The Role of Brassinosteroid-regulated miR395a in Arabidopsis thaliana
Date Issued
2011
Date
2011
Author(s)
Wu, Chia-Chi
Abstract
Brassinosteroids (BRs) are essential plant hormones involved in growth and development. Many high-throughput researches of BRs have been provided by DNA microarray and proteomics; however, the microRNAs-involved mechanisms of BRs are still poorly understood. With the use of time-course microRNA array analysis, we identified BR-regulated microRNAs in Arabidopsis thaliana ecotype Columbia. We found that miR395a was significantly up-regulated after BR treatment, and validated the expression of miR395a and BR-regulated genes using quantitative PCR (q-PCR). In order to clarify the miR395a-involved mechanisms, we integrated bioinformatics methods and publicly available DNA microarray data to predict the potential targets of miR395a. According to these methods, GUN5 was identified as one of the possible targets to miR395a. GUN5 is a multifunctional protein involved in plant metabolism such as chlorophyll synthesis. Recent studies have shown that GUN5 might be involved in abscisic acid (ABA) pathway. ABA is a plant hormone that mediates the adaptation of plants to stress via inhibiting seed germination, root elongation and lateral root formation. We further investigated the gene expression of ABA pathway in BR-treated plants by performing q-PCR. As proposed, the downstream genes of GUN5 were down-regulated. We further used fluorescence assay to validate the relative expression ratio of miR395a and GUN5, and the result showed that the expression of GUN5-GFP fusion gene was down-regulated. Furthermore, the expression of miR395a was up-regulated in leaf veins and root tissues in BR-treated miR395a promoter-GUS plants. Our data revealed that miR395a may inhibit ABA responses by targeting GUN5, indicating that BR may affect the growth of Arabidopsis through miR395a-regulated ABA responses and causing less chlorophyll in the cell around leaf veins.
Subjects
Arabidopsis thaliana
Brassinosteroid
miRNA
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-100-R98b43004-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):aed6c59fa9cdf88921ea67cba7e1c804