Functional Analysis Of MicroRNA Sly-mir156α And Sly-mir169c In Tomato

Tomato is an important crop cultivated widely in the world. Exploitation of agronomically important genes which regulate traits, such as plant height, leaf number, and adapt to environmental stress such as drought, salt and cold stress is crucial for tomato genetic improvement. MicroRNA is such a case.MicroRNA is widely found in eukaryotic organisms. It plays important roles in various biological processes, including development, stress and hormone response, etc.In this study, Sly-mir156a and Sly-mirl69c from miRBase, which represent two different members of tomato miRNAs family, were selected and cloned. Overexpressing vectors were constructed and introduced into tomato genome. This study aims to characterize their function in tomato. Putative targets of the microRNAs were predicted using bioinformatic tool and their tissue expression profile as well as their expression pattern under drought and salt treatments were investigated. The main results were as follows:1. The microRNA precursor genes of Sly-mir156a and Sly-mirl69c were cloned from tomato genome and their overexpression vectors were constructed and introduced into tomato via Agrobacterium-mediated transformation.2. The transgenic tomato plants were obtained. PCR and Southern blot analysis showed that the transgenes were integrated into the tomato genome.3. RT-PCR analysis showed the transgenes were overexpressed in transgenic plants.4. Overexpression of Sly-mir156a in transgenic tomato plants resulted in dwarfism, shorter internode, smaller and more leaves, suggesting its enrollment in various developmental processes. Quantitative RT-PCR was conducted to investigate the tissue expression of the putative target genes. The results provided evidences of the role of Sly-mir156a in tomato plant architecture.5. Transgenic plants over-expressing Sly-mir169c were more resistant to drought and salt stress than wild-type plants. The stomatal aperture and stomata conductance were significantly reduced in transgenic plants, which were consistent with the drought tolerance performance. Tissue expression of putative target genes was monitered using Quantitative RT-PCR. The results provided evidences of the role of Sly-mir169c in stress tolerance of tomato.