Study On The Function Of Arabidopsis Thaliana AtSSA3 Participating In Abiotic Stress Response

Abiotic stress is an important factor affecting plant growth and development,including saline-alkali stress,drought stress and oxidative stress.Nitrogen metabolism is one of the most important metabolic pathways in plants.Our previous transcriptome analysis of key genes in nitrogen metabolism pathway showed that the seed storage protein AtSSA3 gene was significantly down-regulated by salt stress.Therefore,this study will focus on the response of AtSSA3 gene to various abiotic stresses to further explore the relationship between nitrogen metabolism and plant stress resistance.The specific research results are as follows:1.GUS staining analysis of AtSSA3 gene promoter showed that salt-alkali stress,drought stress and oxidative stress inhibited the expression of AtSSA3 gene.2.The growth morphological indexes of wild-type Arabidopsis thaliana（WT）,AtSSA3deletion mutant（atssa3）and AtSSA3 overexpression material（AtSSA3-OE）were analyzed at seed germination stage,seedling stage and bolting stage.The growth,germination rate,cotyledon greening rate,bolting height and blade diameter of AtSSA3-OE were lower than those of WT.atssa3 was higher than WT.Overexpression of AtSSA3 gene can increase the sensitivity of Arabidopsis to saline-alkali stress,drought stress and oxidative stress,while AtSSA3 gene deletion can enhance the tolerance to saline-alkali stress,drought stress and oxidative stress.3.The analysis of enzyme activities related to nitrogen metabolism pathway showed that the activities of arginase and urease in atssa3 were significantly lower than those in WT under various abiotic stresses,while the activity of glutamine synthetase was significantly higher than that in WT.Arginase activity and urease activity in AtSSA3-OE were significantly higher than those in WT,while glutamine synthetase activity was significantly lower than that in WT.4.The analysis of nitrogen metabolism-related product content showed that the contents of urea and NH₄⁺in atssa3 were significantly lower than those in WT under various abiotic stresses,while the contents of urea and NH₄⁺were significantly accumulated in AtSSA3-OE.5.The expression analysis of key genes in nitrogen metabolism pathway showed that under salt stress treatment,compared with WT,ArgAH1,ArgAH2 and Urease genes were down-regulated in atssa3,and GS1.1 and GS2 genes were up-regulated in atssa3.In AtSSA3-OE,ArgAH1,ArgAH2 and Urease genes were up-regulated,and GS1.1 and GS2 genes were down-regulated.In summary,this study explored the role of seed storage protein AtSSA3 in abiotic stress response,and provided an important theoretical basis for further exploration of nitrogen metabolism pathway and plant stress resistance mechanism.