基于籽粒早期发育解析花期高温诱导杂交籼稻垩白形成的机理与调控机制

近年来频发的夏季高温是导致长江流域稻米垩白增加和品质不稳定的主要原因，提高杂交稻垩白性状的耐高温能力已成为亟待解决的问题。诸多研究已从籽粒发育中后期灌浆结实过程中淀粉代谢途径探究高温对垩白的影响机理，而我们前期研究已发现花期高温胁迫对淀粉代谢的影响较小，但花期高温诱导垩白形成的机理仍不明确。花期单个颖花受精后立即进入籽粒早期生长发育，此阶段的发育为后续营养物质的贮藏奠定基础，因此本项目欲通过细胞学、生理学和分子生物学的结合，以不同抗性的杂交籼稻品种为材料，系统研究花期高温胁迫对籽粒早期生长发育如细胞增殖和同化物运输组织结构发育的影响，以及调控籽粒早期生长发育的生理和分子机理，阐明花期高温胁迫诱导垩白的形成机理；研究高温胁迫时施用外源生长素对籽粒生长发育和垩白性状的调控效应与机制，探明调控高温对垩白影响的栽培措施。研究结果将为杂交稻耐高温垩白性状的遗传改良和激素抗逆栽培提供理论支撑。

Increasing temperature during summer in Yangtze valley induce chalkiness and poor grain quality, thus possing a great challenge for improving chalkiness for hybrid rice.To date, studies have been taken to understand the high temperature’s impacts on starch metabolism during grain filling, which was hardly affected by short-term high temperature at flowering although the influence mechanisms of high temperature at flowering on chalkiness remains unknown. Rice spikelets run immediately into cell division and development of transport tissue within grains at flowering, which are closely associated with the subsequent assimilates accumulation and occurrence of chalkiness. Hence, by system analyses via cytological, physiological and molecular methods, this project are aimed at exploring the impacts and mechanisms of short-term heat stress at flowering on endosperm cell division and development of transport tissues within rice grain, to understand the relationship among early grain development and chalkiness under heat stress; underlying the role of exogenous auxin application in improving grain development, sucrose metabolic and reducing chalkiness under heat stress. The findings from the proposed project will provide empirical basis to enhancing the understanding of heat resilience for chalkiness and exploring the role of hormones in plant adaptation to heat stress for the future high-temperature programs.