2 ブラシノステロイドの生合成遺伝子DWF4を過剰発現させると顕著な成長促進を引き起こす

抄録

Arabidopsis dwf4 was shown to be defective in ateroid 220α-hydroxylation step that is the putative rate-limiting step in brassinosteroid (BR) biosynthesis. To better understand the role of DWF4 in BR biosynthesis, transgenic plants ectopically overexpressing DWF4 (AOD4) were generated, and the phenotypes were characterized. The hypocotyl length of both light- and dark-grown AOD4 seedlings was increased dramatically as compared to wild type. The total number of branches and siliques increased in AOD4 plants, leading to a significant increase in the number of seeds produced. Analysis of endogenous BR levels in dwf4, Ws-2, and AOD4 revealed that dwf4 accumulated the precursors of 22α-hydroxylation steps, whereas overexpression of DWF4 resulted in increased levels of downstream compounds relative to Ws-2, indicative of facilitative metabolic flow through the step. These results suggest that it will be possible to control plant growth by engineering DWF4 transcription in plants.