46.ヒメツリガネゴケが生産するステロイドホルモン(口頭発表)  [in Japanese] 46. Endogenous steroid hormones in Physcomitrella patens  [in Japanese]

Genetic studies have revealed that brassinosteroids (BRs) are essential plant hormones for growth and development of seed plants. However, little is known about the occurrence and physiological roles of BRs in ferns and moss. The biosynthesis genes of sterols are highly conserved in lower to higher plants. However, the genome of the moss, Physcomitrella patens comprises no genes with high similarity to BR biosynthesis genes of seed plants. In order to know whether P. patens produces BRs, we analyzed endogenous BRs in the protonema using GC-MS. Furthermore, we also analyzed endogenous animal steroid hormones using the same material although their roles and biosynthesis in plants are unknown. As the result, a small amount of castasterone that is a biological active form in seed plants and a series of the precursors such as 6-dexoxocastasterone were identified in P. patens. In addition, animal steroid hormones including progesterone were also identified. These findings may imply that not only BRs but also animal steroid hormones had been utilized as physiologically active steroids before the branching-off from the common ancestor into moss and seed plants.