Date of Award

2017

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Biochemistry and Molecular Biology (PhD)

Administrative Home Department

Department of Biological Sciences

Advisor 1

Guiliang Tang

Committee Member 1

Xiaoqing Tang

Committee Member 2

Rupali Datta

Committee Member 3

Victor Busov

Abstract

MicroRNAs (miRNAs) are 21-24 nt small RNAs and have been proven to play a critical role in plant development. Many of them have highly conserved sequences which may have conferred functional conservations among different species of the plant kingdom. Unlike Arabidopsis and rice, tomato (Solanum lycopersicum) is a unique model featuring fleshy fruits, compound leaves, and sympodial shoot. To investigate the functional conservation and diversification of miRNAs between tomato and other plant species, we applied technologies of short tandem target mimic (STTM) and artificial miRNAs (amiRNAs) to down-regulate and over-express specific miRNAs, respectively. In total, 21 conserved and non-conserved miRNAs have been selected to construct their STTMs and amiRNAs and finally to generate their transgenic tomato plants. Northern blot and stem-loop qPCR were done to determine miRNA expressional changes in transgenic plants. After a large-scale screening of the above transgenic lines, we identified two miRNA mutant lines, STTM396 and STTM159, which have interesting phenotypes in fruit development. The level of miR396 was closely correlated with fruit productivity, showing a change in fruit size. Knockdown of miR159 has resulted in abnormal electrophysiological behavior, which might be related to ABA signaling. This miRNA might play vital roles in coping with drought stress in both leaves and fruits. The transgenic seeds will be made available to communities for sharing after publications. Our study applied effective approaches and established a valuable resource for functional study of miRNAs in tomato.

Available for download on Tuesday, July 31, 2018

Share

COinS