title: Erect leaves caused by brassinosteroid deficiency increase biomass production and grain yield in rice.
abstract: New cultivars with very erect leaves, which increase light capture for photosynthesis and nitrogen storage for grain filling, may have increased grain yields. Here we show that the erect leaf phenotype of a rice brassinosteroid-deficient mutant, osdwarf4-1, is associated with enhanced grain yields under conditions of dense planting, even without extra fertilizer. Molecular and biochemical studies reveal that two different cytochrome P450s, CYP90B2/OsDWARF4 and CYP724B1/D11, function redundantly in C-22 hydroxylation, the rate-limiting step of brassinosteroid biosynthesis. Therefore, despite the central role of brassinosteroids in plant growth and development, mutation of OsDWARF4 alone causes only limited defects in brassinosteroid biosynthesis and plant morphology. These results suggest that regulated genetic modulation of brassinosteroid biosynthesis can improve crops without the negative environmental effects of fertilizers.
authors.affiliation: Field Production Science Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Midoricho, Nishi-Tokyo, Tokyo 188-0002, Japan. orchardist@fm.a.u-tokyo.ac.jp
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Morinaka
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ohnishi
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Sunohara
authors.forename: Shozo
authors.initials: S
authors.lastname: Fujioka
authors.forename: Miyako
authors.initials: M
authors.lastname: Ueguchi-Tanaka
authors.forename: Masaharu
authors.initials: M
authors.lastname: Mizutani
authors.forename: Kanzo
authors.initials: K
authors.lastname: Sakata
authors.forename: Suguru
authors.initials: S
authors.lastname: Takatsuto
authors.forename: Shigeo
authors.initials: S
authors.lastname: Yoshida
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tanaka
authors.forename: Hidemi
authors.initials: H
authors.lastname: Kitano
authors.forename: Makoto
authors.initials: M
authors.lastname: Matsuoka
mesh_terms: D018533:Biomass; D002523:Edible Grain / Q000502:physiology*; D005638:Fruit / Q000235:genetics / Q000254:growth & development*; D024861:Genetic Enhancement / Q000379:methods*; D012275:Oryza / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000502:physiology*; D011494:Protein Kinases / Q000172:deficiency / Q000235:genetics; D013260:Steroids, Heterocyclic / Q000378:metabolism*
chemical_list: D013260:Steroids, Heterocyclic; D011494:Protein Kinases