51. 乾燥応答におけるアブシジン酸生合成部位は維管束柔組織である

概要

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Accumulation of abscisic acid (ABA) is essential for the response to drought environment in plants. Arabidopsis 9-cis-epoxycarotenoid dioxygenase 3 (NCED3) is known to act as a rate-limiting enzyme in ABA biosynthesis, and the expression of NCED3 gene is rapidly up-regulated under water stress, resulting in the accumulation of endogenous ABA. However, we have no information about the site(s) of expressing NCED3, and therefore the site(s) of ABA biosynthesis in plant is still unknown. In the present study, we obtained specific antibodies against NCED3, ABA2 and AAO3 and used them for immunological analyses. Western blotting revealed that ABA2 and AAO3 were expressed in turgid plants, whereas the signal of NCED3 was not detectable. After the drought treatment, rapid increase of NCED3 protein was induced within 1 hour, especially accumulating in rosette leaves. To investigate the site(s) of the expression of NCED3 in rosette leaves, immunohistochemical analysis was performed. In non-stressed leaves, the signal was not detected. In dehydrated leaves, the clear immunofluorescent signal for NCED3 was observed in vascular parenchymatous tissues. In addition, ABA2 and AAO3 were also localized in the identical tissues. These results indicate that drought induced ABA production occurrs in vascular systems.
植物化学調節学会の論文
2005-10-13