| Summary: | 碩士 === 國立中央大學 === 生命科學研究所 === 97 === The VP1/ABI3, which belongs to B3 domain like transcription factor,plays an importment role during plant seed embryogenesis and maturation. Previous studies have shown that when vp1/abi3 mutate, seeds could not sense endogenous abscisic acid and then direct germinate without dormancy. Recently,three VP1/ABI3-LIKE (VAL) genes, AtVAL1, AtVAL2, and AtVAL3, have been identified from Arabidopsis and played essential roles in seedlings growth. Moreover, AtVAL1/HSI2 has been demonstrated as a transcriptional repressor for a sugar-inducible Spomin promoter.
Rice is one of the most important crops and also a model plant for monocots. In order to study the function of VAL genes in rice seed development and in sugar signal transduction pathway, we identified two AtVAL homologs, OsVAL1 and OsVAL2, and then gain-of-function and loss-of-function analyses were applied. We find that OsVALs are ubiquitously expressed in rice different tissues, and emerge after rice seeds imbibed in water only one day. Moreover, four independent lines of OsVAL1 overexpression transgenic rice exhibit distinct brownish lesions. On the other hand, OsVAL RNAi transgenic rice plants present earlier heading than wild-type. In addtion,OsVALs are sugar-regulated and may play as a repressor for the rice αAmy3 gene.
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