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（Zea mays）植物结构的两个关键决定因素，并且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调节。然而，乙烯在调节玉米植物结构，特别是植物高度和叶片角度方面的机制尚不清楚。在这里，我们表征了一个玉米突变体Semidwarf3（Sdw3），与野生型相比，它表现出较短的身材和较大的叶片角。组织学分析表明，抑制节间纵向细胞伸长和促进耳廓的生长是造成Sdw3株高降低和叶角增大的主要原因。突变体。通过位置克隆，我们在玉米乙烯的乙烯合成中鉴定了候选基因ZmACS7中的转座子插入，该基因编码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基因具有Sdw3突变体的表型。酶活性和蛋白质降解试验表明，Sdw3突变体中ZmACS7的C末端改变，增加了该蛋白质的稳定性，但不影响其催化活性。Sdw3突变体中的ACC和乙烯含量显着提高，导致植株高度降低和叶角增大。另外，我们证明了ZmACS7在根系发育，开花时间和叶数中起关键作用，这表明ZmACS7是玉米生长发育过程中具有多效作用的重要基因。