水稻侧生小穗形成的遗传调控网络解析

Plant architecture is dependent on the activity of the shoot apical meristem and axillary meristems. Axillary meristems generate tillers, inflorescence branch, rachis branch and spikelets. Thus, the pattern of axillary meristem formation is of special significance in crop production. In this project, we identified 2 novel transcription factors required for the development of inflorescence axillary meristem in rice. We will study the relationship between them and LAX1 and LAX2, which are involved in the formation of axillary meristem in inflorescence. By identifying the interaction proteins and the target genes of those transcription factors involved in the formation of axillary spikelets, a genetic regulatory network of spikelet formation will be established in rice. Meanwhile, elucidation of the roles of those genes in auxin biosynthesis and polar transport will characterize how the auxin biosynthesis or polar transport influences the formation of axillary spikelets. Furthermore, based on the whole genome re-sequencing of the rice core collection, we will evaluate the contribution of different haplotypes of those genes involved in spikelet formation to yield. Employing genetics, cell biology and molecular biology strategies, this project will preliminarily uncover the molecular mechanism of rice inflorescence architecture and provide the fundamental basis for the yield genetic improvement in rice.

植物的株型主要取决于茎顶端分生组织和侧生分生组织的活力。水稻侧生分生组织的发育决定了分蘖数、穗枝梗数、着粒密度，是产量性状的重要决定因素。本研究基于2个新的控制水稻穗侧生分生组织形成的转录因子为研究对象，建立它们与LAX1和LAX2等侧生小穗分生组织发育基因的互作和调控关系，并进一步发掘与它们互作基因和受它们调控的靶基因，系统建立水稻小穗形成的遗传调控网络；通过分析这些小穗形成基因在生长素合成和极性运输中的功能，探讨生长素与小穗侧生分生组织发育的关系；利用水稻核心种质资源的基因组测序信息，评估水稻小穗形成基因的不同单倍型对产量的贡献。本项目从遗传学、细胞发育生物学和分子生物学方面深入探究水稻穗形态建成的分子机理，为水稻产量性状的遗传改良奠定理论基础。

水稻侧生分生组织的发育决定了分蘖数、穗枝梗数、着粒密度，是产量性状的重要决定因素。本项目主要研究了水稻侧生分生组织发育的关键基因的功能及其参与的分子网络，取得了如下研究进展：（1）鉴定了LAX1参与侧生小穗发育的蛋白复合物；（2）LAX1通过与NSP1和LIP1互作介导生长素信号调控穗分生组织发育的分子网络；（3）鉴定了穗型相关基因PMM1、VBP1和RBH1的功能，并初步分析了它们可能参与的分子路径；（3）建立了OsmiR167a通过生长素响应蛋白OsARF调控侧生分生组织发育的分子模型；（4）发现水稻成花素复合物蛋白修饰影响穗发育的分子机制。通过项目的实施，初步建立了LAX1蛋白复合物的形成及其活性调控的分子机理，明确了生长素在侧生分生组织发育中的功能；鉴定了多个参与侧生分生组织发育的关键基因，研究结果已在《Mol Plant》、《Plant Cell》等杂志发表论文8篇，申请或授权专利3项。本项目取得的成果为研究植物侧生分生组织发育和水稻穗形态建成积累了基因资源和理论指导。