Transcriptional Response Of Resistance-Related MiRNA In SO₂-fumigated Arabidopsis Plants

microRNA are designated as a type of endogenous non-coding small sized RNA about19-25nt length, which is widespread in eukaryotic oranisms and highly conserved in evolution. Recent years reseach show that miRNA not only play an important role in gene expression regulation during development process, but also take part in gene regulation under abiotic and biotic stress as well as diverse physiological processes. Now we have a new understanding of miRNA function, which provide new idea for cultivation of resistant plants. miRNA research focus on expression patterns of stress-regulated miRNAs and their functions in plant stress adaptation.Arabidopsis was employed to detect expression change of resistance-related miRNA induced by SO2fumigation. Sequential expression patterns of miRNA were detected by RT-PCR with their promoter preliminary analyzed. Combined the results of cDNA microarray, their possible role in stress adaptation process were analyzed. The main results were as follows:1. Expression change of7miRNA genes was detected by RT-PCR. All miRNAs were upregulated differently except MIR398a and MIR398c.2. Based on1000bp upstream sequences of these miRNAs, multiple stress response cis-acting elements were found in these areas, such as the MBS (MYB binding site involved in drought-inducibility), TCA(cis-acting element involved in salicylic acid responsiveness), ABREs (ABA-response elements), HSEs (heat stressresponsive elements), LTRs (low-temperature responsive elements) and TC-rich repeats (defense and stress responsive elements), which indicate that these resistance-related miRNAs could participate in plant response to stress.3. The level of ROS in Arabidopsis could be induced by SO2fumigation. We analyzed the Sequential expression patterns of miR398and target genes, which are related to ROS metabolism. MIR398a and MIR398c decreased transcription while target genes CSD1and CSD2increased, in which Target genes change later than miRNA. miR398participate plant response to SO2fumigation by negatively regulating target genes.4. MIR398a overexpression vector drived by35S was constructed, transformed to Arabidopsis. Transgenic plants were screening and verified by RT-PCR. There was no significant phenotype difference between transgenic plant and wild-type.