Identification Of TaASR Gene Family And Study On The Anti-stress Function Of TaASR1-D In Wheat (Triticum Aestivum L.)

Wheat is an important cereal crop in our country.Abiotic stresses including drought,high salt,as well as extreme temperatures are the main environmental factors causing wheat yield reduction.Therefore,in-depth study of the molecular mechanism underlying abiotic stress tolerance in wheat is of great significance to the breedings of new wheat cultivars with enhanced tolerance to various abiotic stresses and to ensure the safety of food production in our country.Abiotic stresses can induce reactive oxygen species(ROS)production in plant cell,and the growth and yield of crops are inhibited by excessive ROS.Consequently,improving the antioxidant system of wheat under abiotic stress will help improve the tolerance of wheat to stresses.The abscisic acid-stress-ripening(ASR)protein is a transcription factor family which is induced by stresses.Studies have shown that the accumulation of ROS and the activities of antioxidative enzymes under abiotic stress were regulated by ASRs.However,the fine mechanisms of ASR function under stress condition remain largely unclear.In the present study,the ASR genes in the genome of triticeae species were identified and analysed;and on this basis,the Ta ASR1-D gene was selected for further functional analyses in wheat.The main results are as follows:(1)The main mechanism of ASR family expansion was tandem duplication in triticeae species,and the expression of Ta ASR1 gene was the highest among all Ta ASR genes in hexaploid wheat.The results of phylogenetic analysis showed that Ta ASR1 exhibited a close phylogenetic relationship with the ASR genes that could regulate the multiple stress resistance in other plant species.(2)Overexpression of Ta ASR1-D in the elite wheat variety Zhengmai 9023 could improve the tolerance of transgenic wheat plants to oxidative stress.The physiological analysis results indicated that the transgenic lines had lower ROS contents and higher activities of antioxidative enzymes under stress treatments compared with those of wild type control plants.These results suggested that Ta ASR1-D could decrease the oxidative damage of wheat under abiotic stresses.The growth rate and phenotype analysis of transgenic lines under drought,osmotic and high salinity conditions revealed that overexpression of Ta ASR1-D enhanced the tolerance of wheat to abiotic stresses.The agronomic traits and yield parameters suggested that Ta ASR1-D increased the grain yield of wheat under salt condition compared with control.(3)The growth of transgenic wheat seedlings was hypersensitive to exogenous ABA treatment,and the endogenous ABA contents were also raised.The expression levels of Ta NCED1 and Ta ABA1 involved in ABA biosynthesis were higher in transgenic lines compared with wild type plants.These results implied that Ta ASR1-D could regulate the ABA signaling.(4)The results of in situ hybridization showed that the tissue-specific expression pattern of Ta ASR1-D is consistent with the positions of ABA biosynthesis in plants.Yeast one-hybrid assay and electrophoretic mobility shift assay confirmed that Ta ASR1-D could bind the promoters of Ta NCED1 and Ta GPx1-D genes to up-regulate their expression.The above results suggested that Ta ASR1-D improves abiotic stress tolerances by reinforcing antioxidant capacity and ABA signaling,and Ta ASR1-D can be used as a candidate gene to breed new wheat cultivars with enhanced multiple abiotic stress tolerances.