“叶缘裂刻型”油菜Y179耐密植特性的冠层光合生理机制研究

Planting areas of rapeseed in China was strongly reduced in recent years, due to the high labor cost and low relative economic efficiency of rapeseed production. Especially, the yield and mechanized production techniques of rapeseed were limited by low density populations in traditional rapeseed cultivation. So, high density populations of rapeseed was necessary to the development of rape industry and labor-saving mechanized techniques in China. Depending on the benefits of high maturation synchronicity and rational canopy architecture, it will increase the yield of rapeseed by maximizing the population production, and provide one better population structure for the mechanized production of rapeseed.. The new leaf-lobed varieties were breeded by the successive distant cross between Brassica napus L. and Rorippa indica (L.) Hiern in our group. Because of high close-planting tolerance and morphological variation, it was considered as the outstanding genetic material for ideotype population exploration of rapeseed. In order to reveal the canopy photosynthetic physiological characteristics of the rape characterized with high close-planting tolerance, 1) the effect of planting density on gas exchange of canopy from the leaf-lobed rapeseed Y179 will be examined by LI-6400XT (coupled with leaf chamber 6400-40) and CAPTS-100 (canopy photosynthesis and transpiration measurement system); 2) light control experiment will be performed, and key functional genes responded to the high spatial heterogeneity within canopy will be identified by metabolic pathway enrichment analysis and differently expressed genes screening by RNA-Seq sequencing, which will provide gene sources for the genetic improvement and molecular breeding of high efficient photosynthetic leaves of rapeseed. This study will not only address the physiological mechanism of canopy photosynthesis responded to high density population of rapeseed, but also make rapeseed populations more suitable for mechanized production.

传统低密度移栽油菜种植方式不仅难以适应轻简化生产，而且严重限制油菜产量提高。因此，耐密植高产油菜群体构建和冠层光合能力优化不仅可以在群体水平上充分发挥增产潜力；而且，可以利用密植群体成熟期集中和长势同步的特点，推动油菜轻简化生产发展。.我们经过多年油菜与蔊菜远缘杂交选育，已经获得一批性状稳定遗传的“叶缘裂刻型”油菜品系。尤其，该品系叶型变异丰富，表现出突出的耐密植特性，是开展油菜耐密植高产群体构建的理想遗传材料。本项目将以“叶缘裂刻型”油菜品系Y179为材料，综合利用多通道植物群体光合气体交换测量系统、RNA-Seq高通量测序和群体冠层光环境定量控制技术，探讨：1）油菜群体冠层光能利用效率对种植密度的响应机制；2）油菜叶片对群体冠层内部光照环境空间异质性的光合生理响应机制。本项目旨在为适宜轻简化生产的耐密植高产油菜群体构建提供理论依据,为高光效油菜叶型遗传改良和分子育种提供基因资源。

长江流域是我国冬油菜主产区，油菜种植面积和产量均占全国80%以上，在保障我国食用油安全方面具有重要地位。江西省作为长江中下游地区传统的油菜种植大省，落后的栽培理论和配套技术致使油菜平均单产约70 kg，仅为全国平均水平的57%左右。本研究围利用耐密植“叶缘裂刻型”Y179油菜品系，主要开展了油菜群体冠层结构在不同发育阶段的动态变化和冠层光合生理特性、耐密植油菜 Y179 叶片对密植群体冠层内部光照环境异质性的光合生理生化响应机制、密植群体冠层内部光照环境异质性的关键光合功能基因初步筛选与鉴定等研究。在实验基地布置油菜种植密度实验，选用不耐密植品种中双11号和耐密植品系“叶缘裂刻型”油菜Y179，分别安排20、40、60和80株m-2 四个种植密度梯度，分别于苗期、蕾薹期和花期，测量冠层光合、蒸腾和呼吸作用相关参数，统计成熟期株高、分枝部位、有效分枝数、主花序有效角果数、单株有效角果数、每角粒数、千粒重和单株产量等指标。在人工光照控制条件下，测量冠层上/下部功能叶片可溶性蛋白、可溶性糖、淀粉和总氮含量，以及RuBP羧化酶活性等生化指标。采用多组学联合分析方法，比较冠层上下部叶片鉴定潜在的光合生理代谢通路和关键功能差异表达基因，筛选出响应光照强度变化的叶片光合作用关键功能基因。整理撰写研究论文 3篇，其中发表 1 篇，待送审 2 篇，顺利完成了本项目全部研究任务。