Project Number: 5350-21220-001-09
Start Date: May 01, 2014
End Date: Apr 30, 2016
1. The selection of apple genes, for validating their potential association with resistance to ARD, will be based on two large-scale molecular and genetic studies in the labs of the PI and collaborator. About 35-40 groups (families) of candidate gene which are involved in the synthesis of anti-microbial compounds and other defense responses will be investigated in the first year using core resistant and susceptible rootstock genotypes. Based on the first year’s results, 8-12 candidate genes which demonstrate consistent association with resistance phenotypes will be further tested across an expanded rootstock breeding population. 2. The behavior of these candidate genes under pathogen pressure will be studied by quantitative reverse transcription PCR procedure, which offers reliable and accurate data for candidate gene based studies. 3. The core apple rootstock genotypes consist of tolerant (G41, CG4214 and G935) and susceptible (Bud9 and M26) rootstocks. Both tissue culture generated seedlings and commercially available one-year old rootstock liners will used for study. The expanded rootstock germplasm includes over 90 genotypes from a rootstock breeding population from the Fazio program. 4. The primary ARD pathogens Phytophthora, Pythium, Rhizoctonia and Cylindrocarpon, which are commonly isolated from Washington State orchards, will be used to inoculate apple rootstock using established procedures.