirteen of these strains produced enniatins on one or more of these media. To determine whether enniatin production affected virulence, an assay on potato tuber tissue was performed. Seven enniatin-producing and 16 nonproducing strains induced necrosis of potato tuber tissue, so that enniatin synthesis is not essential for the infection of potato tuber tissue. The application of a mixture of enniatins to slices of potato tuber, however, caused necrosis of the tissue. Therefore, enniatin production by the enniatin-synthesizing strains may affect their pathogenicity. The enniatin synthetase gene (esyn1) of Fusarium scirpi ETH 1536 was used as a probe to determine if similar sequences were present in the strains examined. In Southern blot analyses, DNA sequences hybridizing with the esyn1 probe were present in all but two of the strains examined. In some cases, enniatin-nonproducing strains had the same hybridization pattern as enniatin producers. PMID:16535227

Herrmann, M.; Zocher, R.; Haese, A.

1996-01-01

360

Nucleic Acid-Based Detection and Identification of Bacterial and Fungal Plant Pathogens - Final Report  

SciTech Connect

The threat to American interests from terrorists is not limited to attacks against humans. Terrorists might seek to inflict damage to the U.S. economy by attacking our agricultural sector. Infection of commodity crops by bacterial or fungal crop pathogens could adversely impact U.S. agriculture, either directly from damage to crops or indirectly from damage to our ability to export crops suspected of contamination. Recognizing a terrorist attack against U.S. agriculture, to be able to prosecute the terrorists, is among the responsibilities of the members of Hazardous Material Response Unit (HMRU) of the Federal Bureau of Investigation (FBI). Nucleic acid analysis of plant pathogen strains by the use of polymerase chain reaction (PCR) amplification techniques is a powerful method for determining the exact identity of pathogens, as well as their possible region of origin. This type of analysis, however, requires that PCR assays be developed specific to each particular pathogen strain, an d analysis protocols developed that are specific to the particular instrument used for detection. The objectives of the work described here were threefold: (1) to assess the potential terrorist threat to U.S. agricultural crops, (2) to determine whether suitable assays exist to monitor that threat, and (3) where assays are needed for priority plant pathogen threats, to modify or develop those assays for use by specialists at the HMRU. The assessment of potential threat to U.S. commodity crops and the availability of assays for those threats were described in detail in the Technical Requirements Document (9) and will be summarized in this report. This report addresses development of specific assays identified in the Technical Requirements Document, and offers recommendations for future development to ensure that HMRU specialists will be prepared with the PCR assays they need to protect against the threat of economic terrorism.

Kingsley, Mark T

2001-03-13

361

Nucleic Acid-Based Detection and Identification of Bacterial and Fungal Plant Pathogens - Final Report  

SciTech Connect

The threat to American interests from terrorists is not limited to attacks against humans. Terrorists might seek to inflict damage to the U.S. economy by attacking our agricultural sector. Infection of commodity crops by bacterial or fungal crop pathogens could adversely impact U.S. agriculture, either directly from damage to crops or indirectly from damage to our ability to export crops suspected of contamination. Recognizing a terrorist attack against U.S. agriculture, to be able to prosecute the terrorists, is among the responsibilities of the members of Hazardous Material Response Unit (HMRU) of the Federal Bureau of Investigation (FBI). Nucleic acid analysis of plant pathogen strains by the use of polymerase chain reaction (PCR) amplification techniques is a powerful method for determining the exact identity of pathogens, as well as their possible region of origin. This type of analysis, however, requires that PCR assays be developed specific to each particular pathogen strain, and analysis protocols developed that are specific to the particular instrument used for detection. The objectives of the work described here were threefold: 1) to assess the potential terrorist threat to U.S. agricultural crops, 2) to determine whether suitable assays exist to monitor that threat, and 3) where assays are needed for priority plant pathogen threats, to modify or develop those assays for use by specialists at the HMRU. The assessment of potential threat to U.S. commodity crops and the availability of assays for those threats were described in detail in the Technical Requirements Document (9) and will be summarized in this report. This report addresses development of specific assays identified in the Technical Requirements Document, and offers recommendations for future development to ensure that HMRU specialists will be prepared with the PCR assays they need to protect against the threat of economic terrorism.

Kingsley, Mark T.

2001-03-13

362

Pep-13, a plant defense-inducing pathogen-associated pattern from Phytophthora transglutaminases.  

PubMed

Innate immunity, an ancient form of defense against microbial infection, is well described for animals and is also suggested to be important for plants. Discrimination from self is achieved through receptors that recognize pathogen-associated molecular patterns (PAMPs) not found in the host. PAMPs are evolutionarily conserved structures which are functionally important and, thus, not subject to frequent mutation. Here we report that the previously described peptide elicitor of defense responses in parsley, Pep-13, constitutes a surface-exposed fragment within a novel calcium-dependent cell wall transglutaminase (TGase) from Phytophthora sojae. TGase transcripts and TGase activity are detectable in all Phytophthora species analyzed, among which are some of the most destructive plant pathogens. Mutational analysis within Pep-13 identified the same amino acids indispensable for both TGase and defense-eliciting activity. Pep-13, conserved among Phytophthora TGases, activates defense in parsley and potato, suggesting its function as a genus-specific recognition determinant for the activation of plant defense in host and non-host plants. In summary, plants may recognize PAMPs with characteristics resembling those known to trigger innate immune responses in animals. PMID:12485989

Brunner, Frédéric; Rosahl, Sabine; Lee, Justin; Rudd, Jason J; Geiler, Carola; Kauppinen, Sakari; Rasmussen, Grethe; Scheel, Dierk; Nürnberger, Thorsten

2002-12-16

363

In vitro antifungal activity of three geophytic plant extracts against three post-harvest pathogenic fungi.  

PubMed

Plant extracts appear to be one of the most effective alternative methods of plant diseases control which are less harmful to human beings and environment. In vitro antifungal activity of methanolic extracts of three promising wild geophytic plants against three post-harvest pathogenic fungi using radial growth technique was conducted. These extracts included the shoot system (S) and underground parts (R) of Asparagus stipularis, Cyperus capitatus and Stipagrostis lanata. The tested fungi were Alternaria solani, Aspergillus niger and Rhizopus stolonifer. The results exhibited that, all plant extracts had antifungal activity against the tested fungi. The antifungal activity greatly varied depending on plant parts and/or plant species. R. stolonifer was the most susceptible fungus to the tested plant extracts followed by A. niger and then A. solani. On the other hand, the most effective plant extracts against tested fungi were S. lanata (S) and A. stipularis (R). The most effective plant extracts against R. stolonifer were S. lanata (R) and C. capitatus (S). While, the extracts of A. stipularis (R) and S. lanata (S) were the most effective against A. niger. The extracts of C. capitatus (S) and S. lanata (S) exhibited the highest antifungal activity against A. solani. The results demonstrated that, the methanolic extracts of A. stipularis, C. capitatus and S. lanata had potential antifungal activity against A. solani, A. niger and R. stolonifer. PMID:24506036

Maswada, Hanafey F; Abdallah, Sabry A

2013-12-01

364

Detection of Fusarium oxysporum f.sp. basilici in substrates and roots by PCR.  

PubMed

Fusarium oxysporum is a soil-borne fungus that causes vascular wilts in a wide variety of plant species. Basil is recognized as an ecological niche for Fusarium oxysporum f.sp. basilici (FOB) and this fungus is now present in most countries where basil is cultivated. The rapid identification of the species affecting basil plants is necessary to define a successful method for crop protection. The aim of this study was to develop a PCR method for the rapid detection of Fusarium oxysporum f. sp. basilici in substrates. The specificity of the primers used was tested using the DNA extracted directly from substrate samples. Fusarium oxysporum f.sp. basilici was artificially inoculated with decreasing amounts in a commercial substrate (sphagnum peat moss) and in a mixture with 40% of municipal compost, after steam disinfestation. Basil seeds (cv. Fine verde) were sown in pots that were laid on a bench in the greenhouse. At time 0 and after 7, 14 and 21 days from the inoculation, substrate and root samples were collected and prepared for microbial analysis and for the DNA extraction. DNA extraction was carried out using NucleoSpin Soil Kit (Macherey-Nagel, Germany). PCR amplification for the specific detection was carried out using primer sets Bik 1 (5'-ATT CAA GAG CTA AAG GTC C-3') and Bik 4 (5'-TTT GAC CAA GAT AGA TGC C-3') for the first PCR, while primers Bik 1 + Bik 2 (5'-AAA GGT AGT ATA TCG GAG G-3') for the nested PCR to increase detection sensitivity. Disease incidence was also assessed 21 days after seeding. The results showed the presence of amplified fragments of the expected size when the concentration of F. oxysporum f.sp. basilici was at least 3.5 Log CFU g(-1) by using DNA extract directly from substrate, before roots were infected by the pathogen. The detection of Fusarium oxysporum f. sp. basilici by PCR method developed in this study is certainly simple and fast and can be useful for its reliable detection in substrate samples, but not to guarantee that the substrate is totally free of pathogens. PMID:25151841

Pugliese, M; Ferrocino, I; Gullino, M L; Garibaldi, A

2013-01-01

365

Control of Fusarium Wilt of Radish by Combining Pseudomonas putida Strains that have Different Disease-Suppressive Mechanisms.  

PubMed

ABSTRACT Biological control of soilborne plant pathogens in the field has given variable results. By combining specific strains of microorganisms, multiple traits antagonizing the pathogen can be combined and this may result in a higher level of protection. Pseudomonas putida WCS358 suppresses Fusarium wilt of radish by effectively competing for iron through the production of its pseudobactin siderophore. However, in some bioassays pseudobactin-negative mutants of WCS358 also suppressed disease to the same extent as WCS358, suggesting that an, as yet unknown, additional mechanism may be operative in this strain. P. putida strain RE8 induced systemic resistance against fusarium wilt. When WCS358 and RE8 were mixed through soil together, disease suppression was significantly enhanced to approximately 50% as compared to the 30% reduction for the single strain treatments. Moreover, when one strain failed to suppress disease in the single application, the combination still resulted in disease control. The enhanced disease suppression by the combination of P. putida strains WCS358 and RE8 is most likely the result of the combination of their different disease-suppressive mechanisms. These results demonstrate that combining biocontrol strains can lead to more effective, or at least, more reliable biocontrol of fusarium wilt of radish. PMID:18942986

de Boer, Marjan; Bom, Peter; Kindt, Frodo; Keurentjes, Joost J B; van der Sluis, Ientse; van Loon, L C; Bakker, Peter A H M

2003-05-01

366

Draft Genome Sequence of "Candidatus Phytoplasma asteris" Strain OY-V, an Unculturable Plant-Pathogenic Bacterium  

PubMed Central

Phytoplasmas are unculturable plant-pathogenic bacteria causing devastating damage to agricultural production worldwide. Here, we report the draft genome sequence of “Candidatus Phytoplasma asteris” strain OY-V. Most of the known virulence factors and host-interacting proteins were conserved in OY-V. This genome furthers our understanding of genetic diversity and pathogenicity of phytoplasmas. PMID:25291766

Makino, Ayaka; Ishii, Yoshiko; Tamaki, Hideyuki; Kamagata, Yoichi

2014-01-01

367

Draft Genome Sequence of "Candidatus Phytoplasma asteris" Strain OY-V, an Unculturable Plant-Pathogenic Bacterium.  

PubMed

Phytoplasmas are unculturable plant-pathogenic bacteria causing devastating damage to agricultural production worldwide. Here, we report the draft genome sequence of "Candidatus Phytoplasma asteris" strain OY-V. Most of the known virulence factors and host-interacting proteins were conserved in OY-V. This genome furthers our understanding of genetic diversity and pathogenicity of phytoplasmas. PMID:25291766

Kakizawa, Shigeyuki; Makino, Ayaka; Ishii, Yoshiko; Tamaki, Hideyuki; Kamagata, Yoichi

2014-01-01

368

[Impact of long-term continuous cropping on the Fusarium population in soybean rhizosphere].  

PubMed

The impact of long-term continuous cropping on the Fusarium population abundance and diversity, pathogenicity and phylogeny in soybean field were analyzed by using isolation, morphological identification, pathogenicity test, sequencing analysis and molecular marker with restricted fragment length polymorphisms (RFLP). The soybean field was located at the Hailun Experimental Station of Agricultural Ecology of Chinese Academy of Sciences in Northeast China and had been under a long-term rotation experiment designed to two treatments, i. e., long-term continuous cropping (LCC) of soybean for 20 years and short-term continuous cropping (SCC) for 3 years. In SCC field, the population density of Fusarium spp. was 6.0 x 10(4) CFU x g(-1), in which F. oxysporum, F. graminearum and F. verticillioides possessing high pathogenicity and F. solani possessing moderate pathogenicity were the dominant species. In LCC field, the population density of Fusarium population and the dominance index of dominant species were significantly lower than that in SCC. The population density of F. oxysporum, F. graminearum and F. solani were only 36% , 32% and 22% of that in SCC, and F. verticillioide with highest pathogenicity was absent. The diversity and evenness index of Fusarium population were significantly higher than that in SCC. F. tricinctum, F. lateritium and F. avenaceum, just isolated from LCC, possessing a distant genetic relationship with Fusarium isolates possessing high pathogenicity based on internal transcribed spacer (ITS) and translation elongation factor 1-alpha (EF-1alpha) gene, were non-pathogenicity for soybean. Thus, it seemed that LCC of soybean could cause the inhibition of soil Fusarium population size, alteration of Fusarium community composition and genetic diversity, and even the decline of pathogenicity for soybean root rot disease of Fusarium population. PMID:24830251

Wei, Wei; Xu, Yan-Li; Zhu, Lin; Zhang, Si-Jia; Li, S

2014-02-01

369

The Role of the Jasmonate Response in Plant Susceptibility to Diverse Pathogens with a Range of Lifestyles  

Microsoft Academic Search

Plants defend themselves against attack from insects and pathogens with various resistance strategies. The jasmonate and salicylate signaling pathways are two induced responses that protect plants against these attackers. Knowledge of the range of organisms that are affected by each response is important for understanding how plants coordinate their defenses against multiple attackers and the generality of effect of different

Jennifer S. Thaler; Blythe Owen; Verna J. Higgins

2004-01-01

370

Inhibitory effect of Xenorhabdus nematophila TB on plant pathogens Phytophthora capsici and Botrytis cinerea in vitro and in planta.  

PubMed

Entomopathogenic bacteria Xenorhabdus spp. produce secondary metabolites with potential antimicrobial activity for use in agricultural productions. This study evaluated the inhibitory effect of X. nematophila TB culture on plant pathogens Botrytis cinerea and Phytophthora capsici. The cell-free filtrate of TB culture showed strong inhibitory effects (>90%) on mycelial growth of both pathogens. The methanol-extracted bioactive compounds (methanol extract) of TB culture also had strong inhibitory effects on mycelial growth and spore germinations of both pathogens. The methanol extract (1000??g/mL) and cell-free filtrate both showed strong therapeutic and protective effects (>70%) on grey mold both in detached tomato fruits and plants, and leaf scorch in pepper plants. This study demonstrates X. nematophila TB produces antimicrobial metabolites of strong activity on plant pathogens, with great potential for controlling tomato grey mold and pepper leaf scorch and being used in integrated disease control to reduce chemical application. PMID:24599183

Fang, Xiangling; Zhang, Manrang; Tang, Qian; Wang, Yonghong; Zhang, Xing

2014-01-01

371

Inhibitory effect of Xenorhabdus nematophila TB on plant pathogens Phytophthora capsici and Botrytis cinerea in vitro and in planta  

PubMed Central

Entomopathogenic bacteria Xenorhabdus spp. produce secondary metabolites with potential antimicrobial activity for use in agricultural productions. This study evaluated the inhibitory effect of X. nematophila TB culture on plant pathogens Botrytis cinerea and Phytophthora capsici. The cell-free filtrate of TB culture showed strong inhibitory effects (>90%) on mycelial growth of both pathogens. The methanol-extracted bioactive compounds (methanol extract) of TB culture also had strong inhibitory effects on mycelial growth and spore germinations of both pathogens. The methanol extract (1000??g/mL) and cell-free filtrate both showed strong therapeutic and protective effects (>70%) on grey mold both in detached tomato fruits and plants, and leaf scorch in pepper plants. This study demonstrates X. nematophila TB produces antimicrobial metabolites of strong activity on plant pathogens, with great potential for controlling tomato grey mold and pepper leaf scorch and being used in integrated disease control to reduce chemical application. PMID:24599183

Fang, Xiangling; Zhang, Manrang; Tang, Qian; Wang, Yonghong; Zhang, Xing

2014-01-01

372

Activation of Defense Mechanisms against Pathogens in Mosses and Flowering Plants  

PubMed Central

During evolution, plants have developed mechanisms to cope with and adapt to different types of stress, including microbial infection. Once the stress is sensed, signaling pathways are activated, leading to the induced expression of genes with different roles in defense. Mosses (Bryophytes) are non-vascular plants that diverged from flowering plants more than 450 million years ago, allowing comparative studies of the evolution of defense-related genes and defensive metabolites produced after microbial infection. The ancestral position among land plants, the sequenced genome and the feasibility of generating targeted knock-out mutants by homologous recombination has made the moss Physcomitrella patens an attractive model to perform functional studies of plant genes involved in stress responses. This paper reviews the current knowledge of inducible defense mechanisms in P. patens and compares them to those activated in flowering plants after pathogen assault, including the reinforcement of the cell wall, ROS production, programmed cell death, activation of defense genes and synthesis of secondary metabolites and defense hormones. The knowledge generated in P. patens together with comparative studies in flowering plants will help to identify key components in plant defense responses and to design novel strategies to enhance resistance to biotic stress. PMID:23380962

de Leon, Ines Ponce; Montesano, Marcos

2013-01-01

373

Engineering photoassimilate partitioning in tobacco plants improves growth and productivity and provides pathogen resistance.  

PubMed

Expression of pathogenesis-related (PR) genes is part of the plant's natural defense response against pathogen attack. To study the in vivo role and function of the maize PRms protein, tobacco plants were transformed with the PRms cDNA under the control of the CaMV35S promoter. Transgenic tobacco plants grow faster and yield more leaf and seed biomass. By using immunoelectron microscopy, we found that PRms is associated with plasmodesmata in leaves of transgenic tobacco plants. Furthermore, we found that activation of sucrose efflux from photosynthetically active leaves and accumulation of higher levels of sucrose in leaf tissues are characteristic features of PRms tobacco plants. This, in turn, results in the constitutive expression of endogenous tobacco PR genes and resistance to phytopathogens. The expression of multiple plant defense genes can then be achieved by using a single transgene. These data provide a new approach for engineering disease-resistant plants while simultaneously improving plant yield and productivity through the modification of photoassimilate partitioning. PMID:14617090

Murillo, Isabel; Roca, Ramón; Bortolotti, Cristina; Segundo, Blanca San

2003-11-01

374

The Plant Pathogen Phytophthora andina Emerged via Hybridization of an Unknown Phytophthora Species and the Irish Potato Famine Pathogen, P. infestans  

PubMed Central

Emerging plant pathogens have largely been a consequence of the movement of pathogens to new geographic regions. Another documented mechanism for the emergence of plant pathogens is hybridization between individuals of different species or subspecies, which may allow rapid evolution and adaptation to new hosts or environments. Hybrid plant pathogens have traditionally been difficult to detect or confirm, but the increasing ease of cloning and sequencing PCR products now makes the identification of species that consistently have genes or alleles with phylogenetically divergent origins relatively straightforward. We investigated the genetic origin of Phytophthora andina, an increasingly common pathogen of Andean crops Solanum betaceum, S. muricatum, S. quitoense, and several wild Solanum spp. It has been hypothesized that P. andina is a hybrid between the potato late blight pathogen P. infestans and another Phytophthora species. We tested this hypothesis by cloning four nuclear loci to obtain haplotypes and using these loci to infer the phylogenetic relationships of P. andina to P. infestans and other related species. Sequencing of cloned PCR products in every case revealed two distinct haplotypes for each locus in P. andina, such that each isolate had one allele derived from a P. infestans parent and a second divergent allele derived from an unknown species that is closely related but distinct from P. infestans, P. mirabilis, and P. ipomoeae. To the best of our knowledge, the unknown parent has not yet been collected. We also observed sequence polymorphism among P. andina isolates at three of the four loci, many of which segregate between previously described P. andina clonal lineages. These results provide strong support that P. andina emerged via hybridization between P. infestans and another unknown Phytophthora species also belonging to Phytophthora clade 1c. PMID:21949727

Goss, Erica M.; Cardenas, Martha E.; Myers, Kevin; Forbes, Gregory A.; Fry, William E.; Restrepo, Silvia; Grunwald, Niklaus J.

2011-01-01

375

A generic risk-based surveying method for invading plant pathogens.  

PubMed

Invasive plant pathogens are increasing with international trade and travel, with damaging environmental and economic consequences. Recent examples include tree diseases such as sudden oak death in the Western United States and ash dieback in Europe. To control an invading pathogen it is crucial that newly infected sites are quickly detected so that measures can be implemented to control the epidemic. However, since sampling resources are often limited, not all locations can be inspected and locations must be prioritized for surveying. Existing approaches to achieve this are often species specific and rely on detailed data collection and parameterization, which is difficult, especially when new arrivals are unanticipated. Consequently regulatory sampling responses are often ad hoc and developed without due consideration of epidemiology, leading to the suboptimal deployment of expensive sampling resources. We introduce a flexible risk-based sampling method that is pathogen generic and enables available information to be utilized to develop epidemiologically informed sampling programs for virtually any biologically relevant plant pathogen. By targeting risk we aim to inform sampling schemes that identify high-impact locations that can be subsequently treated in order to reduce inoculum in the landscape. This "damage limitation" is often the initial management objective following the first discovery of a new invader. Risk at each location is determined by the product of the basic reproductive number (R0), as a measure of local epidemic size, and the probability of infection. We illustrate how the risk estimates can be used to prioritize a survey by weighting a random sample so that the highest-risk locations have the highest probability of selection. We demonstrate and test the method using a high-quality spatially and temporally resolved data set on Huanglongbing disease (HLB) in Florida, USA. We show that even when available epidemiological information is relatively minimal, the method has strong predictive value and can result in highly effective targeted surveying plans. PMID:24988776

Parnell, S; Gottwald, T R; Riley, T; van den Bosch, F

2014-06-01

376

Efficacy of sludge and manure compost amendments against Fusarium wilt of cucumber.  

PubMed

Fusarium wilt of cucumber caused by the fungus, Fusarium oxysporum, is one of the most destructive soilborne diseases and can result in serious economic loss. No efficient fungicide is currently available to control the disease. The aim of this study was to examine the disease suppression ability of pig manure and sludge composts in peat-based container media and explore the possible disease suppression mechanisms. Pig manure and sewage sludge compost were made in laboratory-scale tanks. Plant growth media were formulated with peat mixture and compost (or 60 °C heated compost) in a 4:1 ratio (v/v). Cucumber seedlings were artificially inoculated with F. oxysporum conidia (5?×?10(5) conidia mL(-1)) by the root-dip method. Cucumber Fusarium wilt was effectively suppressed in sludge compost-amended media, while the disease suppression effect of pig manure compost was limited. The ammonia levels in the manure compost-amended media were significantly higher than those of sludge compost-amended media, which could explain its lower disease suppression ability. Heated composts behaved similarly with respect to disease suppression. Adding composts increased microbial biomass, microbial activity, and the microbial diversity of the growth media. PCR-DGGE results indicated that the fungal community had a significant correlation to the disease severity. The artificially inoculated pathogen was retrieved in all treatments and one possible biocontrol agent was identified as a strain of F. oxysporum by phylogenetic analyses. The results indicated that the sludge compost used in this study could be applied as a method for biocontrol of cucumber Fusarium wilt. PMID:22729873

Huang, Xiao; Shi, Dezhi; Sun, Faqian; Lu, Haohao; Liu, Jingjing; Wu, Weixiang

2012-11-01

377

Genome Sequence of Fusarium graminearum Isolate CS3005.  

PubMed

Fusarium graminearum is one of the most important fungal pathogens of wheat, barley, and maize worldwide. This announcement reports the genome sequence of a highly virulent Australian isolate of this species to supplement the existing genome of the North American F. graminearum isolate Ph1. PMID:24744326

Gardiner, Donald M; Stiller, Jiri; Kazan, Kemal

2014-01-01

378

Genome Sequence of Fusarium graminearum Isolate CS3005  

PubMed Central

Fusarium graminearum is one of the most important fungal pathogens of wheat, barley, and maize worldwide. This announcement reports the genome sequence of a highly virulent Australian isolate of this species to supplement the existing genome of the North American F. graminearum isolate Ph1. PMID:24744326

Stiller, Jiri; Kazan, Kemal

2014-01-01

379

Structure-Activity Determinants in Antifungal Plant Defensins MsDef1 and MtDef4 with Different Modes of Action against Fusarium graminearum  

PubMed Central

Plant defensins are small cysteine-rich antimicrobial proteins. Their three-dimensional structures are similar in that they consist of an ?-helix and three anti-parallel ?-strands stabilized by four disulfide bonds. Plant defensins MsDef1 and MtDef4 are potent inhibitors of the growth of several filamentous fungi including Fusarium graminearum. However, they differ markedly in their antifungal properties as well as modes of antifungal action. MsDef1 induces prolific hyperbranching of fungal hyphae, whereas MtDef4 does not. Both defensins contain a highly conserved ?-core motif (GXCX3–9C), a hallmark signature present in the disulfide-stabilized antimicrobial peptides, composed of ?2 and ?3 strands and the interposed loop. The ?-core motifs of these two defensins differ significantly in their primary amino acid sequences and in their net charge. In this study, we have found that the major determinants of the antifungal activity and morphogenicity of these defensins reside in their ?-core motifs. The MsDef1-?4 variant in which the ?-core motif of MsDef1 was replaced by that of MtDef4 was almost as potent as MtDef4 and also failed to induce hyperbranching of fungal hyphae. Importantly, the ?-core motif of MtDef4 alone was capable of inhibiting fungal growth, but that of MsDef1 was not. The analysis of synthetic ?-core variants of MtDef4 indicated that the cationic and hydrophobic amino acids were important for antifungal activity. Both MsDef1 and MtDef4 induced plasma membrane permeabilization; however, kinetic studies revealed that MtDef4 was more efficient in permeabilizing fungal plasma membrane than MsDef1. Furthermore, the in vitro antifungal activity of MsDef1, MsDef1-?4, MtDef4 and peptides derived from the ?-core motif of each defensin was not solely dependent on their ability to permeabilize the fungal plasma membrane. The data reported here indicate that the ?-core motif defines the unique antifungal properties of each defensin and may facilitate de novo design of more potent antifungal peptides. PMID:21533249

Sagaram, Uma Shankar; Pandurangi, Raghoottama; Kaur, Jagdeep; Smith, Thomas J.; Shah, Dilip M.

2011-01-01

380

Degradation of keratinous materials by the plant pathogenic fungus Myrothecium verrucaria.  

PubMed

In this paper it is described for the first time the capability of Myrothecium verrucaria to grow in submerged and solid state cultures using poultry feathers as the only substrate. The fungus produced a protease with an unusual keratinolytic activity among plant pathogenic fungi. Its crude protease hydrolyzed keratinous substrates at pH 9.0 and 40 degrees C in the following order: poultry feather keratin > sheep wool keratin > human nail keratin > human hair keratin. Protease activity was highly sensitive to phenylmethyl sulphonyl fluoride (PMSF) indicating that the enzyme belonged to the serine protease family. PMID:17356791

Moreira, F G; de Souza, C G M; Costa, M A F; Reis, S; Peralta, R M

2007-03-01

381

Pseudomonas viridiflava, a multi host plant pathogen with significant genetic variation at the molecular level.  

PubMed

The pectinolytic species Pseudomonas viridiflava has a wide host range among plants, causing foliar and stem necrotic lesions and basal stem and root rots. However, little is known about the molecular evolution of this species. In this study we investigated the intraspecies genetic variation of P. viridiflava amongst local (Cretan), as well as international isolates of the pathogen. The genetic and phenotypic variability were investigated by molecular fingerprinting (rep-PCR) and partial sequencing of three housekeeping genes (gyrB, rpoD and rpoB), and by biochemical and pathogenicity profiling. The biochemical tests and pathogenicity profiling did not reveal any variability among the isolates studied. However, the molecular fingerprinting patterns and housekeeping gene sequences clearly differentiated them. In a broader phylogenetic comparison of housekeeping gene sequences deposited in GenBank, significant genetic variability at the molecular level was found between isolates of P. viridiflava originated from different host species as well as among isolates from the same host. Our results provide a basis for more comprehensive understanding of the biology, sources and shifts in genetic diversity and evolution of P. viridiflava populations and should support the development of molecular identification tools and epidemiological studies in diseases caused by this species. PMID:22558343

Sarris, Panagiotis F; Trantas, Emmanouil A; Mpalantinaki, Evaggelia; Ververidis, Filippos; Goumas, Dimitrios E

2012-01-01

382

Pseudomonas viridiflava, a Multi Host Plant Pathogen with Significant Genetic Variation at the Molecular Level  

PubMed Central

The pectinolytic species Pseudomonas viridiflava has a wide host range among plants, causing foliar and stem necrotic lesions and basal stem and root rots. However, little is known about the molecular evolution of this species. In this study we investigated the intraspecies genetic variation of P. viridiflava amongst local (Cretan), as well as international isolates of the pathogen. The genetic and phenotypic variability were investigated by molecular fingerprinting (rep-PCR) and partial sequencing of three housekeeping genes (gyrB, rpoD and rpoB), and by biochemical and pathogenicity profiling. The biochemical tests and pathogenicity profiling did not reveal any variability among the isolates studied. However, the molecular fingerprinting patterns and housekeeping gene sequences clearly differentiated them. In a broader phylogenetic comparison of housekeeping gene sequences deposited in GenBank, significant genetic variability at the molecular level was found between isolates of P. viridiflava originated from different host species as well as among isolates from the same host. Our results provide a basis for more comprehensive understanding of the biology, sources and shifts in genetic diversity and evolution of P. viridiflava populations and should support the development of molecular identification tools and epidemiological studies in diseases caused by this species. PMID:22558343

Mpalantinaki, Evaggelia; Ververidis, Filippos; Goumas, Dimitrios E.

2012-01-01

383

A negative effect of a pathogen on its vector? A plant pathogen increases the vulnerability of its vector to attack by natural enemies.  

PubMed

Plant pathogens that are dependent on arthropod vectors for transmission from host to host may enhance their own success by promoting vector survival and/or performance. The effect of pathogens on vectors may be direct or indirect, with indirect effects mediated by increases in host quality or reductions in the vulnerability of vectors to natural enemies. We investigated whether the bird cherry-oat aphid Rhopalosiphum padi, a vector of cereal yellow dwarf virus (CYDV) in wheat, experiences a reduction in rates of attack by the parasitoid wasp Aphidius colemani when actively harboring the plant pathogen. We manipulated the vector status of aphids (virus carrying or virus free) and evaluated the impact on the rate of attack by wasps. We found that vector status did not influence the survival or fecundity of aphids in the absence of parasitoids. However, virus-carrying aphids experienced higher rates of parasitism and greater overall population suppression by parasitoid wasps than virus-free aphids. Moreover, virus-carrying aphids were accepted as hosts by wasps more often than virus-free aphids, with a greater number of wasps stinging virus-carrying aphids following assessment by antennal palpations than virus-free aphids. Therefore, counter to the prevailing idea that persistent vector-borne pathogens enhance the performance of their vectors, we found that infectious aphids actively carrying a plant pathogen experience greater vulnerability to natural enemies. Our results suggest that parasitoids may contribute to the successful biological control of CYDV by disproportionately impacting virus-carrying vectors, and thus reducing the proportion of vectors in the population that are infectious. PMID:24322446

de Oliveira, Camila F; Long, Elizabeth Y; Finke, Deborah L

2014-04-01

384

Coprinellus curtus (Hitoyo-take) prevents diseases of vegetables caused by pathogenic fungi.  

PubMed

A strain of Coprinellus curtus (designated GM-21), a basidiomycete that suppressed bottom-rot disease of Chinese cabbage, 'pak-choi' (Brassica campestris), caused by the pathogen Rhizoctonia solani Pak-choi 2 was isolated. The mechanism of plant disease suppression was discovered to be hyphal interference, a combative fungal interaction between strain GM-21 and the pathogen. The antifungal spectrum of strain GM-21 was shown to include R. solani and Fusarium sp., i.e. strain GM-21 showed disease-suppressive ability against bottom-rot disease of lettuce and Rhizoctonia-patch disease of mascarene grass caused by strains of R. solani. In addition, clear evidence of hyphal interference between strain GM-21 and Fusarium pathogens that cause crown (foot) and root-rot disease of tomato and Fusarium wilt of melon, respectively, was demonstrated. It was thus considered that GM-21 is effective for suppressing soil-borne pathogens, and that GM-21 presents new possibilities for biological control of vegetable diseases. PMID:17850327

Nakasaki, Kiyohiko; Saito, Miyuki; Suzuki, Nobuaki

2007-10-01

385

Characterization of Fusarium secorum, a new species causing Fusarium yellowing decline of sugar beet in north central USA.  

PubMed

This study characterized a novel sugar beet (Beta vulgaris L.) pathogen from the Red River Valley in north central USA, which was formally named Fusarium secorum. Molecular phylogenetic analyses of three loci (translation elongation factor1?, calmodulin, mitochondrial small subunit) and phenotypic data strongly supported the inclusion of F. secorum in the Fusarium fujikuroi species complex (FFSC). Phylogenetic analyses identified F. secorum as a sister taxon of F. acutatum and a member of the African subclade of the FFSC. Fusarium secorum produced circinate hyphae sometimes bearing microconidia and abundant corkscrew-shaped hyphae in culture. To assess mycotoxin production potential, 45 typical secondary metabolites were tested in F. secorum rice cultures, but only beauvericin was produced in detectable amounts by each isolate. Results of pathogenicity experiments revealed that F. secorum isolates are able to induce half- and full-leaf yellowing foliar symptoms and vascular necrosis in roots and petioles of sugar beet. Inoculation with F. acutatum did not result in any disease symptoms. The sugar beet disease caused by F. secorum is named Fusarium yellowing decline. Since Fusarium yellowing decline incidence has been increasing in the Red River Valley, disease management options are discussed. PMID:25209635

Secor, Gary A; Rivera-Varas, Viviana; Christ, Daniela S; Mathew, Febina M; Khan, Mohamed F R; Varrelmann, Mark; Bolton, Melvin D

2014-01-01

386

Pathogenicity of Fungi to Eggs of Heterodera glycines.  

PubMed

Twenty-one isolates of 18 fungal species were tested on water agar for their pathogenicity to eggs of Heterodera glycines. An egg-parasitic index (EPI) for each of these fungi was recorded on a scale from 0 to 10, and hatch of nematode eggs was determined after exposure to the fungi on water agar for 3 weeks at 24 C. The EPI for Verticillium chlamydosporium was 7.6, and the fungus reduced hatch 74%. Pyrenochaeta terrestris and two sterile fungi also showed a high EPI and reduced hatch 42-73%. Arthrobotrys dactyloides, Fusarium oxysporum, Paecilomyces lilacinus, Stagonospora heteroderae, Neocosmospora vasinfecta, Fusarium solani, and Exophiala pisciphila were moderately pathogenic to eggs (EPI was 2.0-4.5, and hatch was reduced 21-56%). Beauveria bassiana, Hirsutella rhossiliensis, Hirsutella thompsonii, Dictyochaeta heteroderae, Dictyochaeta coffeae, Gliocladium catenulatum, and Cladosporium sp. showed little parasitism of nematode eggs but reduced hatch. A negative correlation was observed between hatch and fungal parasitism of eggs. Fusarium oxysporum, H. rhossiliensis, P. lilacinus, S. heteroderae, V. chlamydosporium, and sterile fungus 1 also were tested in soil in a greenhouse test. After 3 months, the nematode densities were lower in soil treated with H. rhossiliensis and V. chlamydosporium than in untreated soil. The nematode population densities were correlated negatively with the EPI, but not with the percentage of cysts colonized by the fungi. Plant weights and heights generally increased in the soil treated with the fungi. PMID:19277130

Chen, S Y; Dickson, D W; Mitchell, D J

1996-06-01

387

Pathogenicity of Fungi to Eggs of Heterodera glycines  

PubMed Central

Twenty-one isolates of 18 fungal species were tested on water agar for their pathogenicity to eggs of Heterodera glycines. An egg-parasitic index (EPI) for each of these fungi was recorded on a scale from 0 to 10, and hatch of nematode eggs was determined after exposure to the fungi on water agar for 3 weeks at 24 C. The EPI for Verticillium chlamydosporium was 7.6, and the fungus reduced hatch 74%. Pyrenochaeta terrestris and two sterile fungi also showed a high EPI and reduced hatch 42-73%. Arthrobotrys dactyloides, Fusarium oxysporum, Paecilomyces lilacinus, Stagonospora heteroderae, Neocosmospora vasinfecta, Fusarium solani, and Exophiala pisciphila were moderately pathogenic to eggs (EPI was 2.0-4.5, and hatch was reduced 21-56%). Beauveria bassiana, Hirsutella rhossiliensis, Hirsutella thompsonii, Dictyochaeta heteroderae, Dictyochaeta coffeae, Gliocladium catenulatum, and Cladosporium sp. showed little parasitism of nematode eggs but reduced hatch. A negative correlation was observed between hatch and fungal parasitism of eggs. Fusarium oxysporum, H. rhossiliensis, P. lilacinus, S. heteroderae, V. chlamydosporium, and sterile fungus 1 also were tested in soil in a greenhouse test. After 3 months, the nematode densities were lower in soil treated with H. rhossiliensis and V. chlamydosporium than in untreated soil. The nematode population densities were correlated negatively with the EPI, but not with the percentage of cysts colonized by the fungi. Plant weights and heights generally increased in the soil treated with the fungi. PMID:19277130

Chen, S. Y.; Dickson, D. W.; Mitchell, D. J.

1996-01-01

388

The Influence of Genetic Drift and Selection on Quantitative Traits in a Plant Pathogenic Fungus  

PubMed Central

Genetic drift and selection are ubiquitous evolutionary forces acting to shape genetic variation in populations. While their relative importance has been well studied in plants and animals, less is known about their relative importance in fungal pathogens. Because agro-ecosystems are more homogeneous environments than natural ecosystems, stabilizing selection may play a stronger role than genetic drift or diversifying selection in shaping genetic variation among populations of fungal pathogens in agro-ecosystems. We tested this hypothesis by conducting a QST/FST analysis using agricultural populations of the barley pathogen Rhynchosporium commune. Population divergence for eight quantitative traits (QST) was compared with divergence at eight neutral microsatellite loci (FST) for 126 pathogen strains originating from nine globally distributed field populations to infer the effects of genetic drift and types of selection acting on each trait. Our analyses indicated that five of the eight traits had QST values significantly lower than FST, consistent with stabilizing selection, whereas one trait, growth under heat stress (22°C), showed evidence of diversifying selection and local adaptation (QST>FST). Estimates of heritability were high for all traits (means ranging between 0.55–0.84), and average heritability across traits was negatively correlated with microsatellite gene diversity. Some trait pairs were genetically correlated and there was significant evidence for a trade-off between spore size and spore number, and between melanization and growth under benign temperature. Our findings indicate that many ecologically and agriculturally important traits are under stabilizing selection in R. commune and that high within-population genetic variation is maintained for these traits. PMID:25383967

Stefansson, Tryggvi S.; McDonald, Bruce A.; Willi, Yvonne

2014-01-01

389

Pathogen resistance in the moth Orgyia antiqua: direct influence of host plant dominates over the effects of individual condition.  

PubMed

The role of pathogens in insect ecology is widely appreciated but remains insufficiently explored. Specifically, there is little understanding about the sources of the variation in the outcome of insect-pathogen interactions. This study addresses the extent to which immune traits of larvae and pupae of the moth Orgyia antiqua L. (Lepidoptera: Lymantriidae) depend on the host plant species and individual condition of the insects. The two host plants, Salix myrsinifolia Salisb. and S. viminalis L., were chosen because they differ in the concentration of phenolic glycosides, harmful to most polyphagous insects. Individual condition was assumed to be reflected in body weight and development time, and was manipulated by rearing larvae either singly or in groups of four. The resistance traits recorded were survival and time to death after fungal infection in the larval stage and the efficiency of encapsulating a nylon implant by the pupae. The survival of the infected larvae was mainly determined by the species of the host plant. Encapsulation response was not associated with the resistance to the pathogen, suggesting that the host plant affected the pathogen rather than the immune system of the insect. Interestingly, the host plant supporting better larval growth led to inferior resistance to the pathogen, indicating a trade-off between different aspects of host plant quality. PMID:20626929

Sandre, S-L; Tammaru, T; Hokkanen, H M T

2011-02-01

390

Multilocus Phylogenetics Show High Intraspecific Variability within Fusarium avenaceum  

PubMed Central

Fusarium avenaceum is a common soil saprophyte and plant pathogen of a variety of hosts worldwide. This pathogen is often involved in the crown rot and head blight of cereals that affects grain yield and quality. F. avenaceum contaminates grain with enniatins more than any species, and they are often detected at the highest prevalence among fusarial toxins in certain geographic areas. We studied intraspecific variability of F. avenaceum based on partial sequences of elongation factor-1 alpha, enniatin synthase, intergenic spacer of rDNA, arylamine N-acetyltransferase and RNA polymerase II data sets. The phylogenetic analyses incorporated a collection of 63 F. avenaceum isolates of various origin among which 41 were associated with wheat. Analyses of the multilocus sequence (MLS) data indicated a high level of genetic variation within the isolates studied with no significant linkage disequilibrium. Correspondingly, maximum parsimony analyses of both MLS and individual data sets showed lack of clear phylogenetic structure within F. avenaceum in relation to host (wheat) and geographic origin. Lack of host specialization indicates no host selective pressure in driving F. avenaceum evolution, while no geographic lineage structure indicates widespread distribution of genotypes that resulted in nullifying the effects of geographic isolation on the evolution of this species. Moreover, significant incongruence between all individual tree topologies and little clonality is consistent with frequent recombination within F. avenaceum. PMID:22016614

Kulik, Tomasz; Pszczolkowska, Agnieszka; Lojko, Maciej

2011-01-01

391

Responses to elevated c-di-GMP levels in mutualistic and pathogenic plant-interacting bacteria.  

PubMed

Despite a recent burst of research, knowledge on c-di-GMP signaling pathways remains largely fragmentary and molecular mechanisms of regulation and even c-di-GMP targets are yet unknown for most bacteria. Besides genomics or bioinformatics, accompanying alternative approaches are necessary to reveal c-di-GMP regulation in bacteria with complex lifestyles. We have approached this study by artificially altering the c-di-GMP economy of diverse pathogenic and mutualistic plant-interacting bacteria and examining the effects on the interaction with their respective host plants. Phytopathogenic Pseudomonas and symbiotic Rhizobium strains with enhanced levels of intracellular c-di-GMP displayed common free-living responses: reduction of motility, increased production of extracellular polysaccharides and enhanced biofilm formation. Regarding the interaction with the host plants, P. savastanoi pv. savastanoi cells containing high c-di-GMP levels formed larger knots on olive plants which, however, displayed reduced necrosis. In contrast, development of disease symptoms in P. syringae-tomato or P. syringae-bean interactions did not seem significantly affected by high c-di-GMP. On the other hand, increasing c-di-GMP levels in symbiotic R. etli and R. leguminosarum strains favoured the early stages of the interaction since enhanced adhesion to plant roots, but decreased symbiotic efficiency as plant growth and nitrogen contents were reduced. Our results remark the importance of c-di-GMP economy for plant-interacting bacteria and show the usefulness of our approach to reveal particular stages during plant-bacteria associations which are sensitive to changes in c-di-GMP levels. PMID:24626229

Pérez-Mendoza, Daniel; Aragón, Isabel M; Prada-Ramírez, Harold A; Romero-Jiménez, Lorena; Ramos, Cayo; Gallegos, María-Trinidad; Sanjuán, Juan

2014-01-01

392

Responses to Elevated c-di-GMP Levels in Mutualistic and Pathogenic Plant-Interacting Bacteria  

PubMed Central

Despite a recent burst of research, knowledge on c-di-GMP signaling pathways remains largely fragmentary and molecular mechanisms of regulation and even c-di-GMP targets are yet unknown for most bacteria. Besides genomics or bioinformatics, accompanying alternative approaches are necessary to reveal c-di-GMP regulation in bacteria with complex lifestyles. We have approached this study by artificially altering the c-di-GMP economy of diverse pathogenic and mutualistic plant-interacting bacteria and examining the effects on the interaction with their respective host plants. Phytopathogenic Pseudomonas and symbiotic Rhizobium strains with enhanced levels of intracellular c-di-GMP displayed common free-living responses: reduction of motility, increased production of extracellular polysaccharides and enhanced biofilm formation. Regarding the interaction with the host plants, P. savastanoi pv. savastanoi cells containing high c-di-GMP levels formed larger knots on olive plants which, however, displayed reduced necrosis. In contrast, development of disease symptoms in P. syringae-tomato or P. syringae-bean interactions did not seem significantly affected by high c-di-GMP. On the other hand, increasing c-di-GMP levels in symbiotic R. etli and R. leguminosarum strains favoured the early stages of the interaction since enhanced adhesion to plant roots, but decreased symbiotic efficiency as plant growth and nitrogen contents were reduced. Our results remark the importance of c-di-GMP economy for plant-interacting bacteria and show the usefulness of our approach to reveal particular stages during plant-bacteria associations which are sensitive to changes in c-di-GMP levels. PMID:24626229

Perez-Mendoza, Daniel; Aragon, Isabel M.; Prada-Ramirez, Harold A.; Romero-Jimenez, Lorena; Ramos, Cayo; Gallegos, Maria-Trinidad; Sanjuan, Juan

2014-01-01

393

Enteric Pathogen-Plant Interactions: Molecular Connections Leading to Colonization and Growth and Implications for Food Safety  

PubMed Central

Leafy green vegetables have been identified as a source of foodborne illnesses worldwide over the past decade. Human enteric pathogens, such as Escherichia coli O157:H7 and Salmonella, have been implicated in numerous food poisoning outbreaks associated with the consumption of fresh produce. An understanding of the mechanisms responsible for the establishment of pathogenic bacteria in or on vegetable plants is critical for understanding and ameliorating this problem as well as ensuring the safety of our food supply. While previous studies have described the growth and survival of enteric pathogens in the environment and also the risk factors associated with the contamination of vegetables, the molecular events involved in the colonization of fresh produce by enteric pathogens are just beginning to be elucidated. This review summarizes recent findings on the interactions of several bacterial