Functional Analysis Of Tae-miR9661 In Response To Drought Stress In Wheat

Wheat is one of the major food crops in the world and is subject to various abiotic stresses during its growth and development.Among them,drought stress is an important factor during its growth and development,Among others,water stress is an important factor affecting wheat growth,yield and productivity.Studies have shown that micro RNAs are important regulators of plant processes in response to abiotic stresses.In this study,we analyzed the spatiotemporal expression characteristics of tae-miR9661 and its target genes,and investigated the effects of overexpression of tae-miR9661 and its target genes in Arabidopsis plants through transient transformation to SAR1 on their drought-related physiological and biochemical indexes;a BSMV:STTM transformation system was constructed,and the regulatory functions of tae-miR9661 in the process of drought stress were initially explored.The main findings are as follows.(1)The homologs of tae-miR9661 were located on chromosomes 4A,and named tae-miR9661-4A.Analysis of the cis-acting elements in the promoter region revealed that the upstream regulatory region contains not only the basic TATA-box and CAAT-box,but also abscisic acid response elements,methyl jasmonate response elements,Myb-binding sites,salicylic acid response elements and other regulatory elements closely related to the stress of adversity.(2)The results of real-time fluorescence quantitative PCR analysis showed that the expression level of tae-miR9661 under PEG simulated drought stress tended to increase and then decrease with the time of stress.This indicated that it had a positive response to drought stress.(3)The results of drought treatment of BSMV-mediated silencing of tae-miR9661 wheat plants by STTM technology showed that the relative water content,SOD activity and POD activity of tae-miR9661-silenced wheat plants decreased significantly,while the content of MDA increased significantly.It showed that silencing of the tae-miR9661 gene could cause a decrease in the activities of some drought-related enzymes in wheat,resulting in its weakened drought resistance,indicating that the tae-miR9661 gene plays an important role in the drought stress response.(4)Arabidopsis overexpressing tae-miR9661 showed stronger drought resistance in response to drought stress mimicking mannitol.After seedling drought stress,the relative water content,SOD activity and POD activity of leaves of tae-miR9661 Arabidopsis overexpression plants were significantly higher than WT,and the MDA content was significantly lower than WT,indicating that tae-miR9661 overexpression plants had increased antioxidant enzyme activity compared with WT,less cell membrane damage,and enhanced resistance to drought stress.(5)The resistance of seeds overexpressing tae-SAR1 was reduced under mannitol osmotic stress after germination.The relative water content,SOD activity and POD activity of leaves of plants overexpressing tae-SAR1 were significantly reduced and MDA content was significantly increased after drought stress at seedling stage.This indicated that overexpression of tae-SAR1 reduced the drought resistance of plants,which was contrary to the function of tae-miR9661 and consistent with the functional properties of miRNAs and target genes.