Poster: Photomorphogenesis
Abs #
506: The transcription level of an ALLENE OXIDE SYNTHASE gene is up-regulated by red and far-red light in rice (Oryza sativa L.)
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Presenter: |
Haga, Ken , k-haga@interlink.or.jp |
Authors | Haga, Ken (A) Iino, Moritoshi (A) | | Affiliations: |
(A): Botanical Gardens, Osaka City University
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We identified four homologues of ALLENE OXIDE SYNTHASE (AOS) in rice by performing database search (Rice BLAST servers, National Institute of Agrobiological Sciences, Japan) and named them OsAOS1-4. The AOS gene encodes one of key enzymes of jasmonic acid (JA) biosynthesis. OsAOS1 and OsAOS2 are located closely (separated by about 8 kb) in the second chromosome; OsAOS3 and OsAOS4 are located at 31 and 143 cM, respectively, in the third chromosome. The predicted amino acid sequences indicated that OsAOS1-3 are soluble proteins, whereas OsAOS4 is a membrane protein having two transmembrane helices. We conducted Northern blot hybridization and quantitative RT-PCR to investigate the effect of light on the steady-state transcription level of OsAOS genes in coleoptiles of rice (cv. Nihonmasari). It was uncovered that the level of the OsAOS4 transcript is up-regulated by red light (R). When dark-grown seedlings of rice was treated with a 3-min pulse of R, the transcription level increased with a lag of about 15 min, peaked at about 60 min (about 3-4 hold increase), and decreased towards the dark control level in the subsequent period of 60 min. The response was found in the basal part of coleoptiles, but not in the coleoptile tip and leaves. A similar transient increase in the transcription level could be induced by a pulse of far-red light (FR). It is suggested that transcription of OsAOS4 is controlled by phytochrome. It is known that the growth of rice coleoptiles is controlled by phytochrome and is strongly inhibited by R and FR. Since the growth of rice coleoptiles is also inhibited by JA, it is hypothesized that the presumed up-regulation of JA biosynthesis by phytochrome participates in the phytochrome-mediated inhibition of rice coleoptiles.
