Abiotic stress response and adaptive phenology in fruit 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 objective is to use a transcriptome sequencing approach to characterize genotypic effects on the phenylpropanoid gene network transcriptome during endodormancy and 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 Floral bud mRNA from four apricot genotypes collected at 0, 100, 400 and 800 chill hours (CH) and sepal visible, petal visible stages with two or three replicates. Floral buds mRNA from four peach genotypes collected at 0, 100, 600, and 1000 chill hours and pre-bloom stage with four replicates.

由于多年生木本植物具有广泛的气候适应性，其物候性状（例如需冷量（chilling requirement, CR）、开花日期（bloom date, BD））呈现出复杂的遗传模式。从概念上讲，这些性状是对非生物胁迫的适应性响应。由于作物生产依赖于需冷量这类性状，育种者已培育出在表型/基因型上适配特定地理/温度区域的品种。这些基因型是研究调控这些气候关键性状的基因网络的理想材料。本研究通过遗传手段、全基因组关联分析以及果树与林木的功能基因组学和比较基因组学研究，鉴定出了一个核心的遗传活性网络——苯丙烷途径（phenylpropanoid pathway），该途径将冬季低温胁迫响应与内休眠-生态休眠过渡（endodormancy-ecodormancy transition, EET）以及种子层积的调控联系起来。本研究的目标是在内休眠阶段，解析调控与种子层积调控相关的胁迫响应代谢中间产物合成的基因的等位基因效应，从而将这两类低温响应过程联系起来。本研究的目的是利用转录组测序技术，解析内休眠阶段及EET过程中，基因型对苯丙烷途径基因网络转录组的调控效应。这些适应性基因及其基因网络将作为果树与林木知识驱动型育种策略的靶点，以维持并改良这些林木资源，应对快速环境变化带来的挑战。采集了4个杏基因型的花芽mRNA样本，采样时点包括0、100、400、800需冷量小时（chill hours, CH），以及萼片可见期、花瓣可见期，每个组设置2或3次生物学重复；同时采集了4个桃基因型的花芽mRNA样本，采样时点包括0、100、600、1000需冷量小时，以及开花前阶段，每个组设置4次生物学重复。