On April 22, 2020, Professor Jin Weiwei of China Agricultural University and Professor Liu Baoshen of Shandong Agricultural University published a research paper entitled "maize plant architecture is regulated by the ethylene biosynthetic gene zmacs7" on-line for corresponding authors.
Plant height and leaf angle are two key determinants of plant structure of Zea mays L., and they are closely related to lodging resistance and canopy photosynthesis under high planting density. These two characters are mainly regulated by plant hormones, including gibberellin, brassinosteroid and auxin. However, the role of ethylene in the regulation of maize plant structure, especially plant height and leaf angle, is not clear. Here, we characterize a maize mutant, semi-dwarf 3 (sdw3), which shows shorter stature and larger leaf angle than the wild type. The results of histological analysis showed that the main reasons for the decrease of plant height and the increase of leaf angle were the inhibition of longitudinal cell elongation and the promotion of auricle growth. Through site cloning, we identified transposon insertion in the candidate gene zmacs7, which encodes 1-aminocyclopropane-1-carboxylic acid (ACC) synthetase 7 in ethylene biosynthesis of maize. Transposons change the C-terminal of zmacs7. Transgenic analysis confirmed that the mutant zmacs7 gene had the phenotype of sdw3 mutant. The results of enzyme activity and protein degradation showed that the C-terminal change of zmacs7 in sdw3 mutant increased the stability of the protein, but did not affect its catalytic activity. The content of ACC and ethylene in sdw3 mutant increased significantly, which resulted in the decrease of plant height and the increase of leaf angle. In addition, we show that zmacs7 plays an important role in root development, flowering time and leaf number,