Study On The Molecular Characteristics And Resistance Ability To Abiotic Stress Of Wheat TaMIR2275 Gene

In recent years,it was found that MicroRNA(miRNA)played an important role in regulating the plant growth and development,especially in enhancing the plant to adapt to the environment stress.There were a large number of research on plant miRNA.One way of plant responding to stress is by regulating miRNA expression profiles when plant under stress.It was these miRNAs that regulated the expressed genes and made the plant adapt to the stress.Based on our previous research work,we cloned the TaMIR2275 gene from wheat cultivar Shi Xin 828 and studied its molecular characteristics and its function in transferred tobacco under insufficient nitrogen stress and high salty stress.The main results were as follows:1.The initial sequence length of TaMIR2275 was 265 nt,The mature region is located at 223 nt to 245 nt.The matured length of TaMIR2275 was 22 nt and the sequence was UUUGGUUUCCUCCAAUAUCUCG.Under insufficient nitrogen and high salty treatment,the wheat seedlings expressed high level of TaMIR2275 at 48 h.when transferred to the normal solution,the expression level of TaMIR2275 gradually decreased.The results showed that TaMIR2275 responded to insufficient nitrogen and high salty stress and had a character of time-dependent.2.The total RNA was extracted from wheat cultivar Shi Xin 828 and were reverse transcript to cDNA.The TaMIR2275 was successfully cloned by PCR amplification.The sense and anti-sense plant expression vectors of TaMIR2275 were successfully constructed.Using agrobacterium mediated genetic transformation method,we got 10 lines of transgenic tobacco,including 3 lines of sense-transfer and 7 lines of anti-sense-transfer.Tested by spraying herbicide on the leaf,the TaMIR2275 gene were successfully expressed in transgenic tobacco.3.Under insufficient nitrogen stress and high salty stress,compared with the wild type(WT)tobacco,the growth of sense-transgenic tobacco with TaMIR2275 wasmorphology improved with higher plant,more developed roots,and the leaves were less yellow;the growth of anti-sense-transgenic tobacco with TaMIR2275 was less than the WT.The results showed that TaMIR2275 had positive regulation effect on plant resistance to nitrogen stress and salt stress.4.Under insufficient nitrogen stress and high salty stress,compared with the WT,the physiological metabolism of sense-transgenic tobacco with TaMIR2275 were changed significantly.The chlorophyll content of sense-transgenic tobacco with TaMIR2275 was higher than that of WT,the protective enzymes activity,such as SOD,POD CAT,were significantly strong than that of WT,the stomatal opening of sense-transgenic tobacco with TaMIR2275 was bigger than that of WT.While the physiological metabolism of anti-sensetransgenic tobacco with TaMIR2275 were opposite.All the physiological metabolism changes indicated that TaMIR2275 regulating a series of physiological metabolism adaption to abiotic stress.5.Under insufficient nitrogen stress,compared with the WT,the gene expression level of sense-transgenic tobacco with TaMIR2275 changed significantly.Under insufficient nitrogen stress,The expression level of the nitrate transporter gene(NRT),the nitrite reductase gene(NIR)and the glutamine synthetase gene(GS)were up-regulated,while the above enzymes activity in anti-sense-transgenic tobacco with TaMIR2275 were downregulated.It is indicated that TaMIR2275 can improve the ability to endure insufficient nitrogen stress by regulating the expression level of NRT,NIR and GS.Under high salty stress,the expression of protective enzymes SOD1,POD1.2,POD1.7,POD9,CAT,CAT1.1 and CAT3 genes in sense-transgenic tobacco with TaMIR2275 were up-regulated.The expression of ABA receptor(PYL/PYR)genes and related genes of the SnRK2 family gene of ABA signal transduction(PYL1?PYL8?PYR1 and SRK1?SRK2A-4?SRK3?SAPK1)were up-regulated,while the related above genes in anti-sense-transgenic tobacco with TaMIR2275 were down-regulated.It was suggested that TaMIR2275 enhanced the the plant to adapt salt tolerance by regulating the synthesis of protective enzymes and ABA signaling pathway.