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Possamai T, Wiedemann-Merdinoglu S. Phenotyping for QTL identification: A case study of resistance to Plasmopara viticola and Erysiphe necator in grapevine. FRONTIERS IN PLANT SCIENCE 2022; 13:930954. [PMID: 36035702 PMCID: PMC9403010 DOI: 10.3389/fpls.2022.930954] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 06/27/2022] [Indexed: 06/01/2023]
Abstract
Vitis vinifera is the most widely cultivated grapevine species. It is highly susceptible to Plasmopara viticola and Erysiphe necator, the causal agents of downy mildew (DM) and powdery mildew (PM), respectively. Current strategies to control DM and PM mainly rely on agrochemical applications that are potentially harmful to humans and the environment. Breeding for resistance to DM and PM in wine grape cultivars by introgressing resistance loci from wild Vitis spp. is a complementary and more sustainable solution to manage these two diseases. During the last two decades, 33 loci of resistance to P. viticola (Rpv) and 15 loci of resistance to E. necator (Ren and Run) have been identified. Phenotyping is salient for QTL characterization and understanding the genetic basis of resistant traits. However, phenotyping remains a major bottleneck for research on Rpv and Ren/Run loci and disease resistance evaluation. A thorough analysis of the literature on phenotyping methods used for DM and PM resistance evaluation highlighted phenotyping performed in the vineyard, greenhouse or laboratory with major sources of variation, such as environmental conditions, plant material (organ physiology and age), pathogen inoculum (genetic and origin), pathogen inoculation (natural or controlled), and disease assessment method (date, frequency, and method of scoring). All these factors affect resistance assessment and the quality of phenotyping data. We argue that the use of new technologies for disease symptom assessment, and the production and adoption of standardized experimental guidelines should enhance the accuracy and reliability of phenotyping data. This should contribute to a better replicability of resistance evaluation outputs, facilitate QTL identification, and contribute to streamline disease resistance breeding programs.
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Affiliation(s)
- Tyrone Possamai
- CREA—Research Centre for Viticulture and Enology, Conegliano, Italy
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Gur L, Reuveni M, Cohen Y, Cadle-Davidson L, Kisselstein B, Ovadia S, Frenkel O. Population structure of Erysiphe necator on domesticated and wild vines in the Middle East raises questions on the origin of the grapevine powdery mildew pathogen. Environ Microbiol 2021; 23:6019-6037. [PMID: 33459475 DOI: 10.1111/1462-2920.15401] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 11/28/2022]
Abstract
Plant pathogens usually originate and diversify in geographical regions where hosts and pathogens co-evolve. Erysiphe necator, the causal agent of grape powdery mildew, is a destructive pathogen of grapevines worldwide. Although Eastern US is considered the centre of origin and diversity of E. necator, previous reports on resistant native wild and domesticated Asian grapevines suggest Asia as another possible origin of the pathogen. By using multi-locus sequencing, microsatellites and a novel application of amplicon sequencing (AmpSeq), we show that the population of E. necator in Israel is composed of three genetic groups: Groups A and B that are common worldwide, and a new group IL, which is genetically differentiated from any known group in Europe and Eastern US. Group IL showed distinguished ecological characteristics: it was dominant on wild and traditional vines (95%); its abundance increased along the season; and was more aggressive than A and B isolates on both wild and domesticated vines. The low genetic diversity within group IL suggests that it has invaded Israel from another origin. Therefore, we suggest that the Israeli E. necator population was founded by at least two invasions, of which one could be from a non-East American source, possibly from Asian origin.
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Affiliation(s)
- Lior Gur
- Shamir Research Institute, University of Haifa, Katzrin, Israel.,Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel.,Department of Plant Pathology and Weed Research, Agricultural Research Organization (ARO), The Volcani Center, Rishon Lezion, Israel
| | - Moshe Reuveni
- Shamir Research Institute, University of Haifa, Katzrin, Israel
| | - Yigal Cohen
- Faculty of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
| | - Lance Cadle-Davidson
- USDA Agricultural Research Service, Geneva, NY, USA.,School of Integrative Plant Sciences, Cornell AgriTech, Geneva, NY, USA
| | - Breanne Kisselstein
- USDA Agricultural Research Service, Geneva, NY, USA.,School of Integrative Plant Sciences, Cornell AgriTech, Geneva, NY, USA
| | | | - Omer Frenkel
- Department of Plant Pathology and Weed Research, Agricultural Research Organization (ARO), The Volcani Center, Rishon Lezion, Israel
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Précigout PA, Claessen D, Makowski D, Robert C. Does the Latent Period of Leaf Fungal Pathogens Reflect Their Trophic Type? A Meta-Analysis of Biotrophs, Hemibiotrophs, and Necrotrophs. PHYTOPATHOLOGY 2020; 110:345-361. [PMID: 31577162 DOI: 10.1094/phyto-04-19-0144-r] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We performed a meta-analysis to search for a relation between the trophic type and latent period of fungal pathogens. The pathogen incubation period and the level of resistance of the hosts were also investigated. This ecological knowledge would help us to more efficiently regulate crop epidemics for different types of pathogens. We gathered latent period data from 103 studies dealing with 51 fungal pathogens of the three major trophic types (25 biotrophs, 15 hemibiotrophs, and 11 necrotrophs), representing 2,542 mean latent periods. We show that these three trophic types display significantly different latent periods. Necrotrophs exhibited the shortest latent periods (<100 degree-days [DD]), biotrophs had intermediate ones (between 100 and 200 DD), and hemibiotrophs had the longest latent periods (>200 DD). We argue that this relation between trophic type and latent period points to two opposing host exploitation strategies: necrotrophs mount a rapid destructive attack on the host tissue, whereas biotrophs and hemibiotrophs avoid or delay the damaging phase. We query the definition of hemibiotrophic pathogens and discuss whether the length of the latent period is determined by the physiological limits inherent to each trophic type or by the adaptation of pathogens of different trophic types to the contrasting conditions experienced in their interaction with the host.
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Affiliation(s)
- Pierre-Antoine Précigout
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS-ENS-INSERM UMR8197, Ecole Normale Supérieure, 75005 Paris, France
- UMR EcoSys, Institut National de la Recherche Agronomique (INRA), AgroParisTech, 78850 Thiverval-Grignon, France
| | - David Claessen
- Institut de Biologie de l'Ecole Normale Supérieure, CNRS-ENS-INSERM UMR8197, Ecole Normale Supérieure, 75005 Paris, France
| | - David Makowski
- UMR Agronomie, INRA, AgroParisTech, Université Paris-Saclay, 78850 Thiverval-Grignon, France
| | - Corinne Robert
- UMR EcoSys, Institut National de la Recherche Agronomique (INRA), AgroParisTech, 78850 Thiverval-Grignon, France
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Rezzonico F, Rupp O, Fahrentrapp J. Pathogen recognition in compatible plant-microbe interactions. Sci Rep 2017; 7:6383. [PMID: 28743967 PMCID: PMC5526865 DOI: 10.1038/s41598-017-04792-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 05/19/2017] [Indexed: 12/04/2022] Open
Abstract
Microbial infections in plant leaves remain a major challenge in agriculture. Hence an understanding of disease mechanisms at the molecular level is of paramount importance for identifying possible intervention points for their control. Whole-transcriptome changes during early disease stages in susceptible plant species are less well-documented than those of resistant ones. This study focuses on the differential transcriptional changes at 24 hours post inoculation (hpi) in tomato leaflets affected by three pathogens: (1) Phytophthora infestans, (2) Botrytis cinerea, and (3) Oidium neolycopersici. Grey mould (B. cinerea) was the disease that had progressed the most by 24 hpi, both in terms of visible symptoms as well as differential gene expression. By means of RNA-seq, we identified 50 differentially expressed tomato genes specifically induced by B. cinerea infection and 18 specifically induced by P. infestans infection at 24 hpi. Additionally, a set of 63 genes were differentially expressed during all three diseases when compared by a Bayesian approach to their respective mock infections. And Gene expression patterns were found to also depend on the inoculation technique. These findings suggest a specific and distinct transcriptional response in plant leaf tissue in reaction to B. cinerea and P. infestans invasion at 24 hpi, indicating that plants may recognize the attacking pathogen.
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Affiliation(s)
- Fabio Rezzonico
- Research Group Environmental Genomics and Systems Biology, Zurich University of Applied Sciences, Wädenswil, Switzerland
| | - Oliver Rupp
- Bioinformatics and Systems Biology, Justus-Liebig-University Giessen, Giessen, Germany
| | - Johannes Fahrentrapp
- Research Group for Viticulture, Zurich University of Applied Sciences, Wädenswil, Switzerland.
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Cadle-Davidson L, Gadoury D, Fresnedo-Ramírez J, Yang S, Barba P, Sun Q, Demmings EM, Seem R, Schaub M, Nowogrodzki A, Kasinathan H, Ledbetter C, Reisch BI. Lessons from a Phenotyping Center Revealed by the Genome-Guided Mapping of Powdery Mildew Resistance Loci. PHYTOPATHOLOGY 2016; 106:1159-1169. [PMID: 27135675 DOI: 10.1094/phyto-02-16-0080-fi] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The genomics era brought unprecedented opportunities for genetic analysis of host resistance, but it came with the challenge that accurate and reproducible phenotypes are needed so that genomic results appropriately reflect biology. Phenotyping host resistance by natural infection in the field can produce variable results due to the uncontrolled environment, uneven distribution and genetics of the pathogen, and developmentally regulated resistance among other factors. To address these challenges, we developed highly controlled, standardized methodologies for phenotyping powdery mildew resistance in the context of a phenotyping center, receiving samples of up to 140 grapevine progeny per F1 family. We applied these methodologies to F1 families segregating for REN1- or REN2-mediated resistance and validated that some but not all bioassays identified the REN1 or REN2 locus. A point-intercept method (hyphal transects) to quantify colony density objectively at 8 or 9 days postinoculation proved to be the phenotypic response most reproducibly predicted by these resistance loci. Quantitative trait locus (QTL) mapping with genotyping-by-sequencing maps defined the REN1 and REN2 loci at relatively high resolution. In the reference PN40024 genome under each QTL, nucleotide-binding site-leucine-rich repeat candidate resistance genes were identified-one gene for REN1 and two genes for REN2. The methods described here for centralized resistance phenotyping and high-resolution genetic mapping can inform strategies for breeding resistance to powdery mildews and other pathogens on diverse, highly heterozygous hosts.
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Affiliation(s)
- Lance Cadle-Davidson
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - David Gadoury
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Jonathan Fresnedo-Ramírez
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Shanshan Yang
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Paola Barba
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Qi Sun
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Elizabeth M Demmings
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Robert Seem
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Michelle Schaub
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Anna Nowogrodzki
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Hema Kasinathan
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Craig Ledbetter
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
| | - Bruce I Reisch
- First and ninth authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; second, fourth, fifth, seventh, eighth, tenth, eleventh, and thirteenth authors: School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva 14456; third and sixth authors: Bioinformatics Facility, Cornell University, Ithaca, NY 14853; and twelfth author: USDA-ARS, Crop Disease, Pests and Genetics Unit, Parlier, CA 93648
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Barba P, Cadle-Davidson L, Galarneau E, Reisch B. Vitis rupestris B38 Confers Isolate-Specific Quantitative Resistance to Penetration by Erysiphe necator. PHYTOPATHOLOGY 2015; 105:1097-103. [PMID: 26039640 DOI: 10.1094/phyto-09-14-0260-r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Vitis rupestris B38 is a North American grapevine resistant to the major pathogen of cultivated grapevines, Erysiphe necator. Sources of powdery mildew resistance, like V. rotundifolia, are widely used in grape breeding but are already threatened, even before commercialization, by isolates that can reproduce on Run1 and other rotundifolia-derived breeding lines. Thus, complementary sources of resistance are needed to improve resistance durability. The segregation of foliar powdery mildew severity in an F1 family, derived from a cross of V. rupestris B38×V. vinifera 'Chardonnay', was observed in the field over three growing seasons and in potted vines following single-isolate inoculation. A pattern of continuous variation was observed in every instance. Mechanisms of resistance were analyzed on the resistant and susceptible parent by using microscopy to quantify the ability of the pathogen to penetrate and to form a colony on detached leaves. While 'Chardonnay' was susceptible in all tested conditions, V. rupestris B38 resistance was characterized by a reduction in pathogen penetration, with an effect of leaf position and significant differences among powdery mildew isolates. Segregation of the ability of the pathogen to penetrate and form a colony in F1 individuals showed a pattern of quantitative penetration resistance with no delay or restriction on colony formation once penetration has been achieved. Moreover, V. rupestris B38 showed an enhanced penetration resistance to a powdery mildew isolate with the ability to overcome the Run1 gene, making it an interesting resistance source to prolong the durability of this gene.
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Affiliation(s)
- Paola Barba
- First author: Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853; second and third authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; and fourth author: Horticulture Section, School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456
| | - Lance Cadle-Davidson
- First author: Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853; second and third authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; and fourth author: Horticulture Section, School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456
| | - Erin Galarneau
- First author: Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853; second and third authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; and fourth author: Horticulture Section, School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456
| | - Bruce Reisch
- First author: Plant Breeding and Genetics Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853; second and third authors: U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), Grape Genetics Research Unit, Geneva, NY 14456; and fourth author: Horticulture Section, School of Integrative Plant Science, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456
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Frenkel O, Cadle-Davidson L, Wilcox WF, Milgroom MG. Mechanisms of Resistance to an Azole Fungicide in the Grapevine Powdery Mildew Fungus, Erysiphe necator. PHYTOPATHOLOGY 2015; 105:370-7. [PMID: 25271353 DOI: 10.1094/phyto-07-14-0202-r] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We studied the mechanisms of azole resistance in Erysiphe necator by quantifying the sensitivity to myclobutanil (EC50) in 65 isolates from the eastern United States and 12 from Chile. From each isolate, we sequenced the gene for sterol 14α-demethylase (CYP51), and measured the expression of CYP51 and homologs of four putative efflux transporter genes, which we identified in the E. necator transcriptome. Sequence variation in CYP51 was relatively low, with sequences of 40 U.S. isolates identical to the reference sequence. Nine U.S. isolates and five from Chile carried a previously identified A to T nucleotide substitution in position 495 (A495T), which results in an amino acid substitution in codon 136 (Y136F) and correlates with high levels of azole resistance. We also found a nucleotide substitution in position 1119 (A1119C) in 15 U.S. isolates, whose mean EC50 value was equivalent to that for the Y136F isolates. Isolates carrying mutation A1119C had significantly greater CYP51 expression, even though A1119C does not affect the CYP51 amino acid sequence. Regression analysis showed no significant effects of the expression of efflux transporter genes on EC50. Both the Y136F mutation in CYP51 and increased CYP51 expression appear responsible for azole resistance in eastern U.S. populations of E. necator.
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Gadoury DM, Cadle-Davidson L, Wilcox WF, Dry IB, Seem RC, Milgroom MG. Grapevine powdery mildew (Erysiphe necator): a fascinating system for the study of the biology, ecology and epidemiology of an obligate biotroph. MOLECULAR PLANT PATHOLOGY 2012; 13:1-16. [PMID: 21726395 PMCID: PMC6638670 DOI: 10.1111/j.1364-3703.2011.00728.x] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
UNLABELLED Few plant pathogens have had a more profound effect on 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 onwards to France in 1847, 'germ theory' was neither understood among the general populace nor even generally accepted within the scientific community. Louis Pasteur had only recently reported the microbial nature of fermentation, and it would be another 30 years before Robert Koch would publish his proofs of the microbial nature of certain animal diseases. However, within 6 years after the arrival of the pathogen, nearly 6 million grape growers in France were routinely applying sulphur to suppress powdery mildew on nearly 2.5 million hectares of vineyards (Campbell, 2006). The pathogen has remained a focus for disease management efforts ever since. Because of the worldwide importance of the crop and its susceptibility to the disease, and because conventional management with modern, organic fungicides has been compromised on several occasions since 1980 by the evolution of fungicide resistance, there has also been a renewed effort worldwide to explore the pathogen's biology and ecology, its genetics and molecular interactions with host plants, and to refine current and suggest new management strategies. These latter aspects are the subject of our review. TAXONOMY The most widely accepted classification follows. Family Erysiphaceae, Erysiphe necator Schw. [syn. Uncinula necator (Schw.) Burr., E. tuckeri Berk., U. americana Howe and U. spiralis Berk. & Curt; anamorph Oidium tuckeri Berk.]. Erysiphe necator var. ampelopsidis was found on Parthenocissus spp. in North America according to Braun (1987), although later studies revealed isolates whose host range spanned genera, making the application of this taxon somewhat imprecise (Gadoury and Pearson, 1991). The classification of the genera before 1980 was based on features of the mature ascocarp: (i) numbers of asci; and (ii) morphology of the appendages, in particular the appendage tips. The foregoing has been supplanted by phylogeny inferred from the internal transcribed spacer (ITS) of ribosomal DNA sequences (Saenz and Taylor, 1999), which correlates with conidial ontogeny and morphology (Braun et al., 2002). HOST RANGE The pathogen is obligately parasitic on genera within the Vitaceae, including Vitis, Cissus, Parthenocissus and Ampelopsis (Pearson and Gadoury, 1992). The most economically important host is grapevine (Vitis), particularly the European grape, V. vinifera, which is highly susceptible to powdery mildew. Disease symptoms and signs: In the strictest sense, macroscopically visible mildew colonies are signs of the pathogen rather than symptoms resulting from its infection, but, for convenience, we describe the symptoms and signs together as the collective appearance of colonized host tissues. All green tissues of the host may be infected. Ascospore colonies are most commonly found on the lower surface of the first-formed leaves near the bark of the vine, and may be accompanied by a similarly shaped chlorotic spot on the upper surface. Young colonies appear whitish and those that have not yet sporulated show a metallic sheen. They are roughly circular, ranging in size from a few millimetres to a centimetre or more in diameter, and can occur singly or in groups that coalesce to cover much of the leaf. Senescent colonies are greyish, and may bear cleistothecia in various stages of development. Dead epidermal cells often subtend the colonized area, as natural mortality in the mildew colony, the use of fungicides, mycoparasites or resistance responses in the leaf result in the deaths of segments of the mildew colony and infected epidermal cells. Severely affected leaves usually senesce, develop necrotic blotches and fall prematurely. Infection of stems initially produces symptoms similar to those on leaves, but colonies on shoots are eventually killed as periderm forms, producing a dark, web-like scar on the cane (Gadoury et al., 2011). Inflorescences and berries are most susceptible when young, and can become completely coated with whitish mildew. The growth of the berry epidermal tissue stops when severely infected, which may result in splitting as young fruit expand. Berries in a transitional stage between susceptible and resistant (generally between 3 and 4 weeks after anthesis) develop diffuse, nonsporulating mildew colonies only visible under magnification. Diffuse colonies die as berries continue to mature, leaving behind a network of necrotic epidermal cells (Gadoury et al., 2007). Survival over winter as mycelium in buds results in a distinctive foliar symptom. Shoots arising from these buds may be heavily coated with fungal growth, stark white in colour and stand out like white flags in the vine, resulting in the term 'flag shoots'. More commonly, colonization of a flag shoot is less extensive, and infection of a single leaf, or of leaves on one side of the shoot only, is observed (Gadoury et al., 2011).
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Affiliation(s)
- David M Gadoury
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, New York State Agricultural Experiment Station, Geneva, NY 14456, USA.
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Ramming DW, Gabler F, Smilanick JL, Margosan DA, Cadle-Davidson M, Barba P, Mahanil S, Frenkel O, Milgroom MG, Cadle-Davidson L. Identification of race-specific resistance in North American Vitis spp. limiting Erysiphe necator hyphal growth. PHYTOPATHOLOGY 2012; 102:83-93. [PMID: 22165984 DOI: 10.1094/phyto-03-11-0062] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Race-specific resistance against powdery mildews is well documented in small grains but, in other crops such as grapevine, controlled analysis of host-pathogen interactions on resistant plants is uncommon. In the current study, we attempted to confirm powdery mildew resistance phenotypes through vineyard, greenhouse, and in vitro inoculations for test cross-mapping populations for two resistance sources: (i) a complex hybrid breeding line, 'Bloodworth 81-107-11', of at least Vitis rotundifolia, V. vinifera, V. berlandieri, V. rupestris, V. labrusca, and V. aestivalis background; and (ii) Vitis hybrid 'Tamiami' of V. aestivalis and V. vinifera origin. Statistical analysis of vineyard resistance data suggested the segregation of two and three race-specific resistance genes from the two sources, respectively. However, in each population, some resistant progeny were susceptible in greenhouse or in vitro screens, which suggested the presence of Erysiphe necator isolates virulent on progeny segregating for one or more resistance genes. Controlled inoculation of resistant and susceptible progeny with a diverse set of E. necator isolates clearly demonstrated the presence of fungal races differentially interacting with race-specific resistance genes, providing proof of race specificity in the grape powdery mildew pathosystem. Consistent with known race-specific resistance mechanisms, both resistance sources were characterized by programmed cell death of host epidermal cells under appressoria, which arrested or slowed hyphal growth; this response was also accompanied by collapse of conidia, germ tubes, appressoria, and secondary hyphae. The observation of prevalent isolates virulent on progeny with multiple race-specific resistance genes before resistance gene deployment has implications for grape breeding strategies. We suggest that grape breeders should characterize the mechanisms of resistance and pyramid multiple resistance genes with different mechanisms for improved durability.
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Affiliation(s)
- David W Ramming
- United State Department of Agriculture - Agricultural Research Service, Parlier, CA, USA
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Brewer MT, Milgroom MG. Phylogeography and population structure of the grape powdery mildew fungus, Erysiphe necator, from diverse Vitis species. BMC Evol Biol 2010; 10:268. [PMID: 20809968 PMCID: PMC2941690 DOI: 10.1186/1471-2148-10-268] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 09/01/2010] [Indexed: 11/26/2022] Open
Abstract
Background The grape powdery mildew fungus, Erysiphe necator, was introduced into Europe more than 160 years ago and is now distributed everywhere that grapes are grown. To understand the invasion history of this pathogen we investigated the evolutionary relationships between introduced populations of Europe, Australia and the western United States (US) and populations in the eastern US, where E. necator is thought to be native. Additionally, we tested the hypothesis that populations of E. necator in the eastern US are structured based on geography and Vitis host species. Results We sequenced three nuclear gene regions covering 1803 nucleotides from 146 isolates of E. necator collected from the eastern US, Europe, Australia, and the western US. Phylogeographic analyses show that the two genetic groups in Europe represent two separate introductions and that the genetic groups may be derived from eastern US ancestors. Populations from the western US and Europe share haplotypes, suggesting that the western US population was introduced from Europe. Populations in Australia are derived from European populations. Haplotype richness and nucleotide diversity were significantly greater in the eastern US populations than in the introduced populations. Populations within the eastern US are geographically differentiated; however, no structure was detected with respect to host habitat (i.e., wild or cultivated). Populations from muscadine grapes, V. rotundifolia, are genetically distinct from populations from other Vitis host species, yet no differentiation was detected among populations from other Vitis species. Conclusions Multilocus sequencing analysis of the grape powdery mildew fungus is consistent with the hypothesis that populations in Europe, Australia and the western US are derived from two separate introductions and their ancestors were likely from native populations in the eastern US. The invasion history of E. necator follows a pattern consistent with plant-mediated dispersal, however, more exhaustive sampling is required to make more precise conclusions as to origin. E. necator shows no genetic structure across Vitis host species, except with respect to V. rotundifolia.
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Affiliation(s)
- Marin Talbot Brewer
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
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