Project Number: 1910-21220-004-32
Project Type: Reimbursable

Start Date: Oct 01, 2011
End Date: Aug 31, 2013

Objective:
Our contribution to this proposal is in phenotyping powdery mildew resistance in 15 breeding populations in order 1) to develop markers linked with resistance loci and 2) to have standardized assessment of the strength, mechanism, race-specificity, and unique biological features of each resistance.

Approach:
(1) Phenotype the parents and 20 progeny (maintained in Geneva greenhouse) for resistance segregation using a single isolate of E. necator. a. If resistance is not observed, screen with a panel of 4 isolates to identify avirulent isolates. (2) Challenge resistant individuals with a panel of 8 diverse E. necator isolates to identify virulent and avirulent isolates. a. If no virulent isolates are found, repeat with more diverse panel and with natural infection in E. necator center of origin. (3) For each uniquely avirulent isolate in (2), phenotype entire mapping population for resistance, with 10 conidial droplets on 4 leaves per progeny. (4) With virulent and avirulent isolates on 2 susceptible and 4 resistant progeny of each population, quantify penetration success rate, host necrosis, microcolony success rate, and hyphal length at 72 hours post-inoculation for standardized phenotyping of resistance mechanism and strength in the presence and absence of virulence.