隐花色素GmCRY1b过表达提高大豆耐荫性和产量的机制分析

Soybean serves as the major source of vegetable protein and oil for human beings especially in china. Due to the low yield of soybean and the decrease of planting area, the total soybean production has been seriously insufficient for the huge demand in China. As a result, the soybean import dependence rate in china has been achieved more than 90% in recent years. Close planting and intercropping，which can theoretically improve the yields per unit and planting area，however cannot be effectively utilized because most soybean cultivars are inherent with severe shade avoidance responses (SAR) including increased plant height, lodging, reduced branching, and decreased immunity to plant pests and pathogens under shade condition. Cryptochrome is the major photoreceptor mediated low-blue-light induced SAR. Previously, we successfully knocked out the Cryptochrome genes in soybean by the clustered regularly interspaced short panlindromic repeats (CRISPR)-associated protein 9 (Cas9) system. The Gmcry1abcd quadruple mutants showed obvious shade avoidance syndromes even under normal sunlight condition. While GmCRY1b overexpression lines showed significant shade-tolerant and high yield per plant phenotype in shade condition. Taking that the GmCRY1s-mediated blue-light-signal transduction pathway is not clear yet, we plan to identify the GmCRY1b interacting protein and its downstream genes, and further dissect the molecular mechanism of how GmCRY1b suppresses the shade avoidance responses. This work will provide theoretical guidance and breeding materials for developing shade-tolerant and high-yield soybean cultivars.

大豆是世界上主要的植物蛋白和油脂来源。由于我国大豆单产较低和种植面积下降等因素导致国产大豆供应量严重不足，对外依存度已高达90%。密植和间套作理论上可以提高大豆单产和种植面积，但因导致多数品种表现明显的避荫反应症状（徒长、倒伏、分枝减少、抗逆性下降等）而不能有效发挥增产作用。隐花色素（CRY）是感应蓝光强度变化的主要光受体。本课题组前期工作探索了七个GmCRYs在大豆中的生物学功能，发现Gmcry1abcd四突变体在正常光照下表现明显的避荫反应症状，而GmCRY1b过表达大豆株系则在遮荫条件下表现显著的耐荫和高产表型，证实GmCRY1s在调控避荫反应过程中具有重要作用。由于GmCRY1s介导的蓝光信号转导通路尚不清楚，本究将通过多种技术手段鉴定GmCRY1b的互作蛋白和下游基因，解析GmCRY1b抑制避荫反应的分子机制，为培育耐荫高产大豆新品种提供理论依据和育种材料。

大豆是世界上主要的植物蛋白和油脂来源。由于我国大豆单产较低和种植面积下降等因素导致国产大豆供应量严重不足，对外依存度已高达90%。密植和间套作理论上可以提高单产和种植面积，但因导致多数大豆品种表现明显的避荫反应症状（徒长、倒伏、分枝减少、抗逆性下降等）而不能有效发挥增产作用。隐花色素（CRY）是感应蓝光强度变化的主要光受体。本项目通过基因编辑，探索了七个GmCRYs基因在大豆中的生物学功能。研究结果显示Gmcry1abcd四突变体在正常光照下表现明显的避荫反应症状，Gmcry2abc三突变体表现较弱的避荫反应症状，证实GmCRY1s在调控避荫反应过程中起主效作用。进一步研究发现蓝光激活的GmCRY1s促进豆科特异的bZIP转录因子STFs积累，STFs蛋白靶向GmGA2ox基因并上调其表达，从而降低内源赤霉素GA1的含量并抑制大豆茎秆伸长；反之，在弱蓝光条件下，GmCRY1s失活导致STF蛋白水平下降和GmGA2ox基因表达下调，活性赤霉素GA1获得积累从而促进大豆茎秆快速伸长避荫反应。GmCRY1b过表达大豆株系在遮荫条件下表现显著的耐荫和高产表型。本研究解析了GmCRY1抑制避荫反应的分子机制，为培育耐荫高产大豆新品种提供理论依据和育种材料。