Sakamoto Tomoaki, Morinaka Yoichi, Ohnishi Toshiyuki, Sunohara Hidehiko, Fujioka Shozo, Ueguchi-Tanaka Miyako, Mizutani Masaharu, Sakata Kanzo, Takatsuto Suguru, Yoshida Shigeo, Tanaka Hiroshi, Kitano Hidemi, Matsuoka Makoto
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.
Nat Biotechnol. 2006 Jan;24(1):105-9. doi: 10.1038/nbt1173. Epub 2005 Dec 20.
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.
叶片非常直立的新品种，能增加光合作用对光的捕获以及灌浆期的氮储存，可能会提高谷物产量。我们在此表明，水稻油菜素内酯缺陷型突变体osdwarf4-1的直立叶表型与密植条件下提高的谷物产量相关，即便不施额外肥料也是如此。分子和生化研究表明，两种不同的细胞色素P450，即CYP90B2/OsDWARF4和CYP724B1/D11，在油菜素内酯生物合成的限速步骤C-22羟基化中发挥冗余功能。因此，尽管油菜素内酯在植物生长发育中起核心作用，但单独突变OsDWARF4仅在油菜素内酯生物合成和植物形态上造成有限缺陷。这些结果表明，对油菜素内酯生物合成进行调控的基因调节可改善作物，而不会产生肥料对环境的负面影响。
