Wu Jiajing, Yan Guanbo, Duan Zhiqiang, Wang Zhijuan, Kang Chunying, Guo Liang, Liu Kede, Tu Jinxing, Shen Jinxiong, Yi Bin, Fu Tingdong, Li Xia, Ma Chaozhi, Dai Cheng
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
State Key Laboratory of Agricultural Microbiology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.
Front Plant Sci. 2020 May 14;11:577. doi: 10.3389/fpls.2020.00577. eCollection 2020.
Drought is a major threat to plant growth and crop productivity. Reduced level of the gibberellin would result in increased drought tolerance, but the underlying mechanism is still unclear. In , there are four genes that code for DELLA proteins, negative regulators of GA signaling. Among them, expression of was greatly induced by drought and abscisic acid (ABA). Previously, we created the gain-of-function mutant of , , and the loss-of-function quadruple mutant, by CRISPR/Cas9, respectively. Here we show that displayed enhanced drought tolerance, and its stomatal closure was hypersensitive to ABA treatment. By contrast, displayed reduced drought tolerance and was less sensitive to ABA treatment, but there is no difference in drought tolerance between single mutant and WT, suggesting a functional redundancy between the genes in this process. Furthermore, we found that BnaRGAs were able to interact physically with BnaA10.ABF2, an essential transcription factor in ABA signaling. The BnaA10.ABF2-BnaA6.RGA protein complex greatly increased the expression level of the drought responsive gene . Taken together, this work highlighted the fundamental roles of DELLA proteins in drought tolerance in , and provide desirable germplasm for further breeding of drought tolerance in rapeseed.
干旱是植物生长和作物生产力的主要威胁。赤霉素水平降低会导致耐旱性增强，但其潜在机制仍不清楚。在油菜中，有四个基因编码DELLA蛋白，它们是GA信号的负调控因子。其中，BnaA6.RGA的表达受干旱和脱落酸（ABA）的强烈诱导。此前，我们分别通过CRISPR/Cas9技术创建了BnaA6.RGA的功能获得突变体BnaA6.RGA-GFP和功能缺失四重突变体BnaA6.RGA-KO。在此我们表明，BnaA6.RGA-GFP表现出增强的耐旱性，其气孔关闭对ABA处理高度敏感。相比之下，BnaA6.RGA-KO表现出降低的耐旱性，对ABA处理不敏感，但单个BnaRGA突变体与野生型之间的耐旱性没有差异，表明这些基因在此过程中存在功能冗余。此外，我们发现BnaRGAs能够与ABA信号传导中的关键转录因子BnaA10.ABF2进行物理相互作用。BnaA10.ABF2-BnaA6.RGA蛋白复合物极大地提高了干旱响应基因BnaA07.P5CS的表达水平。综上所述，这项工作突出了DELLA蛋白在油菜耐旱性中的重要作用，并为油菜进一步培育耐旱品种提供了理想的种质资源。
