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Sample records for powdery mildew invasion

  1. Powdery Mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew of beet, a disease caused by Erysiphe polygoni, is a problem in most beet growing areas. Symptoms include whitish mats of hyphae and conidia that can cover leaves and flower stalks and cause leaves to turn yellow, then purplish brown. Characteristics of the pathogen, epidemiology and...

  2. Powdery mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew is found sporadically on alfalfa and annual medic species. It has been reported on commercial hay and seed fields in Europe, the People's Republic of China, Egypt, and the U.S. It is a common foliar disease in greenhouse-grown plants. Severe infections can cause defoliation and redu...

  3. Powdery mildew of chickpea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew of chickpea is caused by several fungi including Leveillula taurica, Erysiphe pisi and possible other Erysiphe spp. The most conspicuous sign of infection is diffuse, powdery sporulation on leaves and pods. The disease is favored by cool and dry weather. The relative roles of the sex...

  4. Powdery Mildew Disease Resistance

    SciTech Connect

    Somerville, Shauna C.

    2010-08-31

    The overall goal of this project was to characterize the PMR5 protein, a member of the DUF231/TBR family, and to determine its role in plant cell wall biogenesis. Since the pmr5 mutants are also resistant to the fungal powdery mildew pathogen, we wished to determine what specific cell wall changes are associated with disease resistance and why. The graduate student working on this project made mutations in the putative active site of PMR5, assuming it is a member of the SGNH/GDSL esterase superfamily (Anantharaman and Aravind, 2010, Biology Direct 5, 1). These mutants were inactive in planta suggesting that PMR5 is a functional enzyme and not a binding protein or chaperone. In addition, she determined that cell wall preparations from the pmr5 mutant exhibited a modest reduction (13%) in total acetyl groups. To pursue characterization further, the graduate student expressed the PMR5 protein in a heterologous E. coli system. She could purify PMR5 using a two step protocol based on tags added to the N and C terminus of the protein. She was able to show the PMR5 protein bound to pectins, including homogalacturonan, but not to other cell wall components (e.g., xyloglucans, arabinans). Based on these observations, a postdoctoral fellow is currently developing an enzyme assay for PMR5 based on the idea that it may be acetylating the homogalacturonic acid pectin fraction. Our initial experiments to localize PMR5 subcellularly suggested that it occurred in the endoplasmic reticulum. However, since the various pectins are believed to be synthesized in the Golgi apparatus, we felt it necessary to repeat our results using a native promoter expression system. Within the past year, we have demonstrated conclusively that PMR5 is localized to the endoplasmic reticulum, a location that sets it apart from most cell wall biogenesis and modification enzymes. The graduate student contributed to the characterization of two suppressor mutants, which were selected as restoring powdery

  5. Resistance to Powdery Mildew in Hydrangeas

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew is an important foliar disease of hydrangeas. For developing efficient integrated disease management strategies involving the utilization of resistant cultivars, it is essential to understand how the powdery mildew fungus infects hydrangea plants and how the host resists the parasitis...

  6. Potential alternative hosts for a powdery mildew on pea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew of pea (Pisum sativum) is an important disease in the field and in the greenhouse. The most widely documented powdery mildew on pea is Erysiphe pisi, but E. trifolii and E. baeumleri have also been reported. From greenhouse-grown peas, we obtained powdery mildew samples with rDNA ITS ...

  7. Inoculum detection for managing grape powdery mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grape powdery mildew (caused by Erysiphe necator) often develops explosively and can result in significant yield and quality losses, despite your best efforts. The threat of quality losses often leads to a low risk prophylactic regimen rather than a higher risk IPM approach. Gary Grove and I have co...

  8. Resistance to Powdery Mildew in Hydrangea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew, caused by Erysiphe polygoni, is an important foliar disease of hydrangeas. Infection process and development of E. polygoni on hydrangeas were determined using a leaf disk assay. On susceptible hydrangea cultivars, conidia of E. polygoni germinated and formed primary appressoria with...

  9. Identification of powdery mildew fungi anno 2006

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This is an update of the previous laboratory exercise on powdery mildews at the Plant Health Instructor website. In 2002, there was a drastic change in the taxonomy of the Erysiphales, and most teaching documents had become outdated and even unusable. This exercise was essentially a new creation, ...

  10. Mechanisms of Resistance to Grapevine Powdery Mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although all high quality Vitis vinifera cultivars are highly susceptible to powdery mildew, current efforts show promise for the identification or modulation of resistance within the species and for continued introgression of resistance from resistant accessions of wild Vitis spp. Examination of t...

  11. LIFEGUARD proteins support plant colonization by biotrophic powdery mildew fungi

    PubMed Central

    Weis, Corina; Hückelhoven, Ralph; Eichmann, Ruth

    2013-01-01

    Pathogenic microbes manipulate eukaryotic cells during invasion and target plant proteins to achieve host susceptibility. BAX INHIBITOR-1 (BI-1) is an endoplasmic reticulum-resident cell death suppressor in plants and animals and is required for full susceptibility of barley to the barley powdery mildew fungus Blumeria graminis f.sp. hordei. LIFEGUARD (LFG) proteins resemble BI-1 proteins in terms of predicted membrane topology and cell-death-inhibiting function in metazoans, but display clear sequence-specific distinctions. This work shows that barley (Hordeum vulgare L.) and Arabidopsis thaliana genomes harbour five LFG genes, HvLFGa–HvLFGe and AtLFG1–AtLFG5, whose functions are largely uncharacterized. As observed for HvBI-1, single-cell overexpression of HvLFGa supports penetration success of B. graminis f.sp. hordei into barley epidermal cells, while transient-induced gene silencing restricts it. In penetrated barley epidermal cells, a green fluorescent protein-tagged HvLFGa protein accumulates at the site of fungal entry, around fungal haustoria and in endosomal or vacuolar membranes. The data further suggest a role of LFG proteins in plant–powdery mildew interactions in both monocot and dicot plants, because stable overexpression or knockdown of AtLFG1 or AtLFG2 also support or delay development of the powdery mildew fungus Erysiphe cruciferarum on the respective Arabidopsis mutants. Together, this work has identified new modulators of plant–powdery mildew interactions, and the data further support functional similarities between BI-1 and LFG proteins beyond cell death regulation. PMID:23888068

  12. LIFEGUARD proteins support plant colonization by biotrophic powdery mildew fungi.

    PubMed

    Weis, Corina; Hückelhoven, Ralph; Eichmann, Ruth

    2013-09-01

    Pathogenic microbes manipulate eukaryotic cells during invasion and target plant proteins to achieve host susceptibility. BAX INHIBITOR-1 (BI-1) is an endoplasmic reticulum-resident cell death suppressor in plants and animals and is required for full susceptibility of barley to the barley powdery mildew fungus Blumeria graminis f.sp. hordei. LIFEGUARD (LFG) proteins resemble BI-1 proteins in terms of predicted membrane topology and cell-death-inhibiting function in metazoans, but display clear sequence-specific distinctions. This work shows that barley (Hordeum vulgare L.) and Arabidopsis thaliana genomes harbour five LFG genes, HvLFGa-HvLFGe and AtLFG1-AtLFG5, whose functions are largely uncharacterized. As observed for HvBI-1, single-cell overexpression of HvLFGa supports penetration success of B. graminis f.sp. hordei into barley epidermal cells, while transient-induced gene silencing restricts it. In penetrated barley epidermal cells, a green fluorescent protein-tagged HvLFGa protein accumulates at the site of fungal entry, around fungal haustoria and in endosomal or vacuolar membranes. The data further suggest a role of LFG proteins in plant-powdery mildew interactions in both monocot and dicot plants, because stable overexpression or knockdown of AtLFG1 or AtLFG2 also support or delay development of the powdery mildew fungus Erysiphe cruciferarum on the respective Arabidopsis mutants. Together, this work has identified new modulators of plant-powdery mildew interactions, and the data further support functional similarities between BI-1 and LFG proteins beyond cell death regulation. PMID:23888068

  13. Lasiodiplodia theobromae is a Mycoparasite of a Powdery Mildew Pathogen.

    PubMed

    Sreerama Kumar, P; Singh, Leena

    2009-12-01

    Powdery mildews on over 40 plants in Bangalore were screened during July-December of 2003~2008. Isolates from mycoparasitised Oidium caesalpiniacearum of Bauhinia purpurea comprised Lasiodiplodia theobromae, in addition to Ampelomyces quisqualis. Koch's postulates were satisfied to establish the mycoparasitism of L. theobromae. This is the first report that L. theobromae acts as a mycoparasite of a powdery mildew. PMID:23983554

  14. Lasiodiplodia theobromae is a Mycoparasite of a Powdery Mildew Pathogen

    PubMed Central

    Singh, Leena

    2009-01-01

    Powdery mildews on over 40 plants in Bangalore were screened during July-December of 2003~2008. Isolates from mycoparasitised Oidium caesalpiniacearum of Bauhinia purpurea comprised Lasiodiplodia theobromae, in addition to Ampelomyces quisqualis. Koch's postulates were satisfied to establish the mycoparasitism of L. theobromae. This is the first report that L. theobromae acts as a mycoparasite of a powdery mildew. PMID:23983554

  15. Variation within and between Vitis species for foliar resistance to the powdery mildew pathogen Erysiphe necator

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To complement existing control strategies, grape growers desire cultivars with resistance to powdery mildew caused by Erysiphe necator. Numerous disease resistance screens of diverse Vitis germplasm have been conducted previously to identify powdery mildew resistance, but ratings of named cultivars...

  16. Gene-For-Gene-Mediated Transcriptome Reprogramming in Barley-Powdery Mildew Interactions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Barley has a complex interaction with powdery mildew [Blumeria graminis f. sp. hordei (Bgh)] that begins with early recognition of microbe-associated molecular patterns (MAMPs) from the pathogen. During Bgh invasion of the epidermis, the fate of cells is decided by the presence of resistance (R) gen...

  17. Examination of marker-assisted selection for powdery and downy mildew resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field grown seedlings potentially carrying both the Run1 and Rpv1 loci for powdery and downy mildew resistance, respectively, from muscadine introgressions were assessed for resistance to both powdery and downy mildew. Powdery mildew was assessed in the field under no-spray conditions, while down mi...

  18. The Novel Gene VpPR4-1 from Vitis pseudoreticulata Increases Powdery Mildew Resistance in Transgenic Vitis vinifera L.

    PubMed Central

    Dai, Lingmin; Wang, Dan; Xie, Xiaoqing; Zhang, Chaohong; Wang, Xiping; Xu, Yan; Wang, Yuejin; Zhang, Jianxia

    2016-01-01

    Pathogenesis-related proteins (PRs) can lead to increased resistance of the whole plant to pathogen attack. Here, we isolate and characterize a PR-4 protein (VpPR4-1) from a wild Chinese grape Vitis pseudoreticulata which shows greatly elevated transcription following powdery mildew infection. Its expression profiles under a number of abiotic stresses were also investigated. Powdery mildew, salicylic acid, and jasmonic acid methyl ester significantly increased the VpPR4-1 induction while NaCl and heat treatments just slightly induced VpPR4-1 expression. Abscisic acid and cold treatment slightly affected the expression level of VpPR4-1. The VpPR4-1 gene was overexpressed in 30 regenerated V. vinifera cv. Red Globe via Agrobacterium tumefaciens-mediated transformation and verified by the Western blot. The 26 transgenic grapevines exhibited higher expression levels of PR-4 protein content than wild-type vines and six of them were inoculated with powdery mildew which showed that the growth of powdery mildew was repressed. The powdery mildew-resistance of Red Globe transformed with VpPR4-1 was enhanced inoculated with powdery mildew. Moreover, other powdery mildew resistant genes were associated with feedback regulation since VpPR4-1 is in abundance. This study demonstrates that PR-4 protein in grapes plays a vital role in defense against powdery mildew invasion. PMID:27303413

  19. Developmnent of molecular markers for powdery mildew resistance in grapevines

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molecular markers have been used as a tool for plant breeding for two decades. Markers linked to disease resistance can be used to pyramid resistance genes for improved durability and to improve the efficiency of evaluation. To develop molecular markers linked to resistance to grape powdery mildew ...

  20. New Sources of Resistance to Cucurbit Powdery Mildew in Melon

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many physiological races of the cucurbit powdery mildew pathogen (CPM) Podosphaera xanthii (Castagne) Braun & Shishkoff have been reported on melon (Cucumis melo L.). Melon accession PI 313970 is the only reported source of host plant resistance to race S, which first appeared in Imperial Valley, CA...

  1. Hop powdery mildew control through alteration of spring pruning practices

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Since 1997, Podosphaera macularis, the causal agent of hop powdery mildew, has become a recurrent threat to hops in the Pacific Northwest because of the potential to reduce cone yield and quality. Disease management practices often involve preventative fungicide applications, but alternative approac...

  2. QTL mapping of resistance to Powdery Mildew in lettuce.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Erysiphe cichoracearam causes powdery mildew on most compositae including lettuce and chicory. Variation in susceptibility has been documented both in cultivated lettuce and wild relatives. Little is known about the genetic architecture of resistance to the pathogen, but monogenic resistance has bee...

  3. Erysiphe trifolii causing powdery mildew of lentil (Lens culinaris)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The taxonomy of the powdery mildew fungus infecting lentil in the Pacific Northwest (PNW) of the USA was investigated on the basis of morphology and rDNA ITS sequences. Anamorphic characters were in close agreement with descriptions of E. trifolii. However, teleomorphs formed chasmothecial appenda...

  4. Marker-assisted selection for powdery mildew in pea

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew, caused by Erysiphe pisi Syd. is an important pathogen of pea (Pisum sativum L.) worldwide. It causes significant yield loss and reduced crop quality when present in epidemic proportion. Genetic resistance is controlled by two recessive alleles, er-1 and er-2. Availability of co-domin...

  5. Phoma glomerata as a mycoparasite of powdery mildew.

    PubMed

    Sullivan, R F; White, J F

    2000-01-01

    Ampelomyces and Phoma species are frequently confused with each other. Isolates previously attributed to the genus Ampelomyces were shown to be Phoma isolates through studies of their morphology and life cycle and ribosomal DNA internal transcribed spacer region 1 sequence analysis. Phoma glomerata can colonize and suppress development of powdery mildew on oak and may have utility as a mycoparasitic agent. PMID:10618259

  6. Phoma glomerata as a Mycoparasite of Powdery Mildew

    PubMed Central

    Sullivan, Raymond F.; White, James F.

    2000-01-01

    Ampelomyces and Phoma species are frequently confused with each other. Isolates previously attributed to the genus Ampelomyces were shown to be Phoma isolates through studies of their morphology and life cycle and ribosomal DNA internal transcribed spacer region 1 sequence analysis. Phoma glomerata can colonize and suppress development of powdery mildew on oak and may have utility as a mycoparasitic agent. PMID:10618259

  7. Breeding Table Grapes with Resistance to Powdery Mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Different mechanisms for resistance to powdery mildew exist in grape germplasm. M. rotundifolia and V. aesitvalis progeny show a gradation in response from resistant to susceptible, suggesting multiple resistance genes. V. romanetii progeny segregate into the distinct classes of highly resistant o...

  8. Evaluation of Powdery Mildew Resistance in Hydrangea macrophylla

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew, Erysiphe polygoni DC, can be a significant problem on Hydrangea macrophylla (Thunb.) Ser. in the landscape during late summer to fall and during greenhouse propagation or production of potted plants. Because very little information related to sources of resistance is available, 90 H...

  9. Mildew-Omics: How Global Analyses Aid the Understanding of Life and Evolution of Powdery Mildews

    PubMed Central

    Bindschedler, Laurence V.; Panstruga, Ralph; Spanu, Pietro D.

    2016-01-01

    The common powdery mildew plant diseases are caused by ascomycete fungi of the order Erysiphales. Their characteristic life style as obligate biotrophs renders functional analyses in these species challenging, mainly because of experimental constraints to genetic manipulation. Global large-scale (“-omics”) approaches are thus particularly valuable and insightful for the characterisation of the life and evolution of powdery mildews. Here we review the knowledge obtained so far from genomic, transcriptomic and proteomic studies in these fungi. We consider current limitations and challenges regarding these surveys and provide an outlook on desired future investigations on the basis of the various –omics technologies. PMID:26913042

  10. Rationalization of pesticide treatments against powdery mildew of grape.

    PubMed

    Spera, G; La Torre, A; Gianferro, M; Bugliosi, R

    2007-01-01

    The powdery mildew represents one of the diseases which affect the grape, it is diffused in all agricultural regions with variable intensity and epidemic course in operation of many microclimatic factors. The powdery mildew of grape is caused from Uncinala necator (Schw.) Burr. (nowadays named Erysiphe necator Schwein.); it is controlled with systemic therapy and contact chemicaL products. In some vineyards located in Latium (central Italy), different field trials have been carried out purposely to rationalize the treatments against E. necator. We have studied the powdery mildew infections through monitoring a set of environmental parameters, the evaluation of cultivar sensibility, the agricultural production method and the area characteristics. We have analysed the following environmental parameters monitoring every 15 minutes: precipitation, soil temperature, solar radiation, wind direction, wind speed, atmospheric relative humidity, atmospheric temperature, leaf wetness, soil humidity to cm 20 and soil humidity to cm 40. Besides, we have used Artificial Intelligence analysis techniques to try to forecast U. necator infections. Guideline EPPO/OEPP PP 1/4 (4) has been used. The trials were conducted in conventional and organic farms. In 2 conventional farms and in organic farm we have considered 1 untreated control thesis, in order to follow the course of infection, 1 standard farm reference thesis (standard), where the treatments were carried out according to the usual farm procedures and 1 thesis where the treatments were carried out according to examining the environmental data. In another conventional vineyard, we have considered only 1 untreated control thesis and 1 standard farm reference thesis (standard) to study disease trend. The achieved results have underlined the possibility (through the knowledge of data pedoclimatic and cultural) to position the treatments against the powdery mildew so that to reduce their number. The lower number of treatments that

  11. Effect of grafting on resistant rootstocks on development of powdery mildew on susceptible watermelon scion, 2012

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An experiment was conducted in a greenhouse at the U.S. Vegetable Laboratory in Charleston, SC, to determine if grafting a powdery mildew susceptible variety (scion) onto watermelon rootstocks with resistance to powdery mildew would provide resistance to foliage of the susceptible scion. Plants of ...

  12. Epidemiology of Powdery Mildew on Resistant and Susceptible Flowering Dogwood Cultivars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew, caused by Erysiphe pulchra (syn. Microsphaera pulchra) is an important disease on flowering dogwood (Cornus florida) in the Eastern United States. Temporal progress of powdery mildew on flowering dogwood cultivars with different levels of resistance was investigated in the field in 2...

  13. Sequential sampling for estimation and classification of the incidence of hop powdery mildew I: Leaf sampling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hop powdery mildew (caused by Podosphaera macularis) is an important disease of hops (Humulus lupulus) in the Pacific Northwest. Sequential sampling models for estimation and classification of the incidence of powdery mildew on leaves of hop were developed based on the beta-binomial distribution, u...

  14. DELAY OF EXPRESSION OF POWDERY MILDEW ON ZINNIA GROWN HYDROPONICALLY IN HOAGLAND'S SOLUTION FORTIFIED WITH SILICON

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew, caused by the fungus Erysiphe cichoracearum, is one of the most common foliar diseases that occur in greenhouse bedding plant production. Although powdery mildews are somewhat host specific, E. cichoracearum is reported to have a wide host range which includes the commonly grown be...

  15. Pm37, a new broadly effective powdery mildew resistance gene from Triticum timopheevii

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew, caused by Blumeria graminis f. sp. tritici, is an important foliar disease in wheat (Triticum aestivum L.), especially in areas with a cool or maritime climate. A dominant powdery mildew resistance gene transferred to the hexaploid germplasm line NC99BGTAG11 (NCAG11) from T. timophee...

  16. QTL mapping of powdery mildew resistance in WI 2757 cucumber (Cucumis sativus L)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew is a serious fungal disease of cucumber and other cucurbot crops in the US and many other parts of the world. Resistant cultivars have been deployed in production for a long time, but the genetic mechanisms of powdery mildew resistance in cucumber are not well understood. In a three-y...

  17. First report of powdery mildew of chickpea (Cicer arietinum) caused by Leveillula taurica in Washington State

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chickpea is an important grain legume worldwide, and an important rotational and specialty crop in the US. In October 2007, powdery mildew was found on chickpea plants in a field near Pullman, Washington. Typical powdery mildew symptoms and signs were observed on petioles and adaxial leaf surfaces....

  18. Genetic characterization and targeted mapping of a Triticum timopheevii-dervied powdery mildew resistance gene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There are five alleles conferring race-specific resistance to powdery mildew (caused by Blumeria graminis f. sp. tritici) at the Pm1 locus on the long arm of chromosome 7A of wheat (Triticum aestivum. L). A dominant powdery mildew resistance gene transferred to the hexaploid germplasm line NC99BGTAG...

  19. Characterization of resistance to powdery mildew in the Hop cultivars Newport and Comet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hop powdery mildew, caused by Podosphaera macularis, is an important disease in the Northwestern U.S. Outbreaks of powdery mildew on cultivars previously resistant to the disease have been reported increasingly with the emergence of virulent pathogen strains capable of overcoming a commonly deployed...

  20. Genetic Mapping of a Triticum monococcum-derived Powdery Mildew Resistance Gene in Common Wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew of wheat (Triticum aestivum L.) is a major fungal disease caused by Blumeria graminis DC f sp. tritici. A microsatellite linkage map was developed for the T. monococcum-derived powdery mildew resistant gene present in the North Carolina germplasm line NCBGT96A6 (NCA6). Genetic analys...

  1. Crop damage caused by Powdery Mildew on Hop and its relationship to late season management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew of hop (Podosphaera macularis) may cause economic loss due to reductions in cone yield and quality. Quantitative estimates of crop damage from powdery mildew remain poorly characterised, especially the effect of late season disease management on crop yield and quality. Field studies i...

  2. Virulence structure of the eastern U.S. wheat powdery mildew population

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little is known about the population structure of wheat powdery mildew in the eastern 2 U.S., and the most recent report on virulence in this pathogen population involved isolates 3 collected in 1993-94. In the present study, wheat leaves naturally infected with powdery mildew 4 were collected from ...

  3. Powdery mildew caused by Podosphaera macularis on hop (Humulus lupulus) in North Carolina

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In June 2015, a grower in western North Carolina detected powdery mildew in a small hop yard. Characteristic colonies of the pathogen where observed on cultivars Cashmere, Cascade, and Chinook. Leaves with powdery mildew were collected from cultivar Cashmere for confirmation of the pathogen identi...

  4. Evaluation and Quantitative trait loci mapping of resistance to powdery mildew in lettuce

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lettuce (Lactuca sativa L.) is the major leafy vegetable that is susceptible to powdery mildew disease under greenhouse and field conditions. We mapped quantitative trait loci (QTLs) for resistance to powdery mildew under greenhouse conditions in an interspecific population derived from a cross betw...

  5. Bacillus sp. BS061 Suppresses Powdery Mildew and Gray Mold

    PubMed Central

    Kim, Young-Sook; Song, Ja-Gyeong; Lee, In-Kyoung; Yeo, Woon-Hyung

    2013-01-01

    The use of a microorganism, or its secretions, to prevent plant disease offers an attractive alternative or supplement to synthetic fungicides for the management of plant disease without the negative effects of chemical control mechanisms. During a screening for microorganisms with the potential to be used as microbial fungicides, Bacillus sp. BS061 was isolated from a plant leaf. The strain BS061 potently inhibited the mycelial growth of Botrytis cinerea, and significantly reduced disease incidence of powdery mildew in cucumber and strawberry. We also found that the culture filtrate of BS061 inhibited the mycelial growth of various plant pathogens. PMID:23874134

  6. An Arabidopsis mutant with enhanced resistance to powdery mildew.

    PubMed Central

    Frye, C A; Innes, R W

    1998-01-01

    We have identified an Arabidopsis mutant that displays enhanced disease resistance to the fungus Erysiphe cichoracearum, causal agent of powdery mildew. The edr1 mutant does not constitutively express the pathogenesis-related genes PR-1, BGL2, or PR-5 and thus differs from previously described disease-resistant mutants of Arabidopsis. E. cichoracearum conidia (asexual spores) germinated normally and formed extensive hyphae on edr1 plants, indicating that the initial stages of infection were not inhibited. Production of conidiophores on edr1 plants, however, was <16% of that observed on wild-type Arabidopsis. Reduction in sporulation correlated with a more rapid induction of defense responses. Autofluorescent compounds and callose accumulated in edr1 leaves 3 days after inoculation with E. cichoracearum, and dead mesophyll cells accumulated in edr1 leaves starting 5 days after inoculation. Macroscopic patches of dead cells appeared 6 days after inoculation. This resistance phenotype is similar to that conferred by "late-acting" powdery mildew resistance genes of wheat and barley. The edr1 mutation is recessive and maps to chromosome 1 between molecular markers ATEAT1 and NCC1. We speculate that the edr1 mutation derepresses multiple defense responses, making them more easily induced by virulent pathogens. PMID:9634583

  7. New concept for determination and denomination of pathotypes and races of cucurbit powdery mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucurbit powdery mildew (CPM), which is caused most frequently by two obligate erysiphaceous ectoparasites (Golovinomyces cichoracearum, Podosphaera xanthii), occurs on field and glasshouse cucurbit crops worldwide. We review the current state of understanding of variation for pathogenicity of these...

  8. Bacillus sp. BS061 Suppresses Gray Mold and Powdery Mildew through the Secretion of Different Bioactive Substances.

    PubMed

    Kim, Young-Sook; Song, Ja-Gyeong; Lee, In-Kyoung; Yeo, Woon-Hyung; Yun, Bong-Sik

    2013-09-01

    A Bacillus sp. BS061 significantly reduced disease incidence of gray mold and powdery mildew. To identify the active principle, the culture filtrate was partitioned between butanol and water. The antifungal activity against B. cinerea was evident in the butanol-soluble portion, and active substances were identified as cyclic lipopeptides, iturin A series, by nuclear magnetic resonance spectrometry (NMR) and mass analysis. Interestingly, antifungal activity against powdery mildew was observed in the water-soluble portion, suggesting that cyclic lipopeptides have no responsibility to suppress powdery mildew. This finding reveals that biocontrol agents of Bacillus origin suppress gray mold and powdery mildew through the secretion of different bioactive substances. PMID:24198673

  9. Molecular characterization of a new powdery mildew resistance gene Pm54 in soft red winter wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew has caused increasing damage to wheat production in the southeastern USA. To combat the disease, there is a continuing need to discover new genes or quantitative trait loci for mildew resistance and promptly adopt those loci in breeding programs. Pioneer® variety 26R61 (shortened as 2...

  10. Quantitative and temporal definition of the Mla transcriptional regulon during barley-powdery mildew interactions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Barley Mildew resistance locus a (Mla) is a major determinant of immunity to the powdery mildew pathogen, Blumeria graminis f. sp. hordei. Alleles of Mla encode cytoplasmic- and membrane-localized coiled-coil, nucleotide binding site, leucine-rich repeat proteins that mediate resistance when complem...

  11. Activity of natural products against courgette powdery mildew.

    PubMed

    La Torre, A; Spera, G; Lolleti, D

    2004-01-01

    The effectiveness of several natural products in field trials were tested against powdery mildew on courgette. Sulphur, sodium bicarbonate (alone or in mixture with pinolene, mineral oil or sulphur), sodium silicate in mixture with mineral oil, potassium permanganate, lecithin, Equisetum arvense in mixture with Timus vulgaris, Ampelomyces quisqualis and Reynoutria sachalinensis were evaluated. Generally, in our working conditions (very strong pathogen infection), only some products were effective. Good results were obtained using sulphur and potassium permanganate in the first year and very interesting results about disease control were obtained, in the second year of the trial, using sulphur alone or in mixture with sodium bicarbonate. The products tested did not show any phytotoxic symptoms. PMID:15756857

  12. The wheat powdery mildew genome shows the unique evolution of an obligate biotroph.

    PubMed

    Wicker, Thomas; Oberhaensli, Simone; Parlange, Francis; Buchmann, Jan P; Shatalina, Margarita; Roffler, Stefan; Ben-David, Roi; Doležel, Jaroslav; Šimková, Hana; Schulze-Lefert, Paul; Spanu, Pietro D; Bruggmann, Rémy; Amselem, Joelle; Quesneville, Hadi; Ver Loren van Themaat, Emiel; Paape, Timothy; Shimizu, Kentaro K; Keller, Beat

    2013-09-01

    Wheat powdery mildew, Blumeria graminis forma specialis tritici, is a devastating fungal pathogen with a poorly understood evolutionary history. Here we report the draft genome sequence of wheat powdery mildew, the resequencing of three additional isolates from different geographic regions and comparative analyses with the barley powdery mildew genome. Our comparative genomic analyses identified 602 candidate effector genes, with many showing evidence of positive selection. We characterize patterns of genetic diversity and suggest that mildew genomes are mosaics of ancient haplogroups that existed before wheat domestication. The patterns of diversity in modern isolates suggest that there was no pronounced loss of genetic diversity upon formation of the new host bread wheat 10,000 years ago. We conclude that the ready adaptation of B. graminis f.sp. tritici to the new host species was based on a diverse haplotype pool that provided great genetic potential for pathogen variation. PMID:23852167

  13. MlAB10: a Triticum turgidum subsp. dicoccoides derived powdery mildew resistance gene identified in common wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew is an economically important disease in wheat growing areas with a cool maritime environment. Host genetic resistance is the most economical, consistent, and environmentally sound method of control. NC97BGTAB10 is a germplasm line containing powdery mildew resistance introgressed fr...

  14. MIAG12: A Triticum timopheevii-derived powdery mildew resistance gene in common wheat on chromosome 7AL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat powdery mildew is an economically important disease in cool and humid 2 environments. Powdery mildew causes yield losses as high as 48 percent through a reduction in 3 tiller survival, kernels per head and kernel size. Race-specific host resistance is the most 4 consistent, environmentally fri...

  15. MlNCD1: A novel Aegilops tauschii derived powdery mildew resistance gene identified in common wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew is a major fungal disease in wheat, especially in cool maritime climates. A novel Aegilops tauschii derived wheat powdery mildew resistance gene present in the germplasm line NC96BGTD1 was genetically characterized as a monogenic trait in field trials using F2 and F4-derived lines fr...

  16. Biotrophy at Its Best: Novel Findings and Unsolved Mysteries of the Arabidopsis-Powdery Mildew Pathosystem.

    PubMed

    Kuhn, Hannah; Kwaaitaal, Mark; Kusch, Stefan; Acevedo-Garcia, Johanna; Wu, Hongpo; Panstruga, Ralph

    2016-01-01

    It is generally accepted in plant-microbe interactions research that disease is the exception rather than a common outcome of pathogen attack. However, in nature, plants with symptoms that signify colonization by obligate biotrophic powdery mildew fungi are omnipresent. The pervasiveness of the disease and the fact that many economically important plants are prone to infection by powdery mildew fungi drives research on this interaction. The competence of powdery mildew fungi to establish and maintain true biotrophic relationships renders the interaction a paramount example of a pathogenic plant-microbe biotrophy. However, molecular details underlying the interaction are in many respects still a mystery. Since its introduction in 1990, the Arabidopsis-powdery mildew pathosystem has become a popular model to study molecular processes governing powdery mildew infection. Due to the many advantages that the host Arabidopsis offers in terms of molecular and genetic tools this pathosystem has great capacity to answer some of the questions of how biotrophic pathogens overcome plant defense and establish a persistent interaction that nourishes the invader while in parallel maintaining viability of the plant host. PMID:27489521

  17. Biotrophy at Its Best: Novel Findings and Unsolved Mysteries of the Arabidopsis-Powdery Mildew Pathosystem

    PubMed Central

    Kuhn, Hannah; Kwaaitaal, Mark; Kusch, Stefan; Acevedo-Garcia, Johanna; Wu, Hongpo; Panstruga, Ralph

    2016-01-01

    It is generally accepted in plant-microbe interactions research that disease is the exception rather than a common outcome of pathogen attack. However, in nature, plants with symptoms that signify colonization by obligate biotrophic powdery mildew fungi are omnipresent. The pervasiveness of the disease and the fact that many economically important plants are prone to infection by powdery mildew fungi drives research on this interaction. The competence of powdery mildew fungi to establish and maintain true biotrophic relationships renders the interaction a paramount example of a pathogenic plant-microbe biotrophy. However, molecular details underlying the interaction are in many respects still a mystery. Since its introduction in 1990, the Arabidopsis-powdery mildew pathosystem has become a popular model to study molecular processes governing powdery mildew infection. Due to the many advantages that the host Arabidopsis offers in terms of molecular and genetic tools this pathosystem has great capacity to answer some of the questions of how biotrophic pathogens overcome plant defense and establish a persistent interaction that nourishes the invader while in parallel maintaining viability of the plant host. PMID:27489521

  18. QTL identification in an interspecific grapevine cross segregating for resistance to Powdery Mildew, Downy Mildew, Black Rot, and Phylloxera

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grapevine is a highly heterozygous plant with a complex genetic background. Here, we report the use of an F1 family (N = 125) from a cross of MN1264 × MN1246 made in 2010. The cross contains at least six Vitis species in its ancestry and segregates for resistance to powdery mildew (Erysiphe necator)...

  19. PAMP-triggered immune responses in barley and susceptibility to powdery mildew.

    PubMed

    Hückelhoven, Ralph; Seidl, Anna

    2016-07-01

    Pathogen-associated molecular pattern-triggered immunity (PTI) builds one of the first layers of plant disease resistance. In susceptible plants, PTI is overcome by adapted pathogens. This can be achieved by suppression of PTI with the help of pathogen virulence effectors. However, effectors may also contribute to modification of host metabolism or cell architecture to ensure successful pathogenesis. Barley responds to treatment with the pathogen-associated molecular patterns flg22 or chitin with phosphorylation of mitogen-activated protein kinases and an oxidative burst. RAC/ROP GTPases can act as positive or negative modulators of these plant immune responses. The RAC/ROP GTPase RACB is a powdery mildew susceptibility factor of barley. However, RACB apparently does not negatively control early PTI responses but functions in polar cell development during invasion of the pathogen into living host epidermal cells. Here, we further discuss the incomplete picture of PTI in Triticeae. PMID:27348336

  20. Powdery mildew suppresses herbivore-induced plant volatiles and interferes with parasitoid attraction in Brassica rapa.

    PubMed

    Desurmont, Gaylord A; Xu, Hao; Turlings, Ted C J

    2016-09-01

    The co-occurrence of different antagonists on a plant can greatly affect infochemicals with ecological consequences for higher trophic levels. Here we investigated how the presence of a plant pathogen, the powdery mildew Erysiphe cruciferarum, on Brassica rapa affects (1) plant volatiles emitted in response to damage by a specialist herbivore, Pieris brassicae; (2) the attraction of the parasitic wasp Cotesia glomerata and (3) the performance of P. brassicae and C. glomerata. Plant volatiles were significantly induced by herbivory in both healthy and mildew-infected plants, but were quantitatively 41% lower for mildew-infected plants compared to healthy plants. Parasitoids strongly preferred Pieris-infested plants to dually-infested (Pieris + mildew) plants, and preferred dually infested plants over only mildew-infected plants. The performance of P. brassicae was unaffected by powdery mildew, but C. glomerata cocoon mass was reduced when parasitized caterpillars developed on mildew-infected plants. Thus, avoidance of mildew-infested plants may be adaptive for C. glomerata parasitoids, whereas P. brassicae caterpillars may suffer less parasitism on mildew-infected plants in nature. From a pest management standpoint, the concurrent presence of multiple plant antagonists can affect the efficiency of specific natural enemies, which may in turn have a negative impact on the regulation of pest populations. PMID:27043839

  1. NMR Spectroscopy Identifies Metabolites Translocated from Powdery Mildew Resistant Rootstocks to Susceptible Watermelon Scions.

    PubMed

    Mahmud, Iqbal; Kousik, Chandrasekar; Hassell, Richard; Chowdhury, Kamal; Boroujerdi, Arezue F

    2015-09-16

    Powdery mildew (PM) disease causes significant loss in watermelon. Due to the unavailability of a commercial watermelon variety that is resistant to PM, grafting susceptible cultivars on wild resistant rootstocks is being explored as a short-term management strategy to combat this disease. Nuclear magnetic resonance-based metabolic profiles of susceptible and resistant rootstocks of watermelon and their corresponding susceptible scions (Mickey Lee) were compared to screen for potential metabolites related to PM resistance using multivariate principal component analysis. Significant score plot differences between the susceptible and resistant groups were revealed through Mahalanobis distance analysis. Significantly different spectral buckets and their corresponding metabolites (including choline, fumarate, 5-hydroxyindole-3-acetate, and melatonin) have been identified quantitatively using multivariate loading plots and verified by volcano plot analyses. The data suggest that these metabolites were translocated from the powdery mildew resistant rootstocks to their corresponding powdery mildew susceptible scions and can be related to PM disease resistance. PMID:26302171

  2. The Powdery Mildew Disease of Arabidopsis: A Paradigm for the Interaction between Plants and Biotrophic Fungi

    PubMed Central

    Micali, Cristina; Göllner, Katharina; Humphry, Matt; Consonni, Chiara; Panstruga, Ralph

    2008-01-01

    The powdery mildew diseases, caused by fungal species of the Erysiphales, have an important economic impact on a variety of plant species and have driven basic and applied research efforts in the field of phytopathology for many years. Although the first taxonomic reports on the Erysiphales date back to the 1850's, advances into the molecular biology of these fungal species have been hampered by their obligate biotrophic nature and difficulties associated with their cultivation and genetic manipulation in the laboratory. The discovery in the 1990's of a few species of powdery mildew fungi that cause disease on Arabidopsis has opened a new chapter in this research field. The great advantages of working with a model plant species have translated into remarkable progress in our understanding of these complex pathogens and their interaction with the plant host. Herein we summarize advances in the study of Arabidopsis-powdery mildew interactions and discuss their implications for the general field of plant pathology. We provide an overview of the life cycle of the pathogens on Arabidopsis and describe the structural and functional changes that occur during infection in the host and fungus in compatible and incompatible interactions, with special emphasis on defense signaling, resistance pathways, and compatibility factors. Finally, we discuss the future of powdery mildew research in anticipation of the sequencing of multiple powdery mildew genomes. The cumulative body of knowledge on powdery mildews of Arabidopsis provides a valuable tool for the study and understanding of disease associated with many other obligate biotrophic pathogen species. PMID:22303240

  3. Hybridization of powdery mildew strains gives rise to pathogens on novel agricultural crop species.

    PubMed

    Menardo, Fabrizio; Praz, Coraline R; Wyder, Stefan; Ben-David, Roi; Bourras, Salim; Matsumae, Hiromi; McNally, Kaitlin E; Parlange, Francis; Riba, Andrea; Roffler, Stefan; Schaefer, Luisa K; Shimizu, Kentaro K; Valenti, Luca; Zbinden, Helen; Wicker, Thomas; Keller, Beat

    2016-02-01

    Throughout the history of agriculture, many new crop species (polyploids or artificial hybrids) have been introduced to diversify products or to increase yield. However, little is known about how these new crops influence the evolution of new pathogens and diseases. Triticale is an artificial hybrid of wheat and rye, and it was resistant to the fungal pathogen powdery mildew (Blumeria graminis) until 2001 (refs. 1,2,3). We sequenced and compared the genomes of 46 powdery mildew isolates covering several formae speciales. We found that B. graminis f. sp. triticale, which grows on triticale and wheat, is a hybrid between wheat powdery mildew (B. graminis f. sp. tritici) and mildew specialized on rye (B. graminis f. sp. secalis). Our data show that the hybrid of the two mildews specialized on two different hosts can infect the hybrid plant species originating from those two hosts. We conclude that hybridization between mildews specialized on different species is a mechanism of adaptation to new crops introduced by agriculture. PMID:26752267

  4. Histo-chemical and biochemical analysis reveals association of er1 mediated powdery mildew resistance and redox balance in pea.

    PubMed

    Mohapatra, Chinmayee; Chand, Ramesh; Navathe, Sudhir; Sharma, Sandeep

    2016-09-01

    Powdery mildew caused by Erysiphe pisi is one of the important diseases responsible for heavy yield losses in pea crop worldwide. The most effective method of controlling the disease is the use of resistant varieties. The resistance to powdery mildew in pea is recessive and governed by a single gene er1. The objective of present study is to investigate if er1 mediated powdery mildew resistance is associated with changes in the redox status of the pea plant. 16 pea genotypes were screened for powdery mildew resistance in field condition for two years and, also, analyzed for the presence/absence of er1 gene. Histochemical analysis with DAB and NBT staining indicates accumulation of reactive oxygen species (ROS) in surrounding area of powdery mildew infection which was higher in susceptible genotypes as compared to resistant genotypes. A biochemical study revealed that the activity of superoxide dismutase (SOD) and catalase, enzymes involved in scavenging ROS, was increased in, both, resistant and susceptible genotypes after powdery mildew infection. However, both enzymes level was always higher in resistant than susceptible genotypes throughout time course of infection. Moreover, irrespective of any treatment, the total phenol (TP) and malondialdehyde (MDA) content was significantly high and low in resistant genotypes, respectively. The powdery mildew infection elevated the MDA content but decreased the total phenol in pea genotypes. Statistical analysis showed a strong positive correlation between AUDPC and MDA; however, a negative correlation was observed between AUDPC and SOD, CAT and TP. Heritability of antioxidant was also high. The study identified few novel genotypes resistant to powdery mildew infection that carried the er1 gene and provided further clue that er1 mediated defense response utilizes antioxidant machinery to confer powdery mildew resistance in pea. PMID:27135819

  5. Sequential sampling for estimation and classification of the incidence of hop powdery mildew II: Cone sampling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sequential sampling models for estimation and classification of the incidence of powdery mildew (caused by Podosphaera macularis) on hop (Humulus lupulus) cones were developed using parameter estimates of the binary power law derived from the analysis of 221 transect data sets (model construction da...

  6. Suppression of cucumber powdery mildew by UV-B is affected by background light quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Brief (5-10 min) exposure to UV-B radiation (280-300 nm) suppressed powdery mildew (Podosphaera xanthii) on Cucumis sativus. The effect was enhanced by red light (600-660 nm), but offset by blue light (420-500 nm) and UV-A (300-420 nm). Compared to untreated controls, 2 h red light from specific lig...

  7. Identifying resistance to powdery mildew race 2W in the USDA-ARS watermelon germplasm collection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew caused by Podosphaera xanthii has become a common disease of watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] in the United States. The disease can be controlled with fungicides. However, it is more economical and environmentally safe to use genetic resistance against this di...

  8. FIRST REPORT OF POWDERY MILDEW ON DIPSACUS SYLVESTRIS CAUSED BY SPHAEROTHECA DIPSACEARUM IN NORTH AMERICA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dipsacus sylvestris (syn. D. fullonum, common teasel) (Dipsacaceae) is a European species introduced into North America, and now widely established and regarded as a noxious weed. Powdery mildew fungi (Erysiphales) reported previously from this host included Phyllactinia species in Washington State...

  9. Suppression of Zinnia Powdery Mildew in the Greenhouse with Silicon-containing Media Amendments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have previously reported that supplemental silicon supplied in hydroponic solution or soilless media can reduce the incidence and severity of powdery mildew (PM) on zinnia. This research reports the use of 1) silicon-containing organic amendments, 2) mineral compositions high in silicon content,...

  10. Improving management of grape powdery mildew with new tools and knowledge

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The assumption that inoculum of the grape powdery mildew pathogen is always available once conditions are suitable for inoculum release has been shown to be incorrect. Using various molecular techniques, we have shown that viticulturist can reduce their fungicide applications, on average, by 2.4 ap...

  11. First report of Oidiopsis taurica causing powdery mildew outbreak on pepper in Maryland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pepper plants grown in large experimental plots at Beltsville Maryland showed widespread powdery mildew infection in the late summer of 2008. Extensive coverage of the abaxial surface by white patches of conidia was noted, along with chlorotic regions on the adaxial surface. Samples were taken for ...

  12. QTL Mapping of Powdery Mildew Susceptibility in Hop (Humulus lupulus L)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hop powdery mildew is best controlled via the production of resistant varieties. Recent evidence supports selection for absence of susceptibility to fungal pathogens as a more durable resistance mechanism. The objective of this study was to identify molecular markers associated with susceptibility...

  13. Temperature regulates the initiation of cleistothecia in powdery mildew of strawberry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The formation of cleistothecia by the strawberry powdery mildew pathogen (Podosphaera aphanis) is widespread, but often sporadic throughout the range of strawberry cultivation. In some production regions, notably in warmer climates, they are reportedly rare. We confirmed that the pathogen is heterot...

  14. Taxonomic complexity of powdery mildew pathogens found on lentil and pea in the US Pacific Northwest

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Classification of powdery mildews found on lentil and pea in greenhouse and field production conditions in the US Pacific Northwest was investigated using morphological and molecular characters. Isolates collected from lentil plants grown in the greenhouse or field displayed morphologies in substant...

  15. Tolerance to powdery mildew conferred in susceptible watermelon scion by grafting on resistant rootstocks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucurbit powdery mildew (PM) caused by Podosphaera xanthii, can impact seedling growth and cause serious losses in greenhouse and open field production. We have developed several watermelon and bottle gourd germplasm lines with high levels of resistance to PM. A PM susceptible cultivar Mickey Lee ...

  16. Cucurbit powdery mildews: methodology for objective determination and denomination of races

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucurbit powdery mildew (CPM), a disease on field and greenhouse cucurbit crops worldwide, is caused most frequently by two obligate erysiphaceous ectoparasites (Golovinomyces orontii s.l., Podosphaera xanthii) that are highly variable in their pathogenicity and virulence. Various, independent syste...

  17. Specific isolation of RNA from the grape powdery mildew pathogen Erysiphe necator, an epiphytic, obligate parasite

    Technology Transfer Automated Retrieval System (TEKTRAN)

    RNA expression profiling of obligately parasitic plant microbes is hampered by the requisite interaction of host and parasite. For superficial pathogens like grape powdery mildew as well as for epiphytic saprophytes, growth along the outside surface of the plant allows separation from the host and ...

  18. Outbreak of powdery mildew on watermelon fruit caused by podosphera xanthii in southwest Florida

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew caused by the obligate parasite Podosphera xanthii occurs commonly on foliage, petioles and stems of most cucurbit vegetable crops grown in the U.S. (1). However, in the field, fruit infection on cucurbits including watermelon (Citrullus lanatus), is rarely, if ever, observed. Consequ...

  19. Genetic dissection of resistance to anthracnose and powdery mildew in Medicago truncatula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Medicago truncatula was used to characterize resistance to anthracnose and powdery mildew, respectively caused by Colletotrichum trifolii and Erysiphe pisi. Two isolates of E. pisi (Ep-p from pea and Ep-a from alfalfa) and two races of C. trifolii (races 1 and 2) were used in this study. The A17 gen...

  20. Confirming resistance in bottle gourd germplasm by quantifying powdery mildew conidia using a cellometer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew (PM) caused by Podosphaera xanthii, an important foliar disease affecting cucurbit crops grown in the United States, commonly occurs on foliage, petioles, and stems. We have developed two highly resistant bottle gourd (Lagenaria siceraria) germplasm (USVL351 and USVL482) for use in o...

  1. Transcriptomes that confer to plant defense against powdery mildew disease in Lagerstroemia indica

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The genus Lagerstroemia (common name crape myrtle) is a deciduous shrub or small tree, originaly native to southeast Asia and has became one of the most distinctive and popular summer flowering woody ornamentals anywhere south of USDA from east to west coast. Powdery mildew was one of the most serio...

  2. Mechanisms of resistance to an azole fungicide in the grapevine powdery mildew fungus, Erysiphe necator

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We studied the mechanisms of azole resistance in the grapevine powdery mildew fungus, Erysiphe necator, by quantifying the sensitivity to myclobutanil (EC50) in 65 isolates from the eastern U.S. and 12 from Chile. From each isolate, we sequenced the gene for sterol 14a-demethylase (CYP51), and measu...

  3. The perfect stage of powdery mildew of Beta vulgaris found in Michigan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew (Erysiphe polygoni [synonym E. betae]) affects several different crops in the genus Beta, including sugar beet, Swiss chard, and table beet. The disease has been prevalent in many sugar beet growing areas of the United States since the first major epidemic on beet in the United States...

  4. Tolerance to Cucurbit Powdery Mildew in USDA Bottle Gourd (Lagenaria siceraria) Plant Introductions (PI)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew (Podosphaera xanthii) can cause severe damage to cucurbit crops grown in open fields and greenhouses. Bottle gourd plants (Lagenaria siceraria) are being used throughout the world as rootstocks for grafting watermelon. In recent years, there has been a growing interest in the USA in...

  5. Golovinomyces spadaceus causing powdery mildew on Coreopsis hybrid 'Full Moon' (Heliantheae, Asteraceae) in Washington State

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Symptoms of powdery mildew were observed on a Coreopsis cultivar in the Horticulture and Landscape Architecture Garden on the Washington State University campus, Pullman, Whitman County, Washington. White to off-white sporulating mycelial areas were ~5mm in diam to confluent and confined to adaxial...

  6. Evaluation of watermelon and related species for resistance to race 1W powdery mildew resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Race 1 and race 2 powdery mildew (Podosphaera xanthii) has been reported on watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) in the United States for six years. In this study, the entire available U.S. Plant Introduction collection of Citrullus sp. was evaluated for resistance to P. xanthii r...

  7. Strategies for durable resistance to the grapevine powdery mildew fungus, Erysiphe necator

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nearly all cultivars of Vitis vinifera are highly susceptible to the grapevine powdery mildew fungus, Erysiphe necator. Grape breeders around the world are working to introgress resistance from wild Vitis. Of the widely-used introgressions, most involve dominant, race-specific resistance phenotype...

  8. VitisGenPM: a precision phenotyping center for powdery mildew resistance breeding in grapevine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Analyzing resistance to powdery mildew (Erysiphe necator) can be complicated by race specificity, environment, phenology, and other factors. Of necessity, breeding programs often rely upon natural infection in greenhouses, nurseries, and/or vineyards and use categorical ratings to assess resistance ...

  9. PROPOSED MAJOR POWDERY MILDEW GENES IN EASTERN AND SOUTHERN WHEAT GERMPLASM; IN THE PAST TEN YEARS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Resistance to powdery mildew of wheat is controlled by major genes in adult and seedling stages or quantitative resistance in the adult stage. Entries in the PM nursery from Southern and Eastern US were screened on detached seedling leaves. The observed virulence patterns were then compared to virul...

  10. Grapevine powdery mildew resistance and susceptibility loci identified on a high-resolution SNP map

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved efficacy and durability of powdery mildew resistance requires knowledge of the genetics of resistance and susceptibility and high resolution maps to facilitate combining of multiple resistance genes with desirable traits. In the current study, we studied the inheritance of resistance and s...

  11. Development of a grower performed inoculum detection assay for management of grape powdery mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of grape powdery mildew (Erysiphe necator) and other polycyclic diseases relies on calendar-based pesticide application schedules. However, these schedules may be adjusted to optimize and often reduce the number of applications by utilizing information generated from infection risk foreca...

  12. First report of powdery mildew caused by Podosphaera leucotricha on Callery pear in North America

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Podosphaera leucotricha (Ellis & Everh.) E.S. Salmon (Ascomycetes, Erysiphales) is the etiological agent of a powdery mildew disease that occurs on rosaceous plants, primarily Malus and Pyrus. This fungus is nearly circumglobal. In May 2009, leaves of Bradford pear (Pyrus calleryana Decne.), some di...

  13. Resistance to a New Race of the Cucurbit Powdery Mildew Present in Arizona and California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new strain of the powdery mildew fungus Podosphaera xanthii, designated race S, was first detected on melon (Cucumis melo L.) in the lower desert areas of Yuma, Ariz. and Imperial Valley, Calif. in 2003 when it caused economic losses in some fields. Race S overcomes resistance in 19 reported melon...

  14. Registration of ‘Wyandot-14’ soybean with resistance to soybean aphid and powdery mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    ‘Wyandot-14’ soybean [Glycine max (L.) Merr.] with resistance to soybean aphid biotypes 1 and 2 and resistance to powdery mildew was jointly released by the USDA-Agricultural Research Service and The Ohio Agricultural Research and Development Center (OARDC) as a late maturity group (MG) II (2.9) foo...

  15. Genetic mapping of the powdery mildew resistance gene in soybean PI 567301B

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew (PMD) of soybean [Glycine max (L.) Merr.] is caused by the fungus Microsphaera diffusa. Severe infection of PMD on susceptible varieties often cause premature defoliation and chlorosis of the leaves, which can result in considerable yield losses under favorable environmental condition...

  16. Differential gene expression during conidiation in the grape powdery mildew fungus, Erysiphe necator

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Asexual sporulation (conidiation) is coordinately regulated in the grape powdery mildew fungus Erysiphe necator, but nothing is known about its genetic regulation. We hypothesized that genes required for conidiation in other fungi would be up-regulated at conidiophore initiation and/or full conidia...

  17. Study on powdery mildew resistance transfer from S. cereale L.cv. Weiling rye into wheat.

    PubMed

    Zhang, Huai Yu; Ren, Zheng Long

    2007-02-01

    Weiling rye (S. cereale L.cv.), a Chinese dwarf rye, confers high powdery mildew (Erysiphe gramininis f.sp.tritici) in China. My8443, a wheat cultivars infecting seriously powdery mildew disease, was used as the female parent and Weiling rye was used as the donor of powdery mildew resistance in the study. A new wheat-rye translocation line,named No.147,was developed from BC2F6 progenies of wheat cultivars My8443 and Weiling rye to transfer the resistance from Weiling rye to common wheat. The powdery mildew resistance of No.147 and its parents were investigated in seedling and adult stages by artificially inoculating the mixture of advanced pathogenic races in room and field and the single pathogenic race in room. Improved Giemsa C-banding technique and genomic in situ hybridization (GISH,Genomic in situ hybridization) were used to identify wheat and rye chromosomes. Acid polyacylamide gel electrophoresis(APAGE) separation of endosperm gliadin and simple sequence repeat(SSR) PCR amplification of 11 SCM-Secale cereale markers also were employed for 1RS confirmation in the study. The results showed that No.147 was a new 1BL/1RS wheat-rye chromosome translocation with high powdery mildew resistance derived from Weiling rye. The reason on the formation of the new wheat-rye chromosome translocation was analyzed. The utilizations of resistance gene resource derived from Chinese Weiling rye and the new 1BL/1RS translocation line in wheat genetics and breeding improvement were discussed in the paper. PMID:17357447

  18. Confirmation of Three Quantitative Trait Loci Conferring Adult Plant Resistance to Powdery Mildew in Two Winter Wheat Populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hypersensitive, race specific genes primarily have been deployed to control powdery mildew (caused by Blumeria graminis) in wheat (Triticum aestivum); however, recent efforts have shifted to breeding for more durable resistance. Previously, three QTL for adult plant resistance (APR) to powdery milde...

  19. Knockdown of MLO genes reduces susceptibility to powdery mildew in grapevine.

    PubMed

    Pessina, Stefano; Lenzi, Luisa; Perazzolli, Michele; Campa, Manuela; Dalla Costa, Lorenza; Urso, Simona; Valè, Giampiero; Salamini, Francesco; Velasco, Riccardo; Malnoy, Mickael

    2016-01-01

    Erysiphe necator is the causal agent of powdery mildew (PM), one of the most destructive diseases of grapevine. PM is controlled by sulfur-based and synthetic fungicides, which every year are dispersed into the environment. This is why PM-resistant varieties should become a priority for sustainable grapevine and wine production. PM resistance can be achieved in other crops by knocking out susceptibility S-genes, such as those residing at genetic loci known as MLO (Mildew Locus O). All MLO S-genes of dicots belong to the phylogenetic clade V, including grapevine genes VvMLO7, 11 and 13, which are upregulated during PM infection, and VvMLO6, which is not upregulated. Before adopting a gene-editing approach to knockout candidate S-genes, the evidence that loss of function of MLO genes can reduce PM susceptibility is necessary. This paper reports the knockdown through RNA interference of VvMLO6, 7, 11 and 13. The knockdown of VvMLO6, 11 and 13 did not decrease PM severity, whereas the knockdown of VvMLO7 in combination with VvMLO6 and VvMLO11 reduced PM severity up to 77%. The knockdown of VvMLO7 and VvMLO6 seemed to be important for PM resistance, whereas a role for VvMLO11 does not seem likely. Cell wall appositions (papillae) were present in both resistant and susceptible lines in response to PM attack. Thirteen genes involved in defense were less upregulated in infected mlo plants, highlighting the early mlo-dependent disruption of PM invasion. PMID:27390621

  20. Knockdown of MLO genes reduces susceptibility to powdery mildew in grapevine

    PubMed Central

    Pessina, Stefano; Lenzi, Luisa; Perazzolli, Michele; Campa, Manuela; Dalla Costa, Lorenza; Urso, Simona; Valè, Giampiero; Salamini, Francesco; Velasco, Riccardo; Malnoy, Mickael

    2016-01-01

    Erysiphe necator is the causal agent of powdery mildew (PM), one of the most destructive diseases of grapevine. PM is controlled by sulfur-based and synthetic fungicides, which every year are dispersed into the environment. This is why PM-resistant varieties should become a priority for sustainable grapevine and wine production. PM resistance can be achieved in other crops by knocking out susceptibility S-genes, such as those residing at genetic loci known as MLO (Mildew Locus O). All MLO S-genes of dicots belong to the phylogenetic clade V, including grapevine genes VvMLO7, 11 and 13, which are upregulated during PM infection, and VvMLO6, which is not upregulated. Before adopting a gene-editing approach to knockout candidate S-genes, the evidence that loss of function of MLO genes can reduce PM susceptibility is necessary. This paper reports the knockdown through RNA interference of VvMLO6, 7, 11 and 13. The knockdown of VvMLO6, 11 and 13 did not decrease PM severity, whereas the knockdown of VvMLO7 in combination with VvMLO6 and VvMLO11 reduced PM severity up to 77%. The knockdown of VvMLO7 and VvMLO6 seemed to be important for PM resistance, whereas a role for VvMLO11 does not seem likely. Cell wall appositions (papillae) were present in both resistant and susceptible lines in response to PM attack. Thirteen genes involved in defense were less upregulated in infected mlo plants, highlighting the early mlo-dependent disruption of PM invasion. PMID:27390621

  1. Inhibition Effects of Silver Nanoparticles against Powdery Mildews on Cucumber and Pumpkin.

    PubMed

    Lamsal, Kabir; Kim, Sang-Woo; Jung, Jin Hee; Kim, Yun Seok; Kim, Kyoung Su; Lee, Youn Su

    2011-03-01

    Powdery mildew is one of the most devastating diseases in cucurbits. Crop yield can decline as the disease severity increases. In this study, we evaluated the effect of silver nanoparticles against powdery mildew under different cultivation conditions in vitro and in vivo . Silver nanoparticles (WA-CV-WA13B) at various concentrations were applied before and after disease outbreak in plants to determine antifungal activities. In the field tests, the application of 100 ppm silver nanoparticles showed the highest inhibition rate for both before and after the outbreak of disease on cucumbers and pumpkins. Also, the application of 100 ppm silver nanoparticles showed maximum inhibition for the growth of fungal hyphae and conidial germination in in vivo tests. Scanning electron microscope results indicated that the silver nanoparticles caused detrimental effects on both mycelial growth and conidial germination. PMID:22783069

  2. Hyperparasites of the genus Ampelomyces on powdery mildew fungi in Serbia.

    PubMed

    Ranković, B

    1997-01-01

    From 1982 to 1996, in Serbia, 229 species of plants infected with powdery mildew were collected. Seventy-five species had hyperparasites of the genus Ampelomyces. Distribution analysis showed that hyperparasitism was greatest on plants from the families Asteraceae, Apiaceae and Fabaceae. Ampelomyces was not found on the family Poaceae. It was reported for the first time on the families Amygdalaceae, Cornaceae, Grossulariaceae, Plantaginaceae, Rhamnaceae and other 37 plant species. Hyperparasites of the genus Ampelomyces were found on 33 different species of fungi that are causal agents of powdery mildews. They are reported for the first time on nine species. Pycnidial size varied in the range 45-106 x 25.5-40.5 microm and conidia from 4.5-10.5 x 2.5-4.8 microm. PMID:16283455

  3. Ecological basis of the interaction between Pseudozyma flocculosa and powdery mildew fungi.

    PubMed

    Hammami, Walid; Castro, Candy Quiroga; Rémus-Borel, Wilfried; Labbé, Caroline; Bélanger, Richard R

    2011-02-01

    In this work, we sought to understand how glycolipid production and the availability of nutrients could explain the ecology of Pseudozyma flocculosa and its biocontrol activity. For this purpose, we compared the development of P. flocculosa to that of a close relative, the plant pathogen Ustilago maydis, under different environmental conditions. This approach was further supported by measuring the expression of cyp1, a pivotal gene in the synthesis of unique antifungal cellobiose lipids of both fungi. On healthy cucumber and tomato plants, the expression of cyp1 remained unchanged over time in P. flocculosa and was undetected in U. maydis. At the same time, green fluorescent protein (GFP) strains of both fungi showed only limited green fluorescence on control leaves. On powdery mildew-infected cucumber leaves, P. flocculosa induced a complete collapse of the pathogen colonies, but glycolipid production, as studied by cyp1 expression, was still comparable to that of controls. In complete contrast, cyp1 was upregulated nine times when P. flocculosa was applied to Botrytis cinerea-infected leaves, but the biocontrol fungus did not develop very well on the pathogen. Analysis of the possible nutrients that could stimulate the growth of P. flocculosa on powdery mildew structures revealed that the complex Zn/Mn played a key role in the interaction. Other related fungi such as U. maydis do not appear to have the same nutritional requirements and hence lack the ability to colonize powdery mildews. Whether production of antifungal glycolipids contributes to the release of nutrients from powdery mildew colonies is unclear, but the specificity of the biocontrol activity of P. flocculosa toward Erysiphales does appear to be more complex than simple antibiosis. PMID:21115715

  4. Multiple Evolutionary Events Involved in Maintaining Homologs of Resistance to Powdery Mildew 8 in Brassica napus.

    PubMed

    Li, Qin; Li, Jing; Sun, Jin-Long; Ma, Xian-Feng; Wang, Ting-Ting; Berkey, Robert; Yang, Hui; Niu, Ying-Ze; Fan, Jing; Li, Yan; Xiao, Shunyuan; Wang, Wen-Ming

    2016-01-01

    The Resistance to Powdery Mildew 8 (RPW8) locus confers broad-spectrum resistance to powdery mildew in Arabidopsis thaliana. There are four Homologous to RPW8s (BrHRs) in Brassica rapa and three in Brassica oleracea (BoHRs). Brassica napus (Bn) is derived from diploidization of a hybrid between B. rapa and B. oleracea, thus should have seven homologs of RPW8 (BnHRs). It is unclear whether these genes are still maintained or lost in B. napus after diploidization and how they might have been evolved. Here, we reported the identification and sequence polymorphisms of BnHRs from a set of B. napus accessions. Our data indicated that while the BoHR copy from B. oleracea is highly conserved, the BrHR copy from B. rapa is relatively variable in the B. napus genome owing to multiple evolutionary events, such as gene loss, point mutation, insertion, deletion, and intragenic recombination. Given the overall high sequence homology of BnHR genes, it is not surprising that both intragenic recombination between two orthologs and two paralogs were detected in B. napus, which may explain the loss of BoHR genes in some B. napus accessions. When ectopically expressed in Arabidopsis, a C-terminally truncated version of BnHRa and BnHRb, as well as the full length BnHRd fused with YFP at their C-termini could trigger cell death in the absence of pathogens and enhanced resistance to powdery mildew disease. Moreover, subcellular localization analysis showed that both BnHRa-YFP and BnHRb-YFP were mainly localized to the extra-haustorial membrane encasing the haustorium of powdery mildew. Taken together, our data suggest that the duplicated BnHR genes might have been subjected to differential selection and at least some may play a role in defense and could serve as resistance resource in engineering disease-resistant plants. PMID:27493652

  5. Multiple Evolutionary Events Involved in Maintaining Homologs of Resistance to Powdery Mildew 8 in Brassica napus

    PubMed Central

    Li, Qin; Li, Jing; Sun, Jin-Long; Ma, Xian-Feng; Wang, Ting-Ting; Berkey, Robert; Yang, Hui; Niu, Ying-Ze; Fan, Jing; Li, Yan; Xiao, Shunyuan; Wang, Wen-Ming

    2016-01-01

    The Resistance to Powdery Mildew 8 (RPW8) locus confers broad-spectrum resistance to powdery mildew in Arabidopsis thaliana. There are four Homologous to RPW8s (BrHRs) in Brassica rapa and three in Brassica oleracea (BoHRs). Brassica napus (Bn) is derived from diploidization of a hybrid between B. rapa and B. oleracea, thus should have seven homologs of RPW8 (BnHRs). It is unclear whether these genes are still maintained or lost in B. napus after diploidization and how they might have been evolved. Here, we reported the identification and sequence polymorphisms of BnHRs from a set of B. napus accessions. Our data indicated that while the BoHR copy from B. oleracea is highly conserved, the BrHR copy from B. rapa is relatively variable in the B. napus genome owing to multiple evolutionary events, such as gene loss, point mutation, insertion, deletion, and intragenic recombination. Given the overall high sequence homology of BnHR genes, it is not surprising that both intragenic recombination between two orthologs and two paralogs were detected in B. napus, which may explain the loss of BoHR genes in some B. napus accessions. When ectopically expressed in Arabidopsis, a C-terminally truncated version of BnHRa and BnHRb, as well as the full length BnHRd fused with YFP at their C-termini could trigger cell death in the absence of pathogens and enhanced resistance to powdery mildew disease. Moreover, subcellular localization analysis showed that both BnHRa-YFP and BnHRb-YFP were mainly localized to the extra-haustorial membrane encasing the haustorium of powdery mildew. Taken together, our data suggest that the duplicated BnHR genes might have been subjected to differential selection and at least some may play a role in defense and could serve as resistance resource in engineering disease-resistant plants. PMID:27493652

  6. Development of Partial Ontogenic Resistance to Powdery Mildew in Hop Cones and Its Management Implications

    PubMed Central

    Twomey, Megan C.; Wolfenbarger, Sierra N.; Woods, Joanna L.; Gent, David H.

    2015-01-01

    Knowledge of processes leading to crop damage is central to devising rational approaches to disease management. Multiple experiments established that infection of hop cones by Podosphaera macularis was most severe if inoculation occurred within 15 to 21 days after bloom. This period of infection was associated with the most pronounced reductions in alpha acids, cone color, and accelerated maturation of cones. Susceptibility of cones to powdery mildew decreased progressively after the transition from bloom to cone development, although complete immunity to the disease failed to develop. Maturation of cone tissues was associated with multiple significant affects on the pathogen manifested as reduced germination of conidia, diminished frequency of penetration of bracts, lengthening of the latent period, and decreased sporulation. Cones challenged with P. macularis in juvenile developmental stages also led to greater frequency of colonization by a complex of saprophytic, secondary fungi. Since no developmental stage of cones was immune to powdery mildew, the incidence of powdery mildew continued to increase over time and exceeded 86% by late summer. In field experiments with a moderately susceptible cultivar, the incidence of cones with powdery mildew was statistically similar when fungicide applications were made season-long or targeted only to the juvenile stages of cone development. These studies establish that partial ontogenic resistance develops in hop cones and may influence multiple phases of the infection process and pathogen reproduction. The results further reinforce the concept that the efficacy of a fungicide program may depend largely on timing of a small number of sprays during a relatively brief period of cone development. However in practice, targeting fungicide and other management tactics to periods of enhanced juvenile susceptibility may be complicated by a high degree of asynchrony in cone development and other factors that are situation

  7. Identification of Powdery Mildew Responsive Genes in Hevea brasiliensis through mRNA Differential Display

    PubMed Central

    Li, Xiang; Bi, Zhenghong; Di, Rong; Liang, Peng; He, Qiguang; Liu, Wenbo; Miao, Weiguo; Zheng, Fucong

    2016-01-01

    Powdery mildew is an important disease of rubber trees caused by Oidium heveae B. A. Steinmann. As far as we know, none of the resistance genes related to powdery mildew have been isolated from the rubber tree. There is little information available at the molecular level regarding how a rubber tree develops defense mechanisms against this pathogen. We have studied rubber tree mRNA transcripts from the resistant RRIC52 cultivar by differential display analysis. Leaves inoculated with the spores of O. heveae were collected from 0 to 120 hpi in order to identify pathogen-regulated genes at different infection stages. We identified 78 rubber tree genes that were differentially expressed during the plant–pathogen interaction. BLAST analysis for these 78 ESTs classified them into seven functional groups: cell wall and membrane pathways, transcription factor and regulatory proteins, transporters, signal transduction, phytoalexin biosynthesis, other metabolism functions, and unknown functions. The gene expression for eight of these genes was validated by qRT-PCR in both RRIC52 and the partially susceptible Reyan 7-33-97 cultivars, revealing the similar or differential changes of gene expressions between these two cultivars. This study has improved our overall understanding of the molecular mechanisms of rubber tree resistance to powdery mildew. PMID:26840302

  8. Identification of Powdery Mildew Responsive Genes in Hevea brasiliensis through mRNA Differential Display.

    PubMed

    Li, Xiang; Bi, Zhenghong; Di, Rong; Liang, Peng; He, Qiguang; Liu, Wenbo; Miao, Weiguo; Zheng, Fucong

    2016-01-01

    Powdery mildew is an important disease of rubber trees caused by Oidium heveae B. A. Steinmann. As far as we know, none of the resistance genes related to powdery mildew have been isolated from the rubber tree. There is little information available at the molecular level regarding how a rubber tree develops defense mechanisms against this pathogen. We have studied rubber tree mRNA transcripts from the resistant RRIC52 cultivar by differential display analysis. Leaves inoculated with the spores of O. heveae were collected from 0 to 120 hpi in order to identify pathogen-regulated genes at different infection stages. We identified 78 rubber tree genes that were differentially expressed during the plant-pathogen interaction. BLAST analysis for these 78 ESTs classified them into seven functional groups: cell wall and membrane pathways, transcription factor and regulatory proteins, transporters, signal transduction, phytoalexin biosynthesis, other metabolism functions, and unknown functions. The gene expression for eight of these genes was validated by qRT-PCR in both RRIC52 and the partially susceptible Reyan 7-33-97 cultivars, revealing the similar or differential changes of gene expressions between these two cultivars. This study has improved our overall understanding of the molecular mechanisms of rubber tree resistance to powdery mildew. PMID:26840302

  9. Biocontrol agent Bacillus amyloliquefaciens LJ02 induces systemic resistance against cucurbits powdery mildew

    PubMed Central

    Li, Yunlong; Gu, Yilin; Li, Juan; Xu, Mingzhu; Wei, Qing; Wang, Yuanhong

    2015-01-01

    Powdery mildew is a fungal disease found in a wide range of plants and can significantly reduce crop yields. Bacterial strain LJ02 is a biocontrol agent (BCA) isolated from a greenhouse in Tianjin, China. In combination of morphological, physiological, biochemical and phylogenetic analyses, strain LJ02 was classified as a new member of Bacillus amyloliquefaciens. Greenhouse trials showed that LJ02 fermentation broth (LJ02FB) can effectively diminish the occurrence of cucurbits powdery mildew. When treated with LJ02FB, cucumber seedlings produced significantly elevated production of superoxide dismutase, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase as compared to that of the control. We further confirmed that the production of free salicylic acid (SA) and expression of one pathogenesis-related (PR) gene PR-1 in cucumber leaves were markedly elevated after treating with LJ02FB, suggesting that SA-mediated defense response was stimulated. Moreover, LJ02FB-treated cucumber leaves could secrete resistance-related substances into rhizosphere that inhibit the germination of fungi spores and the growth of pathogens. Finally, we separated bacterium and its fermented substances to test their respective effects and found that both components have SA-inducing activity and bacterium plays major roles. Altogether, we identified a BCA against powdery mildew and its mode of action by inducing systemic resistance such as SA signaling pathway. PMID:26379654

  10. Airborne hyperspectral imaging for the detection of powdery mildew in wheat

    NASA Astrophysics Data System (ADS)

    Franke, Jonas; Mewes, Thorsten; Menz, Gunter

    2008-08-01

    Plant stresses, in particular fungal diseases, show a high variability in spatial and temporal dimension with respect to their impact on the host. Recent "Precision Agriculture"-techniques allow for a spatially and temporally adjusted pest control that might reduce the amount of cost-intensive and ecologically harmful agrochemicals. Conventional stressdetection techniques such as random monitoring do not meet demands of such optimally placed management actions. The prerequisite is an accurate sensor-based detection of stress symptoms. The present study focuses on a remotely sensed detection of the fungal disease powdery mildew (Blumeria graminis) in wheat, Europe's main crop. In a field experiment, the potential of hyperspectral data for an early detection of stress symptoms was tested. A sophisticated endmember selection procedure was used and, additionally, a linear spectral mixture model was applied to a pixel spectrum with known characteristics, in order to derive an endmember representing 100% powdery mildew-infected wheat. Regression analyses of matched fraction estimates of this endmember and in-field-observed powdery mildew severities showed promising results (r=0.82 and r2=0.67).

  11. Effect of climate change on infection of grapevine by downy and powdery mildew under controlled environment.

    PubMed

    Pugliese, M; Gullino, M L; Garibaldi, A

    2011-01-01

    Plant responses to elevated CO2 and temperature have been much studied in recent years, but effects of climate change on pathological responses are largerly unknown. The pathosystems grapevine (Vitis vinifera) - downy mildew (Plasmopara viticola) and powdery mildew (Erysiphe necatrix) were chosen as models to assess the potential impact of increased CO2 and temperature on disease incidence and severity under controlled environment. Grapevine potted plants were grown in phytotrons under 4 different simulated climatic conditions: (1) standard temperature (ranging from 18 degrees to 22 degrees C) and standard CO2 concentration (450 ppm); (2) standard temperature and elevated CO2 concentration (800 ppm); (3) elevated temperature (ranging from 22 degrees to 26 degrees C, 4 degrees C higher than standard) and standard CO2 concentration; (4) elevated temperature and CO2 concentration. Each plant was inoculated with a spore suspension containing 5x10(5) cfu/ml. Disease index and physiological parameters (chlorophyll content, fluorescence, assimilation rate) were assessed. Results showed an increase of the chlorophyll content with higher temperatures and CO2 concentration, to which consequently corresponded an higher fluorescence index. Disease incidence of downy mildew increased when both CO2 and temperatures were higher, while an increase in CO2 did not influenced powdery mildew incidence, probably due to the increased photosynthetic activity of plants under such conditions. Considering that the rising concentrations of CO2 and other greenhouse gases will lead to an increase in global temperature and longer seasons, we can assume that this will allow more time for pathogens evolution and could increase pathogen survival, indirectly affecting downy and powdery mildews of grapevine. PMID:22702176

  12. Avirulence Genes in Cereal Powdery Mildews: The Gene-for-Gene Hypothesis 2.0

    PubMed Central

    Bourras, Salim; McNally, Kaitlin E.; Müller, Marion C.; Wicker, Thomas; Keller, Beat

    2016-01-01

    The gene-for-gene hypothesis states that for each gene controlling resistance in the host, there is a corresponding, specific gene controlling avirulence in the pathogen. Allelic series of the cereal mildew resistance genes Pm3 and Mla provide an excellent system for genetic and molecular analysis of resistance specificity. Despite this opportunity for molecular research, avirulence genes in mildews remain underexplored. Earlier work in barley powdery mildew (B.g. hordei) has shown that the reaction to some Mla resistance alleles is controlled by multiple genes. Similarly, several genes are involved in the specific interaction of wheat mildew (B.g. tritici) with the Pm3 allelic series. We found that two mildew genes control avirulence on Pm3f: one gene is involved in recognition by the resistance protein as demonstrated by functional studies in wheat and the heterologous host Nicotiana benthamiana. A second gene is a suppressor, and resistance is only observed in mildew genotypes combining the inactive suppressor and the recognized Avr. We propose that such suppressor/avirulence gene combinations provide the basis of specificity in mildews. Depending on the particular gene combinations in a mildew race, different genes will be genetically identified as the “avirulence” gene. Additionally, the observation of two LINE retrotransposon-encoded avirulence genes in B.g. hordei further suggests that the control of avirulence in mildew is more complex than a canonical gene-for-gene interaction. To fully understand the mildew–cereal interactions, more knowledge on avirulence determinants is needed and we propose ways how this can be achieved based on recent advances in the field. PMID:26973683

  13. Dynamic evolution of resistance gene analogs in the orthologous genomic regions of powdery mildew resistance gene MlIW170 in Triticum dicoccoides and Aegilops tauschii

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat is one of the most important staple grain crops in the world. Powdery mildew disease caused by Blumeria graminis f.sp. tritici can result in significant losses in both grain yield and quality in wheat. In this study, the wheat powdery mildew resistance gene MlIW170 locus located on the short ...

  14. Fine physical and genetic mapping of powdery mildew resistance gene MlIW172 originating from wild emmer(Triticum dicoccoides)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important wheat diseases in the world. In this study, a single dominant powdery mildew resistance gene MlIW172 was identified in the IW172 wild emmer accession and mapped to the distal region of chromosome arm 7AL (bin7A...

  15. Strategies for RUN1 deployment using RUN2 and REN2 to manage grapevine powdery mildew informed by studies of race-specificity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The TIR-NB-LRR gene, Resistance to Uncinula necator 1 (RUN1), from Vitis rotundifolia was recently identified and confirmed to confer resistance to the grapevine powdery mildew fungus Erysiphe necator (syn. U. necator) in transgenic Vitis vinifera cultivars. However, powdery mildew cleistothecia ha...

  16. Cytological and molecular analysis of nonhost resistance in rice to wheat powdery mildew and leaf rust pathogens.

    PubMed

    Cheng, Yulin; Yao, Juanni; Zhang, Hongchang; Huang, Lili; Kang, Zhensheng

    2015-07-01

    Cereal powdery mildews caused by Blumeria graminis and cereal rusts caused by Puccinia spp. are constant disease threats that limit the production of almost all important cereal crops. Rice is an intensively grown agricultural cereal that is atypical because of its immunity to all powdery mildew and rust fungi. We analyzed the nonhost interactions between rice and the wheat powdery mildew fungus B. graminis f. sp. tritici (Bgt) and the wheat leaf rust fungus Puccinia triticina (Ptr) to identify the basis of nonhost resistance (NHR) in rice against cereal powdery mildew and rust fungi at cytological and molecular levels. No visible symptoms were observed on rice leaves inoculated with Bgt or Ptr. Microscopic observations showed that both pathogens exhibited aberrant differentiation and significantly reduced penetration frequencies on rice compared to wheat. The development of Bgt and Ptr was also completely arrested at early infection stages in cases of successful penetration into rice leaves. Attempted infection of rice by Bgt and Ptr induced similar defense responses, including callose deposition, accumulation of reactive oxygen species, and hypersensitive response in rice epidermal and mesophyll cells, respectively. Furthermore, a set of defense-related genes were upregulated in rice against Bgt and Ptr infection. Rice is an excellent monocot model for genetic and molecular studies. Therefore, our results demonstrate that rice is a useful model to study the mechanisms of NHR to cereal powdery mildew and rust fungi, which provides useful information for the development of novel and durable strategies to control these important pathogens. PMID:25547964

  17. Simultaneous editing of three homoeoalleles in hexaploid bread wheat confers heritable resistance to powdery mildew.

    PubMed

    Wang, Yanpeng; Cheng, Xi; Shan, Qiwei; Zhang, Yi; Liu, Jinxing; Gao, Caixia; Qiu, Jin-Long

    2014-09-01

    Sequence-specific nucleases have been applied to engineer targeted modifications in polyploid genomes, but simultaneous modification of multiple homoeoalleles has not been reported. Here we use transcription activator-like effector nuclease (TALEN) and clustered, regularly interspaced, short palindromic repeats (CRISPR)-Cas9 (refs. 4,5) technologies in hexaploid bread wheat to introduce targeted mutations in the three homoeoalleles that encode MILDEW-RESISTANCE LOCUS (MLO) proteins. Genetic redundancy has prevented evaluation of whether mutation of all three MLO alleles in bread wheat might confer resistance to powdery mildew, a trait not found in natural populations. We show that TALEN-induced mutation of all three TaMLO homoeologs in the same plant confers heritable broad-spectrum resistance to powdery mildew. We further use CRISPR-Cas9 technology to generate transgenic wheat plants that carry mutations in the TaMLO-A1 allele. We also demonstrate the feasibility of engineering targeted DNA insertion in bread wheat through nonhomologous end joining of the double-strand breaks caused by TALENs. Our findings provide a methodological framework to improve polyploid crops. PMID:25038773

  18. Olfactory Cues from Plants Infected by Powdery Mildew Guide Foraging by a Mycophagous Ladybird Beetle

    PubMed Central

    Tabata, Jun; De Moraes, Consuelo M.; Mescher, Mark C.

    2011-01-01

    Powdery mildews (Erysiphales) are economically important plant pathogens that attack many agricultural crops. Conventional management strategies involving fungicide application face challenges, including the evolution of resistance and concerns over impacts on non-target organisms, that call for investigation of more sustainable alternatives. Mycophagous ladybird beetles (Coleoptera: Coccinellidae) feed on powdery mildew and have considerable potential as biological control agents; however, the foraging ecology and behavior of these beetles is not well understood. Here we document the olfactory cues presented by squash plants (Cucurbita moschata) infected by powdery mildew (Podosphaera sp.) and the behavioral responses of twenty-spotted ladybird beetles (Psyllobora vigintimaculata) to these cues. Volatile analyses through gas chromatography revealed a number of volatile compounds characteristic of infected plants, including 3-octanol and its analogues 1-octen-3-ol and 3-octanone. These compounds are typical “moldy” odorants previously reported in volatiles collected from other fungi. In addition, infected plants exhibited elevated emissions of several compounds also observed in collections from healthy leaves, including linalool and benzyl alcohol, which are reported to have anti-fungal properties. In Y-tube choice assays, P. vigintimaculata beetles displayed a significant preference for the odors of infected plants compared to those of healthy plants. Moreover, beetles exhibited strong attraction to one individual compound, 1-octen-3-ol, which was the most abundant of the characteristic fungal compounds identified. These results enhance our understanding of the olfactory cues that guide foraging by mycophagous insects and may facilitate the development of integrated disease-management strategies informed by an understanding of underlying ecological mechanisms. PMID:21876772

  19. Monitoring Powdery Mildew of Winter Wheat by Using Moderate Resolution Multi-Temporal Satellite Imagery

    PubMed Central

    Zhang, Jingcheng; Pu, Ruiliang; Yuan, Lin; Wang, Jihua; Huang, Wenjiang; Yang, Guijun

    2014-01-01

    Powdery mildew is one of the most serious diseases that have a significant impact on the production of winter wheat. As an effective alternative to traditional sampling methods, remote sensing can be a useful tool in disease detection. This study attempted to use multi-temporal moderate resolution satellite-based data of surface reflectances in blue (B), green (G), red (R) and near infrared (NIR) bands from HJ-CCD (CCD sensor on Huanjing satellite) to monitor disease at a regional scale. In a suburban area in Beijing, China, an extensive field campaign for disease intensity survey was conducted at key growth stages of winter wheat in 2010. Meanwhile, corresponding time series of HJ-CCD images were acquired over the study area. In this study, a number of single-stage and multi-stage spectral features, which were sensitive to powdery mildew, were selected by using an independent t-test. With the selected spectral features, four advanced methods: mahalanobis distance, maximum likelihood classifier, partial least square regression and mixture tuned matched filtering were tested and evaluated for their performances in disease mapping. The experimental results showed that all four algorithms could generate disease maps with a generally correct distribution pattern of powdery mildew at the grain filling stage (Zadoks 72). However, by comparing these disease maps with ground survey data (validation samples), all of the four algorithms also produced a variable degree of error in estimating the disease occurrence and severity. Further, we found that the integration of MTMF and PLSR algorithms could result in a significant accuracy improvement of identifying and determining the disease intensity (overall accuracy of 72% increased to 78% and kappa coefficient of 0.49 increased to 0.59). The experimental results also demonstrated that the multi-temporal satellite images have a great potential in crop diseases mapping at a regional scale. PMID:24691435

  20. Molecular cytogenetic identification of a novel 1AL.1RS translocation line with powdery mildew resistance.

    PubMed

    Lu, M; Wang, L; Zhang, J; Sun, S; Li, Y; Du, W; Wu, J; Zhao, J; Yang, Q; Chen, X

    2014-01-01

    A wheat germplasm line 13-2-2 with resistance to powdery mildew was isolated; this line was derived from common wheat cv. W770B and rye, Secale cereale L. (2n = 2x = 14, RR). The line was characterized based on cytological, genomic in situ hybridization (GISH), sequence-characterized amplified region (SCAR), and simple sequence repeat (SSR) analyses. The mitotic and meiotic investigations showed that the chromosome number and configuration of 13-2-2 were 2n = 42 = 21 II. GISH using rye genomic DNA as a probe detected a pair of R genome chromosome arms with strong hybridization signals in 13-2-2. Three 1RS chromosome-specific SCAR markers amplified 1RS specific bands in line 13-2-2. We screened 320 SSR primer pairs on the long or short arms from seven wheat homoeologous groups in the translocation line and parents. However, only three 1AS primers could not be amplified in line 13-2-2, whereas the others were amplified. Thus, these markers suggested that the line 13-2-2 was 1AL.1RS translocation line. Line 13-2-2 was immune to powdery mildew after inoculation with Blumeria graminis f. sp. tritici isolates E05 and E07 during the adult plant stages. In contrast, the maternal parent W770B, Kavkaz with Pm8, and Amigo with Pm17 were heavily infected with spores and had reaction response scores of susceptible. Thus, the new wheat-rye 1AL.1RS translocation line with resistance to powdery mildew could be a new and valuable donor source for wheat improvement. The molecular markers developed in this study might also be useful tools for marker-assisted selection. PMID:25526189

  1. Phylogeography and virulence structure of the powdery mildew population on its 'new' host triticale

    PubMed Central

    2012-01-01

    Background Powdery mildew, caused by the obligate biotrophic fungus Blumeria graminis, is a major problem in cereal production as it can reduce quality and yield. B. graminis has evolved eight distinct formae speciales (f.sp.) which display strict host specialization. In the last decade, powdery mildew has emerged on triticale, the artificial intergeneric hybrid between wheat and rye. This emergence is probably triggered by a host range expansion of the wheat powdery mildew B. graminis f.sp. tritici. To gain more precise information about the evolutionary processes that led to this host range expansion, we pursued a combined pathological and genetic approach. Results B. graminis isolates were sampled from triticale, wheat and rye from different breeding regions in Europe. Pathogenicity tests showed that isolates collected from triticale are highly pathogenic on most of the tested triticale cultivars. Moreover, these isolates were also able to infect several wheat cultivars (their previous hosts), although a lower aggressiveness was observed compared to isolates collected from wheat. Phylogenetic analysis of nuclear gene regions identified two statistically significant clades, which to a certain extent correlated with pathogenicity. No differences in virulence profiles were found among the sampled regions, but the distribution of genetic variation demonstrated to be geography dependent. A multilocus haplotype network showed that haplotypes pathogenic on triticale are distributed at different sites in the network, but always clustered at or near the tips of the network. Conclusions This study reveals a genetic structure in B. graminis with population differentiation according to geography and host specificity. In addition, evidence is brought forward demonstrating that the host range expansion of wheat isolates to the new host triticale occurred recently and multiple times at different locations in Europe. PMID:22658131

  2. Effect of fungicides and of biocontrol agents against powdery mildew of turnip.

    PubMed

    Gilardi, G; Gullino, M L; Garibaldi, A

    2008-01-01

    The activity of several fungicides and of two biocontrol agents, Bacillus subtilis and Ampelomyces quisqualis, alone and in combination, against Erysiphe cruciferarum, causal agent of powdery mildew, was evaluated on turnip under controlled conditions. Among the tested fungicides, quinoxyfen and azoxystrobin provided the best disease control, followed by penconazole, myclobutanil, dinocap and meptyldinocap. Sulphur provided a only partial control. The two biocontrol agents used alone provided a only partial disease control, with B. subtilis being generally more effective. The mixture B. subtilis + azoxystrobin was very effective and generally more active than the two components applied alone. The possibility of introducing biocontrol agents into IPM is discussed. PMID:19226738

  3. Characterization of polymorphic microsatellite loci for Blumeria graminis f. sp. tritici, cause of powdery mildew of wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In many wheat–growing regions of the world, powdery mildew, caused by Blumeria graminis f. sp. tritici is a major disease that results in significant yield losses. Using a microsatellite enrichment protocol, we developed primers for 10 microsatellite DNA loci to aid in studies of B. g. tritici popu...

  4. A disulphide isomerase gene (PDI-V) from Haynaldia villosa contributes to powdery mildew resistance in common wheat.

    PubMed

    Faheem, Muhammad; Li, Yingbo; Arshad, Muhammad; Jiangyue, Cheng; Jia, Zhao; Wang, Zongkuan; Xiao, Jin; Wang, Haiyan; Cao, Aizhong; Xing, Liping; Yu, Feifei; Zhang, Ruiqi; Xie, Qi; Wang, Xiue

    2016-01-01

    In this study, we report the contribution of a PDI-like gene from wheat wild relative Haynaldia villosa in combating powdery mildew. PDI-V protein contains two conserved thioredoxin (TRX) active domains (a and a') and an inactive domain (b). PDI-V interacted with E3 ligase CMPG1-V protein, which is a positive regulator of powdery mildew response. PDI-V was mono-ubiquitinated by CMPG1-V without degradation being detected. PDI-V was located on H. villosa chromosome 5V and encoded for a protein located in the endoplasmic reticulum. Bgt infection in leaves of H. villosa induced PDI-V expression. Virus induced gene silencing of PDIs in a T. durum-H. villosa amphiploid compromised the resistance. Single cell transient over-expression of PDI-V or a truncated version containing the active TXR domain a decreased the haustorial index in moderately susceptible wheat cultivar Yangmai 158. Stable transgenic lines over-expressing PDI-V in Yangmai 158 displayed improved powdery mildew resistance at both the seedling and adult stages. By contrast over-expression of point-mutated PDI-V(C57A) did not increase the level of resistance in Yangmai 158. The above results indicate a pivotal role of PDI-V in powdery mildew resistance and showed that conserved TRX domain a is critical for its function. PMID:27071705

  5. Potential Sources of Resistance to Cucurbit Powdery Mildew in US Plant Introductions (PI) of Lagenaria Siceraria (bottle gourd)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew (Podosphaera xanthii) can cause severe damage to cucurbit crops grown in open fields and greenhouses. In recent years, there has been a growing interest in the USA in grafting watermelon plants onto various cucurbit rootstocks. Bottle gourd plants (Lagenaria siceraria) are being use...

  6. Molecular and cytogenetic identification of new wheat-Dasypyrum breviaristatum additions conferring resistance to stem rust and powdery mildew.

    PubMed

    Liu, Cheng; Li, Guangrong; Yan, Hongfei; Zhou, Jianping; Hu, Lijun; Lei, Mengping; Ran, Ling; Yang, Zujun

    2011-12-01

    Two cytologically stable wheat-Dasypyrum breviarisatatum addition lines, Y93-1-6-6 and Y93-1-A6-4, were identified by integrated molecular and cytogenetic techniques. C-banding and genomic in situ hybridization (GISH) showed that Y93-1-6-6 and Y93-1-A6-4 were different wheat-D. breviaristatum additions. A total of 51 markers (primer/enzyme combinations), including 6 PCR-based Landmark Unique Gene (PLUG) markers and 45 Sequence-Tagged-Site (STS) markers, were selected from 3,774 primer/enzyme combinations to further characterize these two additions. Marker haploytpes suggested that both D. breviaristatum chromosomes in Y93-1-6-6 and Y93-1-A6-4 were rearranged. Stem rust resistance screening indicated that both additions were highly resistant to race RKQQC, whereas only Y93-1-6-6 was resistant to race TTKSK (Ug99). Powdery mildew resistance screening showed that only Y93-1-6-6 was resistant. Pedigree analysis suggested that the stem rust and powdery mildew resistance of Y93-1-6-6 was derived from D. breviaristatum, indicating that the D. breviaristatum chromosomes in Y93-1-6-6 possess a new powdery mildew resistance gene(s), and new stem rust resistance gene(s). These two additions could be used as stem rust or powdery mildew resistance sources in wheat breeding programs. PMID:23136473

  7. Potent in vivo antifungal activity against powdery mildews of pregnane glycosides from the roots of Cynanchum wilfordii.

    PubMed

    Yoon, Mi-Young; Choi, Nam Hee; Min, Byung Sun; Choi, Gyung Ja; Choi, Yong Ho; Jang, Kyoung Soo; Han, Seong-Sook; Cha, Byeongjin; Kim, Jin-Cheol

    2011-11-23

    Two new pregnane glycosides, kidjoranine 3-O-β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 4)-α-L-cymaropyranosyl-(1 → 4)-β-D-cymaropyranosyl-(1→4)-α-L-diginopyranosyl-(1 → 4)-β-D-cymaropyranoside (5) and caudatin 3-O-β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 4)-α-L-cymaropyranosyl-(1 → 4)-β-D-cymaropyranosyl-(1 → 4)-α-L-diginopyranosyl-(1 → 4)-β-D-cymaropyranoside (6), were isolated from the roots of Cynanchum wilfordii along with four known compounds (1-4). The antifungal activities of the six compounds against barley powdery mildew caused by Blumeria graminis f. sp. hordei were compared to the antifungal activity of polyoxin B. The caudatin glycosides (1, 4, and 6) showed stronger antifungal activities than polyoxin B, whereas kidjoranine glycosides (2, 3, and 5) had weaker activities than polyoxin B. A wettable powder-type formulation (C. wilfordii-WP20) of the ethyl acetate extract from C. wilfordii roots prohibited the development of barley powdery mildew much more effectively than the commercial fungicide polyoxin B-WP10. In addition, C. wilfordii-WP20 effectively controlled strawberry powdery mildew caused by Sphaerotheca humuli under greenhouse conditions. Thus, the crude extract containing the pregnane glycosides can be used as a botanical fungicide for the environmentally benign control of powdery mildews. PMID:21992072

  8. Genomic identification, phylogeny, and expression analysis of MLO genes involved in susceptibility to powdery mildew in Fragaria vesca.

    PubMed

    Miao, L X; Jiang, M; Zhang, Y C; Yang, X F; Zhang, H Q; Zhang, Z F; Wang, Y Z; Jiang, G H

    2016-01-01

    The MLO (powdery mildew locus O) gene family is important in resistance to powdery mildew (PM). In this study, all of the members of the MLO family were identified and analyzed in the strawberry (Fragaria vesca) genome. The strawberry contains at least 20 members of the MLO family, and the protein sequence contained between 171 and 1485 amino acids, with 0-34 introns. Chromosomal localization showed that the MLOs were unevenly distributed on each of the chromosomes, except for chromosome 4. The greatest number of MLOs (seven) was found on chromosome 3. A phylogenetic tree showed that the MLOs were divided into seven groups (I-VII), four of which consisted of MLOs from strawberry, Arabidopsis thaliana, rice, and maize, suggesting that these genes may have evolved after the divergence of monocots and dicots. Multiple sequence alignment showed that strawberry MLO candidates related to powdery mildew resistance possessed seven highly conserved transmembrane domains, a calmodulin-binding domain, and two conserved regions, all of which are important domains for powdery mildew resistance genes. Expressed sequence tag analysis revealed that the MLOs were induced by multiple abiotic stressors, including low and high temperature, drought, and high salinity. These findings will contribute to the functional characterization of MLOs related to PM susceptibility, and will assist in the development of disease resistance in strawberries. PMID:27525914

  9. Preliminary evaluation of resistance to powdery mildew (Podosphaera xanthii) in AVRDC collections of bitter gourd (Momordica charantia L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bitter gourd (Momordica charantia L.) is an important market vegetable in Asia, where it is also used in folk medicine to manage type 2 diabetes. Powdery mildew caused by Podosphaera xanthii is a serious fungal disease of bitter gourd and yield losses of up to 50% have been reported. After observi...

  10. Development and evaluation of detection-based air sampling programs for grapevine powdery mildew in eastern Washington

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew of winegrape (Vitis vinifera L.), caused by Erysiphe necator, is one of the most problematic diseases of grapevine worldwide. A real-time PCR assay using species-specific primers was developed for qualitative and quantitative detection of E necator in vineyard air samples collected by...

  11. A single dominant locus Ren4 confers non-race-specific penetration resistance to grapevine powdery mildew.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Most powdery mildew resistance genes act after formation of the haustorial feeding cell and secretion of effector proteins into the host epidermis, enabling some degree of hyphal growth. The few genes identified to-date that act to prevent penetration, haustorial formation, and hyphal growth are, w...

  12. A disulphide isomerase gene (PDI-V) from Haynaldia villosa contributes to powdery mildew resistance in common wheat

    PubMed Central

    Faheem, Muhammad; Li, Yingbo; Arshad, Muhammad; Jiangyue, Cheng; Jia, Zhao; Wang, Zongkuan; Xiao, Jin; Wang, Haiyan; Cao, Aizhong; Xing, Liping; Yu, Feifei; Zhang, Ruiqi; Xie, Qi; Wang, Xiue

    2016-01-01

    In this study, we report the contribution of a PDI-like gene from wheat wild relative Haynaldia villosa in combating powdery mildew. PDI-V protein contains two conserved thioredoxin (TRX) active domains (a and a′) and an inactive domain (b). PDI-V interacted with E3 ligase CMPG1-V protein, which is a positive regulator of powdery mildew response. PDI-V was mono-ubiquitinated by CMPG1-V without degradation being detected. PDI-V was located on H. villosa chromosome 5V and encoded for a protein located in the endoplasmic reticulum. Bgt infection in leaves of H. villosa induced PDI-V expression. Virus induced gene silencing of PDIs in a T. durum-H. villosa amphiploid compromised the resistance. Single cell transient over-expression of PDI-V or a truncated version containing the active TXR domain a decreased the haustorial index in moderately susceptible wheat cultivar Yangmai 158. Stable transgenic lines over-expressing PDI-V in Yangmai 158 displayed improved powdery mildew resistance at both the seedling and adult stages. By contrast over-expression of point-mutated PDI-VC57A did not increase the level of resistance in Yangmai 158. The above results indicate a pivotal role of PDI-V in powdery mildew resistance and showed that conserved TRX domain a is critical for its function. PMID:27071705

  13. Confirmation By QTL mapping Of The Malus Robusta (Cv. Robusta 5) derived powdery mildew resistance gene Pl1

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Geneva® apple rootstock breeding program has made extensive use of Malus robusta cv. Robusta 5 as a source of resistance to fire blight. Robusta 5 has also been used as the source of powdery mildew resistance by other breeding programs and a single locus Pl1 has been associated with this resist...

  14. Identification and translocation of metabolites from powdery mildew resistant rootstocks to susceptible watermelon scions using nuclear magnetic resonance spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Watermelon (Citrullus lanatus), an important commercial crop, and nutritious fruit, is high in antioxidants, vitamins, and lycopene. Powdery mildew (PM) is a serious disease caused by Podosphaera xanthii, which significantly reduces watermelon production in the U.S. and other parts of the world. C...

  15. ‘Appalachian Joy’ is a supernumery, white-bracted cultivar of cornus florida resistant to powdery mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The wholesale nursery industry in Tennessee contributes more than $200 million to the annual economy of the state and are in excess of $50 million annually for flowering dogwood (Cornus florida). Two fungal diseases, dogwood anthracnose and powdery mildew (Discula destructiva and Erysiphe pulchra, r...

  16. Genetic mapping of MlUM15: an Aegilops neglecta-derived powdery mildew resistance gene in common wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew, caused by Blumeria graminis DC f. sp. tritici, is a major fungal disease of wheat (Triticum aestivum L.) in cool and humid climates. Race-specific host plant resistance is a reliable, economical, and environmentally benign form of disease prevention. The identification of molecular m...

  17. Mapping of novel powdery mildew resistance gene Pm53 introgressed from Aegilops speltoides into soft red winter wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew of wheat (Triticum aestivum L.) is a major fungal disease in many areas of the world, caused by Blumeria graminis f.sp. tritici (Bgt). Host plant resistance is the preferred form of disease prevention because it is both economical and environmentally benign. Identification of new resi...

  18. Flor revisited (again): eQTL and mutational analysis of NB-LRR mediated immunity to powdery mildew in barley

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genes encoding early signaling events in pathogen defense often are identified only by their phenotype. Such genes involved in barley-powdery mildew interactions include Mla, specifying race-specific resistance; Rar1 (Required for Mla12-specified resistance1), and Rom1 (Restoration of Mla-specified...

  19. Distribution and characterization of Podosphaera macularis virulent on hop cultivars possessing R6-based resistance to powdery mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2012, an epidemic of powdery mildew occurred in Washington and Idaho on previously resistant cultivars whose resistance was putatively based on the gene designated R6. In 2013, isolates capable of causing severe disease on cultivars with R6-based resistance were confirmed in Oregon and became wid...

  20. First report of QoI-insensitive powdery mildew (Erysiphe polygoni) on sugarbeet in the United States

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The $2.1 billion United States sugar beet (Beta vulgaris L.) industry is the primary provider of domestic sucrose. Sugar beet powdery mildew is caused by Erysiphe polygoni DC and occurs principally in sugar beet growing regions in western United States. In these regions, the quinone outside inhibi...

  1. Progress in Breeding Powdery Mildew Resistant Table Grapes and a Brief Description of ‘Valley Pearl'

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Large quantities of fungicides are being use to control powdery mildew, which is the most important fungal disease in grape growing regions of the world. Without these fungicides, over 95% of the crop could be lost. Repeated use of sterol biosynthesis inhibitor and strobilurin-type fungicides can ...

  2. Genome dynamics and evolution of the Mla (powdery mildew) resistance locus in barley.

    PubMed

    Wei, Fusheng; Wing, Rod A; Wise, Roger P

    2002-08-01

    Genes that confer defense against pathogens often are clustered in the genome and evolve via diverse mechanisms. To evaluate the organization and content of a major defense gene complex in cereals, we determined the complete sequence of a 261-kb BAC contig from barley cv Morex that spans the Mla (powdery mildew) resistance locus. Among the 32 predicted genes on this contig, 15 are associated with plant defense responses; 6 of these are associated with defense responses to powdery mildew disease but function in different signaling pathways. The Mla region is organized as three gene-rich islands separated by two nested complexes of transposable elements and a 45-kb gene-poor region. A heterochromatic-like region is positioned directly proximal to Mla and is composed of a gene-poor core with 17 families of diverse tandem repeats that overlap a hypermethylated, but transcriptionally active, gene-dense island. Paleontology analysis of long terminal repeat retrotransposons indicates that the present Mla region evolved over a period of >7 million years through a variety of duplication, inversion, and transposon-insertion events. Sequence-based recombination estimates indicate that R genes positioned adjacent to nested long terminal repeat retrotransposons, such as Mla, do not favor recombination as a means of diversification. We present a model for the evolution of the Mla region that encompasses several emerging features of large cereal genomes. PMID:12172030

  3. Transcriptomes That Confer to Plant Defense against Powdery Mildew Disease in Lagerstroemia indica

    PubMed Central

    Wang, Xinwang; Shi, Weibing; Rinehart, Timothy

    2015-01-01

    Transcriptome analysis was conducted in two popular Lagerstroemia cultivars: “Natchez” (NAT), a white flower and powdery mildew resistant interspecific hybrid and “Carolina Beauty” (CAB), a red flower and powdery mildew susceptible L. indica cultivar. RNA-seq reads were generated from Erysiphe australiana infected leaves and de novo assembled. A total of 37,035 unigenes from 224,443 assembled contigs in both genotypes were identified. Approximately 85% of these unigenes have known function. Of them, 475 KEGG genes were found significantly different between the two genotypes. Five of the top ten differentially expressed genes (DEGs) involved in the biosynthesis of secondary metabolites (plant defense) and four in flavonoid biosynthesis pathway (antioxidant activities or flower coloration). Furthermore, 5 of the 12 assembled unigenes in benzoxazinoid biosynthesis and 7 of 11 in flavonoid biosynthesis showed higher transcript abundance in NAT. The relative abundance of transcripts for 16 candidate DEGs (9 from CAB and 7 from NAT) detected by qRT-PCR showed general agreement with the abundances of the assembled transcripts in NAT. This study provided the first transcriptome analyses in L. indica. The differential transcript abundance between two genotypes indicates that it is possible to identify candidate genes that are associated with the plant defenses or flower coloration. PMID:26247009

  4. The Barley Powdery Mildew Effector Candidates CSEP0081 and CSEP0254 Promote Fungal Infection Success.

    PubMed

    Ahmed, Ali Abdurehim; Pedersen, Carsten; Thordal-Christensen, Hans

    2016-01-01

    Effectors play significant roles in the success of pathogens. Recent advances in genome sequencing have revealed arrays of effectors and effector candidates from a wide range of plant pathogens. Yet, the vast majority of them remain uncharacterized. Among the ~500 Candidate Secreted Effector Proteins (CSEPs) predicted from the barley powdery mildew fungal genome, only a few have been studied and shown to have a function in virulence. Here, we provide evidence that CSEP0081 and CSEP0254 contribute to infection by the fungus. This was studied using Host-Induced Gene Silencing (HIGS), where independent silencing of the transcripts for these CSEPs significantly reduced the fungal penetration and haustoria formation rate. Both CSEPs are likely required during and after the formation of haustoria, in which their transcripts were found to be differentially expressed, rather than in epiphytic tissue. When expressed in barley leaf epidermal cells, both CSEPs appears to move freely between the cytosol and the nucleus, suggesting that their host targets locate in these cellular compartments. Collectively, our data suggest that, in addition to the previously reported effectors, the barley powdery mildew fungus utilizes these two CSEPs as virulence factors to enhance infection. PMID:27322386

  5. Transcriptional Reprogramming of the Mycoparasitic Fungus Ampelomyces quisqualis During the Powdery Mildew Host-Induced Germination.

    PubMed

    Siozios, Stefanos; Tosi, Lorenzo; Ferrarini, Alberto; Ferrari, Alessandro; Tononi, Paola; Bellin, Diana; Maurhofer, Monika; Gessler, Cesare; Delledonne, Massimo; Pertot, Ilaria

    2015-02-01

    Ampelomyces quisqualis is a mycoparasite of a diverse range of phytopathogenic fungi associated with the powdery mildew disease. Among them are several Erysiphaceae species with great economic impact on high-value crops such as grape. Due to its ability to parasitize and prevent the spread of powdery mildews, A. quisqualis has received considerable attention for its biocontrol potential. However, and in sharp contrast to the extensively studied biocontrol species belonging to the genus Trichoderma, little is known about the biology of A. quisqualis at the molecular and genetic levels. We present the first genome-wide transcription profiling in A. quisqualis during host-induced germination. A total of 1,536 putative genes showed significant changes in transcription during the germination of A. quisqualis. This finding denotes an extensive transcriptional reprogramming of A. quisqualis induced by the presence of the host. Several upregulated genes were predicted to encode for putative mycoparasitism-related proteins such as secreted proteases, virulence factors, and proteins related to toxin biosynthesis. Our data provide the most comprehensive sequence resource currently available for A. quisqualis in addition to offering valuable insights into the biology of A. quisqualis and its mycoparasitic lifestyle. Eventually, this may improve the biocontrol capacity of this mycoparasite. PMID:25185010

  6. Mutations in PMR5 result in powdery mildew resistance and altered cell wall composition.

    PubMed

    Vogel, John P; Raab, Theodore K; Somerville, Chris R; Somerville, Shauna C

    2004-12-01

    Powdery mildews and other obligate biotrophic pathogens are highly adapted to their hosts and often show limited host ranges. One facet of such host specialization is likely to be penetration of the host cell wall, a major barrier to infection. A mutation in the pmr5 gene rendered Arabidopsis resistant to the powdery mildew species Erysiphe cichoracearum and Erysiphe orontii, but not to the unrelated pathogens Pseudomonas syringae or Peronospora parasitica. PMR5 belongs to a large family of plant-specific genes of unknown function. pmr5-mediated resistance did not require signaling through either the salicylic acid or jasmonic acid/ethylene defense pathways, suggesting resistance in this mutant may be due either to the loss of a susceptibility factor or to the activation of a novel form of defense. Based on Fourier transform infrared analysis, the pmr5 cell walls were enriched in pectin and exhibited a reduced degree of pectin modification relative to wild-type cell walls. In addition, the mutant had smaller cells, suggesting a defect in cell expansion. A double mutant with pmr6 (defective in a glycosylphosphatidylinositol-anchored pectate lyase-like gene) exhibited a strong increase in total uronic acid content and a more severe reduction in size, relative to the single mutants, suggesting that the two genes affect pectin composition, either directly or indirectly, via different mechanisms. These two mutants highlight the importance of the host cell wall in plant-microbe interactions. PMID:15584961

  7. Interactions between the Powdery Mildew Effector BEC1054 and Barley Proteins Identify Candidate Host Targets.

    PubMed

    Pennington, Helen G; Gheorghe, Dana M; Damerum, Annabelle; Pliego, Clara; Spanu, Pietro D; Cramer, Rainer; Bindschedler, Laurence V

    2016-03-01

    There are over 500 candidate secreted effector proteins (CSEPs) or Blumeria effector candidates (BECs) specific to the barley powdery mildew pathogen Blumeria graminis f.sp. hordei. The CSEP/BEC proteins are expressed and predicted to be secreted by biotrophic feeding structures called haustoria. Eight BECs are required for the formation of functional haustoria. These include the RNase-like effector BEC1054 (synonym CSEP0064). In order to identify host proteins targeted by BEC1054, recombinant BEC1054 was expressed in E. coli, solubilized, and used in pull-down assays from barley protein extracts. Many putative interactors were identified by LC-MS/MS after subtraction of unspecific binders in negative controls. Therefore, a directed yeast-2-hybrid assay, developed to measure the effectiveness of the interactions in yeast, was used to validate putative interactors. We conclude that BEC1054 may target several host proteins, including a glutathione-S-transferase, a malate dehydrogenase, and a pathogen-related-5 protein isoform, indicating a possible role for BEC1054 in compromising well-known key players of defense and response to pathogens. In addition, BEC1054 interacts with an elongation factor 1 gamma. This study already suggests that BEC1054 plays a central role in barley powdery mildew virulence by acting at several levels. PMID:26813582

  8. [Pyramiding and marker-assisted selection for powdery mildew resistance genes in common wheat].

    PubMed

    Wang, X Y; Chen, P D; Zhang, S Z

    2001-01-01

    This project used the strategy of discarding susceptible individual plants and keeping resistance ones by resistance identification in breeding populations and planted resistant plants next in earlier generations (F1-F3), and performing marker-assisted selection combining resistance identification in later generation (F4 generation) for pyramiding powdery mildew resistance. F4 populations from crosses of elite parents possessing different Pm genes were screened by using molecular markers tightly linked to Pm2, Pm4a, Pm8 and Pm21 genes, respectively. Fourteen individual plants with Pm4a and Pm21 out of 40 F4 plants were identified. Sixteen individual plants containing Pm2 and Pm4a out of 80 F4 plants and six plants possessing Pm8 + Pm21 out of 58 F2 plants were screened. Notably, the plants with Pm2 and Pm4a showed high level resistance or immunity to powdery mildew, while plants with single Pm2 or Pm4a had lower resistance. The results suggest that the strategy of pyramiding different Pm genes provide an alternative way of utilizing resistance gene resources for breeding new types of resistance lines and cultivars, which will have significance not only in breeding practice but also in theoretical research. PMID:11480176

  9. The Barley Powdery Mildew Effector Candidates CSEP0081 and CSEP0254 Promote Fungal Infection Success

    PubMed Central

    Ahmed, Ali Abdurehim; Pedersen, Carsten

    2016-01-01

    Effectors play significant roles in the success of pathogens. Recent advances in genome sequencing have revealed arrays of effectors and effector candidates from a wide range of plant pathogens. Yet, the vast majority of them remain uncharacterized. Among the ~500 Candidate Secreted Effector Proteins (CSEPs) predicted from the barley powdery mildew fungal genome, only a few have been studied and shown to have a function in virulence. Here, we provide evidence that CSEP0081 and CSEP0254 contribute to infection by the fungus. This was studied using Host-Induced Gene Silencing (HIGS), where independent silencing of the transcripts for these CSEPs significantly reduced the fungal penetration and haustoria formation rate. Both CSEPs are likely required during and after the formation of haustoria, in which their transcripts were found to be differentially expressed, rather than in epiphytic tissue. When expressed in barley leaf epidermal cells, both CSEPs appears to move freely between the cytosol and the nucleus, suggesting that their host targets locate in these cellular compartments. Collectively, our data suggest that, in addition to the previously reported effectors, the barley powdery mildew fungus utilizes these two CSEPs as virulence factors to enhance infection. PMID:27322386

  10. Microsatellite mapping of a Triticum urartu Tum. derived powdery mildew resistance gene transferred to common wheat (Triticum aestivum L.).

    PubMed

    Qiu, Y C; Zhou, R H; Kong, X Y; Zhang, S S; Jia, J Z

    2005-11-01

    A powdery mildew resistance gene from Triticum urartu Tum. accession UR206 was successfully transferred into hexaploid wheat (Triticum aestivum L.) through crossing and backcrossing. The F1 plants, which had 28 chromosomes and an average of 5.32 bivalents and 17.36 univalents in meiotic pollen mother cells (PMC), were obtained through embryos rescued owing to shriveling of endosperm in hybrid seed of cross Chinese Spring (CS) x UR206. Hybrid seeds were produced through backcrossing F1 with common wheat parents. The derivative lines had normal chromosome numbers and powdery mildew resistance similar to the donor UR206, indicating that the powdery mildew resistance gene originating from T. urartu accession UR206 was successfully transferred and expressed in a hexaploid wheat background. Genetic analysis indicated that a single dominant gene controlled the powdery mildew resistance at the seedling stage. To map and tag the powdery mildew resistance gene, 143 F2 individuals derived from a cross UR206 x UR203 were used to construct a linkage map. The resistant gene was mapped on the chromosome 7AL based on the mapped microsatellite makers. The map spanned 52.1 cM and the order of these microsatellite loci agreed well with the established microsatellite map of chromosome arm 7AL. The resistance gene was flanked by the microsatellite loci Xwmc273 and Xpsp3003, with the genetic distances of 2.2 cM and 3.8 cM, respectively. On the basis of the origin and chromosomal location of the gene, it was temporarily designated PmU. PMID:16177900

  11. Elevated Early Callose Deposition Results in Complete Penetration Resistance to Powdery Mildew in Arabidopsis1[C][W][OA

    PubMed Central

    Ellinger, Dorothea; Naumann, Marcel; Falter, Christian; Zwikowics, Claudia; Jamrow, Torsten; Manisseri, Chithra; Somerville, Shauna C.; Voigt, Christian A.

    2013-01-01

    A common response by plants to fungal attack is deposition of callose, a (1,3)-β-glucan polymer, in the form of cell wall thickenings called papillae, at site of wall penetration. While it has been generally believed that the papillae provide a structural barrier to slow fungal penetration, this idea has been challenged in recent studies of Arabidopsis (Arabidopsis thaliana), where fungal resistance was found to be independent of callose deposition. To the contrary, we show that callose can strongly support penetration resistance when deposited in elevated amounts at early time points of infection. We generated transgenic Arabidopsis lines that express POWDERY MILDEW RESISTANT4 (PMR4), which encodes a stress-induced callose synthase, under the control of the constitutive 35S promoter. In these lines, we detected callose synthase activity that was four times higher than that in wild-type plants 6 h post inoculation with the virulent powdery mildew Golovinomyces cichoracearum. The callose synthase activity was correlated with enlarged callose deposits and the focal accumulation of green fluorescent protein-tagged PMR4 at sites of attempted fungal penetration. We observed similar results from infection studies with the nonadapted powdery mildew Blumeria graminis f. sp. hordei. Haustoria formation was prevented in resistant transgenic lines during both types of powdery mildew infection, and neither the salicylic acid-dependent nor jasmonate-dependent pathways were induced. We present a schematic model that highlights the differences in callose deposition between the resistant transgenic lines and the susceptible wild-type plants during compatible and incompatible interactions between Arabidopsis and powdery mildew. PMID:23335625

  12. Loss of Function in Mlo Orthologs Reduces Susceptibility of Pepper and Tomato to Powdery Mildew Disease Caused by Leveillula taurica

    PubMed Central

    Zheng, Zheng; Pavan, Stefano; Matsuda, Yoshinori; Toyoda, Hideyoshi; Wolters, Anne-Marie A.; Visser, Richard G. F.; Bai, Yuling

    2013-01-01

    Powdery mildew disease caused by Leveillula taurica is a serious fungal threat to greenhouse tomato and pepper production. In contrast to most powdery mildew species which are epiphytic, L. taurica is an endophytic fungus colonizing the mesophyll tissues of the leaf. In barley, Arabidopsis, tomato and pea, the correct functioning of specific homologues of the plant Mlo gene family has been found to be required for pathogenesis of epiphytic powdery mildew fungi. The aim of this study was to investigate the involvement of the Mlo genes in susceptibility to the endophytic fungus L. taurica. In tomato (Solanum lycopersicum), a loss-of-function mutation in the SlMlo1 gene results in resistance to powdery mildew disease caused by Oidium neolycopersici. When the tomato Slmlo1 mutant was inoculated with L. taurica in this study, it proved to be less susceptible compared to the control, S. lycopersicum cv. Moneymaker. Further, overexpression of SlMlo1 in the tomato Slmlo1 mutant enhanced susceptibility to L. taurica. In pepper, the CaMlo2 gene was isolated by applying a homology-based cloning approach. Compared to the previously identified CaMlo1 gene, the CaMlo2 gene is more similar to SlMlo1 as shown by phylogenetic analysis, and the expression of CaMlo2 is up-regulated at an earlier time point upon L. taurica infection. However, results of virus-induced gene silencing suggest that both CaMlo1 and CaMlo2 may be involved in the susceptibility of pepper to L. taurica. The fact that overexpression of CaMlo2 restored the susceptibility of the tomato Slmlo1 mutant to O. neolycopersici and increased its susceptibility to L. taurica confirmed the role of CaMlo2 acting as a susceptibility factor to different powdery mildews, though the role of CaMlo1 as a co-factor for susceptibility cannot be excluded. PMID:23923019

  13. MALDI-based intact spore mass spectrometry of downy and powdery mildews.

    PubMed

    Chalupová, Jana; Sedlářová, Michaela; Helmel, Michaela; Rehulka, Pavel; Marchetti-Deschmann, Martina; Allmaier, Günter; Sebela, Marek

    2012-08-01

    Fast and easy identification of fungal phytopathogens is of great importance in agriculture. In this context, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as a powerful tool for analyzing microorganisms. This study deals with a methodology for MALDI-TOF MS-based identification of downy and powdery mildews representing obligate biotrophic parasites of crop plants. Experimental approaches for the MS analyses were optimized using Bremia lactucae, cause of lettuce downy mildew, and Oidium neolycopersici, cause of tomato powdery mildew. This involved determining a suitable concentration of spores in the sample, selection of a proper MALDI matrix, looking for the optimal solvent composition, and evaluation of different sample preparation methods. Furthermore, using different MALDI target materials and surfaces (stainless steel vs polymer-based) and applying various conditions for sample exposure to the acidic MALDI matrix system were investigated. The dried droplet method involving solvent evaporation at room temperature was found to be the most suitable for the deposition of spores and MALDI matrix on the target and the subsequent crystallization. The concentration of spore suspension was optimal between 2 and 5 × 10(9) spores per ml. The best peptide/protein profiles (in terms of signal-to-noise ratio and number of peaks) were obtained by combining ferulic and sinapinic acids as a mixed MALDI matrix. A pretreatment of the spore cell wall with hydrolases was successfully introduced prior to MS measurements to obtain more pronounced signals. Finally, a novel procedure was developed for direct mass spectra acquisition from infected plant leaves. PMID:22899506

  14. Genetic modification of European winegrapes with genes from an American wild relative confers resistance to the major diseases powdery and downy mildew

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The two most economically important diseases of grapevine cultivation worldwide are caused by the fungal pathogen powdery mildew (Erysiphe necator syn. Uncinula necator) and the oomycete, downy mildew (Plasmopara viticola). These pathogens, endemic to North America, were introduced into Europe in t...

  15. PMR6, a pectate lyase-like gene required for powdery mildew susceptibility in Arabidopsis.

    PubMed

    Vogel, John P; Raab, Theodore K; Schiff, Celine; Somerville, Shauna C

    2002-09-01

    The plant genes required for the growth and reproduction of plant pathogens are largely unknown. In an effort to identify these genes, we isolated Arabidopsis mutants that do not support the normal growth of the powdery mildew pathogen Erysiphe cichoracearum. Here, we report on the cloning and characterization of one of these genes, PMR6. PMR6 encodes a pectate lyase-like protein with a novel C-terminal domain. Consistent with its predicted gene function, mutations in PMR6 alter the composition of the plant cell wall, as shown by Fourier transform infrared spectroscopy. pmr6-mediated resistance requires neither salicylic acid nor the ability to perceive jasmonic acid or ethylene, indicating that the resistance mechanism does not require the activation of well-described defense pathways. Thus, pmr6 resistance represents a novel form of disease resistance based on the loss of a gene required during a compatible interaction rather than the activation of known host defense pathways. PMID:12215508

  16. Gene action for adult-plant resistance to powdery mildew in wheat.

    PubMed

    Das, M K; Griffey, C A

    1995-04-01

    Gene action for adult-plant resistance to powdery mildew was studied using generation mean analyses of parents and of F1, F2, and backcross populations derived from a diallel cross of one susceptible and three adult-plant resistant wheat cultivars. Joint scaling tests showed that an additive-dominance model was sufficient to explain the variability in the expression of adult-plant resistance in one cross, while digenic epistasis was involved in the other five crosses. Additive gene effects were predominant; however, dominance was significant in four crosses, additive x additive interaction was significant in three crosses, additive x dominance interaction was significant in three crosses, and dominance x dominance interaction was significant in one cross. Therefore, selection for adult-plant resistance would likely be most effective in advanced generations derived from crosses among the adult-plant resistant cultivars Redcoat, Houser, and Massey. PMID:18470166

  17. QTL mapping of powdery mildew resistance in WI 2757 cucumber (Cucumis sativus L.).

    PubMed

    He, Xiaoming; Li, Yuhong; Pandey, Sudhakar; Yandell, Brain S; Pathak, Mamta; Weng, Yiqun

    2013-08-01

    Powdery mildew (PM) is a very important disease of cucumber (Cucumis sativus L.). Resistant cultivars have been deployed in production for a long time, but the genetic mechanisms of PM resistance in cucumber are not well understood. A 3-year QTL mapping study of PM resistance was conducted with 132 F2:3 families derived from two cucumber inbred lines WI 2757 (resistant) and True Lemon (susceptible). A genetic map covering 610.4 cM in seven linkage groups was developed with 240 SSR marker loci. Multiple QTL mapping analysis of molecular marker data and disease index of the hypocotyl, cotyledon and true leaf for responses to PM inoculation identified six genomic regions in four chromosomes harboring QTL for PM resistance in WI 2757. Among the six QTL, pm1.1 and pm1.2 in chromosome 1 conferred leaf resistance. Minor QTL pm3.1 (chromosome 3) and pm4.1 (chromosome 4) contributed to disease susceptibility. The two major QTL, pm5.1 and pm5.2 were located in an interval of ~40 cM in chromosome 5 with each explaining 21.0-74.5 % phenotypic variations. Data presented herein support two recessively inherited, linked major QTL in chromosome 5 plus minor QTL in other chromosomes that control the PM resistance in WI 2757. The QTL pm5.2 for hypocotyl resistance plays the most important role in host resistance. Multiple observations in the same year revealed the importance of scoring time in the detection of PM resistance QTL. Results of this study provided new insights into phenotypic and genetic mechanisms of powdery mildew resistance in cucumber. PMID:23689747

  18. Powdery Mildew Decreases the Radial Growth of Oak Trees with Cumulative and Delayed Effects over Years

    PubMed Central

    Bert, Didier; Lasnier, Jean-Baptiste; Capdevielle, Xavier; Dugravot, Aline; Desprez-Loustau, Marie-Laure

    2016-01-01

    Quercus robur and Q. petraea are major European forest tree species. They have been affected by powdery mildew caused by Erysiphe alphitoides for more than a century. This fungus is a biotrophic foliar pathogen that diverts photosynthetate from the plant for its own nutrition. We used a dendrochronological approach to investigate the effects of different levels of infection severity on the radial growth of young oak trees. Oak infection was monitored at individual tree level, at two sites in southwestern France, over a five-year period (2001–2005). Mean infection severity was almost 75% (infected leaf area) at the end of the 2001 growing season, at both sites, but only about 40% in 2002, and 8%, 5% and 2% in 2003, 2004 and 2005, respectively. Infection levels varied considerably between trees and were positively related between 2001 and 2002. Increment cores were taken from each tree to assess annual ring widths and increases in basal area. Annual radial growth was standardised to take the effect of tree size into account. Annual standardised radial growth was significantly and negatively correlated with infection severity in the same year, for both 2001 and 2002, and at both sites. The decrease in growth reached 70–90% for highly infected trees. The earlywood width was poorly correlated with infection severity, but the proportion of latewood in tree rings was lower in highly infected trees (60%) than in less heavily infected trees (85%). Infection in 2001 and 2002 was found to have a cumulative effect on radial growth in these years, together with a delayed effect detectable in 2003. Thus, even non-lethal pathogens like powdery mildew can have a significant impact on tree functioning. This impact should be taken into account in growth and yield models, to improve predictions of forest net primary production. PMID:27177029

  19. Biological control of the grapevine diseases 'grey mold' and 'powdery mildew' by Bacillus B27 and B29 strains.

    PubMed

    Maachia, Ben; Rafik, Errakhi; Chérif, M; Nandal, Preeti; Mohapatra, Trupti; Bernard, Paul

    2015-02-01

    Uncinula necator and Botrytis cinerea are the most destructive pathogens of the grapevine in Tunisia and elsewhere. We used two strains of Bacillus subtilis group, B27 and B29 to control powdery mildew and the grey mold disease of the grapevine. Green house experiments showed that B29 and B27 strains of the bacteria efficiently reduced the severity of powdery mildew up to 50% and 60%, respectively. Further, they decreased Botrytis cinerea development on grape leaf by 77% and 99%, respectively. The mode of action has been shown to be chitinolytic. These two bacteria showed significant production of total proteins discharged into the culture medium. Determination of some chitinolytic enzymes revealed the involvement of N-acetyl glucosaminidase (Nagase), the chitin-1,4-chitobiosidase (Biase) and endochitinase in degrading the mycelium of B. cinerea. PMID:25757242

  20. Allocation of the S-genome chromosomes of Aegilops variabilis Eig. carrying powdery mildew resistance in triticale (× Triticosecale Wittmack).

    PubMed

    Kwiatek, M; Belter, J; Majka, M; Wiśniewska, H

    2016-03-01

    It has been hypothesized that the powdery mildew adult plant resistance (APR) controlled by the Pm13 gene in Aegilops longissima Schweinf. & Muschl. (S(l)S(l)) has been evolutionary transferred to Aegilops variabilis Eig. (UUSS). The molecular marker analysis and the visual evaluation of powdery mildew symptoms in Ae. variabilis and the Ae. variabilis × Secale cereale amphiploid forms (2n = 6x = 42, UUSSRR) showed the presence of product that corresponded to Pm13 marker and the lower infection level compared to susceptible model, respectively. This study also describes the transfer of Ae. variabilis Eig. (2n = 4x = 28, U(v)U(v)S(v)S(v)) chromosomes, carrying powdery mildew resistance, into triticale (× Triticosecale Wittm., 2n = 6x = 42, AABBRR) using Ae. variabilis × S. cereale amphiploid forms. The individual chromosomes of Ae. variabilis, triticale 'Lamberto' and hybrids were characterized by genomic and fluorescence in situ hybridization (GISH/FISH). The chromosome configurations of obtained hybrid forms were studied at first metaphase of meiosis of pollen mother cells (PMCs) using GISH. The statistical analysis showed that the way of S-genome chromosome pairing and transmission to subsequent hybrid generations was diploid-like and had no influence on chromosome pairing of triticale chromosomes. The cytogenetic study of hybrid forms were supported by the marker-assisted selection using Pm13 marker and visual evaluation of natural infection by Blumeria graminis, that allowed to select the addition or substitution lines of hybrids carrying chromosome 3S(v) which were tolerant to the powdery mildew infection. PMID:25868512

  1. Whole Genome Re-Sequencing and Characterization of Powdery Mildew Disease-Associated Allelic Variation in Melon

    PubMed Central

    Natarajan, Sathishkumar; Kim, Hoy-Taek; Thamilarasan, Senthil Kumar; Veerappan, Karpagam; Park, Jong-In; Nou, Ill-Sup

    2016-01-01

    Powdery mildew is one of the most common fungal diseases in the world. This disease frequently affects melon (Cucumis melo L.) and other Cucurbitaceous family crops in both open field and greenhouse cultivation. One of the goals of genomics is to identify the polymorphic loci responsible for variation in phenotypic traits. In this study, powdery mildew disease assessment scores were calculated for four melon accessions, ‘SCNU1154’, ‘Edisto47’, ‘MR-1’, and ‘PMR5’. To investigate the genetic variation of these accessions, whole genome re-sequencing using the Illumina HiSeq 2000 platform was performed. A total of 754,759,704 quality-filtered reads were generated, with an average of 82.64% coverage relative to the reference genome. Comparisons of the sequences for the melon accessions revealed around 7.4 million single nucleotide polymorphisms (SNPs), 1.9 million InDels, and 182,398 putative structural variations (SVs). Functional enrichment analysis of detected variations classified them into biological process, cellular component and molecular function categories. Further, a disease-associated QTL map was constructed for 390 SNPs and 45 InDels identified as related to defense-response genes. Among them 112 SNPs and 12 InDels were observed in powdery mildew responsive chromosomes. Accordingly, this whole genome re-sequencing study identified SNPs and InDels associated with defense genes that will serve as candidate polymorphisms in the search for sources of resistance against powdery mildew disease and could accelerate marker-assisted breeding in melon. PMID:27311063

  2. Whole Genome Re-Sequencing and Characterization of Powdery Mildew Disease-Associated Allelic Variation in Melon.

    PubMed

    Natarajan, Sathishkumar; Kim, Hoy-Taek; Thamilarasan, Senthil Kumar; Veerappan, Karpagam; Park, Jong-In; Nou, Ill-Sup

    2016-01-01

    Powdery mildew is one of the most common fungal diseases in the world. This disease frequently affects melon (Cucumis melo L.) and other Cucurbitaceous family crops in both open field and greenhouse cultivation. One of the goals of genomics is to identify the polymorphic loci responsible for variation in phenotypic traits. In this study, powdery mildew disease assessment scores were calculated for four melon accessions, 'SCNU1154', 'Edisto47', 'MR-1', and 'PMR5'. To investigate the genetic variation of these accessions, whole genome re-sequencing using the Illumina HiSeq 2000 platform was performed. A total of 754,759,704 quality-filtered reads were generated, with an average of 82.64% coverage relative to the reference genome. Comparisons of the sequences for the melon accessions revealed around 7.4 million single nucleotide polymorphisms (SNPs), 1.9 million InDels, and 182,398 putative structural variations (SVs). Functional enrichment analysis of detected variations classified them into biological process, cellular component and molecular function categories. Further, a disease-associated QTL map was constructed for 390 SNPs and 45 InDels identified as related to defense-response genes. Among them 112 SNPs and 12 InDels were observed in powdery mildew responsive chromosomes. Accordingly, this whole genome re-sequencing study identified SNPs and InDels associated with defense genes that will serve as candidate polymorphisms in the search for sources of resistance against powdery mildew disease and could accelerate marker-assisted breeding in melon. PMID:27311063

  3. A complex protein derivative acts as biogenic elicitor of grapevine resistance against powdery mildew under field conditions

    PubMed Central

    Nesler, Andrea; Perazzolli, Michele; Puopolo, Gerardo; Giovannini, Oscar; Elad, Yigal; Pertot, Ilaria

    2015-01-01

    Powdery mildew caused by Erysiphe necator is one of the most important grapevine diseases in several viticulture areas, and high fungicide input is required to control it. However, numerous synthetic chemical pesticides are under scrutiny due to concerns about their impact on human health and the environment. Biopesticides, such as biogenic elicitors, are a promising alternative to chemical fungicides. Although several studies have reported on effective elicitors against grapevine diseases, their efficacy under field conditions has not been investigated extensively or has occurred at rather limited levels. Our goal was to examine the efficacy of a protein-based composition, namely nutrient broth (NB), against powdery mildew under field conditions and to characterize its mechanism of action. Weekly treatments with NB was highly effective in controlling powdery mildew on grapevine across seasons with different disease pressures. The level of disease control achieved with NB was comparable to standard fungicide treatments both on leaves and bunches across three different years. NB has no direct toxic effect on the germination of E. necator conidia, and it activates plant resistance with both systemic and translaminar effect in experiments with artificial inoculation under controlled conditions. NB induced the expression of defense-related genes in grapevine, demonstrating stimulation of plant defense mechanisms, prior to and in the early stages of pathogen infection. NB is a natural derivative from meat and yeast, substances that tend not to raise concerns about toxicological and ecotoxicological properties. NB represents a valid control tool for integrated plant protection programs against powdery mildew, to reduce the use of synthetic pesticides on grapevine. PMID:26442029

  4. Antisense expression of peach mildew resistance locus O (PpMlo1) gene confers cross-species resistance to powdery mildew in Fragaria x ananassa.

    PubMed

    Jiwan, Derick; Roalson, Eric H; Main, Dorrie; Dhingra, Amit

    2013-12-01

    Powdery mildew (PM) is one of the major plant pathogens. The conventional method of PM control includes frequent use of sulfur-based fungicides adding to production costs and potential harm to the environment. PM remains a major scourge for Rosaceae crops where breeding approaches mainly resort to gene-for-gene resistance. We have tested an alternate source of PM resistance in Rosaceae. Mildew resistance locus O (MLO) has been well studied in barley due to its role in imparting broad spectrum resistance to PM. We identified PpMlo1 (Prunus persica Mlo) in peach and characterized it further to test if a similar mechanism of resistance is conserved in Rosaceae. Due to its recalcitrance in tissue culture, reverse genetic studies involving PpMloI were not feasible in peach. Therefore, Fragaria x ananassa LF9 line, a taxonomic surrogate, was used for functional analysis of PpMlo1. Agrobacterium-mediated transformation yielded transgenic strawberry plants expressing PpMlo1 in sense and antisense orientation. Antisense expression of PpMlo1 in transgenic strawberry plants conferred resistance to Fragaria-specific powdery mildew, Podosphaera macularis. Phylogenetic analysis of 208 putative Mlo gene copies from 35 plant species suggests a large number of duplications of this gene family prior to the divergence of monocots and eudicots, early in eudicot diversification. Our results indicate that the Mlo-based resistance mechanism is functional in Rosaceae, and that Fragaria can be used as a host to test mechanistic function of genes derived from related tree species. To the best of our knowledge, this work is one of the first attempts at testing the potential of using a Mlo-based resistance strategy to combat powdery mildew in Rosaceae. PMID:23728780

  5. Mutation of the Glucosinolate Biosynthesis Enzyme Cytochrome P450 83A1 Monooxygenase Increases Camalexin Accumulation and Powdery Mildew Resistance

    PubMed Central

    Liu, Simu; Bartnikas, Lisa M.; Volko, Sigrid M.; Ausubel, Frederick M.; Tang, Dingzhong

    2016-01-01

    Small secondary metabolites, including glucosinolates and the major phytoalexin camalexin, play important roles in immunity in Arabidopsis thaliana. We isolated an Arabidopsis mutant with increased resistance to the powdery mildew fungus Golovinomyces cichoracearum and identified a mutation in the gene encoding cytochrome P450 83A1 monooxygenase (CYP83A1), which functions in glucosinolate biosynthesis. The cyp83a1-3 mutant exhibited enhanced defense responses to G. cichoracearum and double mutant analysis showed that this enhanced resistance requires NPR1, EDS1, and PAD4, but not SID2 or EDS5. In cyp83a1-3 mutants, the expression of genes related to camalexin synthesis increased upon G. cichoracearum infection. Significantly, the cyp83a1-3 mutant also accumulated higher levels of camalexin. Decreasing camalexin levels by mutation of the camalexin synthetase gene PAD3 or the camalexin synthesis regulator AtWRKY33 compromised the powdery mildew resistance in these mutants. Consistent with these observations, overexpression of PAD3 increased camalexin levels and enhanced resistance to G. cichoracearum. Taken together, our data indicate that accumulation of higher levels of camalexin contributes to increased resistance to powdery mildew. PMID:26973671

  6. Genetic basis of qualitative and quantitative resistance to powdery mildew in wheat: from consensus regions to candidate genes

    PubMed Central

    2013-01-01

    Background Powdery mildew (Blumeria graminis f. sp. tritici) is one of the most damaging diseases of wheat. The objective of this study was to identify the wheat genomic regions that are involved in the control of powdery mildew resistance through a quantitative trait loci (QTL) meta-analysis approach. This meta-analysis allows the use of collected QTL data from different published studies to obtain consensus QTL across different genetic backgrounds, thus providing a better definition of the regions responsible for the trait, and the possibility to obtain molecular markers that will be suitable for marker-assisted selection. Results Five QTL for resistance to powdery mildew were identified under field conditions in the durum-wheat segregating population Creso × Pedroso. An integrated map was developed for the projection of resistance genes/ alleles and the QTL from the present study and the literature, and to investigate their distribution in the wheat genome. Molecular markers that correspond to candidate genes for plant responses to pathogens were also projected onto the map, particularly considering NBS-LRR and receptor-like protein kinases. More than 80 independent QTL and 51 resistance genes from 62 different mapping populations were projected onto the consensus map using the Biomercator statistical software. Twenty-four MQTL that comprised 2–6 initial QTL that had widely varying confidence intervals were found on 15 chromosomes. The co-location of the resistance QTL and genes was investigated. Moreover, from analysis of the sequences of DArT markers, 28 DArT clones mapped on wheat chromosomes have been shown to be associated with the NBS-LRR genes and positioned in the same regions as the MQTL for powdery mildew resistance. Conclusions The results from the present study provide a detailed analysis of the genetic basis of resistance to powdery mildew in wheat. The study of the Creso × Pedroso durum-wheat population has revealed some QTL that had

  7. Genetic mapping of two genes conferring resistance to powdery mildew in common bean (Phaseolus vulgaris L.).

    PubMed

    Pérez-Vega, Elena; Trabanco, Noemí; Campa, Ana; Ferreira, Juan José

    2013-06-01

    Powdery mildew (PM) is a serious disease in many legume species, including the common bean (Phaseolus vulgaris L.). This study investigated the genetic control behind resistance reaction to PM in the bean genotype, Cornell 49242. The results revealed evidence supporting a qualitative mode of inheritance for resistance and the involvement of two independent genes in the resistance reaction. The location of these resistance genes was investigated in a linkage genetic map developed for the XC RIL population. Contingency tests revealed significant associations for 28 loci out of a total of 329 mapped loci. Fifteen were isolated or formed groups with less than two loci. The thirteen remaining loci were located at three regions in linkage groups Pv04, Pv09, and Pv11. The involvement of Pv09 was discarded due to the observed segregation in the subpopulation obtained from the Xana genotype for the loci located in this region. In contrast, the two subpopulations obtained from the Xana genotype for the BM161 locus, linked to the Co-3/9 anthracnose resistance gene (Pv04), and from the Xana genotype for the SCAReoli locus, linked to the Co-2 anthracnose resistance gene (Pv11), exhibited monogenic segregations, suggesting that both regions were involved in the genetic control of resistance. A genetic dissection was carried out to verify the involvement of both regions in the reaction to PM. Two resistant recombinant lines were selected, according to their genotypes, for the block of loci included in the Co-2 and Co-3/9 regions, and they were crossed with the susceptible parent, Xana. Linkage analysis in the respective F2 populations supported the hypothesis that a dominant gene (Pm1) was located in the linkage group Pv11 and another gene (Pm2) was located in the linkage group Pv04. This is the first report showing the localization of resistance genes against powdery mildew in Phaseolus vulgaris and the results offer the opportunity to increase the efficiency of breeding

  8. Detection of powdery mildew in two winter wheat plant densities and prediction of grain yield using canopy hyperspectral reflectance.

    PubMed

    Cao, Xueren; Luo, Yong; Zhou, Yilin; Fan, Jieru; Xu, Xiangming; West, Jonathan S; Duan, Xiayu; Cheng, Dengfa

    2015-01-01

    To determine the influence of plant density and powdery mildew infection of winter wheat and to predict grain yield, hyperspectral canopy reflectance of winter wheat was measured for two plant densities at Feekes growth stage (GS) 10.5.3, 10.5.4, and 11.1 in the 2009-2010 and 2010-2011 seasons. Reflectance in near infrared (NIR) regions was significantly correlated with disease index at GS 10.5.3, 10.5.4, and 11.1 at two plant densities in both seasons. For the two plant densities, the area of the red edge peak (Σdr680-760 nm), difference vegetation index (DVI), and triangular vegetation index (TVI) were significantly correlated negatively with disease index at three GSs in two seasons. Compared with other parameters Σdr680-760 nm was the most sensitive parameter for detecting powdery mildew. Linear regression models relating mildew severity to Σdr680-760 nm were constructed at three GSs in two seasons for the two plant densities, demonstrating no significant difference in the slope estimates between the two plant densities at three GSs. Σdr680-760 nm was correlated with grain yield at three GSs in two seasons. The accuracies of partial least square regression (PLSR) models were consistently higher than those of models based on Σdr680760 nm for disease index and grain yield. PLSR can, therefore, provide more accurate estimation of disease index of wheat powdery mildew and grain yield using canopy reflectance. PMID:25815468

  9. Detection of Powdery Mildew in Two Winter Wheat Plant Densities and Prediction of Grain Yield Using Canopy Hyperspectral Reflectance

    PubMed Central

    Cao, Xueren; Luo, Yong; Zhou, Yilin; Fan, Jieru; Xu, Xiangming; West, Jonathan S.; Duan, Xiayu; Cheng, Dengfa

    2015-01-01

    To determine the influence of plant density and powdery mildew infection of winter wheat and to predict grain yield, hyperspectral canopy reflectance of winter wheat was measured for two plant densities at Feekes growth stage (GS) 10.5.3, 10.5.4, and 11.1 in the 2009–2010 and 2010–2011 seasons. Reflectance in near infrared (NIR) regions was significantly correlated with disease index at GS 10.5.3, 10.5.4, and 11.1 at two plant densities in both seasons. For the two plant densities, the area of the red edge peak (Σdr680–760 nm), difference vegetation index (DVI), and triangular vegetation index (TVI) were significantly correlated negatively with disease index at three GSs in two seasons. Compared with other parameters Σdr680–760 nm was the most sensitive parameter for detecting powdery mildew. Linear regression models relating mildew severity to Σdr680–760 nm were constructed at three GSs in two seasons for the two plant densities, demonstrating no significant difference in the slope estimates between the two plant densities at three GSs. Σdr680–760 nm was correlated with grain yield at three GSs in two seasons. The accuracies of partial least square regression (PLSR) models were consistently higher than those of models based on Σdr680760 nm for disease index and grain yield. PLSR can, therefore, provide more accurate estimation of disease index of wheat powdery mildew and grain yield using canopy reflectance. PMID:25815468

  10. Tempered mlo broad-spectrum resistance to barley powdery mildew in an Ethiopian landrace

    PubMed Central

    Ge, Xintian; Deng, Weiwei; Lee, Zheng Zhou; Lopez-Ruiz, Francisco J.; Schweizer, Patrick; Ellwood, Simon R.

    2016-01-01

    Recessive mutations in the Mlo gene confer broad spectrum resistance in barley (Hordeum vulgare) to powdery mildew (Blumeria graminis f. sp. hordei), a widespread and damaging disease. However, all alleles discovered to date also display deleterious pleiotropic effects, including the naturally occurring mlo-11 mutant which is widely deployed in Europe. Recessive resistance was discovered in Eth295, an Ethiopian landrace, which was developmentally controlled and quantitative without spontaneous cell wall appositions or extensive necrosis and loss of photosynthetic tissue. This resistance is determined by two copies of the mlo-11 repeat units, that occur upstream to the wild-type Mlo gene, compared to 11–12 in commonly grown cultivars and was designated mlo-11 (cnv2). mlo-11 repeat unit copy number-dependent DNA methylation corresponded with cytological and macroscopic phenotypic differences between copy number variants. Sequence data indicated mlo-11 (cnv2) formed via recombination between progenitor mlo-11 repeat units and the 3′ end of an adjacent stowaway MITE containing region. mlo-11 (cnv2) is the only example of a moderated mlo variant discovered to date and may have arisen by natural selection against the deleterious effects of the progenitor mlo-11 repeat unit configuration. PMID:27404990

  11. Conidial germination, infection structure formation, and early colony development of powdery mildew on poinsettia.

    PubMed

    Celio, G J; Hausbeck, M K

    1998-02-01

    ABSTRACT Powdery mildew disease on poinsettias (Euphorbia pulcherrima) growing in commercial greenhouses was first observed in the United States in 1990 and has become an economically significant problem for poinsettia growers in the Midwest and northern United States since 1992. The temporal development of infection structures produced by conidial germ tubes of the pathogen (Oidium sp.) and the effect of high temperature on their development were investigated using poinsettia leaf disks placed in humidity chambers. Observations were made using light microscopy and scanning electron microscopy. At 20 degrees C (85% relative humidity), conidia germinated and formed an appressorium within 6 h of inoculation. Germination over time followed a monomolecular curve (r(2) = 0.77, P

  12. Tempered mlo broad-spectrum resistance to barley powdery mildew in an Ethiopian landrace.

    PubMed

    Ge, Xintian; Deng, Weiwei; Lee, Zheng Zhou; Lopez-Ruiz, Francisco J; Schweizer, Patrick; Ellwood, Simon R

    2016-01-01

    Recessive mutations in the Mlo gene confer broad spectrum resistance in barley (Hordeum vulgare) to powdery mildew (Blumeria graminis f. sp. hordei), a widespread and damaging disease. However, all alleles discovered to date also display deleterious pleiotropic effects, including the naturally occurring mlo-11 mutant which is widely deployed in Europe. Recessive resistance was discovered in Eth295, an Ethiopian landrace, which was developmentally controlled and quantitative without spontaneous cell wall appositions or extensive necrosis and loss of photosynthetic tissue. This resistance is determined by two copies of the mlo-11 repeat units, that occur upstream to the wild-type Mlo gene, compared to 11-12 in commonly grown cultivars and was designated mlo-11 (cnv2). mlo-11 repeat unit copy number-dependent DNA methylation corresponded with cytological and macroscopic phenotypic differences between copy number variants. Sequence data indicated mlo-11 (cnv2) formed via recombination between progenitor mlo-11 repeat units and the 3' end of an adjacent stowaway MITE containing region. mlo-11 (cnv2) is the only example of a moderated mlo variant discovered to date and may have arisen by natural selection against the deleterious effects of the progenitor mlo-11 repeat unit configuration. PMID:27404990

  13. Transcriptomic analysis reveals distinct resistant response by physcion and chrysophanol against cucumber powdery mildew.

    PubMed

    Li, Yanping; Tian, Shilin; Yang, Xiaojun; Wang, Xin; Guo, Yuhai; Ni, Hanwen

    2016-01-01

    Physcion and chrysophanol induce defense responses against powdery mildew in cucumbers. The combination of these two compounds has synergistic interaction against the disease. We performed RNA-seq on cucumber leaf samples treated with physcion and chrysophanol alone and with their combination. We generated 17.6 Gb of high-quality sequencing data (∼2 Gb per sample) and catalogued the expressions profiles of 12,293 annotated cucumber genes in each sample. We identified numerous differentially expressed genes that exhibited distinct expression patterns among the three treatments. The gene expression patterns of the Chr and Phy treatments were more similar to each other than to the Phy × Chr treatment. The Phy × Chr treatment induced the highest number of differentially expressed genes. This dramatic transcriptional change after Phy × Chr treatment leaves reflects that physcion combined with chrysophanol treatment was most closely associated with induction of disease resistance. The analysis showed that the combination treatment caused expression changes of numerous defense-related genes. These genes have known or potential roles in structural, chemical and signaling defense responses and were enriched in functional gene categories potentially responsible for cucumber resistance. These results clearly demonstrated that disease resistance in cucumber leaves was significantly influenced by the combined physcion and chrysophanol treatment. Thus, physcion and chrysophanol are appealing candidates for further investigation of the gene expression and associated regulatory mechanisms related to the defense response. PMID:27231648

  14. Prediction Model for Predicting Powdery Mildew using ANN for Medicinal Plant—Picrorhiza kurrooa

    NASA Astrophysics Data System (ADS)

    Shivling, V. D.; Ghanshyam, C.; Kumar, Rakesh; Kumar, Sanjay; Sharma, Radhika; Kumar, Dinesh; Sharma, Atul; Sharma, Sudhir Kumar

    2016-06-01

    Plant disease fore casting system is an important system as it can be used for prediction of disease, further it can be used as an alert system to warn the farmers in advance so as to protect their crop from being getting infected. Fore casting system will predict the risk of infection for crop by using the environmental factors that favor in germination of disease. In this study an artificial neural network based system for predicting the risk of powdery mildew in Picrorhiza kurrooa was developed. For development, Levenberg-Marquardt backpropagation algorithm was used having a single hidden layer of ten nodes. Temperature and duration of wetness are the major environmental factors that favor infection. Experimental data was used as a training set and some percentage of data was used for testing and validation. The performance of the system was measured in the form of the coefficient of correlation (R), coefficient of determination (R2), mean square error and root mean square error. For simulating the network an inter face was developed. Using this interface the network was simulated by putting temperature and wetness duration so as to predict the level of risk at that particular value of the input data.

  15. Transcriptomic analysis reveals distinct resistant response by physcion and chrysophanol against cucumber powdery mildew

    PubMed Central

    Li, Yanping; Tian, Shilin; Yang, Xiaojun; Wang, Xin; Guo, Yuhai

    2016-01-01

    Physcion and chrysophanol induce defense responses against powdery mildew in cucumbers. The combination of these two compounds has synergistic interaction against the disease. We performed RNA-seq on cucumber leaf samples treated with physcion and chrysophanol alone and with their combination. We generated 17.6 Gb of high-quality sequencing data (∼2 Gb per sample) and catalogued the expressions profiles of 12,293 annotated cucumber genes in each sample. We identified numerous differentially expressed genes that exhibited distinct expression patterns among the three treatments. The gene expression patterns of the Chr and Phy treatments were more similar to each other than to the Phy × Chr treatment. The Phy × Chr treatment induced the highest number of differentially expressed genes. This dramatic transcriptional change after Phy × Chr treatment leaves reflects that physcion combined with chrysophanol treatment was most closely associated with induction of disease resistance. The analysis showed that the combination treatment caused expression changes of numerous defense-related genes. These genes have known or potential roles in structural, chemical and signaling defense responses and were enriched in functional gene categories potentially responsible for cucumber resistance. These results clearly demonstrated that disease resistance in cucumber leaves was significantly influenced by the combined physcion and chrysophanol treatment. Thus, physcion and chrysophanol are appealing candidates for further investigation of the gene expression and associated regulatory mechanisms related to the defense response. PMID:27231648

  16. Allele Mining in Barley Genetic Resources Reveals Genes of Race-Non-Specific Powdery Mildew Resistance

    PubMed Central

    Spies, Annika; Korzun, Viktor; Bayles, Rosemary; Rajaraman, Jeyaraman; Himmelbach, Axel; Hedley, Pete E.; Schweizer, Patrick

    2012-01-01

    Race-non-specific, or quantitative, pathogen resistance is of high importance to plant breeders due to its expected durability. However, it is usually controlled by multiple quantitative trait loci (QTL) and therefore difficult to handle in practice. Knowing the genes that underlie race-non-specific resistance (NR) would allow its exploitation in a more targeted manner. Here, we performed an association-genetic study in a customized worldwide collection of spring barley accessions for candidate genes of race-NR to the powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) and combined data with results from QTL mapping as well as functional-genomics approaches. This led to the identification of 11 associated genes with converging evidence for an important role in race-NR in the presence of the Mlo gene for basal susceptibility. Outstanding in this respect was the gene encoding the transcription factor WRKY2. The results suggest that unlocking plant genetic resources and integrating functional-genomic with genetic approaches can accelerate the discovery of genes underlying race-NR in barley and other crop plants. PMID:22629270

  17. Inheritance of Resistance to Powdery Mildew Race 1W in Watermelon.

    PubMed

    Ben-Naim, Yariv; Cohen, Yigal

    2015-11-01

    Powdery mildew caused by Podosphaera xanthii is a major disease of watermelon in Israel. In this study, 291 accessions of Citrullus spp. were evaluated for resistance against P. xanthii race 1W. Only eight accessions exhibited high level of resistance. Inheritance of resistance against P. xanthii race 1W was studied by crossing three resistant accession of Citrullus lanatus var. citroides BIU 119, PI 189225, or PI 482312 with the susceptible cultivar 'Malali' or 'Sugar Baby'. Parents, F1, F2, and back cross progenies were evaluated for resistance in growth chambers at the cotyledon stage and the 4-leaf stage and in the field, at the 15-leaf stage. Resistance at the cotyledon stage was controlled by a single, partially dominant gene, whereas at the 4-leaf stage or the 15-leaf stage resistance was controlled by three complimentary, partially dominant genes. Crosses made among these resistant accessions revealed that BIU 119 and PI 189225 carry the same genes for resistance, whereas PI 482312 shares two out of three genes with both BIU 119 and PI 189225. A breeding line with high resistance level and good fruit qualities was developed from BIU 119 × HA5500. PMID:26267543

  18. No indication of strict host associations in a widespread mycoparasite: grapevine powdery mildew (Erysiphe necator) is attacked by phylogenetically distant Ampelomyces strains in the field.

    PubMed

    Pintye, Alexandra; Bereczky, Zsolt; Kovács, Gábor M; Nagy, László G; Xu, Xiangming; Legler, Sara Elisabetta; Váczy, Zsuzsanna; Váczy, Kálmán Zoltán; Caffi, Tito; Rossi, Vittorio; Kiss, Levente

    2012-07-01

    Pycnidial fungi belonging to the genus Ampelomyces are common intracellular mycoparasites of powdery mildews worldwide. Some strains have already been developed as commercial biocontrol agents (BCAs) of Erysiphe necator and other powdery mildew species infecting important crops. One of the basic, and still debated, questions concerning the tritrophic relationships between host plants, powdery mildew fungi, and Ampelomyces mycoparasites is whether Ampelomyces strains isolated from certain species of the Erysiphales are narrowly specialized to their original mycohosts or are generalist mycoparasites of many powdery mildew fungi. This is also important for the use of Ampelomyces strains as BCAs. To understand this relationship, the nuclear ribosomal DNA internal transcribed spacer (ITS) and partial actin gene (act1) sequences of 55 Ampelomyces strains from E. necator were analyzed together with those of 47 strains isolated from other powdery mildew species. These phylogenetic analyses distinguished five major clades and strains from E. necator that were present in all but one clade. This work was supplemented with the selection of nine inter-simple sequence repeat (ISSR) markers for strain-specific identification of Ampelomyces mycoparasites to monitor the environmental fate of strains applied as BCAs. The genetic distances among strains calculated based on ISSR patterns have also highlighted the genetic diversity of Ampelomyces mycoparasites naturally occurring in grapevine powdery mildew. Overall, this work showed that Ampelomyces strains isolated from E. necator are genetically diverse and there is no indication of strict mycohost associations in these strains. However, these results cannot rule out a certain degree of quantitative association between at least some of the Ampelomyces lineages identified in this work and their original mycohosts. PMID:22512466

  19. Ampelomyces mycoparasites from apple powdery mildew identified as a distinct group based on single-stranded conformation polymorphism analysis of the rDNA ITS region.

    PubMed

    Szentiványi, Orsolya; Kiss, Levente; Russell, John C; Kovács, Gábor M; Varga, Krisztina; Jankovics, Tünde; Lesemann, Silke; Xu, Xiang-Ming; Jeffries, Peter

    2005-04-01

    Pycnidial fungi belonging to the genus Ampelomyces are the most common natural antagonists of powdery mildews worldwide. During a study of the interactions between apple powdery mildew (Podosphaera leucotricha) and Ampelomyces mycoparasites, 52 new Ampelomyces isolates were obtained from P. leucotricha and, in addition, 13 new isolates from other species of the Erysiphaceae in four European countries. Their genetic diversity was screened using single-stranded conformation polymorphism (SSCP) analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA). For comparison, 24 isolates obtained from genetic resource collections or other sources were included in this study. Based on the ITS-SSCP patterns, the isolates were placed in eight groups. The isolates belonged to two types based on their growth in culture. The faster-growing and the slower-growing isolates were included in different SSCP groups. A phylogenetic analysis of the ITS sequences of representatives of these groups confirmed the results obtained with the SSCP method, and showed that the faster-growing isolates do not belong to Ampelomyces as suggested by earlier studies. All the isolates from P. leucotricha fell into a distinct SSCP group of genetically homogeneous isolates. This suggests that Ampelomyces mycoparasites which occur in apple powdery mildew are slightly different from the other Ampelomyces groups which contain mycoparasites from various powdery mildew species. This may be because the main growth period of Ampelomyces mycoparasites in apple powdery mildew is isolated in time from that of Ampelomyces isolates that occur in other species of the Erysiphaceae. P. leucotricha starts its life-cycle early in the season, usually in March-April, while most powdery mildews are active in the same environments only late in the year. PMID:15912930

  20. Molecular Cytogenetic Identification of a New Wheat-Rye 6R Chromosome Disomic Addition Line with Powdery Mildew Resistance

    PubMed Central

    An, Diaoguo; Zheng, Qi; Luo, Qiaoling; Ma, Pengtao; Zhang, Hongxia; Li, Lihui; Han, Fangpu; Xu, Hongxing; Xu, Yunfeng; Zhang, Xiaotian; Zhou, Yilin

    2015-01-01

    Rye (Secale cereale L.) possesses many valuable genes that can be used for improving disease resistance, yield and environment adaptation of wheat (Triticum aestivum L.). However, the documented resistance stocks derived from rye is faced severe challenge due to the variation of virulent isolates in the pathogen populations. Therefore, it is necessary to develop desirable germplasm and search for novel resistance gene sources against constantly accumulated variation of the virulent isolates. In the present study, a new wheat-rye line designated as WR49-1 was produced through distant hybridization and chromosome engineering protocols between common wheat cultivar Xiaoyan 6 and rye cultivar German White. Using sequential GISH (genomic in situ hybridization), mc-FISH (multicolor fluorescence in situ hybridization), mc-GISH (multicolor GISH) and EST (expressed sequence tag)-based marker analysis, WR49-1 was proved to be a new wheat-rye 6R disomic addition line. As expected, WR49-1 showed high levels of resistance to wheat powdery mildew (Blumeria graminis f. sp. tritici, Bgt) pathogens prevalent in China at the adult growth stage and 19 of 23 Bgt isolates tested at the seedling stage. According to its reaction pattern to different Bgt isolates, WR49-1 may possess new resistance gene(s) for powdery mildew, which differed from the documented powdery mildew gene, including Pm20 on chromosome arm 6RL of rye. Additionally, WR49-1 was cytologically stable, had improved agronomic characteristics and therefore could serve as an important bridge for wheat breeding and chromosome engineering. PMID:26237413

  1. Mapping of Powdery Mildew Resistance Gene pmCH89 in a Putative Wheat-Thinopyrum intermedium Introgression Line

    PubMed Central

    Hou, Liyuan; Zhang, Xiaojun; Li, Xin; Jia, Juqing; Yang, Huizhen; Zhan, Haixian; Qiao, Linyi; Guo, Huijuan; Chang, Zhijian

    2015-01-01

    Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a globally serious disease adversely affecting wheat production. The Bgt-resistant wheat breeding line CH09W89 was derived after backcrossing a Bgt resistant wheat-Thinopyrum intermedium partial amphiploid TAI7045 with susceptible wheat cultivars. At the seedling stage, CH09W89 exhibited immunity or high resistance to Bgt pathotypes E09, E20, E21, E23, E26, Bg1, and Bg2, similar to its donor line TAI7045 and Th. intermedium. No Th. intermedium chromatin was detected based on genomic in situ hybridization of mitotic chromosomes. To determine the mode of inheritance of the Bgt resistance and the chromosomal location of the resistance gene, CH09W89 was crossed with two susceptible wheat cultivars. The results of the genetic analysis showed that the adult resistance to Bgt E09 in CH09W89 was controlled by a single recessive gene, which was tentatively designated as pmCH89. Two polymorphic SSR markers, Xwmc310 and Xwmc125, were linked to the resistance gene with genetic distances 3.1 and 2.7 cM, respectively. Using the Chinese Spring aneuploid and deletion lines, the resistance gene and its linked markers were assigned to chromosome arm 4BL in the bin 0.68–0.78. Due to its unique position on chromosome 4BL, pmCH89 appears to be a new locus for resistance to powdery mildew. These results will be of benefit for improving powdery mildew resistance in wheat breeding programs. PMID:26225967

  2. Molecular Cytogenetic Identification of a New Wheat-Rye 6R Chromosome Disomic Addition Line with Powdery Mildew Resistance.

    PubMed

    An, Diaoguo; Zheng, Qi; Luo, Qiaoling; Ma, Pengtao; Zhang, Hongxia; Li, Lihui; Han, Fangpu; Xu, Hongxing; Xu, Yunfeng; Zhang, Xiaotian; Zhou, Yilin

    2015-01-01

    Rye (Secale cereale L.) possesses many valuable genes that can be used for improving disease resistance, yield and environment adaptation of wheat (Triticum aestivum L.). However, the documented resistance stocks derived from rye is faced severe challenge due to the variation of virulent isolates in the pathogen populations. Therefore, it is necessary to develop desirable germplasm and search for novel resistance gene sources against constantly accumulated variation of the virulent isolates. In the present study, a new wheat-rye line designated as WR49-1 was produced through distant hybridization and chromosome engineering protocols between common wheat cultivar Xiaoyan 6 and rye cultivar German White. Using sequential GISH (genomic in situ hybridization), mc-FISH (multicolor fluorescence in situ hybridization), mc-GISH (multicolor GISH) and EST (expressed sequence tag)-based marker analysis, WR49-1 was proved to be a new wheat-rye 6R disomic addition line. As expected, WR49-1 showed high levels of resistance to wheat powdery mildew (Blumeria graminis f. sp. tritici, Bgt) pathogens prevalent in China at the adult growth stage and 19 of 23 Bgt isolates tested at the seedling stage. According to its reaction pattern to different Bgt isolates, WR49-1 may possess new resistance gene(s) for powdery mildew, which differed from the documented powdery mildew gene, including Pm20 on chromosome arm 6RL of rye. Additionally, WR49-1 was cytologically stable, had improved agronomic characteristics and therefore could serve as an important bridge for wheat breeding and chromosome engineering. PMID:26237413

  3. Arabidopsis Phospholipase Dδ Is Involved in Basal Defense and Nonhost Resistance to Powdery Mildew Fungi1[W

    PubMed Central

    Pinosa, Francesco; Buhot, Nathalie; Kwaaitaal, Mark; Fahlberg, Per; Thordal-Christensen, Hans; Ellerström, Mats; Andersson, Mats X.

    2013-01-01

    Plants have evolved a complex array of defensive responses against pathogenic microorganisms. Recognition of microbes initiates signaling cascades that activate plant defenses. The membrane lipid phosphatidic acid, produced by phospholipase D (PLD), has been shown to take part in both abiotic and biotic stress signaling. In this study, the involvement of PLD in the interaction between Arabidopsis (Arabidopsis thaliana) and the barley powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) was investigated. This nonadapted pathogen is normally resisted by a cell wall-based defense, which stops the fungal hyphae from penetrating the epidermal cell wall. Chemical inhibition of phosphatidic acid production by PLD increased the penetration rate of Bgh spores on wild-type leaves. The analysis of transfer DNA knockout lines for all Arabidopsis PLD genes revealed that PLDδ is involved in penetration resistance against Bgh, and chemical inhibition of PLDs in plants mutated in PLDδ indicated that this isoform alone is involved in Bgh resistance. In addition, we confirmed the involvement of PLDδ in penetration resistance against another nonadapted pea powdery mildew fungus, Erysiphe pisi. A green fluorescent protein fusion of PLDδ localized to the plasma membrane at the Bgh attack site, where it surrounded the cell wall reinforcement. Furthermore, in the pldδ mutant, transcriptional up-regulation of early microbe-associated molecular pattern response genes was delayed after chitin stimulation. In conclusion, we propose that PLD is involved in defense signaling in nonhost resistance against powdery mildew fungi and put PLDδ forward as the main isoform participating in this process. PMID:23979971

  4. Characterization of a New Pm2 Allele Conferring Powdery Mildew Resistance in the Wheat Germplasm Line FG-1

    PubMed Central

    Ma, Pengtao; Xu, Hongxng; Li, Lihui; Zhang, Hongxia; Han, Guohao; Xu, Yunfeng; Fu, Xiaoyi; Zhang, Xiaotian; An, Diaoguo

    2016-01-01

    Powdery mildew has a negative impact on wheat production. Novel host resistance increases the diversity of resistance genes and helps to control the disease. In this study, wheat line FG-1 imported from France showed a high level of powdery mildew resistance at both the seedling and adult stages. An F2 population and F2:3 families from the cross FG-1 × Mingxian 169 both fit Mendelian ratios for a single dominant resistance gene when tested against multiple avirulent Blumeria tritici f. sp. tritici (Bgt) races. This gene was temporarily designated PmFG. PmFG was mapped on the multi-allelic Pm2 locus of chromosome 5DS using seven SSR, 10 single nucleotide polymorphism (SNP)-derived and two SCAR markers with the flanking markers Xbwm21/Xcfd81/Xscar112 (distal) and Xbwm25 (proximal) at 0.3 and 0.5 cM being the closest. Marker SCAR203 co-segregated with PmFG. Allelism tests between PmFG and documented Pm2 alleles confirmed that PmFG was allelic with Pm2. Line FG-1 produced a significantly different reaction pattern compared to other lines with genes at or near Pm2 when tested against 49 Bgt isolates. The PmFG-linked marker alleles detected by the SNP-derived markers revealed significant variation between FG-1 and other lines with genes at or near Pm2. It was concluded that PmFG is a new allele at the Pm2 locus. Data from seven closely linked markers tested on 31 wheat cultivars indicated opportunities for marker-assisted pyramiding of this gene with other genes for powdery mildew resistance and additional traits. PMID:27200022

  5. Genetic analysis of the T. aestivum/Ae. sharonensis introgressive lines of common wheat for resistance to powdery mildew.

    PubMed

    Vdovychenko, Zh V; Antonyuk, M Z; Ternovskaya, T K

    2005-01-01

    Results of investigation of peculiarities of common wheat hybridological analysis for a discrete character, resistance for powdery mildew, governed by the alien gene from Ae. sharonensis are present. Relation between genome structure of crossed introgressive lines and deviation of empirical ratios of segregation in F2 from theoretical, based on the assumption about monogenic inheritance of considered character is established. The approach to the quantitative count of influence of such connection on distortion of actual segregation in comparison with theoretically expected ratio is developed. PMID:16250248

  6. Systemic Resistance to Powdery Mildew in Brassica napus (AACC) and Raphanus alboglabra (RRCC) by Trichoderma harzianum TH12

    PubMed Central

    Alkooranee, Jawadayn Talib; Yin, Yongtai; Aledan, Tamarah Raad; Jiang, Yingfen; Lu, Guangyuan; Wu, Jiangsheng; Li, Maoteng

    2015-01-01

    Trichoderma harzianum TH12 is a microbial pesticide for certain rapeseed diseases. The mechanism of systemic resistance induced by TH12 or its cell-free culture filtrate (CF) in Brassica napus (AACC) and Raphanus alboglabra (RRCC) to powdery mildew disease caused by ascomycete Erysiphe cruciferarum was investigated. In this study, we conducted the first large-scale global study on the cellular and molecular aspects of B. napus and R. alboglabra infected with E. cruciferarum. The histological study showed the resistance of R. alboglabra to powdery mildew disease. The growth of fungal colonies was not observed on R. alboglabra leaves at 1, 2, 4, 6, 8, and 10 days post-inoculation (dpi), whereas this was clearly observed on B. napus leaves after 6 dpi. In addition, the gene expression of six plant defense-related genes, namely, PR-1, PR-2 (a marker for SA signaling), PR-3, PDF 1.2 (a marker for JA/ET signaling), CHI620, and CHI570, for both genotypes were analyzed in the leaves of B. napus and R. alboglabra after treatment with TH12 or CF and compared with the non-treated ones. The qRT-PCR results showed that the PR-1 and PR-2 expression levels increased in E. cruciferarum-infected leaves, but decreased in the TH12-treated leaves compared with leaves treated with CF. The expression levels of PR-3 and PDF1.2 decreased in plants infected by E. cruciferarum. However, expression levels increased when the leaves were treated with TH12. For the first time, we disclosed the nature of gene expression in B. napus and R. alboglabra to explore the resistance pathways in the leaves of both genotypes infected and non-infected by powdery mildew and inoculated or non-inoculated with elicitor factors. Results suggested that R. alboglabra exhibited resistance to powdery mildew disease, and the application of T. harzianum and its CF are a useful tool to facilitate new protection methods for resist or susceptible plants. PMID:26540161

  7. Comparative transcriptomics of Central Asian Vitis vinifera accessions reveals distinct defense strategies against powdery mildew

    PubMed Central

    Amrine, Katherine C H; Blanco-Ulate, Barbara; Riaz, Summaira; Pap, Dániel; Jones, Laura; Figueroa-Balderas, Rosa; Walker, M Andrew; Cantu, Dario

    2015-01-01

    Grape powdery mildew (PM), caused by the biotrophic ascomycete Erysiphe necator, is a devastating fungal disease that affects most Vitis vinifera cultivars. We have previously identified a panel of V. vinifera accessions from Central Asia with partial resistance to PM that possess a Ren1-like local haplotype. In this study, we show that in addition to the typical Ren1-associated late post-penetration resistance, these accessions display a range of different levels of disease development suggesting that alternative alleles or additional genes contribute to determining the outcome of the interaction with the pathogen. To identify potential Ren1-dependent transcriptional responses and functions associated with the different levels of resistance, we sequenced and analyzed the transcriptomes of these Central Asian accessions at two time points of PM infection. Transcriptomes were compared to identify constitutive differences and PM-inducible responses that may underlie their disease resistant phenotype. Responses to E. necator in all resistant accessions were characterized by an early up-regulation of 13 genes, most encoding putative defense functions, and a late down-regulation of 32 genes, enriched in transcriptional regulators and protein kinases. Potential Ren1-dependent responses included a hotspot of co-regulated genes on chromosome 18. We also identified 81 genes whose expression levels and dynamics correlated with the phenotypic differences between the most resistant accessions ‘Karadzhandahal’, DVIT3351.27, and O34-16 and the other genotypes. This study provides a first exploration of the functions associated with varying levels of partial resistance to PM in V. vinifera accessions that can be exploited as sources of genetic resistance in grape breeding programs. PMID:26504579

  8. Grapevine powdery mildew (Erysiphe necator): a fascinating system for the study of the biology, ecology, and epidemiology of an obligate biotroph

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Few plant pathogens have had a more profound effect upon the evolution of disease management than Erysiphe necator, which causes grapevine powdery mildew. When the pathogen first spread from North America to England in 1845, and onward to France in 1847, “germ theory” was neither understood among th...

  9. Chromosomal location of Pm35, a novel Aegilops tauschii derived powdery mildew resistance gene introgressed into common wheat (Triticum aestivum L.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A single gene controlling powdery mildew resistance was identified in the North Carolina germplasm line NC96BGTD3 (NCD3) using genetic analysis of F2 derived lines from a NCD3 X Saluda cross. Microsatellite markers linked to this Pm gene were identified and their most likely order was Xcfd7, 10.3cM,...

  10. Using a limited mapping strategy to identify major QTL’s for resistance to grapevine powdery mildew (Erysiphe necator) and their use in marker-assisted breeding.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A limited genetic mapping strategy was used to develop genetic markers in populations segregating for powdery mildew (Erysiphe necator) resistance. A genetic map was constructed and QTL analysis completed on a population derived from Muscadinia rotundifolia cv. Magnolia. In two additional populati...

  11. Appearance of Powdery Mildew of Wheat (caused by Blumeria graminis f. sp. Tritici) on Pm17-bearing Cultivars in North Carolina

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pm17 is a gene for resistance to powdery mildew (caused by Blumeria graminis f. sp. tritici) that was first confirmed in the wheat-rye translocation cultivar Amigo (1). In Amigo, the translocation is T1AL-1RS, and the 1RS arm has the gene Pm17. In the Mid-Atlantic USA, at least two widely deployed...

  12. Application of a new approach for characterization and denomination of races of cucurbit powdery mildews – a case study on the Czech pathogen population

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Golovinomyces cichoracearum (Gc) and Podosphaera xanthii (Px) (Ascomycetes, Erysiphaceae) are the most important fungal species causing cucurbit powdery mildew (CPM), a serious disease of field and greenhouse cucurbits. Both species are highly variable, as indicated by the existence of large number ...

  13. Development of marker sets useful in the early selection of Ren4 powdery mildew resistance and seedlessness for table and raisin grape breeding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The single, dominant powdery mildew resistance locus Ren4 from Vitis romanetii prevents hyphal growth by Erysiphe necator. Previously, we showed that when introgressed into V. vinifera in the modified BC2 population 03-3004, Ren4 was linked with the SSR marker VMC7f2 on chromosome 18, which is also...

  14. Evolutionary Conserved Function of Barley and Arabidopsis 3-KETOACYL-CoA SYNTHASES in Providing Wax Signals for Germination of Powdery Mildew Fungi1[C][W

    PubMed Central

    Weidenbach, Denise; Jansen, Marcus; Franke, Rochus B.; Hensel, Goetz; Weissgerber, Wiebke; Ulferts, Sylvia; Jansen, Irina; Schreiber, Lukas; Korzun, Viktor; Pontzen, Rolf; Kumlehn, Jochen; Pillen, Klaus; Schaffrath, Ulrich

    2014-01-01

    For plant pathogenic fungi, such as powdery mildews, that survive only on a limited number of host plant species, it is a matter of vital importance that their spores sense that they landed on the right spot to initiate germination as quickly as possible. We investigated a barley (Hordeum vulgare) mutant with reduced epicuticular leaf waxes on which spores of adapted and nonadapted powdery mildew fungi showed reduced germination. The barley gene responsible for the mutant wax phenotype was cloned in a forward genetic screen and identified to encode a 3-KETOACYL-CoA SYNTHASE (HvKCS6), a protein participating in fatty acid elongation and required for synthesis of epicuticular waxes. Gas chromatography-mass spectrometry analysis revealed that the mutant has significantly fewer aliphatic wax constituents with a chain length above C-24. Complementation of the mutant restored wild-type wax and overcame germination penalty, indicating that wax constituents less present on the mutant are a crucial clue for spore germination. Investigation of Arabidopsis (Arabidopsis thaliana) transgenic plants with sense silencing of Arabidopsis REQUIRED FOR CUTICULAR WAX PRODUCTION1, the HvKCS6 ortholog, revealed the same germination phenotype against adapted and nonadapted powdery mildew fungi. Our findings hint to an evolutionary conserved mechanism for sensing of plant surfaces among distantly related powdery mildews that is based on KCS6-derived wax components. Perception of such a signal must have been evolved before the monocot-dicot split took place approximately 150 million years ago. PMID:25201879

  15. Identification and structure of the mating-type locus and development of PCR-based markers for mating type in powdery mildew fungi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In fungi, mating compatibility is regulated by mating-type loci. The objectives of this study were to identify and sequence mating-type genes at the MAT1 locus in the grape powdery mildew fungus, Erysiphe necator, to develop a PCR-based marker for determining mating type in E. necator, and to devel...

  16. Population Genetic Analysis of an Eastern U.S. Wheat Powdery Mildew Population Reveals Geographic and Recent Common Ancestry with U.K. and Israeli Populations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The structure of the U.S. wheat powdery mildew population (Blumeria graminis f. sp. tritici) has not been investigated, and the global evolutionary history of B. g. tritici is largely unknown. After gathering 141 single-ascoporic B. g. tritici isolates from 10 eastern U.S. locations, 34 isolates fr...

  17. Dominant negative RPW8.2 fusion proteins reveal the importance of haustorium-oriented protein trafficking for resistance against powdery mildew in Arabidopsis.

    PubMed

    Zhang, Qiong; Berkey, Robert; Pan, Zhiyong; Wang, Wenming; Zhang, Yi; Ma, Xianfeng; King, Harlan; Xiao, Shunyuan

    2015-01-01

    Powdery mildew fungi form feeding structures called haustoria inside epidermal cells of host plants to extract photosynthates for their epiphytic growth and reproduction. The haustorium is encased by an interfacial membrane termed the extrahaustorial membrane (EHM). The atypical resistance protein RPW8.2 from Arabidopsis is specifically targeted to the EHM where RPW8.2 activates haustorium-targeted (thus broad-spectrum) resistance against powdery mildew fungi. EHM-specific localization of RPW8.2 suggests the existence of an EHM-oriented protein/membrane trafficking pathway during EHM biogenesis. However, the importance of this specific trafficking pathway for host defense has not been evaluated via a genetic approach without affecting other trafficking pathways. Here, we report that expression of EHM-oriented, nonfunctional RPW8.2 chimeric proteins exerts dominant negative effect over functional RPW8.2 and potentially over other EHM-localized defense proteins, thereby compromising both RPW8.2-mediated and basal resistance to powdery mildew. Thus, our results highlight the importance of the EHM-oriented protein/membrane trafficking pathway for host resistance against haustorium-forming pathogens such as powdery mildew fungi. PMID:25830634

  18. Molecular cytogenetic identification of a wheat-rye 1R addition line with multiple spikelets and resistance to powdery mildew.

    PubMed

    Yang, Wujuan; Wang, Changyou; Chen, Chunhuan; Wang, Yajuan; Zhang, Hong; Liu, Xinlun; Ji, Wanquan

    2016-04-01

    Alien addition lines are important for transferring useful genes from alien species into common wheat. Rye is an important and valuable gene resource for improving wheat disease resistance, yield, and environment adaptation. A new wheat-rye addition line, N9436B, was developed from the progeny of the cross of common wheat (Triticum aestivum L., 2n = 6x = 42, AABBDD) cultivar Shaanmai 611 and rye (Secale cereal L., 2n = 2x = 14, RR) accession Austrian rye. We characterized this new line by cytology, genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), molecular markers, and disease resistance screening. N9436B was stable in morphology and cytology, with a chromosome composition of 2n = 42 + 2t = 22II. GISH investigations showed that this line contained two rye chromosomes. GISH, FISH, and molecular maker identification suggested that the introduced R chromosome and the missing wheat chromosome arms were 1R chromosome and 2DL chromosome arm, respectively. N9436B exhibited 30-37 spikelets per spike and a high level of resistance to powdery mildew (Blumeria graminis f. sp. tritici, Bgt) isolate E09 at the seedling stage. N9436B was cytologically stable, had the trait of multiple spikelets, and was resistant to powdery mildew; this line should thus be useful in wheat improvement. PMID:27021228

  19. A small GTP-binding host protein is required for entry of powdery mildew fungus into epidermal cells of barley.

    PubMed

    Schultheiss, Holger; Dechert, Cornelia; Kogel, Karl-Heinz; Hückelhoven, Ralph

    2002-04-01

    Small GTP-binding proteins such as those from the RAC family are cytosolic signal transduction proteins that often are involved in processing of extracellular stimuli. Plant RAC proteins are implicated in regulation of plant cell architecture, secondary wall formation, meristem signaling, and defense against pathogens. We isolated a RacB homolog from barley (Hordeum vulgare) to study its role in resistance to the barley powdery mildew fungus (Blumeria graminis f.sp. hordei). RacB was constitutively expressed in the barley epidermis and its expression level was not strongly influenced by inoculation with B. graminis. However, after biolistic bombardment of barley leaf segments with RacB-double-stranded RNA, sequence-specific RNA interference with RacB function inhibited fungal haustorium establishment in a cell-autonomous and genotype-specific manner. Mutants compromised in function of the Mlo wild-type gene and the Ror1 gene (genotype mlo5 ror1) that are moderately susceptible to B. graminis showed no alteration in powdery mildew resistance upon RacB-specific RNA interference. Thus, the phenotype, induced by RacB-specific RNA interference, was apparently dependent on the same processes as mlo5-mediated broad resistance, which is suppressed by ror1. We conclude that an RAC small GTP-binding protein is required for successful fungal haustorium establishment and that this function may be linked to MLO-associated functions. PMID:11950993

  20. Coexpression network analysis of the genes regulated by two types of resistance responses to powdery mildew in wheat.

    PubMed

    Zhang, Juncheng; Zheng, Hongyuan; Li, Yiwen; Li, Hongjie; Liu, Xin; Qin, Huanju; Dong, Lingli; Wang, Daowen

    2016-01-01

    Powdery mildew disease caused by Blumeria graminis f. sp. tritici (Bgt) inflicts severe economic losses in wheat crops. A systematic understanding of the molecular mechanisms involved in wheat resistance to Bgt is essential for effectively controlling the disease. Here, using the diploid wheat Triticum urartu as a host, the genes regulated by immune (IM) and hypersensitive reaction (HR) resistance responses to Bgt were investigated through transcriptome sequencing. Four gene coexpression networks (GCNs) were developed using transcriptomic data generated for 20 T. urartu accessions showing IM, HR or susceptible responses. The powdery mildew resistance regulated (PMRR) genes whose expression was significantly correlated with Bgt resistance were identified, and they tended to be hubs and enriched in six major modules. A wide occurrence of negative regulation of PMRR genes was observed. Three new candidate immune receptor genes (TRIUR3_13045, TRIUR3_01037 and TRIUR3_06195) positively associated with Bgt resistance were discovered. Finally, the involvement of TRIUR3_01037 in Bgt resistance was tentatively verified through cosegregation analysis in a F2 population and functional expression assay in Bgt susceptible leaf cells. This research provides insights into the global network properties of PMRR genes. Potential molecular differences between IM and HR resistance responses to Bgt are discussed. PMID:27033636

  1. Coexpression network analysis of the genes regulated by two types of resistance responses to powdery mildew in wheat

    PubMed Central

    Zhang, Juncheng; Zheng, Hongyuan; Li, Yiwen; Li, Hongjie; Liu, Xin; Qin, Huanju; Dong, Lingli; Wang, Daowen

    2016-01-01

    Powdery mildew disease caused by Blumeria graminis f. sp. tritici (Bgt) inflicts severe economic losses in wheat crops. A systematic understanding of the molecular mechanisms involved in wheat resistance to Bgt is essential for effectively controlling the disease. Here, using the diploid wheat Triticum urartu as a host, the genes regulated by immune (IM) and hypersensitive reaction (HR) resistance responses to Bgt were investigated through transcriptome sequencing. Four gene coexpression networks (GCNs) were developed using transcriptomic data generated for 20 T. urartu accessions showing IM, HR or susceptible responses. The powdery mildew resistance regulated (PMRR) genes whose expression was significantly correlated with Bgt resistance were identified, and they tended to be hubs and enriched in six major modules. A wide occurrence of negative regulation of PMRR genes was observed. Three new candidate immune receptor genes (TRIUR3_13045, TRIUR3_01037 and TRIUR3_06195) positively associated with Bgt resistance were discovered. Finally, the involvement of TRIUR3_01037 in Bgt resistance was tentatively verified through cosegregation analysis in a F2 population and functional expression assay in Bgt susceptible leaf cells. This research provides insights into the global network properties of PMRR genes. Potential molecular differences between IM and HR resistance responses to Bgt are discussed. PMID:27033636

  2. Molecular Characterization of a New Wheat-Thinopyrum intermedium Translocation Line with Resistance to Powdery Mildew and Stripe Rust

    PubMed Central

    Zhan, Haixian; Zhang, Xiaojun; Li, Guangrong; Pan, Zhihui; Hu, Jin; Li, Xin; Qiao, Linyi; Jia, Juqing; Guo, Huijuan; Chang, Zhijian; Yang, Zujun

    2015-01-01

    A new wheat-Thinopyrum translocation line CH13-21 was selected from the progenies derived from a cross between wheat-Th. intermedium partial amphiploid TAI7047 and wheat line Mianyang11. CH13-21 was characterized by using genomic in situ hybridization (GISH), multicolor-GISH (mc-GISH), multicolor-fluorescence in situ hybridization (mc-FISH) and chromosome-specific molecular markers. When inoculated with stripe rust and powdery mildew isolates, CH13-21 displayed novel resistance to powdery mildew and stripe rust which inherited from its Thinopyrum parent. The chromosomal counting analyses indicated that CH13-21 has 42 chromosomes, with normal bivalent pairing at metaphase I of meiosis. GISH probed by Th. intermedium genomic DNA showed that CH13-21 contained a pair of wheat-Th. intermedium translocated chromosomes. Sequential mc-FISH analyses probed by pSc119.2 and pAs1 clearly revealed that chromosome arm 6BS of CH13-21 was replaced by Thinopyrum chromatin in the translocation chromosome. The molecular markers analysis further confirmed that the introduced Th. intermedium chromatin in CH13-21 belonged to the long arm of homoeologous group 6 chromosome. Therefore, CH13-21 was a new T6BS.6Ai#1L compensating Robertsonian translocation line. It concludes that CH13-21 is a new genetic resource for wheat breeding programs providing novel variation for disease resistances. PMID:25608651

  3. Protection of wheat against leaf and stem rust and powdery mildew diseases by inhibition of polyamine metabolism

    NASA Technical Reports Server (NTRS)

    Weinstein, L. H.; Osmeloski, J. F.; Wettlaufer, S. H.; Galston, A. W.

    1987-01-01

    In higher plants, polyamines arise from arginine by one of two pathways: via ornithine and ornithine decarboxylase or via agmatine and arginine decarboxylase but in fungi, only the ornithine decarboxylase pathway is present. Since polyamines are required for normal growth of microorganisms and plants and since the ornithine pathway can be irreversibly blocked by alpha-difluoromethylornithine (DFMO) which has no effect on arginine decarboxylase, fungal infection of green plants might be controlled by the site-directed use of such a specific metabolic inhibitor. DFMO at relatively low concentrations provided effective control of the three biotrophic fungal pathogens studied, Puccinia recondita (leaf rust), P. graminis f. sp. tritici (stem rust), and Erysiphe graminis (powdery mildew) on wheat (Triticum aestivum L.) Effective control of infection by leaf or stem rust fungi was obtained with sprays of DFMO that ranged from about 0.01 to 0.20 mM in experiments where the inhibitor was applied after spore inoculation. The powdery mildew fungus was somewhat more tolerant of DFMO, but good control of the pathogen was obtained at less than 1.0 mM. In general, application of DFMO after spore inoculation was more effective than application before inoculation. Less control was obtained following treatment with alpha-difluoromethylarginine (DFMA) but the relatively high degree of control obtained raises the possibility of a DFMA to DFMO conversion by arginase.

  4. Mla- and Rom1-mediated control of microRNA398 and chloroplast copper/zinc superoxide dismutase regulates cell death in response to the barley powdery mildew fungus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Barley Mla (Mildew resistance locus a) confers allele-specific interactions with natural variants of the ascomycete fungus, Blumeria graminis f. sp. hordei (Bgh), causal agent of powdery mildew disease. Significant reprogramming of host gene expression occurs upon infection by this obligate biotrop...

  5. Defence reactions of plants to fungal pathogens: principles and perspectives, using powdery mildew on cereals as an example

    NASA Astrophysics Data System (ADS)

    Heitefuss, Rudolf

    2001-06-01

    Diseases of crop plants may lead to considerable yield losses. To control fungal diseases, fungicides are used extensively in present-day agricultural production. In order to reduce such external inputs, cultivars with natural resistance to important fungal pathogens are recommended in systems of integrated plant protection. Basic research, including genetics and molecular methods, is required to elucidate the mechanisms by which plants react to an attack by fungal pathogens and successfully defend themselves. This review examines our knowledge with respect to the multicomponent systems of resistance in plants, using powdery mildew on barley as an example. In addition, the question is adressed whether systemic acquired resistance and plants with transgenic resistance may be utilized in future plant protection strategies.

  6. Fine Physical and Genetic Mapping of Powdery Mildew Resistance Gene MlIW172 Originating from Wild Emmer (Triticum dicoccoides)

    PubMed Central

    Han, Jun; Zhao, Xiaojie; Cui, Yu; Song, Wei; Huo, Naxin; Liang, Yong; Xie, Jingzhong; Wang, Zhenzhong; Wu, Qiuhong; Chen, Yong-Xing; Lu, Ping; Zhang, De-Yun; Wang, Lili; Sun, Hua; Yang, Tsomin; Keeble-Gagnere, Gabriel; Appels, Rudi; Doležel, Jaroslav; Ling, Hong-Qing; Luo, Mingcheng; Gu, Yongqiang; Sun, Qixin; Liu, Zhiyong

    2014-01-01

    Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important wheat diseases in the world. In this study, a single dominant powdery mildew resistance gene MlIW172 was identified in the IW172 wild emmer accession and mapped to the distal region of chromosome arm 7AL (bin7AL-16-0.86-0.90) via molecular marker analysis. MlIW172 was closely linked with the RFLP probe Xpsr680-derived STS marker Xmag2185 and the EST markers BE405531 and BE637476. This suggested that MlIW172 might be allelic to the Pm1 locus or a new locus closely linked to Pm1. By screening genomic BAC library of durum wheat cv. Langdon and 7AL-specific BAC library of hexaploid wheat cv. Chinese Spring, and after analyzing genome scaffolds of Triticum urartu containing the marker sequences, additional markers were developed to construct a fine genetic linkage map on the MlIW172 locus region and to delineate the resistance gene within a 0.48 cM interval. Comparative genetics analyses using ESTs and RFLP probe sequences flanking the MlIW172 region against other grass species revealed a general co-linearity in this region with the orthologous genomic regions of rice chromosome 6, Brachypodium chromosome 1, and sorghum chromosome 10. However, orthologous resistance gene-like RGA sequences were only present in wheat and Brachypodium. The BAC contigs and sequence scaffolds that we have developed provide a framework for the physical mapping and map-based cloning of MlIW172. PMID:24955773

  7. Fine physical and genetic mapping of powdery mildew resistance gene MlIW172 originating from wild emmer (Triticum dicoccoides).

    PubMed

    Ouyang, Shuhong; Zhang, Dong; Han, Jun; Zhao, Xiaojie; Cui, Yu; Song, Wei; Huo, Naxin; Liang, Yong; Xie, Jingzhong; Wang, Zhenzhong; Wu, Qiuhong; Chen, Yong-Xing; Lu, Ping; Zhang, De-Yun; Wang, Lili; Sun, Hua; Yang, Tsomin; Keeble-Gagnere, Gabriel; Appels, Rudi; Doležel, Jaroslav; Ling, Hong-Qing; Luo, Mingcheng; Gu, Yongqiang; Sun, Qixin; Liu, Zhiyong

    2014-01-01

    Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important wheat diseases in the world. In this study, a single dominant powdery mildew resistance gene MlIW172 was identified in the IW172 wild emmer accession and mapped to the distal region of chromosome arm 7AL (bin7AL-16-0.86-0.90) via molecular marker analysis. MlIW172 was closely linked with the RFLP probe Xpsr680-derived STS marker Xmag2185 and the EST markers BE405531 and BE637476. This suggested that MlIW172 might be allelic to the Pm1 locus or a new locus closely linked to Pm1. By screening genomic BAC library of durum wheat cv. Langdon and 7AL-specific BAC library of hexaploid wheat cv. Chinese Spring, and after analyzing genome scaffolds of Triticum urartu containing the marker sequences, additional markers were developed to construct a fine genetic linkage map on the MlIW172 locus region and to delineate the resistance gene within a 0.48 cM interval. Comparative genetics analyses using ESTs and RFLP probe sequences flanking the MlIW172 region against other grass species revealed a general co-linearity in this region with the orthologous genomic regions of rice chromosome 6, Brachypodium chromosome 1, and sorghum chromosome 10. However, orthologous resistance gene-like RGA sequences were only present in wheat and Brachypodium. The BAC contigs and sequence scaffolds that we have developed provide a framework for the physical mapping and map-based cloning of MlIW172. PMID:24955773

  8. Are ineffective defence reactions potential target for induced resistance during the compatible wheat-powdery mildew interaction?

    PubMed

    Tayeh, Ch; Randoux, B; Tisserant, B; Khong, G; Jacques, Ph; Reignault, Ph

    2015-11-01

    Powdery mildew caused by Blumeria graminis f.sp. tritici, an obligate aerial biotrophic fungus, would be one of the most damaging wheat (Triticum aestivum) diseases without the extensive use of conventional fungicides. In our study, the expression levels of some basal defence-related genes were investigated during a compatible interaction in order to evaluate wheat reactions to infection, along with the different stages of the infectious process in planta. As fungal conidia initiated their germination and developed appressorial germ tube (AGT), early defence reactions involved the expression of a lipoxygenase (LOX)- and an oxalate oxidase (OXO)-encoding genes, followed by activations of corresponding LOX (EC 1.13.11.12) and OXO (EC 1.2.3.4) activities, respectively. When penetration of AGT took place, up-regulation of chitinases (CHI) and PR1-encoding genes expression occurred along with an increase of CHI (EC 3.2.1.14) activity. Meanwhile, expression of a phenylalanine ammonia-lyase-encoding gene also took place. Up-regulation of a phospholipase C- and lipid transfer proteins-encoding genes expression occurred during the latest stages of infection. Neither the phi glutathione S-transferase (GST)-encoding gene expression nor the GST (EC 2.5.1.13) activity was modified upon wheat infection by powdery mildew. Whether these defence reactions during such a compatible interaction are markers of immunity or susceptibility, and whether they have the ability to contribute to protection upon modulation of their timing and their intensity by resistance inducers are discussed. PMID:26218548

  9. Identification of candidate MLO powdery mildew susceptibility genes in cultivated Solanaceae and functional characterization of tobacco NtMLO1.

    PubMed

    Appiano, Michela; Pavan, Stefano; Catalano, Domenico; Zheng, Zheng; Bracuto, Valentina; Lotti, Concetta; Visser, Richard G F; Ricciardi, Luigi; Bai, Yuling

    2015-10-01

    Specific homologs of the plant Mildew Locus O (MLO) gene family act as susceptibility factors towards the powdery mildew (PM) fungal disease, causing significant economic losses in agricultural settings. Thus, in order to obtain PM resistant phenotypes, a general breeding strategy has been proposed, based on the selective inactivation of MLO susceptibility genes across cultivated species. In this study, PCR-based methodologies were used in order to isolate MLO genes from cultivated solanaceous crops that are hosts for PM fungi, namely eggplant, potato and tobacco, which were named SmMLO1, StMLO1 and NtMLO1, respectively. Based on phylogenetic analysis and sequence alignment, these genes were predicted to be orthologs of tomato SlMLO1 and pepper CaMLO2, previously shown to be required for PM pathogenesis. Full-length sequence of the tobacco homolog NtMLO1 was used for a heterologous transgenic complementation assay, resulting in its characterization as a PM susceptibility gene. The same assay showed that a single nucleotide change in a mutated NtMLO1 allele leads to complete gene loss-of-function. Results here presented, also including a complete overview of the tobacco and potato MLO gene families, are valuable to study MLO gene evolution in Solanaceae and for molecular breeding approaches aimed at introducing PM resistance using strategies of reverse genetics. PMID:25947088

  10. Chromosomal Location and Comparative Genomics Analysis of Powdery Mildew Resistance Gene Pm51 in a Putative Wheat-Thinopyrum ponticum Introgression Line

    PubMed Central

    Zhang, Xiaojun; Li, Xin; Guo, Huijuan; Gong, Wenping; Jia, Juqing; Qiao, Linyi; Ren, Yongkang; Yang, Zujun; Chang, Zhijian

    2014-01-01

    Powdery mildew (PM) is a very destructive disease of wheat (Triticum aestivum L.). Wheat-Thinopyrum ponticum introgression line CH7086 was shown to possess powdery mildew resistance possibly originating from Th. ponticum. Genomic in situ hybridization and molecular characterization of the alien introgression failed to identify alien chromatin. To study the genetics of resistance, CH7086 was crossed with susceptible genotypes. Segregation in F2 populations and F2:3 lines tested with Chinese Bgt race E09 under controlled conditions indicated that CH7086 carries a single dominant gene for powdery mildew resistance. Fourteen SSR and EST-PCR markers linked with the locus were identified. The genetic distances between the locus and the two flanking markers were 1.5 and 3.2 cM, respectively. Based on the locations of the markers by nullisomic-tetrasomic and deletion lines of ‘Chinese Spring’, the resistance gene was located in deletion bin 2BL-0.89-1.00. Conserved orthologous marker analysis indicated that the genomic region flanking the resistance gene has a high level of collinearity to that of rice chromosome 4 and Brachypodium chromosome 5. Both resistance specificities and tests of allelism suggested the resistance gene in CH7086 was different from previously reported powdery mildew resistance genes on 2BL, and the gene was provisionally designated PmCH86. Molecular analysis of PmCH86 compared with other genes for resistance to Bgt in the 2BL-0.89-1.00 region suggested that PmCH86 may be a new PM resistance gene, and it was therefore designated as Pm51. The closely linked flanking markers could be useful in exploiting this putative wheat-Thinopyrum translocation line for rapid transfer of Pm51 to wheat breeding programs. PMID:25415194

  11. The adult plant rust resistance loci Lr34/Yr18 and Lr46/Yr29 are important determinants of partial resistance to powdery mildew in bread wheat line Saar.

    PubMed

    Lillemo, M; Asalf, B; Singh, R P; Huerta-Espino, J; Chen, X M; He, Z H; Bjørnstad, A

    2008-05-01

    Powdery mildew, caused by Blumeria graminis f. sp. tritici is a major disease of wheat (Triticum aestivum L.) that can be controlled by resistance breeding. The CIMMYT bread wheat line Saar is known for its good level of partial and race non-specific resistance, and the aim of this study was to map QTLs for resistance to powdery mildew in a population of 113 recombinant inbred lines from a cross between Saar and the susceptible line Avocet. The population was tested over 2 years in field trials at two locations in southeastern Norway and once in Beijing, China. SSR markers were screened for association with powdery mildew resistance in a bulked segregant analysis, and linkage maps were created based on selected SSR markers and supplemented with DArT genotyping. The most important QTLs for powdery mildew resistance derived from Saar were located on chromosomes 7DS and 1BL and corresponded to the adult plant rust resistance loci Lr34/Yr18 and Lr46/Yr29. A major QTL was also located on 4BL with resistance contributed by Avocet. Additional QTLs were detected at 3AS and 5AL in the Norwegian testing environments and at 5BS in Beijing. The population was also tested for leaf rust (caused by Puccinia triticina) and stripe rust (caused by P. striiformis f. sp. tritici) resistance and leaf tip necrosis in Mexico. QTLs for these traits were detected on 7DS and 1BL at the same positions as the QTLs for powdery mildew resistance, and confirmed the presence of Lr34/Yr18 and Lr46/Yr29 in Saar. The powdery mildew resistance gene at the Lr34/Yr18 locus has recently been named Pm38. The powdery mildew resistance gene at the Lr46/Yr29 locus is designated as Pm39. PMID:18347772

  12. Biological control of the cucurbit powdery mildew pathogen Podosphaera xanthii by means of the epiphytic fungus Pseudozyma aphidis and parasitism as a mode of action.

    PubMed

    Gafni, Aviva; Calderon, Claudia E; Harris, Raviv; Buxdorf, Kobi; Dafa-Berger, Avis; Zeilinger-Reichert, Einat; Levy, Maggie

    2015-01-01

    Epiphytic yeasts, which colonize plant surfaces, may possess activity that can be harnessed to help plants defend themselves against various pathogens. Due to their unique characteristics, epiphytic yeasts belonging to the genus Pseudozyma hold great potential for use as biocontrol agents. We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis. Here, we show that strain L12 of P. aphidis can reduce the severity of powdery mildew caused by Podosphaera xanthii on cucumber plants with an efficacy of 75%. Confocal and scanning electron microscopy analyses demonstrated P. aphidis proliferation on infected tissue and its production of long hyphae that parasitize the powdery mildew hyphae and spores as an ectoparasite. We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta. Our results suggest that in addition to its antibiosis as mode of action, P. aphidis may also act as an ectoparasite on P. xanthii. These results indicate that P. aphidis strain L12 has the potential to control powdery mildew. PMID:25814995

  13. Biological control of the cucurbit powdery mildew pathogen Podosphaera xanthii by means of the epiphytic fungus Pseudozyma aphidis and parasitism as a mode of action

    PubMed Central

    Gafni, Aviva; Calderon, Claudia E.; Harris, Raviv; Buxdorf, Kobi; Dafa-Berger, Avis; Zeilinger-Reichert, Einat; Levy, Maggie

    2015-01-01

    Epiphytic yeasts, which colonize plant surfaces, may possess activity that can be harnessed to help plants defend themselves against various pathogens. Due to their unique characteristics, epiphytic yeasts belonging to the genus Pseudozyma hold great potential for use as biocontrol agents. We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis. Here, we show that strain L12 of P. aphidis can reduce the severity of powdery mildew caused by Podosphaera xanthii on cucumber plants with an efficacy of 75%. Confocal and scanning electron microscopy analyses demonstrated P. aphidis proliferation on infected tissue and its production of long hyphae that parasitize the powdery mildew hyphae and spores as an ectoparasite. We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta. Our results suggest that in addition to its antibiosis as mode of action, P. aphidis may also act as an ectoparasite on P. xanthii. These results indicate that P. aphidis strain L12 has the potential to control powdery mildew. PMID:25814995

  14. Naturally occurring broad-spectrum powdery mildew resistance in a Central American tomato accession is caused by loss of mlo function.

    PubMed

    Bai, Yuling; Pavan, Stefano; Zheng, Zheng; Zappel, Nana F; Reinstädler, Anja; Lotti, Concetta; De Giovanni, Claudio; Ricciardi, Luigi; Lindhout, Pim; Visser, Richard; Theres, Klaus; Panstruga, Ralph

    2008-01-01

    The resistant cherry tomato (Solanum lycopersicum var. cerasiforme) line LC-95, derived from an accession collected in Ecuador, harbors a natural allele (ol-2) that confers broad-spectrum and recessively inherited resistance to powdery mildew (Oidium neolycopersici). As both the genetic and phytopathological characteristics of ol-2-mediated resistance are reminiscent of powdery mildew immunity conferred by loss-of-function mlo alleles in barley and Arabidopsis, we initiated a candidate-gene approach to clone Ol-2. A tomato Mlo gene (SlMlo1) with high sequence-relatedness to barley Mlo and Arabidopsis AtMLO2 mapped to the chromosomal region harboring the Ol-2 locus. Complementation experiments using transgenic tomato lines as well as virus-induced gene silencing assays suggested that loss of SlMlo1 function is responsible for powdery mildew resistance conferred by ol-2. In progeny of a cross between a resistant line bearing ol-2 and the susceptible tomato cultivar Moneymaker, a 19-bp deletion disrupting the SlMlo1 coding region cosegregated with resistance. This polymorphism results in a frameshift and, thus, a truncated nonfunctional SlMlo1 protein. Our findings reveal the second example of a natural mlo mutant that possibly arose post-domestication, suggesting that natural mlo alleles might be evolutionarily short-lived due to fitness costs related to loss of mlo function. PMID:18052880

  15. Genome-Wide Study of the Tomato SlMLO Gene Family and Its Functional Characterization in Response to the Powdery Mildew Fungus Oidium neolycopersici.

    PubMed

    Zheng, Zheng; Appiano, Michela; Pavan, Stefano; Bracuto, Valentina; Ricciardi, Luigi; Visser, Richard G F; Wolters, Anne-Marie A; Bai, Yuling

    2016-01-01

    The MLO (Mildew Locus O) gene family encodes plant-specific proteins containing seven transmembrane domains and likely acting in signal transduction in a calcium and calmodulin dependent manner. Some members of the MLO family are susceptibility factors toward fungi causing the powdery mildew disease. In tomato, for example, the loss-of-function of the MLO gene SlMLO1 leads to a particular form of powdery mildew resistance, called ol-2, which arrests almost completely fungal penetration. This type of penetration resistance is characterized by the apposition of papillae at the sites of plant-pathogen interaction. Other MLO homologs in Arabidopsis regulate root response to mechanical stimuli (AtMLO4 and AtMLO11) and pollen tube reception by the female gametophyte (AtMLO7). However, the role of most MLO genes remains unknown. In this work, we provide a genome-wide study of the tomato SlMLO gene family. Besides SlMLO1, other 15 SlMLO homologs were identified and characterized with respect to their structure, genomic organization, phylogenetic relationship, and expression profile. In addition, by analysis of transgenic plants, we demonstrated that simultaneous silencing of SlMLO1 and two of its closely related homologs, SlMLO5 and SlMLO8, confer higher level of resistance than the one associated with the ol-2 mutation. The outcome of this study provides evidence for functional redundancy among tomato homolog genes involved in powdery mildew susceptibility. Moreover, we developed a series of transgenic lines silenced for individual SlMLO homologs, which lay the foundation for further investigations aimed at assigning new biological functions to the MLO gene family. PMID:27579028

  16. Genome-Wide Study of the Tomato SlMLO Gene Family and Its Functional Characterization in Response to the Powdery Mildew Fungus Oidium neolycopersici

    PubMed Central

    Zheng, Zheng; Appiano, Michela; Pavan, Stefano; Bracuto, Valentina; Ricciardi, Luigi; Visser, Richard G. F.; Wolters, Anne-Marie A.; Bai, Yuling

    2016-01-01

    The MLO (Mildew Locus O) gene family encodes plant-specific proteins containing seven transmembrane domains and likely acting in signal transduction in a calcium and calmodulin dependent manner. Some members of the MLO family are susceptibility factors toward fungi causing the powdery mildew disease. In tomato, for example, the loss-of-function of the MLO gene SlMLO1 leads to a particular form of powdery mildew resistance, called ol-2, which arrests almost completely fungal penetration. This type of penetration resistance is characterized by the apposition of papillae at the sites of plant-pathogen interaction. Other MLO homologs in Arabidopsis regulate root response to mechanical stimuli (AtMLO4 and AtMLO11) and pollen tube reception by the female gametophyte (AtMLO7). However, the role of most MLO genes remains unknown. In this work, we provide a genome-wide study of the tomato SlMLO gene family. Besides SlMLO1, other 15 SlMLO homologs were identified and characterized with respect to their structure, genomic organization, phylogenetic relationship, and expression profile. In addition, by analysis of transgenic plants, we demonstrated that simultaneous silencing of SlMLO1 and two of its closely related homologs, SlMLO5 and SlMLO8, confer higher level of resistance than the one associated with the ol-2 mutation. The outcome of this study provides evidence for functional redundancy among tomato homolog genes involved in powdery mildew susceptibility. Moreover, we developed a series of transgenic lines silenced for individual SlMLO homologs, which lay the foundation for further investigations aimed at assigning new biological functions to the MLO gene family. PMID:27579028

  17. Elemental micro-PIXE mapping of hypersensitive lesions in Lagenaria sphaerica (Cucurbitaceae) resistant to Sphaerotheca fuliginea (powdery mildew)

    NASA Astrophysics Data System (ADS)

    Weiersbye-Witkowski, I. M.; Przybylowicz, W. J.; Straker, C. J.; Mesjasz-Przybylowicz, J.

    1997-07-01

    Genotypes of the Southern African cucurbit, Lagenaria sphaerica, that are resistant to powdery-mildew ( Sphaerotheca fuliginea) exhibit foliar hypersensitive (HS) lesions on inoculation with this fungal pathogen. Elemental distributions across radially symmetrical HS lesions, surrounding unlesioned leaf tissue and uninoculated leaf tissue, were obtained using the true elemental imaging system (Dynamic Analysis) of the NAC Van de Graaff nuclear microprobe. Raster scans of 3 MeV protons were complemented by simultaneous PIXE and BS point analyses. The composition of cellulose (C 6H 10O 5) was used as constant matrix composition for scans, and the sample thickness was found from BS spectra. Si and elements heavier than Ca contributed to matrix composition within HS lesions and the locally elevated Ca raised the limits of detection for some trace metals of interest. In comparison to uninoculated tissue, inoculated tissue was characterised by higher overall concentrations of all measured elements except Cu. Fully developed, 6 day-old HS lesions and the surrounding tissue could be divided into five zones, centred on the fungal infection site. Each zone was characterized by distinct local elemental distributions (either depletion, or accumulation to potentially phytotoxic levels).

  18. Evidence that the cAMP pathway controls emergence of both primary and appressorial germ tubes of barley powdery mildew.

    PubMed

    Kinane, J; Dalvin, S; Bindslev, L; Hall, A; Gurr, S; Oliver, R

    2000-05-01

    Development of conidia of barley powdery mildew involves the formation of a primary germ tube (PGT), an appressorial germ tube (AGT), and an appressorium. Previously, it was found that cyclic AMP (cAMP) was involved in these developmental processes. Comparison of development on the host surface with two types of cellulose membrane revealed that frequency of PGT emergence was surface independent. On one type of cellulose, where the frequencies of both AGT and appressorial differentiation were similar to that on the host surface, cAMP levels and protein kinase A (PKA) activities had a biphasic pattern with peaks at 15 min and 4 h after inoculation (prior to PGT and AGT emergence, respectively). The effect of manipulating cAMP levels was tested on another type of cellulose membrane, which stimulated a lower degree of AGT and appressorial formation than the host surface. Cholera toxin and forskolin, activators of adenylyl cyclase, significantly increased PGT emergence, but cAMP did not. Cholera toxin, forskolin, and cAMP increased the frequency of AGT and appressorial formation, but in a time-dependent manner. PMID:10796015

  19. Molecular cloning, functional verification, and evolution of TmPm3, the powdery mildew resistance gene of Triticum monococcum L.

    PubMed

    Zhao, C Z; Li, Y H; Dong, H T; Geng, M M; Liu, W H; Li, F; Ni, Z F; Wang, X J; Xie, C J; Sun, Q X

    2016-01-01

    Powdery mildew (Pm) is one of the most harmful diseases in wheat. Three Pm-resistance genes, Pm3, Pm21, and Pm8, have been cloned but most Pm3/Pm8 alleles have lost their resistance to Pm in hexaploid wheat. In this study, a new Pm3 homolog gene (TmPm3) was isolated from Triticum monococcum L. using a homology-based cloning strategy, being the first report of a functional Pm3 homolog gene from a diploid wheat species. The transient expression of TmPm3 in leaf epidermal cells showed that over-expressed TmPm3 could significantly inhibit the penetration of Blumeria graminis f. sp tritici conidia spores and the formation of haustoria. Sequence analysis of Pm3 alleles shed new light on the evolution of Pm3 genes, providing a better understanding of the molecular basis of disease resistance. This study also suggested that homology-based cloning of resistance genes is a feasible method for the isolation of functional resistance genes from wheat germplasm. PMID:27173250

  20. Validation of molecular markers associated with boron tolerance, powdery mildew resistance and salinity tolerance in field peas

    PubMed Central

    Javid, Muhammad; Rosewarne, Garry M.; Sudheesh, Shimna; Kant, Pragya; Leonforte, Antonio; Lombardi, Maria; Kennedy, Peter R.; Cogan, Noel O. I.; Slater, Anthony T.; Kaur, Sukhjiwan

    2015-01-01

    Field pea (Pisum sativum L.) is an important grain legume consumed both as human food and animal feed. However, productivity in low rainfall regions can be significantly reduced by inferior soils containing high levels of boron and/or salinity. Furthermore, powdery mildew (PM) (Erysiphe pisi) disease also causes significant yield loss in warmer regions. Breeding for tolerance to these abiotic and biotic stresses are major aims for pea breeding programs and the application of molecular markers for these traits could greatly assist in developing improved germplasm at a faster rate. The current study reports the evaluation of a near diagnostic marker, PsMlo, associated with PM resistance and boron (B) tolerance as well as linked markers associated with salinity tolerance across a diverse set of pea germplasm. The PsMlo1 marker predicted the PM and B phenotypic responses with high levels of accuracy (>80%) across a wide range of field pea genotypes, hence offers the potential to be widely adapted in pea breeding programs. In contrast, linked markers for salinity tolerance were population specific; therefore, application of these markers would be suitable to relevant crosses within the program. Our results also suggest that there are possible new sources of salt tolerance present in field pea germplasm that could be further exploited. PMID:26579164

  1. Evidence of Phytoalexins in Cucumber Leaves Infected with Powdery Mildew following Treatment with Leaf Extracts of Reynoutria sachalinensis.

    PubMed Central

    Daayf, F.; Schmitt, A.; Belanger, R. R.

    1997-01-01

    Phenolic compounds extracted from cucumber (Cucumis sativus L.) leaves were separated and analyzed for their differential presence and fungitoxicity in relation to a prophylactic treatment with Milsana (Compo, Munster, Germany) against powdery mildew (Sphaerotheca fuliginea). Based on our extraction and purification procedures, at least eight separate phenolic compounds with antifungal activity were identified as intrinsic components of cucumber plants. Of these compounds, six displayed a significant increase in concentration as a result of elicitation with Milsana, this being particularly evident when the plant was stressed by the pathogen. The combined amounts of these antifungal compounds in treated plants was nearly five times the level found in control plants. One week after Milsana application, some of the antifungal compounds obtained through hydrolysis of their glycosidic links were also detected in their free form, indicating that they are likely liberated from conjugated phenolics by enzymatic hydrolysis in planta. To our knowledge, these results provide the first direct evidence that cucumber plants produce elevated levels of phytoalexins in response to an eliciting treatment after infection. PMID:12223638

  2. Current understanding of grapevine defense mechanisms against the biotrophic fungus (Erysiphe necator), the causal agent of powdery mildew disease

    PubMed Central

    Qiu, Wenping; Feechan, Angela; Dry, Ian

    2015-01-01

    The most economically important disease of cultivated grapevines worldwide is powdery mildew (PM) caused by the ascomycete fungus Erysiphe necator. The majority of grapevine cultivars used for wine, table grape, and dried fruit production are derived from the Eurasian grape species Vitis vinifera because of its superior aroma and flavor characteristics. However, this species has little genetic resistance against E. necator meaning that grape production is highly dependent on the frequent use of fungicides. The integration of effective genetic resistance into cultivated grapevines would lead to significant financial and environmental benefits and represents a major challenge for viticultural industries and researchers worldwide. This review will outline the strategies being used to increase our understanding of the molecular basis of V. vinifera susceptibility to this fungal pathogen. It will summarize our current knowledge of different resistance loci/genes that have evolved in wild grapevine species to restrict PM infection and assess the potential application of these defense genes in the generation of PM-resistant grapevine germplasm. Finally, it addresses future research priorities which will be important in the rapid identification, evaluation, and deployment of new PM resistance genes which are capable of conferring effective and durable resistance in the vineyard. PMID:26504571

  3. Oak powdery mildew (Erysiphe alphitoides) induced volatile emissions scale with the degree of infection in Quercus robur

    PubMed Central

    Copolovici, Lucian; Väärtnõu, Fred; Estrada, Miguel Portillo; Niinemets, Ülo

    2015-01-01

    Oak powdery mildew (Erysiphe alphitoides) is a major foliar pathogen of Quercus robur often infecting entire tree stands. In this study, foliage photosynthetic characteristics and constitutive and induced volatile emissions were studied in Q. robur leaves asking whether the changes in foliage physiological traits are quantitatively associated with the degree of leaf infection, and whether infection changes the light responses of physiological traits. Infection by E. alphitoides reduced net assimilation rate by 3.5-fold, and isoprene emission rate by 2.4-fold and increased stomatal conductance by 1.6-fold in leaves with the largest degree of infection of ca. 60%. These alterations in physiological activity were quantitatively associated with the fraction of leaf area infected. In addition, light-saturation of net assimilation and isoprene emission was reached at lower light intensity in infected leaves, and infection also reduced the initial quantum yield of isoprene emission. Infection-induced emissions of lipoxygenase pathway volatiles and monoterpenes were light-dependent and scaled positively with the degree of infection. Overall, this study indicates that the reduction of foliage photosynthetic activity and constitutive emissions and the onset of stress volatile emissions scales with the degree of infection, but also that infection modifies the light responses of foliage physiological activities. PMID:25428827

  4. Multiple Avirulence Loci and Allele-Specific Effector Recognition Control the Pm3 Race-Specific Resistance of Wheat to Powdery Mildew[OPEN

    PubMed Central

    Roffler, Stefan; Stirnweis, Daniel; Treier, Georges; Herren, Gerhard; Korol, Abraham B.; Wicker, Thomas

    2015-01-01

    In cereals, several mildew resistance genes occur as large allelic series; for example, in wheat (Triticum aestivum and Triticum turgidum), 17 functional Pm3 alleles confer agronomically important race-specific resistance to powdery mildew (Blumeria graminis). The molecular basis of race specificity has been characterized in wheat, but little is known about the corresponding avirulence genes in powdery mildew. Here, we dissected the genetics of avirulence for six Pm3 alleles and found that three major Avr loci affect avirulence, with a common locus_1 involved in all AvrPm3-Pm3 interactions. We cloned the effector gene AvrPm3a2/f2 from locus_2, which is recognized by the Pm3a and Pm3f alleles. Induction of a Pm3 allele-dependent hypersensitive response in transient assays in Nicotiana benthamiana and in wheat demonstrated specificity. Gene expression analysis of Bcg1 (encoded by locus_1) and AvrPm3 a2/f2 revealed significant differences between isolates, indicating that in addition to protein polymorphisms, expression levels play a role in avirulence. We propose a model for race specificity involving three components: an allele-specific avirulence effector, a resistance gene allele, and a pathogen-encoded suppressor of avirulence. Thus, whereas a genetically simple allelic series controls specificity in the plant host, recognition on the pathogen side is more complex, allowing flexible evolutionary responses and adaptation to resistance genes. PMID:26452600

  5. Nuclear Function of Subclass I Actin-Depolymerizing Factor Contributes to Susceptibility in Arabidopsis to an Adapted Powdery Mildew Fungus1[OPEN

    PubMed Central

    Inada, Noriko; Higaki, Takumi; Hasezawa, Seiichiro

    2016-01-01

    Actin-depolymerizing factors (ADFs) are conserved proteins that function in regulating the structure and dynamics of actin microfilaments in eukaryotes. In this study, we present evidence that Arabidopsis (Arabidopsis thaliana) subclass I ADFs, particularly ADF4, functions as a susceptibility factor for an adapted powdery mildew fungus. The null mutant of ADF4 significantly increased resistance against the adapted powdery mildew fungus Golovinomyces orontii. The degree of resistance was further enhanced in transgenic plants in which the expression of all subclass I ADFs (i.e. ADF1–ADF4) was suppressed. Microscopic observations revealed that the enhanced resistance of adf4 and ADF1-4 knockdown plants (ADF1-4Ri) was associated with the accumulation of hydrogen peroxide and cell death specific to G. orontii-infected cells. The increased resistance and accumulation of hydrogen peroxide in ADF1-4Ri were suppressed by the introduction of mutations in the salicylic acid- and jasmonic acid-signaling pathways but not by a mutation in the ethylene-signaling pathway. Quantification by microscopic images detected an increase in the level of actin microfilament bundling in ADF1-4Ri but not in adf4 at early G. orontii infection time points. Interestingly, complementation analysis revealed that nuclear localization of ADF4 was crucial for susceptibility to G. orontii. Based on its G. orontii-infected-cell-specific phenotype, we suggest that subclass I ADFs are susceptibility factors that function in a direct interaction between the host plant and the powdery mildew fungus. PMID:26747284

  6. Use of fungicides against powdery mildew during an artificial scab inoculation test in an apple breeding programme focused on partial resistance.

    PubMed

    Lefrancq, B; Lateur, M

    2005-01-01

    Our project aimed to develop an effective selection methodology for partial disease resistance. One of its objectives was to define the optimal selection threshold for discarding individual seedlings after artificial scab inoculation tests. Working with large populations of seedlings, it was necessary to conduct the scab tests at intervals throughout the season, with the risk of powdery mildew infection of the young plantlets during the summer. Because Podosphaera leucotricha symptoms prevent breeders from properly evaluating scab symptoms, a trial was conducted to assess the effect of specific anti-mildew fungicides on the results of the scab inoculation test. The results allowed the active ingredient and the optimum time for application in relation to the inoculation date to be determined. PMID:16637179

  7. Reprint of "Sequence and phylogenetic analyses of novel totivirus-like double-stranded RNAs from field-collected powdery mildew fungi".

    PubMed

    Kondo, Hideki; Hisano, Sakae; Chiba, Sotaro; Maruyama, Kazuyuki; Andika, Ida Bagus; Toyoda, Kazuhiro; Fujimori, Fumihiro; Suzuki, Nobuhiro

    2016-07-01

    The identification of mycoviruses contributes greatly to understanding of the diversity and evolutionary aspects of viruses. Powdery mildew fungi are important and widely studied obligate phytopathogenic agents, but there has been no report on mycoviruses infecting these fungi. In this study, we used a deep sequencing approach to analyze the double-stranded RNA (dsRNA) segments isolated from field-collected samples of powdery mildew fungus-infected red clover plants in Japan. Database searches identified the presence of at least ten totivirus (genus Totivirus)-like sequences, termed red clover powdery mildew-associated totiviruses (RPaTVs). The majority of these sequences shared moderate amino acid sequence identity with each other (<44%) and with other known totiviruses (<59%). Nine of these identified sequences (RPaTV1a, 1b and 2-8) resembled the genome of the prototype totivirus, Saccharomyces cerevisiae virus-L-A (ScV-L-A) in that they contained two overlapping open reading frames (ORFs) encoding a putative coat protein (CP) and an RNA dependent RNA polymerase (RdRp), while one sequence (RPaTV9) showed similarity to another totivirus, Ustilago maydis virus H1 (UmV-H1) that encodes a single polyprotein (CP-RdRp fusion). Similar to yeast totiviruses, each ScV-L-A-like RPaTV contains a -1 ribosomal frameshift site downstream of a predicted pseudoknot structure in the overlapping region of these ORFs, suggesting that the RdRp is translated as a CP-RdRp fusion. Moreover, several ScV-L-A-like sequences were also found by searches of the transcriptome shotgun assembly (TSA) libraries from rust fungi, plants and insects. Phylogenetic analyses show that nine ScV-L-A-like RPaTVs along with ScV-L-A-like sequences derived from TSA libraries are clustered with most established members of the genus Totivirus, while one RPaTV forms a new distinct clade with UmV-H1, possibly establishing an additional genus in the family. Taken together, our results indicate the presence of

  8. A trade off between mlo resistance to powdery mildew and increased susceptibility of barley to a newly important disease, Ramularia leaf spot

    PubMed Central

    McGrann, Graham R. D.; Brown, James K. M.

    2014-01-01

    Ramularia leaf spot (RLS), caused by the fungus Ramularia collo-cygni, is a serious, recently emerged disease of barley in Europe and other temperate regions. This study investigated the trade off between strong resistance to powdery mildew conferred by mlo mutant alleles and increased susceptibility to RLS. In field trials and seedling tests, the presence of mlo alleles increased severity of RLS. Genetic analysis of a doubled-haploid population identified one quantitative trait locus for susceptibility to RLS, colocalizing with the mlo-11 allele for mildew resistance. The effect of mlo-11 on RLS severity was environmentally sensitive. Analysis of near-isogenic lines of different mlo mutations in various genetic backgrounds confirmed that mlo alleles increased RLS severity in seedlings and adult plants. For mlo resistance to mildew to be fully effective, the genes ROR1 and ROR2 are required. RLS symptoms were significantly reduced on mlo-5 ror double mutants but fungal DNA levels remained as high as in mlo-5 single mutants, implying that ror alleles modify the transition of the fungus from endophytism to necrotrophy. These results indicate that the widespread use of mlo resistance to control mildew may have inadvertently stimulated the emergence of RLS as a major disease of barley. PMID:24399175

  9. Transcriptome of Erysiphe necator-infected Vitis pseudoreticulata leaves provides insight into grapevine resistance to powdery mildew

    PubMed Central

    Weng, Kai; Li, Zhi-Qian; Liu, Rui-Qi; Wang, Lan; Wang, Yue-Jin; Xu, Yan

    2014-01-01

    Powdery mildew (PM), which is caused by the pathogen Erysiphe necator (Schw.) Burr., is the single most damaging disease of cultivated grapes (Vitis vinifera) worldwide. However, little is known about the transcriptional response of grapes to infection with PM. RNA-seq analysis was used for deep sequencing of the leaf transcriptome to study PM resistance in Chinese wild grapes (V. pseudoreticulata Baihe 35-1) to better understand the interaction between host and pathogen. Greater than 100 million (M) 90-nt cDNA reads were sequenced from a cDNA library derived from PM-infected leaves. Among the sequences obtained, 6541 genes were differentially expressed (DEG) and were annotated with Gene Ontology terms and by pathway enrichment. The significant categories that were identified included the following: defense, salicylic acid (SA) and jasmonic acid (JA) responses; systemic acquired resistance (SAR); hypersensitive response; plant–pathogen interaction; flavonoid biosynthesis; and plant hormone signal transduction. Various putative secretory proteins were identified, indicating potential defense responses to PM infection. In all, 318 putative R-genes and 183 putative secreted proteins were identified, including the defense-related R-genes BAK1, MRH1 and MLO3 and the defense-related secreted proteins GLP and PR5. The expression patterns of 16 genes were further illuminated by RT-qPCR. The present study identified several candidate genes and pathways that may contribute to PM resistance in grapes and illustrated that RNA-seq is a powerful tool for studying gene expression. The RT-qPCR results reveal that effective resistance responses of grapes to PM include enhancement of JA and SAR responses and accumulation of phytoalexins. PMID:26504551

  10. Calcium transport in protoplasts isolated from ml-o barley isolines resistant and susceptible to powdery mildew. [Hordeum vulgare L

    SciTech Connect

    Wrona, A.F.; Spanswick, R.M.; Aist, J.R. )

    1988-12-01

    Free cytoplasmic calcium has been postulated to play a role in preventing powdery mildew in a series of homozygous ml-o mutants of barley, Hordeum vulgare L. Protoplasts isolated from 7-day-old plants of the ml-o resistant-susceptible (R-S) barley isolines, Riso 5678/3* {times} Carlsberg II R and S, were used to test for differences in fluxes of Ca{sup 2+} across the plasmalemma. Greater influx or lesser efflux might account for a higher free cytosolic Ca{sup 2+} postulated to exist in ml-o R mutants. Uniform patterns of uptake were maintained for 3 hours from solutions of 0.2 and 2 millimolar Ca{sup 2+}. Washout curves of {sup 45}Ca{sup 2+} from R and S protoplasts revealed three compartments - presumed to represent release from the vacuole, organelles, and the cytoplasm (which included bound as well as free Ca{sup 2+}). Uptake and washout did not differ between isolines. On the basis of recent determinations of submicromolar levels of free cytoplasmic Ca{sup 2+} and their initial rates of {sup 45}ca-labeled Ca{sup 2+} uptake, they show that measurement of the unidirectional influx of Ca{sup 2+} across the plasmalemma is not feasible because the specific activity of the pool of free cytoplasmic calcium increases almost instantaneously to a level that would result in a significant, but unknown, efflux of label. Similarly, measurement of the efflux of Ca{sup 2+} across the plasmalemma is not possible since the activity of the pool of free cytoplasmic calcium is a factor of 350 smaller than the most rapid component of the washout experiment. This pool of cytoplasmic free Ca{sup 2+} will wash out too rapidly and be too small to detect under the conditions of these experiments.

  11. Loss-of-Function Mutations in CsMLO1 Confer Durable Powdery Mildew Resistance in Cucumber (Cucumis sativus L.)

    PubMed Central

    Nie, Jingtao; Wang, Yunli; He, Huanle; Guo, Chunli; Zhu, Wenying; Pan, Jian; Li, Dandan; Lian, Hongli; Pan, Junsong; Cai, Run

    2015-01-01

    Powdery mildew (PM) is a serious fungal disease of cucumber worldwide. The identification of resistance genes is very important for resistance breeding to ensure cucumber production. Here, natural loss-of-function mutations at an MLO homologous locus, CsMLO1, were found to confer durable PM resistance in cucumber. CsMLO1 encoded a cell membrane protein, was mainly expressed in leaves and cotyledons, and was up-regulated by PM at the early stage of host–pathogen interaction. Ectopic expression of CsMLO1 rescued the phenotype of the PM resistant Atmlo2 Atmlo12 double mutant to PM susceptible in Arabidopsis. Domesticated and wild resistant cucumbers originating from various geographical regions of the world were found to harbor three independent natural mutations that resulted in CsMLO1 loss of function. In addition, between the near-isogenic lines (NILs) of PM resistant and susceptible, S1003 and NIL(Pm5.1), quantitative RT-PCR revealed that there is no difference at expression levels of several genes in the pathways of ethylene, jasmonic acid or salicylic acid. Moreover, the two NILs were used for transcriptome profiling to explore the mechanism underlying the resistance. Several genes correlated with plant cell wall thickening are possibly involved in the PM resistance. This study revealed that loss of function of CsMLO1 conferred durable PM resistance, and that this loss of function is necessary but alone may not be sufficient for PM resistance in cucumber. These findings will facilitate the molecular breeding of PM resistant varieties to control this destructive disease in cucumber. PMID:26734050

  12. Fine mapping of a dominantly inherited powdery mildew resistance major-effect QTL, Pm1.1, in cucumber identifies a 41.1 kb region containing two tandemly arrayed cysteine-rich receptor-like protein kinase genes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Powdery mildew (PM) is a severe fungal disease in cucumber, but the molecular genetic mechanisms of PM resistance in cucumber are still poorly understood. In this study, through marker-assisted backcrossing with an elite susceptible inbred line D8, we developed a single segment substitution line SSS...

  13. Genome-wide association study for crown rust (Puccinia coronata f. sp. avenae) and powdery mildew (Blumeria graminis f. sp. avenae) resistance in an oat (Avena sativa) collection of commercial varieties and landraces.

    PubMed

    Montilla-Bascón, Gracia; Rispail, Nicolas; Sánchez-Martín, Javier; Rubiales, Diego; Mur, Luis A J; Langdon, Tim; Howarth, Catherine J; Prats, Elena

    2015-01-01

    Diseases caused by crown rust (Puccinia coronata f. sp. avenae) and powdery mildew (Blumeria graminis f. sp. avenae) are among the most important constraints for the oat crop. Breeding for resistance is one of the most effective, economical, and environmentally friendly means to control these diseases. The purpose of this work was to identify elite alleles for rust and powdery mildew resistance in oat by association mapping to aid selection of resistant plants. To this aim, 177 oat accessions including white and red oat cultivars and landraces were evaluated for disease resistance and further genotyped with 31 simple sequence repeat and 15,000 Diversity Arrays Technology (DArT) markers to reveal association with disease resistance traits. After data curation, 1712 polymorphic markers were considered for association analysis. Principal component analysis and a Bayesian clustering approach were applied to infer population structure. Five different general and mixed linear models accounting for population structure and/or kinship corrections and two different statistical tests were carried out to reduce false positive. Five markers, two of them highly significant in all models tested were associated with rust resistance. No strong association between any marker and powdery mildew resistance at the seedling stage was identified. However, one DArT sequence, oPt-5014, was strongly associated with powdery mildew resistance in adult plants. Overall, the markers showing the strongest association in this study provide ideal candidates for further studies and future inclusion in strategies of marker-assisted selection. PMID:25798140

  14. A reference genetic map of Muscadinia rotundifolia and identification of Ren5, a new major locus for resistance to grapevine powdery mildew.

    PubMed

    Blanc, Sophie; Wiedemann-Merdinoglu, Sabine; Dumas, Vincent; Mestre, Pere; Merdinoglu, Didier

    2012-12-01

    Muscadinia rotundifolia, a species closely related to cultivated grapevine Vitis vinifera, is a major source of resistance to grapevine downy and powdery mildew, two major threats to cultivated traditional cultivars of V. vinifera respectively caused by the oomycete Plasmopara viticola and the ascomycete Erisyphe necator. The aim of the present work was to develop a reference genetic linkage map based on simple sequence repeat (SSR) markers for M. rotundifolia. This map was created using S1 M. rotundifolia cv. Regale progeny, and covers 948 cM on 20 linkage groups, which corresponds to the expected chromosome number for muscadine. The comparison of the genetic maps of V. vinifera and M. rotundifolia revealed a high macrosynteny between the genomes of both species. The S1 progeny was used to assess the general level of resistance of M. rotundifolia to P. viticola and E. necator, by scoring different parameters of pathogen development. A quantitative trait locus (QTL) analysis allowed us to highlight a major QTL on linkage group 14 controlling resistance to powdery mildew, which explained up to 58 % of the total phenotypic variance. This QTL was named 'Resistance to Erysiphe Necator 5' (Ren5). A microscopic evaluation E. necator mycelium development on resistant and susceptible genotypes of the S1 progeny showed that Ren5 exerts its action after the formation of the first appressorium, and acts by delaying, and then stopping, mycelium development. PMID:22865124

  15. Ectopic expression of a grape aspartic protease gene, AP13, in Arabidopsis thaliana improves resistance to powdery mildew but increases susceptibility to Botrytis cinerea.

    PubMed

    Guo, Rongrong; Tu, Mingxing; Wang, Xianhang; Zhao, Jiao; Wan, Ran; Li, Zhi; Wang, Yuejin; Wang, Xiping

    2016-07-01

    The grape aspartic protease gene, AP13 was previously reported to be responsive, in Chinese wild Vitis quinquangularis cv. 'Shang-24', to infection by Erysiphe necator, the causal agent of powdery mildew disease, as well as to treatment with salicylic acid in V. labrusca×V. vinifera cv. 'Kyoho'. In the current study, we evaluated the expression levels of AP13 in 'Shang-24' in response to salicylic acid (SA), methyl jasmonate (MeJA) and ethylene (ET) treatments, as well as to infection by the necrotrophic fungus, Botrytis cinerea, and the transcript levels of VqAP13 decreased after B. cinerea infection and MeJA treatment, but increased following ET and SA treatments. Transgenic Arabidopsis thaliana lines over-expressing VqAP13 under the control of a constitutive promoter showed enhanced resistance to powdery mildew and to the bacterium Pseudomonas syringae pv. tomato DC3000, and accumulated more callose than wild type plants, while the resistance of transgenic A. thaliana lines to B. cinerea inoculation was reduced. In addition, the expression profiles of various disease resistance- related genes in the transgenic A. thaliana lines following infection by different pathogens were compared to the equivalent profiles in the wild type plants. The results suggest that VqAP13 action promotes the SA dependent signal transduction pathway, but suppresses the JA signal transduction pathway. PMID:27181943

  16. Discovery of a Novel er1 Allele Conferring Powdery Mildew Resistance in Chinese Pea (Pisum sativum L.) Landraces

    PubMed Central

    Sun, Suli; Fu, Haining; Wang, Zhongyi; Duan, Canxing; Zong, Xuxiao; Zhu, Zhendong

    2016-01-01

    Pea powdery mildew, caused by Erysiphe pisi D.C., is an important disease worldwide. Deployment of resistant varieties is the main way to control this disease. This study aimed to screen Chinese pea (Pisum sativum L.) landraces resistant to E. pisi, and to characterize the resistance gene(s) at the er1 locus in the resistant landraces, and to develop functional marker(s) specific to the novel er1 allele. The 322 landraces showed different resistance levels. Among them, 12 (3.73%), 4 (1.24%) and 17 (5.28%) landraces showed immunity, high resistance and resistance to E. pisi, respectively. The other landraces appeared susceptible or highly susceptible to E. pisi. Most of the immune and highly resistant landraces were collected from Yunnan province. To characterize the resistance gene at the er1 locus, cDNA sequences of PsMLO1 gene were determined in 12 immune and four highly resistant accessions. The cDNAs of PsMLO1 from the immune landrace G0005576 produced three distinct transcripts, characterized by a 129-bp deletion, and 155-bp and 220-bp insertions, which were consistent with those of er1-2 allele. The PsMLO1 cDNAs in the other 15 resistant landraces produced identical transcripts, which had a new point mutation (T→C) at position 1121 of PsMLO1, indicating a novel er1 allele, designated as er1-6. This mutation caused a leucine to proline change in the amino acid sequence. Subsequently, the resistance allele er1-6 in landrace G0001778 was confirmed by resistance inheritance analysis and genetic mapping on the region of the er1 locus using populations derived from G0001778 × Bawan 6. Finally, a functional marker specific to er1-6, SNP1121, was developed using the high-resolution melting technique, which could be used in pea breeding via marker-assisted selection. The results described here provide valuable genetic information for Chinese pea landraces and a powerful tool for pea breeders. PMID:26809053

  17. Natural Selection Causes Adaptive Genetic Resistance in Wild Emmer Wheat against Powdery Mildew at “Evolution Canyon” Microsite, Mt. Carmel, Israel

    PubMed Central

    Yin, Huayan; Ben-Abu, Yuval; Wang, Hongwei; Li, Anfei; Nevo, Eviatar; Kong, Lingrang

    2015-01-01

    Background “Evolution Canyon” (ECI) at Lower Nahal Oren, Mount Carmel, Israel, is an optimal natural microscale model for unraveling evolution in action highlighting the basic evolutionary processes of adaptation and speciation. A major model organism in ECI is wild emmer, Triticum dicoccoides, the progenitor of cultivated wheat, which displays dramatic interslope adaptive and speciational divergence on the tropical-xeric “African” slope (AS) and the temperate-mesic “European” slope (ES), separated on average by 250 m. Methods We examined 278 single sequence repeats (SSRs) and the phenotype diversity of the resistance to powdery mildew between the opposite slopes. Furthermore, 18 phenotypes on the AS and 20 phenotypes on the ES, were inoculated by both Bgt E09 and a mixture of powdery mildew races. Results In the experiment of genetic diversity, very little polymorphism was identified intra-slope in the accessions from both the AS or ES. By contrast, 148 pairs of SSR primers (53.23%) amplified polymorphic products between the phenotypes of AS and ES. There are some differences between the two wild emmer wheat genomes and the inter-slope SSR polymorphic products between genome A and B. Interestingly, all wild emmer types growing on the south-facing slope (SFS=AS) were susceptible to a composite of Blumeria graminis, while the ones growing on the north-facing slope (NFS=ES) were highly resistant to Blumeria graminis at both seedling and adult stages. Conclusion/Significance Remarkable inter-slope evolutionary divergent processes occur in wild emmer wheat, T. dicoccoides at EC I, despite the shot average distance of 250 meters. The AS, a dry and hot slope, did not develop resistance to powdery mildew, whereas the ES, a cool and humid slope, did develop resistance since the disease stress was strong there. This is a remarkable demonstration in host-pathogen interaction on how resistance develops when stress causes an adaptive result at a micro

  18. TaCPK2-A, a calcium-dependent protein kinase gene that is required for wheat powdery mildew resistance enhances bacterial blight resistance in transgenic rice.

    PubMed

    Geng, Shuaifeng; Li, Aili; Tang, Lichuan; Yin, Lingjie; Wu, Liang; Lei, Cailin; Guo, Xiuping; Zhang, Xin; Jiang, Guanghuai; Zhai, Wenxue; Wei, Yuming; Zheng, Youliang; Lan, Xiujin; Mao, Long

    2013-08-01

    Calcium-dependent protein kinases (CPKs) are important Ca2+ signalling components involved in complex immune and stress signalling networks; but the knowledge of CPK gene functions in the hexaploid wheat is limited. Previously, TaCPK2 was shown to be inducible by powdery mildew (Blumeria graminis tritici, Bgt) infection in wheat. Here, its functions in disease resistance are characterized further. This study shows the presence of defence-response and cold-response cis-elements on the promoters of the A subgenome homoeologue (TaCPK2-A) and D subgenome homoeologue (TaCPK2-D), respectively. Their expression patterns were then confirmed by quantitative real-time PCR (qRT-PCR) using genome-specific primers, where TaCPK2-A was induced by Bgt treatment while TaCPK2-D mainly responded to cold treatment. Downregulation of TaCPK2-A by virus-induced gene silencing (VIGS) causes loss of resistance to Bgt in resistant wheat lines, indicating that TaCPK2-A is required for powdery mildew resistance. Furthermore, overexpression of TaCPK2-A in rice enhanced bacterial blight (Xanthomonas oryzae pv. oryzae, Xoo) resistance. qRT-PCR analysis showed that overexpression of TaCPK2-A in rice promoted the expression of OsWRKY45-1, a transcription factor involved in both fungal and bacterial resistance by regulating jasmonic acid and salicylic acid signalling genes. The opposite effect was found in wheat TaCPK2-A VIGS plants, where the homologue of OsWRKY45-1 was significantly repressed. These data suggest that modulation of WRKY45-1 and associated defence-response genes by CPK2 genes may be the common mechanism for multiple disease resistance in grass species, which may have undergone subfunctionalization in promoters before the formation of hexaploid wheat. PMID:23918959

  19. Transcriptome analysis of genes related to resistance against powdery mildew in wheat-Thinopyrum alien addition disomic line germplasm SN6306.

    PubMed

    Li, Quanquan; Niu, Zubiao; Bao, Yinguang; Tian, Qiuju; Wang, Honggang; Kong, Lingrang; Feng, Deshun

    2016-09-15

    Wheat powdery mildew, which is mainly caused by Blumeria graminis f. sp. tritici (Bgt), seriously damages wheat production. The wheat-Thinopyrum intermedium alien addition disomic line germplasm SN6306, being one of the important sources of genes for wheat resistance, is highly resistant to Bgt E09 and to many other powdery mildew physiological races. However, knowledge on the resistance mechanism of SN6306 remains limited. Our study employed high-throughput RNA sequencing based on next-generation sequencing technology (Illumina) to obtain an overview of the transcriptome characteristics of SN6306 and its parent wheat Yannong 15 (YN15) during Bgt infection. The sequencing generated 104,773 unigenes, 9909 of which showed varied expression levels. Among the 9909 unigenes, 1678 unigenes showed 0 reads in YN15. The expression levels in Bgt-inoculated SN6306 and YN15 of exactly 39 unigenes that showed 0 or considerably low reads in YN15 were validated to identify the genes involved in Bgt resistance. Among the 39 unigenes, 12 unigenes were upregulated in SN6306 by 3-45 times. These unigenes mainly encoded kinase, synthase, proteases, and signal transduction proteins, which may play an important role in the resistance against Bgt. To confirm whether the unigenes that showed 0 reads in YN15 are really unique to SN6306, 8 unigenes were cloned and sequenced. Results showed that the selected unigenes are more similar to SN6306 and Th. intermedium than to the wheat cultivar YN15. The sequencing results further confirmed that the unigenes showing 0 reads in YN15 are unique to SN6306 and are most likely derived from Th. intermedium (Host) Nevski. Thus, the genes from Th. intermedium most probably conferred the resistance of SN6306 to Bgt. PMID:27265028

  20. The antagonistic strain Bacillus subtilis UMAF6639 also confers protection to melon plants against cucurbit powdery mildew by activation of jasmonate- and salicylic acid-dependent defence responses.

    PubMed

    García-Gutiérrez, Laura; Zeriouh, Houda; Romero, Diego; Cubero, Jaime; de Vicente, Antonio; Pérez-García, Alejandro

    2013-05-01

    Biological control of plant diseases has gained acceptance in recent years. Bacillus subtilis UMAF6639 is an antagonistic strain specifically selected for the efficient control of the cucurbit powdery mildew fungus Podosphaera fusca, which is a major threat to cucurbits worldwide. The antagonistic activity relies on the production of the antifungal compounds iturin and fengycin. In a previous study, we found that UMAF6639 was able to induce systemic resistance (ISR) in melon and provide additional protection against powdery mildew. In the present work, we further investigated in detail this second mechanism of biocontrol by UMAF6639. First, we examined the signalling pathways elicited by UMAF6639 in melon plants, as well as the defence mechanisms activated in response to P. fusca. Second, we analysed the role of the lipopeptides produced by UMAF6639 as potential determinants for ISR activation. Our results demonstrated that UMAF6639 confers protection against cucurbit powdery mildew by activation of jasmonate- and salicylic acid-dependent defence responses, which include the production of reactive oxygen species and cell wall reinforcement. We also showed that surfactin lipopeptide is a major determinant for stimulation of the immune response. These results reinforce the biotechnological potential of UMAF6639 as a biological control agent. PMID:23302493

  1. The antagonistic strain Bacillus subtilis UMAF6639 also confers protection to melon plants against cucurbit powdery mildew by activation of jasmonate-and salicylic acid-dependent defence responses

    PubMed Central

    García-Gutiérrez, Laura; Zeriouh, Houda; Romero, Diego; Cubero, Jaime; Vicente, Antonio; Pérez-García, Alejandro

    2013-01-01

    Biological control of plant diseases has gained acceptance in recent years. Bacillus subtilis UMAF6639 is an antagonistic strain specifically selected for the efficient control of the cucurbit powdery mildew fungus Podosphaera fusca, which is a major threat to cucurbits worldwide. The antagonistic activity relies on the production of the antifungal compounds iturin and fengycin. In a previous study, we found that UMAF6639 was able to induce systemic resistance (ISR) in melon and provide additional protection against powdery mildew. In the present work, we further investigated in detail this second mechanism of biocontrol by UMAF6639. First, we examined the signalling pathways elicited by UMAF6639 in melon plants, as well as the defence mechanisms activated in response to P. fusca. Second, we analysed the role of the lipopeptides produced by UMAF6639 as potential determinants for ISR activation. Our results demonstrated that UMAF6639 confers protection against cucurbit powdery mildew by activation of jasmonate- and salicylic acid-dependent defence responses, which include the production of reactive oxygen species and cell wall reinforcement. We also showed that surfactin lipopeptide is a major determinant for stimulation of the immune response. These results reinforce the biotechnological potential of UMAF6639 as a biological control agent. PMID:23302493

  2. Expression of a Grapevine NAC Transcription Factor Gene Is Induced in Response to Powdery Mildew Colonization in Salicylic Acid-Independent Manner.

    PubMed

    Toth, Zsofia; Winterhagen, Patrick; Kalapos, Balazs; Su, Yingcai; Kovacs, Laszlo; Kiss, Erzsebet

    2016-01-01

    Tissue colonization by grape powdery mildew (PM) pathogen Erysiphe necator (Schw.) Burr triggers a major remodeling of the transcriptome in the susceptible grapevine Vitis vinifera L. While changes in the expression of many genes bear the signature of salicylic acid (SA) mediated regulation, the breadth of PM-induced changes suggests the involvement of additional regulatory networks. To explore PM-associated gene regulation mediated by other SA-independent systems, we designed a microarray experiment to distinguish between transcriptome changes induced by E. necator colonization and those triggered by elevated SA levels. We found that the majority of genes responded to both SA and PM, but certain genes were responsive to PM infection alone. Among them, we identified genes of stilbene synthases, PR-10 proteins, and several transcription factors. The microarray results demonstrated that the regulation of these genes is either independent of SA, or dependent, but SA alone is insufficient to bring about their regulation. We inserted the promoter-reporter fusion of a PM-responsive transcription factor gene into a wild-type and two SA-signaling deficient Arabidopsis lines and challenged the resulting transgenic plants with an Arabidopsis-adapted PM pathogen. Our results provide experimental evidence that this grape gene promoter is activated by the pathogen in a SA-independent manner. PMID:27488171

  3. Down-regulation of Arabidopsis DND1 orthologs in potato and tomato leads to broad-spectrum resistance to late blight and powdery mildew.

    PubMed

    Sun, Kaile; Wolters, Anne-Marie A; Loonen, Annelies E H M; Huibers, Robin P; van der Vlugt, René; Goverse, Aska; Jacobsen, Evert; Visser, Richard G F; Bai, Yuling

    2016-04-01

    Multiple susceptibility genes (S), identified in Arabidopsis, have been shown to be functionally conserved in crop plants. Mutations in these S genes result in resistance to different pathogens, opening a new way to achieve plant disease resistance. The aim of this study was to investigate the role of Defense No Death 1 (DND1) in susceptibility of tomato and potato to late blight (Phytophthora infestans). In Arabidopsis, the dnd1 mutant has broad-spectrum resistance against several fungal, bacterial, and viral pathogens. However this mutation is also associated with a dwarfed phenotype. Using an RNAi approach, we silenced AtDND1 orthologs in potato and tomato. Our results showed that silencing of the DND1 ortholog in both crops resulted in resistance to the pathogenic oomycete P. infestans and to two powdery mildew species, Oidium neolycopersici and Golovinomyces orontii. The resistance to P. infestans in potato was effective to four different isolates although the level of resistance (complete or partial) was dependent on the aggressiveness of the isolate. In tomato, DND1-silenced plants showed a severe dwarf phenotype and autonecrosis, whereas DND1-silenced potato plants were not dwarfed and showed a less pronounced autonecrosis. Our results indicate that S gene function of DND1 is conserved in tomato and potato. We discuss the possibilities of using RNAi silencing or loss-of-function mutations of DND1 orthologs, as well as additional S gene orthologs from Arabidopsis, to breed for resistance to pathogens in crop plants. PMID:26577903

  4. Ribosomal DNA internal transcribed spacer sequences do not support the species status of Ampelomyces quisqualis, a hyperparasite of powdery mildew fungi.

    PubMed

    Kiss, L; Nakasone, K K

    1998-05-01

    Phylogenetic relationships among Ampelomyces isolates, pycnidial hyperparasites and biological control agents of powdery mildews, were inferred from internal transcribed spacer (ITS) sequences of the ribosomal DNA (rDNA). Currently, these hyperparasites are considered to be a single species, A. quisqualis, despite observed morphological and cultural differences. Ten Ampelomyces isolates, representing seven previously defined ITS RFLP groups, were sequenced and analyzed. Sequence-divergence values among isolates belonging to different RFLP groups ranged from 4.3 to 22.4%, suggesting that these isolates may represent different taxa. When Ampelomyces ITS sequences were analyzed by cladistic methods with the sequences of other ascomycetous fungi, they formed two lineages in the Dothideales. Slow-growing Ampelomyces isolates formed a clade with Leptosphaeria microscopica and L. nodorum, whereas fast-growing Ampelomyces isolates formed a clade with Epicoccum nigrum. Sequence-divergence values between these two clades ranged from 17.3 to 22.4%, suggesting that the taxa in the two clades are not closely related and possibly not congeneric. The data presented here indicate that the identification of 'A. quisqualis' isolates used in biological control experiments should be re-evaluated. PMID:9618587

  5. Expression of a Grapevine NAC Transcription Factor Gene Is Induced in Response to Powdery Mildew Colonization in Salicylic Acid-Independent Manner

    PubMed Central

    Toth, Zsofia; Winterhagen, Patrick; Kalapos, Balazs; Su, Yingcai; Kovacs, Laszlo; Kiss, Erzsebet

    2016-01-01

    Tissue colonization by grape powdery mildew (PM) pathogen Erysiphe necator (Schw.) Burr triggers a major remodeling of the transcriptome in the susceptible grapevine Vitis vinifera L. While changes in the expression of many genes bear the signature of salicylic acid (SA) mediated regulation, the breadth of PM-induced changes suggests the involvement of additional regulatory networks. To explore PM-associated gene regulation mediated by other SA-independent systems, we designed a microarray experiment to distinguish between transcriptome changes induced by E. necator colonization and those triggered by elevated SA levels. We found that the majority of genes responded to both SA and PM, but certain genes were responsive to PM infection alone. Among them, we identified genes of stilbene synthases, PR-10 proteins, and several transcription factors. The microarray results demonstrated that the regulation of these genes is either independent of SA, or dependent, but SA alone is insufficient to bring about their regulation. We inserted the promoter-reporter fusion of a PM-responsive transcription factor gene into a wild-type and two SA-signaling deficient Arabidopsis lines and challenged the resulting transgenic plants with an Arabidopsis-adapted PM pathogen. Our results provide experimental evidence that this grape gene promoter is activated by the pathogen in a SA-independent manner. PMID:27488171

  6. The knottin-like Blufensin family regulates genes involved in nuclear import and the secretory pathway in barley-powdery mildew interactions

    PubMed Central

    Xu, Weihui; Meng, Yan; Surana, Priyanka; Fuerst, Greg; Nettleton, Dan; Wise, Roger P.

    2015-01-01

    Plants have evolved complex regulatory mechanisms to control a multi-layered defense response to microbial attack. Both temporal and spatial gene expression are tightly regulated in response to pathogen ingress, modulating both positive and negative control of defense. BLUFENSINs, small knottin-like peptides in barley, wheat, and rice, are highly induced by attack from fungal pathogens, in particular, the obligate biotrophic fungus, Blumeria graminis f. sp. hordei (Bgh), causal agent of barley powdery mildew. Previous research indicated that Blufensin1 (Bln1) functions as a negative regulator of basal defense mechanisms. In the current report, we show that BLN1 and BLN2 can both be secreted to the apoplast and Barley stripe mosaic virus (BSMV)-mediated overexpression of Bln2 increases susceptibility of barley to Bgh. Bimolecular fluorescence complementation (BiFC) assays signify that BLN1 and BLN2 can interact with each other, and with calmodulin. We then used BSMV-induced gene silencing to knock down Bln1, followed by Barley1 GeneChip transcriptome analysis, to identify additional host genes influenced by Bln1. Analysis of differential expression revealed a gene set enriched for those encoding proteins annotated to nuclear import and the secretory pathway, particularly Importin α1-b and Sec61 γ subunits. Further functional analysis of these two affected genes showed that when silenced, they also reduced susceptibility to Bgh. Taken together, we postulate that Bln1 is co-opted by Bgh to facilitate transport of disease-related host proteins or effectors, influencing the establishment of Bgh compatibility on its barley host. PMID:26089830

  7. Silicon-mediated resistance of Arabidopsis against powdery mildew involves mechanisms other than the salicylic acid (SA)-dependent defence pathway.

    PubMed

    Vivancos, Julien; Labbé, Caroline; Menzies, James G; Bélanger, Richard R

    2015-08-01

    On absorption by plants, silicon (Si) offers protection against many fungal pathogens, including powdery mildews. The mechanisms by which Si exerts its prophylactic role remain enigmatic, although a prevailing hypothesis suggests that Si positively influences priming. Attempts to decipher Si properties have been limited to plants able to absorb Si, which excludes the model plant Arabidopsis because it lacks Si influx transporters. In this work, we were able to engineer Arabidopsis plants with an Si transporter from wheat (TaLsi1) and to exploit mutants (pad4 and sid2) deficient in salicylic acid (SA)-dependent defence responses to study their phenotypic response and changes in defence expression against Golovinomyces cichoracearum (Gc) following Si treatment. Our results showed that TaLsi1 plants contained significantly more Si and were significantly more resistant to Gc infection than control plants when treated with Si, the first such demonstration in a plant transformed with a heterologous Si transporter. The resistant plants accumulated higher levels of SA and expressed higher levels of transcripts encoding defence genes, thus suggesting a role for Si in the process. However, TaLsi1 pad4 and TaLsi1 sid2 plants were also more resistant to Gc than were pad4 and sid2 plants following Si treatment. Analysis of the resistant phenotypes revealed a significantly reduced production of SA and expression of defence genes comparable with susceptible controls. These results indicate that Si contributes to Arabidopsis defence priming following pathogen infection, but highlight that Si will confer protection even when priming is altered. We conclude that Si-mediated protection involves mechanisms other than SA-dependent defence responses. PMID:25346281

  8. Broadly Conserved Fungal Effector BEC1019 Suppresses Host Cell Death and Enhances Pathogen Virulence in Powdery Mildew of Barley (Hordeum vulgare L.).

    PubMed

    Whigham, Ehren; Qi, Shan; Mistry, Divya; Surana, Priyanka; Xu, Ruo; Fuerst, Gregory; Pliego, Clara; Bindschedler, Laurence V; Spanu, Pietro D; Dickerson, Julie A; Innes, Roger W; Nettleton, Dan; Bogdanove, Adam J; Wise, Roger P

    2015-09-01

    The interaction of barley, Hordeum vulgare L., with the powdery mildew fungus Blumeria graminis f. sp. hordei is a well-developed model to investigate resistance and susceptibility to obligate biotrophic pathogens. The 130-Mb Blumeria genome encodes approximately 540 predicted effectors that are hypothesized to suppress or induce host processes to promote colonization. Blumeria effector candidate (BEC)1019, a single-copy gene encoding a putative, secreted metalloprotease, is expressed in haustorial feeding structures, and host-induced gene silencing of BEC1019 restricts haustorial development in compatible interactions. Here, we show that Barley stripe mosaic virus-induced gene silencing of BEC1019 significantly reduces fungal colonization of barley epidermal cells, demonstrating that BEC1019 plays a central role in virulence. In addition, delivery of BEC1019 to the host cytoplasm via Xanthomonas type III secretion suppresses cultivar nonspecific hypersensitive reaction (HR) induced by Xanthomonas oryzae pv. oryzicola, as well as cultivar-specific HR induced by AvrPphB from Pseudomonas syringae pv. phaseolicola. BEC1019 homologs are present in 96 of 241 sequenced fungal genomes, including plant pathogens, human pathogens, and free-living nonpathogens. Comparative analysis revealed variation at several amino acid positions that correlate with fungal lifestyle and several highly conserved, noncorrelated motifs. Site-directed mutagenesis of one of these, ETVIC, compromises the HR-suppressing activity of BEC1019. We postulate that BEC1019 represents an ancient, broadly important fungal protein family, members of which have evolved to function as effectors in plant and animal hosts. PMID:25938194

  9. Wheat gene bank accessions as a source of new alleles of the powdery mildew resistance gene Pm3: a large scale allele mining project

    PubMed Central

    2010-01-01

    Background In the last hundred years, the development of improved wheat cultivars has led to the replacement of landraces and traditional varieties by modern cultivars. This has resulted in a decline in the genetic diversity of agriculturally used wheat. However, the diversity lost in the elite material is somewhat preserved in crop gene banks. Therefore, the gene bank accessions provide the basis for genetic improvement of crops for specific traits and and represent rich sources of novel allelic variation. Results We have undertaken large scale molecular allele mining to isolate new alleles of the powdery mildew resistance gene Pm3 from wheat gene bank accessions. The search for new Pm3 alleles was carried out on a geographically diverse set of 733 wheat accessions originating from 20 countries. Pm3 specific molecular tools as well as classical pathogenicity tests were used to characterize the accessions. Two new functional Pm3 alleles were identified out of the eight newly cloned Pm3 sequences. These new resistance alleles were isolated from accessions from China and Nepal. Thus, the repertoire of functional Pm3 alleles now includes 17 genes, making it one of the largest allelic series of plant resistance genes. The combined information on resistant and susceptible Pm3 sequences will allow to study molecular function and specificity of functional Pm3 alleles. Conclusions This study demonstrates that molecular allele mining on geographically defined accessions is a useful strategy to rapidly characterize the diversity of gene bank accessions at a specific genetic locus of agronomical importance. The identified wheat accessions with new resistance specificities can be used for marker-assisted transfer of the Pm3 alleles to modern wheat lines. PMID:20470444

  10. Temporal global expression data reveal known and novel salicylate-impacted processes and regulators mediating powdery mildew growth and reproduction on Arabidopsis.

    PubMed

    Chandran, Divya; Tai, Yu Chuan; Hather, Gregory; Dewdney, Julia; Denoux, Carine; Burgess, Diane G; Ausubel, Frederick M; Speed, Terence P; Wildermuth, Mary C

    2009-03-01

    Salicylic acid (SA) is a critical mediator of plant innate immunity. It plays an important role in limiting the growth and reproduction of the virulent powdery mildew (PM) Golovinomyces orontii on Arabidopsis (Arabidopsis thaliana). To investigate this later phase of the PM interaction and the role played by SA, we performed replicated global expression profiling for wild-type and SA biosynthetic mutant isochorismate synthase1 (ics1) Arabidopsis from 0 to 7 d after infection. We found that ICS1-impacted genes constitute 3.8% of profiled genes, with known molecular markers of Arabidopsis defense ranked very highly by the multivariate empirical Bayes statistic (T(2) statistic). Functional analyses of T(2)-selected genes identified statistically significant PM-impacted processes, including photosynthesis, cell wall modification, and alkaloid metabolism, that are ICS1 independent. ICS1-impacted processes include redox, vacuolar transport/secretion, and signaling. Our data also support a role for ICS1 (SA) in iron and calcium homeostasis and identify components of SA cross talk with other phytohormones. Through our analysis, 39 novel PM-impacted transcriptional regulators were identified. Insertion mutants in one of these regulators, PUX2 (for plant ubiquitin regulatory X domain-containing protein 2), results in significantly reduced reproduction of the PM in a cell death-independent manner. Although little is known about PUX2, PUX1 acts as a negative regulator of Arabidopsis CDC48, an essential AAA-ATPase chaperone that mediates diverse cellular activities, including homotypic fusion of endoplasmic reticulum and Golgi membranes, endoplasmic reticulum-associated protein degradation, cell cycle progression, and apoptosis. Future work will elucidate the functional role of the novel regulator PUX2 in PM resistance. PMID:19176722