FUNCTIONAL STUDIES OF HIGHLY EXPRESSED MICRORNAS IN ARABIDOPSIS THALIANA BY APPLYING STTM STRATEGY

miRNAs are important upstream gene regulators that modulate gene expression through mRNA degradation, translational inhibition or epigenetic pathways. They were found in almost all eukaryotic organisms and were reported to be involved in almost all developmental processes. Till now, in Arabidopsis thaliana there are 298 miRNAs, belonging to 190 miRNA families, published on miRBase. Among them, about 40 miRNA families are of comparatively high expressional levels, however, only a couple of them were well-studied in the past. STTM method, developed in Dr. Guiliang Tang’s, can be used to knock down specific miRNA’s expression and the transgenic STTM plants displayed alterations in many aspects including growth and development due to the loss of specific miRNA. It is thus a useful tool to study miRNA functions. In this thesis, a review of miR156 functional conservation, as an example, was first presented to demonstrate the importance of miRNAs. Next, I presented my preliminary studies and results of miR165/166-regulated anthocyanin accumulation in plants of loss of functions of miR165/166. Finally, I demonstrated dramatic growth and developmental changes in transgenic plants that lose certain highly expressed miRNA by STTM application in Arabidopsis. STTM efficacy in a wider application was proved, and the necessities of certain highly expressed miRNAs in plant development were displayed