水稻纤维素合酶基因OsCesA调控根系发育的分子机制研究

Cellulose is the most abundant biopolymer and the main structural component of plant cell walls. Previous studies have shown that cellulose biosynthesis-related gene expression is involved in rice root development. However, functions of cellulose synthase (CESA) gene in rice root development is unclear. The mutant CESA generated by employing the CRISPR-Cas9 system was used as materials. The transgenic technique was used to confirm the function of the gene OsCESA. Tissue expression analysis and sub-cellular localization of the gene OsCESA were utilized to investigate the tissue specific expression pattern and the functional position of the protein expression in the cell, respectively. RNA-Seq analysis of CESA mutant and wild-type plant was conducted to understand which metabolic pathway the gene OsCESA was involved in. The overexpression vector was constructed and transformed to the restorer line R9308 to find out the impact of OsCESA by changing root structure on crop yield and other agronomic traits. This project will provide an opportunity to further understand the molecular mechanism of OsCESA in rice root growth and development, and provide a theoretical reference for root breeding in rice.

纤维素是最丰富的生物高分子，也是植物细胞壁的主要成分。前人研究表明纤维素合成途径中相关酶基因的表达与水稻根系发育有关，但纤维素合酶（CESA）基因在水稻根系发育中的功能尚不清楚。本研究拟利用CRISPR-Cas9技术获得的水稻CESA突变体为材料，通过转基因技术验证OsCESA基因的功能；对OsCESA基因进行组织表达分析及亚细胞定位研究，明确该基因在不同器官中的表达特征及其编码蛋白在细胞中发挥功能的具体部位；对CESA突变体与野生型进行RNA-Seq分析，了解OsCESA基因参与的代谢途径；通过构建过表达载体转化恢复系中恢9308（R9308），明确OsCESA基因通过改变根系结构对水稻产量及相关农艺性状的影响。本研究将有助于明确OsCESA基因调控水稻根系生长发育的作用机制，同时为水稻根系育种提供理论参考。

纤维素是最丰富的生物高分子，也是植物细胞壁的主要成分。前人研究表明纤维素合成途径中相关酶基因的表达与水稻根系发育有关，但纤维素合酶（CESA）基因在水稻根系发育中的功能尚不清楚。本研究通过转基因（包括干涉、敲除和过表达）技术验证了OsCESA基因与根系的生长发育有关，该基因功能缺失导致根系变短甚至不能正常生长。该基因在细胞核中无表达，在线粒体中有表达，可能与能量代谢相关。该基因在根、茎、叶中均有表达，推测该基因为组成型表达。OsCESA基因在茎秆中的表达量最高，其次为根，在叶片中的表达量最低，与根系与茎秆中纤维素含量较高一致。CRISPR/Cas突变体与野生型日本晴叶片和根系的RNA-Seq分析结果表明，根系和叶片中发生的生理过程有很大差别，其中淀粉和蔗糖代谢途径仅在根系中富集，相关基因表达具有极显著差异。将OsCESA基因过表达载体转育恢复系R9308，获得转育阳性株系1株。对后代进行田间农艺性状观察，与R9308相比，转育株系株高明显变高。本研究将有助于明确OsCESA基因调控水稻根系生长发育的作用机制，同时为水稻根系育种提供理论参考。

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