甘蓝型油菜BnRRF基因调控种子大小和千粒重的功能研究

Rapeseed (Brassica napus L.) is one of the most important oil crops in China. Improving the yield of rapeseed for the supply of edible oil is very important in China and 1000-grain weight is an important factor affecting the yield of Brassica napus. In our previous study, a novel major quantitative trait locus (QTL) locus SWC8 on the chromosome C08 and the candidate gene BnaC0830 were identified using genome-wide associate study (GWAS) with whole genome resequencing. The BnaC0830 encodes a chloroplastic ribosome recycling factor (BnRRF). Preliminary functional analysis showed that overexpression of BnRRF in Arabidopsis lead to enlarge the seed size and increase grain weight, indicating BnRRF may play important roles in seed development. To elucidate the molecular mechanism of BnRRF regulating seed development and grain weight in rapeseed, transgenic plants of BnRRF modified by overexpression and CRISPR/Cas9 genome editing technology in rapeseed will be obtained to identify the difference of seed size. Furthermore, transcriptome, cytological observation, subcellular localization, physiological and biochemical analysis were also used to systematic verify the function of BnRRF in seed development and regulation of 1000-grain weight. This project will provide a theoretical basis and genetic resources for the molecular genetic improvement of the yield in rapeseed.

油菜是我国重要的油料作物之一，提高油菜产量对保证我国食用油的供应至关重要，千粒重是影响甘蓝型油菜产量的重要因素。前期，我们利用基于重测序的全基因组关联分析(GWAS)发掘油菜C08染色体上一个新的粒重主效QTL位点SWC8及候选基因BnaC0830。该基因编码一个叶绿体核糖体循环因子BnRRF，我们初步分析表明，超量表达BnRRF转化拟南芥植株种子变大，粒重增加，推测BnRRF可能在种子发育中发挥作用。为阐明BnRRF调控油菜种子发育和粒重大小的分子机制, 本项目拟采用超量表达和CRISPR/Cas9基因组编辑技术，获得BnRRF的油菜转化植株，鉴定转基因材料中种子大小变化。并利用转录组测序方法分析转基因材料中相关基因表达情况，结合细胞学观察、亚细胞定位、生理生化测定等系统分析BnRRF基因在油菜种子发育中功能和调控千粒重的分子机理，为油菜产量分子改良提供理论基础和遗传资源。

油菜是我国第一大油料作物，提高油菜产量对保障我国食用油供给安全至关重要。千粒重是决定作物产量重要的三要素之一，粒重很大程度上与种子大小相关，阐明调控籽粒大小和粒重的分子机制对油菜高产稳产有着重要意义。本项目在前期发掘C08染色体上强关联的千粒重位点基础上，鉴定到粒重基因BnRRF，并通过细胞学观察、分子生物学和转录组等技术方法系统的解析BnRRF控制甘蓝型油菜种子大小和千粒重的分子机理和调控网络。将BnRRF基因分别在拟南芥和甘蓝型油菜中超量表达显著提高了种子的大小和千粒重。研究发现超量表达BnRRF基因的油菜中，与生长素相关基因、细胞周期和糖转运基因显著上调表达。表明，BnRRF基因通过生长素介导的信号通路，调控细胞分裂、糖转运和贮藏，影响油菜籽粒细胞大小和内含物充实，进而调控种子大小和千粒重。对418份甘蓝型油菜自然群体重测序发现BnRRF基因存在3种主要的单倍型。对这3种单倍型与千粒重表型关联，发现优势单倍型在甘蓝型油菜育种过程中受到选择。这些结果不仅有助于丰富甘蓝型油菜千粒重基因调控途径，而且为油菜产量性状改良提供理论基础和基因资源。