水稻高产抗倒伏主效QTL克隆及分子机理解析

Lodge resistance is an important agronomic trait controlled by many genes. It is also a limiting factor to decide whether a super high-yielding variety can be widely planted. However, the molecular mechanism underlying lodge resistance remains elusive because the constitution parameters contributing to this trait are unclear. In recent years, our knowledge about the molecular basis of lodge resistance has been largely improved based on investigating the impacts of some visible phenotypes. But all those studies have not got to the root of this issue. It is well known that secondary walls provide mechanical support for plant bodies. The physicochemical properties of secondary walls, including the composition, structure and distribution, contribute directly to the mechanical strength. Therefore, we propose that multiple genes involved in secondary wall formation regulate plant lodge resistance. In this study, we focus on two rice populations and hundreds of rice sequenced germplasm resources and aim to: 1. Identify the QTLs that control lodge resistance and secondary wall formation through analyzing the cell wall composition in a recombinant inbred line population (Zhenxiqiuguang vas SWR78) and a chromosome segment substitution line population (9311 vas Nipponbare); 2. Identify the SNPs that contribute to lodge resistance through genome wide association studies for lodge resistance–related phenotypes in hundreds of sequenced cultivar resources; 3. Clone the QTLs based on constructing the relevant near isogenic lines; 4. Characterize the QTLs function and related genetic regulatory pathways. Finally, reveal the molecular mechanisms underlying the lodge resistance, which will benefit for breeding of the new varieties with increased mechanical strength, aiming to increase crop yield.

抗倒伏性是由多基因控制复杂且重要的农艺性状，是超高产品种能否大面积推广的决定因素。但人们对抗倒伏分子机理的认知却极其有限，这源于抗倒伏性状没有明确的指标解析。尽管近年来有一些从可见表型入手研究抗倒伏性的报道，却未触及抗倒伏的本质----次生壁特征。次生壁构成了植物的支撑‘骨架’，其结构、成分与分布直接决定了茎秆强度。本研究首次从水稻茎秆次生壁形成和发育的遗传调控网络入手，以细胞壁成分分析平台为依托，利用真系秋光与SWR78高世代重组自交系及9311与日本晴的染色体单片段代换系开展调控次生壁形成与成分的QTL作图与定位分析。在数百份已完成测序的水稻种质资源材料中开展抗倒伏性状的全基因组关联分析，全面挖掘及克隆抗倒伏QTL。结合遗传学、生物化学、分子生物学等手段解析抗倒伏主效QTL的分子机制与遗传调控网络，阐明次生壁形成对抗倒伏的贡献，为培育出高产抗倒伏的水稻新品种提供新基因和优异等位变异。

抗倒伏性是由多基因控制复杂且重要的农艺性状，也是超高产品种能否大面积推广的决定因素。但人们对抗倒伏分子机理的认知却极其有限。次生细胞壁可为植物体提供支撑，其结构、成分与分布直接决定了支撑力的强弱。本研究从水稻茎秆次生壁形成和发育的遗传调控网络入手，以细胞壁成分分析平台为依托，利用数百份水稻自然群体和遗传群体材料，开展调控次生壁形成与成分的QTL作图与定位分析，进行抗倒伏性状的全基因组关联分析，挖掘抗倒伏QTL。鉴定到数十个抗倒伏关联位点，并对11个位点开展了QTL克隆及遗传验证等工作。明确了2个关联位点对抗倒伏性的贡献，解析了qCel1的作用机制。在细胞壁结构控制方面取得了突破性进展，发现了一类新的多糖乙酰酯酶，揭示了多糖乙酰化修饰的双向调控机制，解析了BS1、DARX1、OsTBL1等基因调控细胞壁功能结构的规律，取得了具有重要国际学术影响力的创新性成果。另外，还鉴定了ILA1-IIP4与KNAT7-NAC31/29介导的两条水稻细胞壁形成的新调控通路，发掘可应用于抗倒伏育种的优异自然变异2个。这些发现极大地推动了细胞壁结构与抗倒伏性状的调控机制研究，为抗倒伏性状的精准设计改良提供了分子依据和靶标。