Location: Crops Pathology and Genetics Research
Project Number: 2032-21220-008-004-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 15, 2017
End Date: Sep 14, 2022
Exploit the genetically diverse Juglans gerplasm collection at the National Clonal Germplasm repository and available Juglans rootstock and scion breeding populations to identify genotypes which exhibit elevated levels of drought resistance. Develop a rapid, reliable and high throughput bioassay, and characterize the mechanisms underlying drought resistance in the genotypes identified above. Promising walnut genotypes with confirmed drought resistance will be clonally propagated and examined in small scale field trials where performance under drought conditions will be examined.
Develop a bioassay to assess relative drought resistance of Juglans germplasm initially using rootstocks/genotypes known to differ in resistance to drought stress. Assess utility of bioassay to identify physiological and genetic markers/indicators linked with drought resistance using a variety of approaches, e.g. root hydraulic conductivity, root/shoot biomass, gene expression for important metabolic pathways involved in drought resistance in model systems, fine root growth kinetics and water uptake. Using the bioassay developed above, screen the genetically diverse collection of Juglans germplasm to identify and characterize drought resistance genotypes. The collections to be screen include; the Juglans collection at the National Clonal Germplasm Repository, the J. microcarpa x J. regia hybrid breeding population (shown to segregate for disease resistance) and selected J. regia and J. microcarpa genotypes from the walnut improvement program and wild species collection respectively. Establish the relative contribution of scion and rootstock to the performance of grafted walnut trees under drought conditions. Walnut genotypes with confirmed drought resistance will be clonally propagated and examined in small scale field trials to test whether results from potted experiments translate to field conditions.