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ARS Home » Northeast Area » Geneva, New York » Grape Genetics Research Unit (GGRU) » Research » Publications at this Location » Publication #309185
Title: Mechanisms of quantitative resistance to Erysiphe necator in Vitis rupestris B38

Author
item BARBA, PAOLA - Cornell University
item GALARNEAU, ERIN - University Of California
item REISCH, BRUCE - Cornell University
item Cadle-Davidson, Lance

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2015
Publication Date: 7/15/2015
Publication URL: http://dx.doi.org/10.1094/PHYTO-09-14-0260-R.
Citation: Barba, P., Galarneau, E., Reisch, B., Cadle Davidson, L.E. 2015. Mechanisms of quantitative resistance to Erysiphe necator in Vitis rupestris B38. Phytopathology. DOI. http://dx.doi.org/10.1094/PHYTO-09-14-0260-R.

Interpretive Summary: Vitis rupestris B38 is a North American grapevine resistant to the powdery mildew fungus. V. rupestris B38 and V. vinifera ‘Chardonnay’ were cross-hybridized to create a family of full sibling progeny. In the vineyard and as potted vines, individual progeny ranged from resistant to susceptible and in between. Mechanisms of resistance were analyzed by microscopy. V. rupestris B38 resistance frequently stopped the fungus early in its development; however, when the fungus infected successfully, there was no subsequent barrier. Resistance was affected by leaf age and powdery mildew isolate used. Importantly, V. rupestris B38 resistance was effective against an isolate that had overcome the Run1 resistance gene, which is widely used in grape breeding. This suggests that V. rupestris B38 could be an interesting resistance source to prolong the durability of Run1.

Technical Abstract: Vitis rupestris B38 is a North American grapevine resistant to the powdery mildew pathogen, Erysiphe necator. The segregation of foliar powdery mildew severity in a F1 family derived from a cross of V. rupestris B38 x 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 microscopy, by quantifying the ability of the pathogen to penetrate and to form a microcolony 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 microcolony in F1 individuals showed a pattern of quantitative penetration resistance with no delay or restriction on microcolony 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 Run1 gene, making it an interesting resistance source to prolong the durability of this gene.