Abstract Manipulating leaf inclination angle is a feasible approach to improve canopy photosynthesis and dry matter production in rice (Oryza sativa) via enhancing light penetration into the canopy. The importance of the semi-dwarf 1 (sd1) gene, a loss-of-function allele of SD1 encoding GA-20 oxidase-2 in gibberellin (GA) biosynthesis, in rice yield through improving lodging resistance is well known. However, little is known about the effects of sd1 as well as GA on leaf inclination angle. A near-isogenic line carrying the ‘Takanari’ sd1 allele in the ‘Koshihikari’ genetic background (NIL-sd1) had leaves with larger (more erect) leaf inclination angle and showed a smaller canopy extinction coefficient at the ripening stage than did ‘Koshihikari’. Furthermore, the leaf inclination angle of ‘Reimei’, an sd1 mutant in the ‘Fujiminori’ background, and of several other sd1 mutants in ‘Koshihikari’ background, was larger at the ripening stage than in parental lines, ‘Fujiminori’ and ‘Koshihikari’, respectively. The flag leaves of ‘Koshihikari’ plants treated with a GA biosynthesis inhibitor, paclobutrazol (PBZ), displayed a larger leaf inclination angle than did those of mock-treated plants during ripening. Treatment at the lamina joint of a flag leaf with exogenous GA3 or brassinolide (BL) significantly decreased leaf inclination angle. BL treatment increased the thickness of lamina joint tissue and the longitudinal cell length on the adaxial side of the marginal region of lamina joint, whereas GA3 treatment only increased the longitudinal cell length. NIL-sd1 had a lamina joint with decreased longitudinal adaxial cell length, but no difference in abaxial cell length nor tissue thickness in lamina joint cross section compared with that of ‘Koshihikari’. Thus, sd1 regulates the leaf inclination angle via a GA-based mechanism but not via BL involved in the crosstalk with GA.

中文翻译：

---

半矮化 1 (sd1) 基因通过调节水稻叶片倾角增强光进入冠层

摘要 控制叶片倾斜角是通过增强光对冠层的渗透来提高水稻（Oryza sativa）冠层光合作用和干物质产量的一种可行方法。半矮化 1 (sd1) 基因是 SD1 编码 GA-20 氧化酶-2 的功能丧失等位基因，在赤霉素 (GA) 生物合成中通过提高抗倒伏性在水稻产量中的重要性是众所周知的。然而，关于 sd1 和 GA 对叶片倾角的影响知之甚少。在'Koshihikari'遗传背景（NIL-sd1）中携带'Takanari' sd1等位基因的近等基因系具有更大（更直立）的叶片倾斜角，并且在成熟阶段显示出比'Koshihikari更小的冠层消光系数'。此外，在 'Fujiminori' 背景下的 sd1 突变体 'Reimei' 的叶倾角，和其他几个 sd1 突变体在 'Koshihikari' 背景下，在成熟阶段比亲本 'Fujiminori' 和 'Koshihikari' 大。用 GA 生物合成抑制剂多效唑 (PBZ) 处理的“越光”植物的旗叶在成熟期间显示出比模拟处理植物更大的叶片倾斜角。用外源 GA3 或芸苔素内酯 (BL) 在旗叶的叶片关节处处理显着降低了叶片倾角。BL 处理增加了椎板关节组织的厚度和椎板关节边缘区域近轴侧的纵向细胞长度，而 GA3 处理仅增加了纵向细胞长度。NIL-sd1 有一个椎板关节，纵向近轴细胞长度减少，但与“越光”相比，椎板关节横截面的背面细胞长度和组织厚度没有差异。因此，sd1 通过基于 GA 的机制而不是通过 BL 参与与 GA 的串扰来调节叶片倾角。