干旱胁迫下玉米会通过信号传递，产生表观遗传变异（DNA甲基化修饰），并引起一系列基因作出应答，调节对水分的吸收、利用，以适应胁迫环境。本研究对耐旱RIL 群体的两亲本以及筛选的强耐旱、干旱敏感重组自交系进行全基因组甲基化与转录组测序，发掘应答干旱胁迫的甲基化变异位点与特异表达候选基因，揭示干旱胁迫引起基因表达显著变化且可遗传的甲基化机制；针对甲基化变异与基因表达显著关联的候选基因，在核心关联群体中进行甲基化亚硫酸盐测序及表达差异分析，同时利用该群体已有的SNP基因型数据，进行关键基因甲基化水平的meQTL 定位和表达水平的 eQTL定位，寻找调控甲基化与基因表达的热点区域，验证耐旱 QTL 与关键基因 eQTL、meQTL 的相互关系以及作用效应。对关键基因进行遗传转化验证与分子标记开发，系统解析玉米应答干旱胁迫的甲基化模式与分子调控机制。

Drought stress affects the water relations of plants at cellular, tissue and organ levels,causing damage and adaptation reacions.Plants respond and adapt to survive under drought stress by the induction of various morphological, biochemical, physiological and epigenetic responses. In previous study, a recombinant inbred line (RIL) population and core association population with highly dense SSR and SNP maps were created for drought tolerance study. To reveal mechanism of gene expression and DNA methylation variation in response to drought tolerance, both methylated DNA immune precipitation (MeDIP) and RNA-seq will performed on the biparental inbreds and two recombinant inbred lines from RIL with drought-tolerant and drought-sensitive characters. Potential and key candidate genes will be screened to verify their gene expression and DNA methylation variation in different development stages and tissues of drought-tolerant and drought-sensitive inbreds. Methylation QTL (meQTL) and expression QTL (eQTL) mapping for candidate genes in target tissues under two water regimes will be conducted using linkage and association analyses. Then, biological function for the candidate genes will be validated through genetic transformation and molecular makers will be further developed. The complex genetic and epigenetic systems response to drought stress will be dissected through joint analysis of interaction and effect on QTL, eQTL and meQTL under different genetic backgrouds. The results of project will provide beneficial gene resources and elucidate molecular mechanism response to drought stress, and lay a foundation for molecular breeding on maize.