小麦茎鞘贮藏物质花后再转运的调控机理研究

For a long time, we have been focused on the increase of photosynthetic productivity after flowering of wheat in order to enhance the final yield. However, the yield further enhancement is restricted by the limitation of the group structure, physiological function and the length of grain filling stage..It is an effective and feasible way to increase the contribution rate of the dry matter stored in the stem sheath to the grain. Fructan is the dominant stored reserve in wheat stem, its accumulation and remobilization determines the amount of the stored reserve in stem. Meanwhile, fructans plays important role in the distribution of carbon, the regulation of the carbon source-sink relation and the final grain yield. However, the regularities of fructans metabolism show different trends in different studies, and the underlying regulation mechanism of fructans accumulation and remobilization in winter wheat is still unclear. These become limitation for the development of high yield breeding and high yield cultural techniques. .In this program, 2 wheat varieties differed in the accumulation amount and remobilization rate of stem stored reserve will be analysed. They were screened from 30 main popularized varieties during recent years in Huang-Huai-Hai region. The changes of frucants in different internodes of the 2 varieties winter wheat during grain filling stage will be studied. The carbon content in leaves, grains and stem will be studied, and the activity of carbon-catalyzing enzymes and their encoding gene expression, the content of main endogenous hormones (IAA, GAs, ZR and ABA) also will be studied, thus, the regularities of fructans metabolism and the underlying regulation mechanism will be clarified. The effect of abscisic acid on the fructants accumulation and remobilization in winter wheat and the underlying regulation mechanism will be also studied. The expected results will further deepen the knowledge of the formation mechanism of grain yield and the development of high yield cultural techniques.

一直以来，我国小麦高产实践主要聚焦于花后光合生产力的提升上，并取得了显著成果。但随着产量的进一步提高，受群体结构、生理机能及灌浆时长等因素的制约，花后光合面积、强度及时长的再提高受到限制，产量的再提升遭遇瓶颈。正常状态下茎鞘内贮藏物质仍存在可利用的空间，而通过挖掘茎鞘贮藏物再转运潜能，提高其对籽粒的贡献，是实现产量和效益协同增长有效可行的途径。.果聚糖是小麦茎鞘内最主要的贮存糖类之一，其代谢决定了茎鞘物质贮藏量的大小。本项目拟以果聚糖代谢为切入点，通过对茎鞘贮藏物质转运能力不同的小麦品种设置不同的库源关系，分析从果聚糖含量和聚合度在空间和时间上的变化，从底物供应水平、碳代谢关键酶活性、内源激素含量变化等角度，明确小麦茎鞘果聚糖转运生理机理。并进一步结合代谢组学和蛋白组学，分析小麦茎鞘果聚糖转运输出相关调控通路，预期结果将进一步深化小麦籽粒产量形成机理与调控技术研究。

小麦花后光合同化和花前营养器官贮藏碳的再转运是籽粒形成的物质来源。但随着产量的进一步提高，受群体结构、生理机能及灌浆时长等因素的制约，花后光合面积、强度及时长的再提高受到限制。正常状态下为籽粒贡献5%～28%，但其转运率会在小麦遭遇环境或非环境胁迫时提高，可见，正常状态下营养器官贮藏物质仍存在可利用的空间，而通过探索这些贮藏物质再转运的调控机理，深挖其再转运潜能，提高其对籽粒的贡献，进而提高小麦的收获指数，是实现产量和效益协同增长有效可行的途径。.为探索小麦营养器官贮藏物质再转运调控机理，本项目在小麦灌浆期通过减叶、遮光、去除小穗等方法设置不同库源关系，通过分析库源关系改变对小麦物质积累及转运的影响，发现小麦贮藏物质约有40%可用于转运再利用，但正常状态下植株贮藏物质再转运率仅为其最大转运率的2/5，仍有约3/5的潜在可用物质未被充分利用；通过分析碳代谢相关酶组学、内源激素含量的变化，明确了库源关系发生改变后源器官中的胞质转化酶（cytInv）和蔗糖合酶（SuSy），以及库器官中的UDP-葡萄糖焦磷酸化酶（UGPase）和磷酸葡萄糖变位酶（PGM）在物质积累和再转运中起到的关键作用，解析了细胞分裂素、吲哚乙酸3-酸和茉莉酸a与物质转运之间的关系；完成了不同库源关系样品转录组测序、代谢组和蛋白质组分析，鉴定了差异表达基因、差异表达代谢物和差异表达蛋白，并得到差异表达基因、代谢物和蛋白显著富集的GO功能条目，筛选到与物质生产、积累及转运相关的差异表达基因、差异表达代谢物和差异表达蛋白；结合多组学，解析了小麦贮藏物质积累及再转运利用的分子调控机制。.实验工作部分完成了预期目标。本项目资助发表论文4篇，申请发明专利1项。课题组参加国内会议2次（线上），所内学术会议1次，并进行了学术报告，交流了项目的进展情况。