Roles of the Brassica napus DELLA Protein BnaA6.RGA, in Modulating Drought Tolerance by Interacting With the ABA Signaling Component BnaA10.ABF2

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.