48 アラビドプシスのブラシノステロイド非感受性矮性変異体はブラシノステロイドを蓄積している

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Seven dwarf mutants resembling brassinosteroid biosynthetic dwarfs were isolated that did not respond significantly to the application of exogenous brassinosteroids (BRs). Genetic and molecular analyses revealed that these are novel alleles of BRI1(Brassinosteroid Insensitive-1), which encodes a receptor kinase that may act as a receptor for BRs or be involved in downstream signaling. The endogenous BRs were examined for 5-week-old plants of a null allele (bril-4) and two weak alleles (bril-5 and bril-6). Previous analysis of endogenous BRs in several BR biosynthetic dwarf mutants revealed that active BRs are dificient in these mutants. However, bril-4 plants accumulated very high levels of brassinolide, castasterone and typhasterol (57-fold, 128-fold and 33-fold higher, respectively, than those of wild-type plants). Weaker alleles (bril-5 and bril-6) also accumulated considerable levels of brassinolide, castasterone and typhasterol, but less than those of the null allele (bril-4). The levels of 6-deoxoBRs in bril mutants were comparable to those in wild type. Accumulation of biologically active BRs may result from the inability to utilize these active BRs, the inability to regulate BR biosynthesis in bril mutants, or both.
植物化学調節学会の論文
1999-10-01