Expression Pattern And Functional Analysis Of MicroRNA Peu-miR156j And Peu-miR169o From Populus Euphratica

MicroRNAs (miRNAs) are, widespread in the eukaryotic cells, a class of16～29nt small non-coding RNAs that regulation eukaryotic cell gene expression via cleavage or translational inhibition of their target mRNAs. Populus euphratica is the only tall tree species forming natural forest in arid desert area of our country that has strong resistence such as salt tolerance, barren resistence and drought resistence. The research concern with regulation mechanism of microRNA from Populus euphratica under abiotic stress will produce far-reaching basic and applied research value for the discovery of the mechanism of miRNAs with target proteins and cultivate high-resistance new varieties.The experiment based on the former research of laboratory, we chose peu-miR156j and peu-miR169o as the research object from P. euphratica. To detect their expression under dehydration and high salinity stress, we used RT-PCR half quantitative and SYBR Green RT-PCR real-time quantitative assay. The results showed that both peu-miR156j and peu-miR169o appeared express rises in different degree, and showed that they might be involved in regulating dehydration and high salt adversity process. In order to further explore peu-miR156j and peu-miR169o biological function, we cloned peu-miR156j and peu-miR169o from P. euphratica and constructed the corresponding precursor of over-expression vector, thus obtained the corresponding35S:MIR156j and35S:MIR169o transgenic plants. The results showed that overexpression of miR156j increased the number of rosette leaves, leading to thick leaves and delayed flowering, also germination rate and growth condition of35S:MIR156j transgenic Arabidopsis under salt treatment were better than that of the wild type, and the expression assay of gene SPL6, SPL9and SPL11demonstrated the down-regulation caused by miR156. Based on the predicted stress-associated target gene STRS2(stress response suppressor2), we presumed that the molecular mechanism underlying the involvement of miR156in salt-tolerance may be ascribed to the regulation of STRS2expression.35S:MIR169o transgenic plants with wild-type in shape are basically the same, but had the higher germination ratio and survival under salt treatment, also wild-type plant showed early leaf withering phenomenon. The results showed that35S:MIR169o transgenic plants had stronger salt-tolerance than wild-type. The expression assay of gene NF-YA1, NF-YA2and NF-YA8demonstrated the down-regulation caused by miR169. We can conclude that the three target genes may be involved in miR169o regulation to salt the molecular mechanism of function. The study preliminary verified peu-miR156j and peu-miR169o function, laiding the foundation for further research on miRNA stress-resistant genetic engineering.