Identification Of MicroRNA In Populus Pruinosa And The Analyses Of Regulatory Mechanism

MicroRNAs (miRNAs) are a group of endogenous small RNAs, approximately21-25nt in length. MiRNA shows regulatory ability in not only plants growth, development, but also in various stresses responses. Populus pruinosa is a typical model species for studying the resistance of woody plant, which grows in desert areas of Nothwest China. After long time natural selection, it has became one of most resistant (drougt, high-temperature, salt) woody plants. Here, we present the first high-throughput sequencing and analyses of P. pruinosa callus small RNAs.:Based on these data, we identified salt-tolerant miRNA genes and mechanism related to salt stressed regulation. The results in this research included:(1)22,777,692and21,611,778reads were obtained by constructing the normal and salt-stressed libraries. Sequence analyses identified129conserved miRNA sequences and38novel miRNA sequences.(2) By analyzing the expression of miRNAs,25miRNA sequences showed significantly changed expressions in which15were up-regulated and10were down-regulated.(3) the prediction of targets implied the function of miRNAs with significantly different expression mainly regulated the ion exchange genes and transcriptional factors as a strategy in response to salt stress, such as ARF and laccase gene families.(4) We also detected85complementary miRNA*strands. Intriguingly, there’re nine miRNA*of conserved miRNAs more abundant than their corresponding miRNAs.(5) Furthermore, to analyse the regulatory pattern between miRNA and its targets, we also performed a transcriptional sequencing of P. pruinosa in the same two conditions and compared the results with miRNAs expression profile.This research expands and completes the miRNA data in poplar plants, and identified and salt-stress related miRNAs will add useful knowledge for plants, especially trees in studying salt-stress responding miRNAs. Besides, by associating analysis of the transcriptom and miRNAs in the same condition, our results provide a new approach for further studies of regulatory pattern betwee miRNA and targets.