Functional Research Of Tomato MiR172 In Disease Resistance

MicroRNA (miRNA) is a class of non-coding RNA molecules with 21-25 nucleotide in length, and play vital roles in the interaction between tomato and pathogen. MiR172 is a highly conserved plant miRNA family, its function on disease defense has been well studied in various plants, unfortunately, few research in tomato. Therefore, we over-expressed the precursor gene of miR172a and miR172b in tomato by using the molecular biology technologies in the study, and analyzed their function and acting mechanism in tomato disease defense.Firstly, the sequence characteristics of tomato miR172a and miR172b were analyzed and target genes were predicted by using of the bioinformatics. The results showed that miR172a and miR172b had different precursor but same mature miRNA sequence. They targeted a class of AP2 ethylene-response transcription factor. In addition, analysis of upstream sequences indicated that there are a lot of cis-elements which related to biotic stress in their promoter regions.Secondly, qRT-PCR was performed to determine the expression pattern of individual miR172 genes (precursor and mature miRNA) and target genes under the treatment with pathogen and signaling molecules involved in plant defense responses. The results showed that Pre-MIR172a and Pre-MIR172b can be both responded to the stresses mentioned above. In addition, the expression of miR172 was inversely correlated with the two targets under stress conditions.To investigate the function of miR172 in disease defense response, miR172a and miR172b precursor genes were introduced into tomato respectively by transformation. Then, the disease resistance of transgenic plants was detected. The results showed that overexpression of MIR 172a and MIR 172b could enhance disease resistance of tomato.The present study investigated the possible solution of tomato disease defense from miRNA. In additon, we also analyzed the function of tomato miR172 in disease resistance systematically. Our research could make the foundation for further functional verification of miRNA in tomato.