独角金内酯调控油菜根系生长的生理及分子机制研究

Winter rapeseed is one of the most important oilcrops in China. In recent years, the works of numerous crop cultivators and breeders were focused on the optimizing of ideal canopy and roots. Many documents have reported the canopy structure of high yield population, whereas root is out of sight and out of mind. Up to now, few studies have demonstrated the regulating methods and corresponding mechanism of root. In this project, Zhongshuang 11 and other seventeen varieties with different genetic background were used as experimental materials, the discrepancy of root morphology were explored after treated with different concentrations of strigolactones at different times. On the based of the researches on root length, lateral root numbers, root ultrastructure, leaf photosynthetic characteristics and endogenous hormones contents of root-canopy, the physiological and biochemical analysis, including 14C and 15N isotope tracer and RNAseq analysis methods will be used to clarify the influence of strigolactones treatment on the nitrogen utilization and distribution in different rapeseed varieties. In addition, the assimilate accumulation and distribution proportion in all the organs of the plants will be studied. Most importantly, the gene expression related to the root growth treated by strigolatones at different times will be analyzed. Moreover, the root growth, physiological charactristics and molecular mechanism involving in the interactions between plant hormones will be figured out. The implementation of the project will elucidate the physiological characters and gene expression of root growth after strigolactones treatment in different varieties, and the network of metabolic pathways will be described. The objectives of this study are to provide information on the resonable regulation of root growth and high yield cultivation in winter rapeseed.

油菜是我国主要的油料作物，构建高产高效群体株型和根系结构是栽培和育种工作者重要的研究目标。目前较多的报道关注于油菜高产群体冠层构建，而对根系的研究很少，亟待探明调控油菜根系生长的有效途径及机理。项目以中双11号等18个不同遗传背景油菜品种为材料，在苗期用不同浓度独角金内酯处理，探明了不同基因型品种的根系形态差异。在对根系长度、侧根数目、根系超微结构、叶片光合特性和根冠内源激素含量等进行研究的基础上，拟采用生理生化分析、14C和15N同位素示踪和RNAseq分析方法，探索独角金内酯处理后不同基因型油菜氮素利用和分配差异，同化物在植株各器官的分配比例，分析处理后不同时间根系的基因表达情况，并通过不同植物激素交互处理，明确独角金内酯调控油菜根系生长的生理及分子机制。本项目的实施将阐明独角金内酯调控油菜根系生长的生理特征及基因表达差异，构建网络代谢途径，为调控油菜根系生长和高产栽培提供理论依据。

一、研究意义.独角金内酯是一种新型植物激素，能调控根系发育和构型，通过信号转导协调地上和地下部植株生长。阐明根系生长过程中碳氮积累的生理机制，解析不同处理时间基因表达差异。研究独角金内酯对油菜根系的调控机理，将为作物高产栽培及育种研究提供理论依据。.二、研究内容及主要结果.（一）独角金内酯对中双11号和中油杂12侧根生长的影响.中双11号根系形态在浓度较低时变化不明显，当浓度为1.8×10-8M 时根系长度、根系表面积、根系体积及根系数量随浓度显著增加；中油杂12根系形态指标在低浓度独角金内酯处理下即出现明显变化，根系长度和根尖数目等指标随浓度增加而显著增加。.（二）独角金内酯调控油菜根系生长的碳氮代谢特征.15N标记研究表明，独角金内酯处理后氮素向根系中转运的比例显著高于对照，增加20.5mg/株；13C标记结果表明，独角金内酯处理后油菜叶片光合速率提高30%，POD和叶绿素含量分别增加22%和16%。叶片中的可溶性糖含量增加，表明SLs能较快将光合产物从根系转运到叶片中。.（三）独角金内酯通过调控油菜侧根生长的分子机制.RNA-seq分析显示GR24处理后调控侧根生长的差异基因在植物激素转导途径、色氨酸代谢途径和苯丙醇类生物合成途径通路中显著富集。代谢组学分析进一步证明，GR24处理后12 h和1 d油菜幼苗内源IAA浓度分别显著下降52.4%和75.8%。.三、科学意义.本项目研究揭示了独角金内酯调控油菜根系和叶片生长的生理和分子机制，发现它与其它植物激素如IAA、乙烯利的互作，发展了植物激素调控植物生长的理论。.四、技术及产品创新.本项目团队已研发出3个栽培物化产品，对调节油菜出苗（出苗率增加20%以上）、苗期植株早发都具有较好的效果。正拟申报专利和发表论文。.五、文章、专利和奖励.项目资助发表研究论文8篇，其中SCI论文5篇，申报专利4项，制定农业行业标准2项，获得省部级科技成果奖励2项，2人次参加第15届国际油菜大会并作口头报告，培养3名硕士生。获得国家自然科学基金面上项目1项。