LAUSR

Basal internode length is important for lodging resistance of maize (Zea mays L.). In this study, foliar application of coronatine (COR) at the V8 stage differentially suppressed the length of the eighth internode of 10 cultivars, and three, five, and two cultivars were demonstrated to have strong (SC), moderate (MC), and weak (WC) degrees of internode shortening, respectively. RNA-Seq of the eighth internode of these cultivars revealed a total of 7895 internode elongation-regulating genes (IEGs, including 777 transcription factors (TFs)). Compared with those in WC, the hormone-related genes of cytokinin (CTK), gibberellin (GA), auxin and ethylene (ET) genes in SC were significantly downregulated, and more cell cycle regulatory factors and cell wall related genes showed significant changes, which severely inhibited internode elongation. Furthermore, we explored the direct regulatory relationship between two important TFs and target genes using EMSA, ZmABI7 and ZmMYB117, which regulate the cell cycle and cell wall modification by directly binding to the promoters of ZmCYC1, ZmCYC3, ZmCYC7, and ZmCPP1. The landscape transcriptome atlas reported herein provides a useful resource for studying maize internode development, which may provide a genetic basis for targeted control of internode length to improve lodging tolerance of maize.