Functional Analysis Of Abiotic Stress Responsive Genes TaDSU

Wheat is an important food crop.Abiotic stresses such as salt and drought seriously affect the yield of wheat,so it is ugent to identify abiotic stress tolerant genes and enforce wheat molecular breeding.Previously,we bred a wheat introgression cultivar SR3 with the approach of asymmetric somatic hybridization.Based on the transcriptomic analysis,we identified a wheat SUMO protease gene TaDSU,who exhibited stronger response to salt stress than its parent wheat cultivar JN177.Sumoylation is an important protein modification,and play crucial roles in development and response to environmental stimuli.The SUMO tag of a somoylated protein can be removed by SUMO protease.However,the role of SUMO protease in the response to abiotic stress has not been well documented.In order to outline the issue,we previously constructed the transgenic Arabidopsis lines heterogeously overexpressing TaDSU(OE),and primarily analyzed the function of TaDSU in the response.In this work,we utilized the OE lines,and performed the following studies:1.The role and physiological basis of TaDSU in the tolerance to abiotic stress were further confirmed.In comparison with the wildtype Col-0,the OE lines exhibited the following characteristics:enhanced tolerance to salt stress at the germination and seedling stages,lower Na+ contents but higher K+ contents and K+/Na+ ratios;higher drought tolerance,but lower water loss rates;superior tolerance to osmotic stress stimulated by applying manitol,and higher contents of osmolytes such as soluble sugars and praline;increased tolerance to exogenous H2O2,higher content of catalase;and lower level of H2O2 in leaves;reduced sensitivity to ABA.These results indicate that TaDSU overexpression enhances tolerance to various abiotic stress,which is accomplished by orchestrating the physiological bases including ionic homeostasis maintenance,osmotic balance modulation,anti-oxidation.In order to know the role of TaDSU in wheat,we constructed transgenic wheat constitutively expressing TaDSU,and got 19 lines of T2 generation.2.The interacting proteins of TaDSU were identified.We performed in vitro enzymatic assay and western bloting,and primarily confirmed that TaDSU possessed both in vitro and in vivo enzymatic activities.In line with in vitro pull-down assay,mass spetrum analysis,and bioinfomatic prediction,six candidate interacting proteins of TaDSU(DIP1-DIP6)were selected,and three candidates were confirmed by yeast two hybridization.TaDSU localized in the nucleus,and BiFC assay indicated that TaDSU and DIP2 interacted in the nucleus.After exposure to salt stress,TaDSU overexpression accelerated the enrichment of DIP2,and elevated the expression of a DIP2 downstream gene.The data imply that TaDSU interacts with DIP2,impacts the level of DIP2 somoylation and its abundance,and modulate the expression of DIP2 downstream genes.3.The component modulating TaDSU expression was primarily identified.TaDSU promoter with 1.1 kb in length was isolated.We constructed the transgenic Arabidopsis lines transformed with proTaDSU-GUS,and GUS staining assay indicated that TaDSU was transcribed in various tissues.TaDSU promoter had a DIP2 binding element,and EMSA showed that DIP2 directly binded to DIP2 binding element of TaDSU promoter.In line with above findings,we speculate that abiotic stress induce drastic accumulation of DIP2,wich promote the expression of TaDSU;TaDSU bind with DIP2,module the sumoylation level of DIP2,improve the expression of DIP2 downstream genes,and finally enhance tolerance to abiotic stress.