92 アラビドプシスにおけるブラシノステロイドの器官特異的生合成

概要

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Brassinosteroids (BRs) are steroidal plant hormones that are essential for growth and development. There is only limited information on where BRs are synthesized and used. We studied the organ-specificity of BR biosynthesis in Arabidopsis, using two different approaches : we analyzed the expression of BR-related genes using real-time quantitative RT-PCR, and analyzed endogenous BRs using gas chromatography-mass spectrometry. Endogenous BRs and the expression of BR-related genes were detected in all organs tested. The highest level of endogenous BRs and the highest expression of the BR6ox1,the BR6ox2,and the DWF4 genes were observed in flower buds, which contain actively developing organs, such as the shoot apical meristem, young stems, and young cauline leaves. These genes are important in BR biosynthesis, since they encode the rate-limiting or farthest downstream enzyme in the BR biosynthesis pathway. The second highest level of endogenous BRs and expression of BR6ox1 and DWF4 were observed in silique, which contains actively developing embryos and seeds. These findings indicate that BRs are synthesized in all organs tested, but are most actively synthesized in young actively developing organs. In contrast, synthesis was limited in mature organs. Our observations are consistent with the idea that BRs function as the growth-promoting hormone in plants.
植物化学調節学会の論文
2002-10-31