脆秆水稻机理研究方面取得进展

　　

　中国科学院合肥物质科学研究院技术生物与农业工程研究所研究员吴跃进课题组与中国科学院遗传与发育生物学研究所研究员傅向东课题组合作，围绕调控水稻脆秆突变性状的分子机理开展研究，通过图位克隆技术获得了控制脆秆特性的基因CEF1，并对基因功能以及调控模式进行了深入解析，相关研究结果9月8日在线发表于Plant Molecular Biology，博士研究生叶亚峰和副研究员刘斌美为该论文的共同作者。

　　由于水稻秸秆数量多、体积大且降解速度慢，难以在短时间内及时处理，影响后茬作物播种，成为生产上的棘手问题。秸秆直接焚烧会造成环境污染和资源浪费。为了破解秸秆还田的难题，技术生物所科研人员通过离子束诱变技术创建水稻脆秆突变体，在保持优良农艺性状的同时，收获时秸秆更加容易破碎，有利于直接还田，变废为宝。

　　水稻脆秆突变体CEF1的脆性特征表现为组织特异性，不同组织的机械抗折力差异显著，茎秆易于折断，而叶片表现正常。克隆的脆秆基因CEF1是编码水稻MYB家族的一个转录因子OsMYB103L。表达模式分析表明CEF1基因主要在抽穗期水稻节间和穗部表达，通过直接结合纤维素合成相关基因CESA4、CESA7、CESA9和BC1的启动子，调控次生细胞壁结构的形成。CEF1基因能够调控下游多个转录因子的表达，是次生细胞壁合成的重要控制因子。另外，功能研究也表明CEF1基因参与了GA介导的纤维素合成途径。这些研究结果从分子水平揭示了脆秆特性形成的机制，为分子设计培育新的脆秆水稻品种奠定理论基础。

　　该工作得到农业部转基因重大科技专项和国家自然科学青年基金等项目的支持。

　　CEF1基因表达模式分析 CEF1基因调控模式分析

CEF1基因参与GA调控纤维素合成

原文摘要：

CEF1/OsMYB103L is involved in GA-mediated regulation of secondary wall biosynthesis in rice

Although the main genes in rice involved in the biosynthesis of secondary wall components have been characterized, the molecular mechanism underlying coordinated regulation of genes expression is not clear. In this study, we reported a new rice variety, cef1, showed the culm easily fragile (CEF) without other concomitant phenotypes. The CEF1 gene encodes a MYB family transcription factor OsMYB103L, was cloned based on map-based approach. Bioinformatics analyses indicated that CEF1 belongs to the R2R3-MYB subfamily and highly similar to Arabidopsis AtMYB103. Expression pattern analysis indicated that CEF1 is mainly expressed in internodes and panicles. Biochemical assays demonstrated that OsMYB103L is a nuclear protein and shows high transcriptional activation activity at C-terminus. OsMYB103L mediates cellulose biosynthesis and secondary walls formation mainly through directly binding the CESA4, CESA7, CESA9 and BC1 promoters and regulating their expression. OsMYB103L may also function as a master switch to regulate the expression of several downstream TFs, which involved in secondary cell wall biosynthesis. Furthermore, OsMYB103L physically interacts with SLENDER RICE1 (SLR1), a DELLA repressor of GA signaling, and involved in GA-mediated regulation of cellulose synthesis pathway. Our findings revealed that OsMYB103L plays an important role in GA-regulating secondary cell wall synthesis, and the manipulation of this gene provide a new strategy to help the straw decay in soil.