Location: Grape Genetics Research Unit (GGRU)Title: Strategies for RUN1 deployment using RUN2 and REN2 to manage grapevine powdery mildew informed by studies of race-specificity
|FEECHAN, ANGELA - Commonwealth Scientific And Industrial Research Organisation (CSIRO)|
|KOCSIS, MARIANNA - University Of Pecs|
|RIAZ, SUMMAIRA - University Of California|
|ZHANG, WEI - Beijing Academy Of Agricultural Sciences|
|WALKER, ANDREW - University Of California|
|DRY, IAN - Csiro European Laboratory|
|REISCH, BRUCE - Cornell University - New York|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2014
Publication Date: 2/15/2015
Citation: Feechan, A., Kocsis, M., Riaz, S., Zhang, W., Walker, A., Dry, I., Reisch, B., Cadle Davidson, L.E. 2015. Strategies for RUN1 deployment using RUN2 and REN2 to manage grapevine powdery mildew informed by studies of race-specificity. Phytopathology. DOI: 10.1094/Phyto-09-14-0244-R.
Interpretive Summary: The grapevine RUN1 gene was recently identified and confirmed to confer resistance to the grapevine powdery mildew fungus. However, two powdery mildew isolates were found in New York growing on breeding lines containing RUN1 and were collected for the current study. To develop a strategy for durable RUN1 deployment, these and other powdery mildew isolates were studied on vines containing variants of the resistance genes RUN1, RUN2, and/or REN2. The results clearly demonstrate that RUN1, RUN2, and REN2 resistance genes confer resistance to some but not all North American isolates of powdery mildew. The results suggest that RUN1 resistance may be enhanced by pyramiding with RUN2.1 and/or REN2. However, since some isolates can infect vines with these resistance genes, additional resistance sources and combinations should be characterized for enhanced durability. For the resistance gene combinations currently available, we recommend using complimentary management strategies including occasional fungicide application to reduce populations of virulent isolates.
Technical Abstract: 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 have been found on introgression lines containing the RUN1 locus growing in New York (NY). The resulting E. necator isolates designated NY1-131 and NY1-137 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, and/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. RUN2.1 was found to provide PCD-mediated resistance to both a NY1 isolate and Musc4. Importantly, REN2 vines were resistant to the NY1 isolates, and RUN1 REN2 vines combining both genes displayed additional resistance. Based on these results, RUN1 mediated resistance in grapevine may be enhanced by pyramiding with RUN2.1 and/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 complimentary management strategies including fungicide application to reduce populations of virulent isolates.