春化处理控制冬小麦的小穗发育

春化作用是决定冬性及二年生草本植物成花和穗分化的一个关键生理过程。通过用不同时间的前期低温处理 ,观察对冬小麦 (TriticumaestivumL .)后期形态建成中穗分化启动、小花发育及结实率的影响 ,发现前期低温处理对穗启动分化的早晚具有决定作用。春化时间越长 ,穗分化启动越早。较长时间低温有利于促进穗分化。在实验室低温处理条件下 ,促进小花分化和提高结实率的最佳春化处理时间是 45d左右。实验观察表明 ,春化处理促进小麦生长锥分化启动时间和分化速率 ,减少小穗退化。这一结果表明了春化处理不仅是冬小麦开花启动过程所必需的 ,而且是花序正常发育过程和顶部与基部小穗完全结实所不可缺少的。

EMS诱变的小麦基部小穗不孕突变体的鉴定与小穗形态发育

为了解小麦基部小穗不孕突变体的农艺性状和小穗形态发育特点，对EMS诱变小麦品系山农1186所得的基部小穗不孕突变体进行了农艺性状鉴定和小穗发育过程观察。结果表明，10个突变株系基部有2～4个不孕小穗，而山农1186基部小穗正常结实；与受体山农1186相比，10个突变株系的穗长、小穗数没有变化，但穗粒数显著降低，降低幅度为20.63%～44.44%；突变株系的株高、穗下节、倒二节、倒四节、倒五节间长度显著增加，平均增长27.28%、20.55%、51.10%、93.55%，倒三节间长度增加不显著，表明株高的增加是由多个节间伸长造成的；大多数株系的旗叶、倒二叶、倒三叶长度增加不显著，但宽度显著变窄，分别比对照平均减少16.93%、18.15%、14.36%，叶长、叶宽的变异并未引起叶面积的明显变化。对小穗发育的形态学观察发现，突变体基部小穗在四分体时期开始退化，雌蕊、雄蕊、子房萎焉失水，变成模糊的一团组织，进而导致基部小穗不孕。

Changes in Levels of Endogenous Plant Hormones During Floret Development in Wheat Genotypes of Different Spike Sizes

The levels of endogenous plant hormones regulate floret development and degeneration, and thus grain set in flower crops. This study was undertaken to characterize the changes of endogenous hormone levels during floret development in three wheat ( Triticum aestivum L.) genotypes: “97J1' with the highest grain set and fertile florets per spike, “H8679' with the lowest grain set and fertile florets per spike, and a medium, “YM158'. The results showed that the peak level of ABA appeared between stamen and pistil differentiation and antherlobe formation of floret development, and the timing delayed with the size of spike (earliest in “H8679” and latest in “97J1”). From antherlobe formation to meiosis, the levels of ABA and GA 1+3 decreased sharply in the ears of “97J1”, while in the ears of “H8679” there was only a slight decrease in ABA, and even an increase in GA 1+3 . The ratio of isopentenyladenosine (iPA)/ABA and IAA/ABA in the ears of “97J1” increased sharply from antherlobe formation to meiosis, but changed only slightly in the ears of “H8679”. At antherlobe formation, IAA and GA 1+3 levels were higher in the ears of “97J1”, but lower in the ears of “H8679” than in the leaves. At meiosis, ABA, GA 1+3 and IAA levels in the “97J1” ears were much lower than in the leaves, but similar in “H8679”. These results indicated that the sharp decreases of ABA and GA 1+3 in ears from antherlobe formation to meiosis and the lowest maintenance at meiosis may be favorable for development of fertile florets and enhancement of grain set in wheat.

水稻小穗异常发育调控关键基因的加权共表达网络分析

水稻(Oryza sativa L.)是世界上需求量最大的粮食来源之一,其产量和品质与分蘖和花序结构的发育有关。以往的花序发育研究已经鉴定出大量与水稻营养生长和生殖生长相关的基因,但对花序发育和抽穗期的遗传机制尚未完全了解。本研究利用前期构建的水稻小穗异常发育表型的重组自交系(recombinant inbred lines,RIL),通过转录表达谱分析,探讨穗部异常发育和穗部缺陷(pds1)表型调控的分子机制。通过差异表达基因(differentially expressed genes,DEGs)的筛选,鉴定了可能与pds1表型相关的基因。在6组差异表达基因中,分别鉴定出1578、463、1295、687、397、175个差异表达基因。本研究通过加权共表达网络分析(weighted gene co-expression network analysis,WGCNA),发现了与pds1表型高度相关的4个基因模块(Module)。通过对模块中所包含的基因进行功能富集分析,发现与花序发育相关的生物学过程。随后在这些模块中鉴定出多个高度相关的关键基因(Hub genes),如开花促进因子OsFKF1(Os11g0547000)和TCP转录因子OsTB1(Os03g0706500)。结果表明,水稻小穗异常发育和抽穗缺陷表型可能是由小穗发育调控相关基因的遗传互作引起的。研究结果为进一步探讨穗伸长缺陷的调控机制提供了有价值的参考。