Abiotic stress and adaptive phenology in fruit and forest trees

Due to the broad climate adaptation of perennial trees, phenological traits (e.g. chilling requirement-CR, bloom date-BD) exhibit complex inheritance patterns. Conceptually, these are adaptive responses to abiotic stress. As production depends on traits like CR, breeders have developed varieties that are phenotypically/genotypically matched to particular geographic/temperature zones. These genotypes are ideal for study of gene networks governing these climate-critical traits. Using genetic approaches, genome-wide association analyses, functional and comparative genomics in fruit and forest trees, we identified a foundational network of genetic activity (phenylpropanoid pathway) linking winter cold stress response to control of the endodormancy-ecodormancy transition (EET) and seed stratification. Our goal is to examine during endodormancy the allelic effects of genes controlling the production of stress related metabolic intermediates that regulate seed stratification, thus linking these two cold temperature responses. Our objectives are: 1. Using functional genomics approaches characterize genotypic effects on the phenylpropanoid gene network transcriptome during endodormancy and the EET. 2. Examine the genotypic effects on the flux of specific phenylpropanoid intermediates and the timing of resumption of growth post-dormancy. 3. Employ transgenic systems to characterize the phenotypes of expression pertubations of specific pathway genes potentially implicated as control points for the EET. These adaptive genes and gene networks will be targets for knowledge based breeding strategies of fruit and forest trees to sustain and improve these resources to meet the challenges of rapid environmental change.