芥菜BjuWRKY71-1通过调节SOC1的表达促进开花

Brassica juncea BjuWRKY71-1 accelerates flowering by regulating the expression of SOC1

摘要:

芥菜(Brassica juncea)是十字花科芸薹属的蔬菜作物，在我国广泛种植。茎用芥菜主要以膨大的变态茎为食用器官，其产量和品质很大程度上取决于营养生长到生殖生长的过渡，即开花。WRKY转录因子家族在高等植物中普遍存在，其成员参与调控许多生长发育进程，包括生物/非生物胁迫响应、开花调控等。WRKY71是WRKY家族中的一个重要成员，但它在芥菜中的功能及作用机制还未见报道。本研究克隆得到芥菜BjuWRKY71-1基因，对其进行生物信息学分析和系统进化树分析表明，其蛋白具有一个保守的WRKY结构域，属于Ⅱ类WRKY蛋白，与白菜BraWRKY71-1亲缘关系较近。BjuWRKY71-1在叶和花中表达丰度显著高于根和茎，且随着植株的发育表达量逐渐增多。烟草亚细胞定位显示BjuWRKY71-1位于细胞核中。过表达BjuWRKY71-1的转基因拟南芥开花时间较野生型显著提前。酵母单杂交和双荧光素酶试验结果显示，其能够结合到开花整合子BjuSOC1的启动子上并促进相应基因的表达。综上表明，BjuWRKY71-1蛋白能够直接靶向BjuSOC1从而促进植株开花。这一发现为深入研究芥菜BjuWRKY71-1开花调控的分子机制及其耐抽薹开花新种质创制等奠定了基础。

Abstract:

Brassica juncea (mustard) is a vegetable crop of Brassica, which is widely planted in China. The yield and quality of stem mustard are greatly influenced by the transition from vegetative growth to reproductive growth, i.e., flowering. The WRKY transcription factor family is ubiquitous in higher plants, and its members are involved in the regulation of many growth and development processes, including biological/abiotic stress responses and flowering regulation. WRKY71 is an important member of the WRKY family. However, its function and mechanism in mustard have not been reported. In this study, the BjuWRKY71-1 gene was cloned from B. juncea. Bioinformatics analysis and phylogenetic tree analysis showed that the protein encoded by BjuWRKY71-1 has a conserved WRKY domain, belonging to class II WRKY protein, which is closely related to BraWRKY71-1 in Brassica rapa. The expression abundance of BjuWRKY71-1 in leaves and flowers was significantly higher than that in roots and stems, and the expression level increased gradually along with plant development. The result of subcellular localization showed that BjuWRKY71-1 protein was located in nucleus. The flowering time of overexpressing BjuWRKY71-1 Arabidopsis plants was significantly earlier than that of the wild type. Yeast two-hybrid assay and dual-luciferase reporter assay showed that BjuWRKY71-1 interacted with the promoter of the flowering integrator BjuSOC1 and promoted the expression of its downstream genes. In conclusion, BjuWRKY71-1 protein can directly target BjuSOC1 to promote plant flowering. This discovery may facilitate further clarifying the molecular mechanism of BjuWRKY71-1 in flowering time control, and creating new germplasm with bolting and flowering tolerance in mustard.