Promoter Activity and Alternative Splicing Gene Expression Analysis of White-back Associated Gene (OsWB) in Rice (Oryza sativa L.)
Date Issued
2008
Date
2008
Author(s)
Lin, Ying-Chen
Abstract
Regulation of gene expression is an essential issue for plant growth, development and environmental responses. In this study, we focus on the gene expression study of a white back associated gene, OsWB, in rice. The accumulation of OsWB protein had been shown to be negatively correlated with chalkiness during rice grain formation under high temperature. However, the regulation of OsWB gene expression and its corresponding physiological function remains to be addressed. To reach this goal, we first characterized the alternative splicing gene expression pattern of OsWB1 at post-transcriptional level. Also, we carried out the promoter activity analysis of OsWB1 either with transient gene activation analysis or transgenic rice plant. By RT-PCR analysis, we identified putative 11 alternative splicing transcript variants (ASTVs) of OsWB1 in TNG 67 rice. The length of these ASTVs can be distributed from 210 bp to 1.5 kb. Comparison of various OsWB1 ASTVs sequence revealed that the process of alternative splicing is dependent on short direct repeat sequence. We are also interested in understanding whether the alternative splicing gene expression of OsWB1 can be affected under different tissues, developmental stages and different abiotic stresses. The results showed that among various OsWB1 transcript variants, the expression of OsWB1-c transcript is highest in booting tissues of rice. OsWB1-b transcript expression was decreased under high temperature but the amount of OsWB1-c transcript remained constant. In addition, the gene expression pattern of OsWB1 is unique in mature rice grains. To further understand how OsWB1 gene expression is regulated at transcriptional level, the promoter sequence of OsWB1 is analyzed and searched for various responsive cis-acting DNA elements. Several elements can be found, including ABA、Me-JA、LTRECOREATCOR15 within OsWB1 promoter. We then used transient gene expression assay to study the relationship between OsWB1 gene expression and plant hormone ABA. Preliminary result indicated that the expression of OsWB1 (1.4 Kb)::GUS can be induced at least ten folds by ABA. To fully understand the subcellular-level gene expression and regulation of OsWB1, the transgenic rice plant of OsWB1 (1.4 Kb)::GUS was also produced. It may due to the weak activity of OsWB1 promoter, the GUS staining did not provide any positive result in various tissues of transgenic rice. Taken together, this study proved that OsWB1 expression is not only controlled by its own promoter but also regulated by alternative splicing.
Subjects
OsWB
alternative splicing
short direct repeat
promoter
cis-acting DNA element
Type
thesis
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