Study on Biosynthesis and Physiological Roles of Progesterone in Plants

1.质谱分析表明孕酮在植物中广泛存在。黄体酮的内源水平与已知的植物激素水平相似。除孕酮外，在水稻、拟南芥和豌豆中也发现了孕酮代谢产物5-α-二氢孕酮和别孕酮。此外，还从拟南芥中鉴定出雌二醇，尽管含量很低。这些发现表明，动物类固醇激素是在植物组织中合成的。用气相色谱-质谱法分析了拟南芥和豌豆油菜素类固醇生物合成或受体突变体的内源激素水平。因此，油菜素类固醇的生物合成酶和信号转导不直接参与植物体内动物类固醇激素的合成。孕酮对拟南芥(野生型)和豌豆(赤豆)幼苗的生长有促进作用。雌二醇对豌豆突变体1h的生长没有促进作用，表明黄体酮具有生物活性，不转化为雌二醇。从水稻或拟南芥中克隆了与动物孕酮结合蛋白具有高度同源性的基因，这些基因具有单一或七个跨膜结构域。这些基因在植物组织中的表达模式以及基因中断突变体的表型表明，孕酮在植物的生殖和营养生长中都发挥着生理作用。

1. Mass spectrometric analysis indicated that progesterone occurs widely in plants. The endogenous level of progesterone was found to be similar to those of known plant hormones.2. In addition to progesterone, its metabolites such as 5α-dihydroprogesterone and allopregnanolone were also identified from rice, Arabidopsis and pea. Furthermore estradiol was identified from Arabidopsis although at very low level. These findings indicate that animal steroid hormones are synthesized in plant tissues.3. Brassinosteroid biosynthesis or receptor mutants of Arabidopsis and pea were analyzed for endogenous levels of animal steroid hormones by gas-chromatography-mass spectrometry. As the result, biosynthesis enzymes and signal transduction of brassinosteroids are not directly involved in the synthesis of animal steroid hormones in plants.4. Progesterone promoted the growth of Arabidopsis (wild type) and pea (gibberell in biosynthesis mutant 1h) seedlings. Estradiol did not promoted the growth of the pea mutant 1h, suggesting the progesterone is biologically active without transformation to estradiol.5. Genes having high homologies with those of animal progesterone binding proteins with either single or seven transmembrane domains were cloned from rice or Arabidopsis. The expression patterns of these genes in plant tissues as well as the phenotypes of gene disruption mutants indicated that progesterone play physiological roles in both reproductive and vegetative growth of plants.