Mechanism Of Wheat SUMO Protease TaDSU In Abiotic Stress Response

SUMOylation is a ubiquitin-like modification whose dynamic reversibility is important and plays an important role in growth and stress response.SUMOylation of proteins can be removed by SUMO protease.However,little is known about the mechanism of action of SUMO proteases in abiotic stresses.We previously bred a wheat introgression cultivar SR3 with the common wheat Jinan 177(JN177)as the parent using the asymmetric somatic hybridization technique.A SUMO protease gene TaDSU which differed in the salt stress response of SR3 and JN177 was identified in the early stage.TaDSU heterologously expressed Arabidopsis thaliana transgenic lines were constructed,and the physiological phenotype of TaDSU in abiotic stress response was analyzed.Function,found that TaDSU overexpression can improve the salt tolerance and drought resistance of Arabidopsis thaliana.In this study,based on the previous results,we conducted the study on the mechanism of TaDSU underlying abiotic stress tolerance,and obtained following outcomes.1.TaDSU modulated the SUMO level of its interacting protein DIP2,and enhance the expression of DIP2 target geneThe previous study identified a TaDSU interaction proteinDIP2,but how TaDSU modulates its activity has not been addressed.DIP2 is known to be a transcription factor that responds to abiotic stress responses.Here,we found DIP2 can be SUMOylated,and TaDSU reduced the SUMOylation level of DIP2.TaDSU promoted the binding of DIP2 to the promoter of its target gene RD29A,and enhanced the expression of RD29A.The results showed that TaDSU enhanced the induction of downstream target genes by DIP2 by reducing the level of SUMOylation of DIP2,and promoted the expression of downstream target genes and enhanced the tolerance of plants2.DIP2 can directly regulate the expression of TaDSUDIP2 can bind to the promoters of TaDSU and its homologs of Arabidopsis thaliana,and promoted the expression of these genes in an ABA-dependent manner.The result implies that,DIP2 and TaDSU are involved in a positive feedback regulation loop,which could enlarge DIP2-mediated signaling pathway of abiotic stress response,and enhance tolerance to abiotic stress.3.TaDSU may modulate stomatal movement via regulating the SUMOylation level of its interacting protein DBP1TaDSU overexpression enhanced NOX activity and improved H2O2 level in guard cells to accelerate stomatal closure in an ABA-dependent manner.We identified a TaDSU interacting protein DBP1 that modulating stomatal movement.TaDSU reduced the SUMOylation level of DBP1.The results suggest that TaDSU may promote the activation of NOX activity by DBP1 via reducing the SUMOylation level of DBP1 to accelerate stomatal closure and enhance drought tolerance.