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

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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Genetic and physical mapping of the grapevine powdery mildew resistance gene, Run1, using a bacterial artificial chromosome library

Theoretical and Applied Genetics ◽

10.1007/s00122-005-2030-8 ◽

2005 ◽

Vol 111 (2) ◽

pp. 370-377 ◽

Cited By ~ 100

Author(s):

C. L. Barker ◽

T. Donald ◽

J. Pauquet ◽

M. B. Ratnaparkhe ◽

A. Bouquet ◽

...

Keyword(s):

Bacterial Artificial Chromosome ◽

Powdery Mildew ◽

Resistance Gene ◽

Physical Mapping ◽

Bacterial Artificial Chromosome Library ◽

Powdery Mildew Resistance ◽

Artificial Chromosome ◽

Powdery Mildew Resistance Gene ◽

Mildew Resistance ◽

Grapevine Powdery Mildew

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Strategies for RUN1 Deployment Using RUN2 and REN2 to Manage Grapevine Powdery Mildew Informed by Studies of Race Specificity

Phytopathology ◽

10.1094/phyto-09-14-0244-r ◽

2015 ◽

Vol 105 (8) ◽

pp. 1104-1113 ◽

Cited By ~ 27

Author(s):

Angela Feechan ◽

Marianna Kocsis ◽

Summaira Riaz ◽

Wei Zhang ◽

David M. Gadoury ◽

...

Keyword(s):

Powdery Mildew ◽

Resistance Gene ◽

Resistance Genes ◽

Powdery Mildew Resistance ◽

Interleukin 1 ◽

Resistance Locus ◽

Mildew Resistance ◽

Grapevine Powdery Mildew ◽

Additional Resistance ◽

Race Specificity

The Toll/interleukin-1 receptor nucleotide-binding site leucine-rich repeat 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 V. vinifera cultivars. However, sporulating powdery mildew colonies and cleistothecia of the heterothallic pathogen have been found on introgression lines containing the RUN1 locus growing in New York (NY). Two E. necator isolates collected from RUN1 vines were designated NY1-131 and NY1-137 and were used in this study to inform a strategy for durable RUN1 deployment. In order to achieve this, fitness parameters of NY1-131 and NY1-137 were quantified relative to powdery mildew isolates collected from V. rotundifolia and V. vinifera on vines containing alleles of the powdery mildew resistance genes RUN1, RUN2, or REN2. The results clearly demonstrate the race specificity of RUN1, RUN2, and REN2 resistance alleles, all of which exhibit programmed cell death (PCD)-mediated resistance. The NY1 isolates investigated were found to have an intermediate virulence on RUN1 vines, although this may be allele specific, while the Musc4 isolate collected from V. rotundifolia was virulent on all RUN1 vines. Another powdery mildew resistance locus, RUN2, was previously mapped in different V. rotundifolia genotypes, and two alleles (RUN2.1 and RUN2.2) were identified. The RUN2.1 allele was found to provide PCD-mediated resistance to both an NY1 isolate and Musc4. Importantly, REN2 vines were resistant to the NY1 isolates and RUN1REN2 vines combining both genes displayed additional resistance. Based on these results, RUN1-mediated resistance in grapevine may be enhanced by pyramiding with RUN2.1 or REN2; however, naturally occurring isolates in North America display some virulence on vines with these resistance genes. The characterization of additional resistance sources is needed to identify resistance gene combinations that will further enhance durability. For the resistance gene combinations currently available, we recommend using complementary management strategies, including fungicide application, to reduce populations of virulent isolates.

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