The Study Of BnaRGA Protein Promotes Drought Tolerance Through Interacting With BnaA10.ABF2 In Brassica Napus

Brassica napus is cultivated worldwide to produce edible oil,animal feed and biodiesel,making it an agriculturally important crop in China.B.napus is very sensitive to water deficits from germination to seed set.However,the molecular basis of drought tolerance in B.napus is still largely unknown.There are four BnaRGA genes,encoding DELLA protein in B.napus.In our previous work,the single mutant of individual RGA genes,quadruple mutant bnarga and gain of function mutants bnaa6.rga-D were created by CRISPR/Cas9 gene editing technology.Then,we discovered that BnaRGAs were involved in plant drought resistance by a series of physiological,biochemical and molecular experiments.The main results were as follows:1.The RNA-seq and qRT-PCR data showed that BnaA6.RGA was induced by drought and abscisic acid(ABA).2.The results showed that bnaa6.rga-D has strong drought tolerance.The stomatal closure of bnaa6.rga-D was faster after ABA treatment.On the contrary,bnarga showed less drought tolerance and it was insensitive to ABA treatment,but there was no difference between single mutant bnaa6.rga and WT,indicating that BnaRGAs had functional redundancy in ABA mediated drought response.3.Yeast two-hybrid and BiFC experiments showed that the four paralogues of BnaRGA were physical interacted with BnaA10.ABF2,an essential transcription factor in ABA signal pathway.Moreover,BnaA6.RGA enhanced the binding activity of BnaA10.ABF2 to the promoter of BnaC9.RAB18.In summary,our findings indicate that BnaRGA proteins play important roles in plant adaptation to water-deficit stress.Our findings provide novel insights into the crosstalk between GA and ABA signaling pathways,which fine-tune drought responses.