Poster: Late and Moved Abstracts
Abs #
1409: Functional study of Osh69 gene associated with plant leaf senescence
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Presenter: |
Lee, Ruey-Hua , rhlee@gate.sinica.edu.tw |
Authors | Lee, Ruey-Hua (A) Lin, Mei-Chun (A) Chen, Shu-Chen Grace (A) | | Affiliations: |
(A): Institute of Botany, Academia Sinica, Taipei, TAIWAN
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Leaf senescence is genetically programmed, which ultimately leads to organ death and allows nutrients to be recycled to other parts of the plants. This developmental process involves an ordered series of molecular events for initiation and completion of senescence. We have previously identified numerous senescence-associated genes (SAGs) in rice. However, the biochemical functions and the regulatory mechanisms of many SAGs remain unknown. Here we characterized the structure and function of a novel SAG-Osh69, which encodes putatively alkaline a-galactosidase using rice and Arabidopsis as the plant materials. Rice Osh69 is a single-copy gene containing 13 exons with 70-80% sequence homology to the Arabidopsis homologs. The expression of Osh69 is not only associated with natural leaf senescence but also induced to high expression levels by darkness, hormone treatments (ABA, GA3, IBA and MeJA) and under stress conditions (H2O2 and wounding). Analysis of rice insertion mutant generated by Tos17 retrotransposon showed delayed leaf senescence during natural and dark-induced senescence compared to the wild-type plants. Arabidopsis T-DNA insertion mutant for Osh69 ortholog is also being characterized. The recombinant Osh69 protein has been expressed in E. coli and partially purified for biochemical characterization. The alkaline a-galactosidase activity for the recombinant protein has been tested and confirmed. Cellular localization of Osh69 protein at different stages of rice leaf development and senescence using transmission electron microscopy with specific Osh69 antibodies has been performed. The result indicates Osh69 protein is present majorly in the chloroplasts of senescing leaves. The possible biological function of Osh69 during leaf senescence is discussed.
