Effects Of Exogenous Abscisic Acid On MicroRNA Expression Pattern Of Winter Wheat At Low Temperatures

Winter wheat was the most important food corps in China, and the main reason of the limiting condition for planting the winter wheat was the cold weather. As the strong cold tolerance of Winter wheat cultivar Dongnongdongmai1, it had been the first over wintering breed in the region of Heilongjiang Province. MiRNA was a little single stranded RNA, which length is21-24nt and widely excisted in eukaryotic. It could identify the targets of mRNA and control the target gene in transcriptional and post-transcriptional regulation, and playing an important role on regulating effect when plants under the individual growth and adverse stress. So the study about the miRNA was So it would be a significance to study the miRNA’s influence on the cold tolerance of Winter wheat cultivar Dongnongdongmai1. Most of research about adversity regulation of miRNA were focused on the species of gene sequences and under a simulated stress conditions. In this study, we used the Winter wheat cultivar Dongnongdongmai1as the material,and14miRNAs that we previous obtained were significant differences in expression abundance for the object, to study the expression pattern modle of miR165、miR166、miR319、miR5070、miR513、miR3704after disposed by ABA when temperatura cooled to4℃、0℃、-10℃、-25℃in the field of nature. And we got the cold resistance mechanism of the critical temperature point of Winter wheat cultivar Dongnongdongmai1at-10℃, simulating the important cold-resistant physiological indexes (chlorophyll, mda, proline, SOD and POD) and the real-time accumulation of fourteen miRNA (miR165、miR166、miR319、miR5070、miR5139、miR3704、miR168、miR169、 miR172、miR393、miR397、miR5029、miR5218、miR5565) at-10℃indoors and the impact of ABA on them. Main results for this study are as follows:(1) In the field under the condition of natural cooling, through the real-time fluorescent quantitative analysis we got that:As the temperature decreases, the variation tendency of miR165,miR166,miR319,miR5139without ABA treatment in the control groups was presented as the first down later, the miR5070showed a up-down-up trend, the miR3704was on the rise. The variation tendency of miR165,miR166,miR5070,miR5139and miR3704in the sample which was treated by ABA showed a down-up-down trend, the miR319first fell and then rose.The results above illustrated the expression patterns of miRNA was changed by ABA. Compared with the control,the expression quantity of miRNA was higher at4℃and-10℃,but down-regulated expression at0℃,and all miRNAs which was detected were up-regulated expect miR5070at-25℃.It demonstrated the various changes may be associated with the function of miRNA target genes at low temperatures,and the one important temperature spot which may start the cold resistance mechanism was-10℃.(2) The chlorophyll content,proline content, SOD activity and POD activity of leaves and rhizome of wheat showd a down-up-down trend at-10℃under the condition of indoor simulation.They began to accumulate at2h in leaves,but accumulate at12h in rhizome,and they were improved by ABA.The content of malondialdehyde was a up-down trend,and the content reached highest at2h in leaves,but at12h in rhizome,and exogenous ABA decreased it The results above indicated winter wheat suffered the most serious injury when it was at-10℃for2h,and the cold material began to accumulated after the short stress.(3) Under the condition of-10℃of indoor simulation, through the real-time fluorescent quantitative analysis we got that:ABA changed expression pattern of all miRNAs in leaves,but the effect on expression pattern in rhizome were not big.Besides miR5218,13miRNAs expression were lowest at0.5h, significant up-regulated expression in leaves at2h, and were dropped at7d.In rhizome,14miRNAs were excessive expression at24h.Comperated with the control,the miRNAs in leaves which were treated by ABA had the minimum expression quantity in24h,but some rised at7d.In rhizome,13miRNAs showed down-regulated expression except miR5139at24h.