'Rinrei', a brassinosteroid-deficient dwarf mutant of faba bean (Vicia faba)

A dwarf mutant of broad bean (Vicia faba L.), the variety Rinrei, has been created by gamma-ray irradiation. Rinrei is characterized by dark green leaves and by reduced plant length, internode and petiole length, shoot weight, and number of branches. Genetic analysis of hybrids between Rinrei and two wild-type lines indicated that these characteristics are controlled by a single recessive gene. The phenotype of Rinrei was restored to that of the wild type by application of brassinolide, but not by GA(3). Qualitative and quantitative analysis by gas chromatography-mass spectrometry indicated that 24-methylenecholesterol and isofucosterol accumulated in Rinrei to levels more than 30 times higher than in the wild type. In contrast, Rinrei had lower than wild-type levels of campesterol, sitosterol and brassinosteroids. Therefore, Rinrei is a brassinosteroid-deficient mutant defective in sterol C-24 reduction. The gene was tentatively designated as brassinosteroid deficient dwarf 1, bdd1, which seems to be a homologue of Arabidopsis dwf1 (dim, cbb1) and pea lkb.