Plant height and leaf angle are two crucial determinants of plant architecture in maize (Zea mays) and are closely related to lodging resistance and canopy photosynthesis at high planting density. These two traits are primarily regulated by several phytohormones. However, the mechanism of ethylene in regulating plant architecture in maize, especially plant height and leaf angle, is unclear. Here, we characterized a maize mutant, Semidwarf3 (Sdw3), which exhibits shorter stature and larger leaf angle than the wild type. Histological analysis showed that inhibition of longitudinal cell elongation in the internode and promotion in the auricle were mainly responsible for reduced plant height and enlarged leaf angle in the Sdw3 mutant. Through positional cloning, we identified a transposon insertion in the candidate gene ZmACS7, encoding 1-aminocyclopropane-1-carboxylic acid (ACC) Synthase 7 in ethylene biosynthesis of maize. The transposon alters the C terminus of ZmACS7. Transgenic analysis confirmed that the mutant ZmACS7 gene confers the phenotypes of the Sdw3 mutant. Enzyme activity and protein degradation assays indicated that the altered C terminus of ZmACS7 in the Sdw3 mutant increases this protein’s stability but does not affect its catalytic activity. The ACC and ethylene contents are dramatically elevated in the Sdw3 mutant, leading to reduced plant height and increased leaf angle. In addition, we demonstrated that ZmACS7 plays crucial roles in root development, flowering time, and leaf number, indicating that ZmACS7 is an important gene with pleiotropic effects during maize growth and development.

株高和叶角是玉米植物株型的两个关键决定因素，与高种植密度下的抗倒伏性和冠层光合作用密切相关。这两个性状主要受几种植物激素的调节。然而，乙烯调节玉米株型尤其是株高和叶角的机制尚不清楚。在这里，我们表征了玉米突变体Semidwarf3 ( Sdw3 )，它比野生型表现出更短的身材和更大的叶角。组织学分析表明，节间纵向细胞伸长的抑制和耳廓细胞纵向伸长的促进是Sdw3突变体株高降低和叶角增大的主要原因。通过定位克隆，我们鉴定了候选基因ZmACS7中的转座子插入，该基因编码玉米乙烯生物合成中的 1-氨基环丙烷-1-羧酸 (ACC) 合酶 7。转座子改变 ZmACS7 的 C 末端。转基因分析证实突变体ZmACS7基因赋予Sdw3突变体的表型。酶活性和蛋白质降解测定表明， Sdw3突变体中 ZmACS7 C 末端的改变增加了该蛋白质的稳定性，但不影响其催化活性。 Sdw3突变体中 ACC 和乙烯含量显着升高，导致株高降低、叶角增大。此外，我们证明ZmACS7在根系发育、开花时间和叶片数量方面发挥着至关重要的作用，表明ZmACS7是玉米生长发育过程中具有多效性的重要基因。