title: Blockage of Brassinosteroid Biosynthesis and Sensitivity Causes Dwarfism in Garden Pea.
abstract: Endogenous brassinosteroids (BRs) in the dwarf mutants lka and lkb of garden pea (Pisum sativum L.) and comparable wild-type plants were quantified by gas chromatography-selected ion monitoring using deuterated internal standards. In young shoots of the lkb mutant, the levels of brassinolide, castasterone, and 6-deoxocastasterone were 23-, 22-, and 9-fold lower, respectively, than those of wild-type plants. Applications of brassinolide, castasterone, typhasterol, 3-dehydroteasterone, and teasterone normalized internode growth of lkb seedlings. These findings indicate that the lkb plants are BR-deficient mutants, probably as a consequence of a block in the BR biosynthetic pathway prior to the production of teasterone. Young shoots of lka plants contained only 50% less brassinolide and 5 times more castasterone than the equivalent wild-type tissues. The lka seedlings were approximately 100 times less responsive to brassinolide than the lkb mutant, and application of castasterone had only a marginal effect on lka internode growth, suggesting that the lka lesion results in impaired sensitivity to BR.
authors.affiliation: Department of Bioproductive Science (T.N.), and Weed Science Center (Y.T.), Utsunomiya University, Utsunomiya 321, Japan.
authors.forename: T.
authors.initials: T
authors.lastname: Nomura
authors.forename: M.
authors.initials: M
authors.lastname: Nakayama
authors.forename: J. B.
authors.initials: JB
authors.lastname: Reid
authors.forename: Y.
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: T.
authors.initials: T
authors.lastname: Yokota