抄録
Progesterone is an animal steroid hormone that functions as a corpus luteum hormone. Recently, we identified progesterone from Arabidopsis, rice, tomato and pea, suggesting that progesterone is a ubiquitous constituent of plants. We have already found that Arabidopsis hypocotyl elongation was promoted by progesterone in the weak light condition, and these result could suggest that progesterone has biological activities in plant. To clarify the molecular mechanism of progesterone bioactivity for plant, we analyzed candidate genes related to progesterone biosynthesis and perception. Nuclear receptor for progesterone is well known in animal, but not been found in the Arabidopsis and rice genome. In 2003, the novel type as progesterone receptor, which structure could have in a family of G protein-coupled seven transmembrane receptors (GPCR), was identified in fish, human and mouse with experimental result of binding activity to progesterone. In the Arabidopsis genome, we identified some homologous genes with animal GPCR-type progesterone receptors, and these are about similarity 40%. Digitalis, a kind of medical plant, produces Digitoxigenin cardiac glycoside inducing cardiac action. In 1960s, progesterone was reported as intermediate in Digitosigenin biosynthesis pathway, and progesterone 5β-reductase gene has been also isolated in Digitalis. We identified the homologous genes of Digitalis 5β-reductase Arabidopsis genome, and these similarity was about 82%.
