ZmDRL1 regulates maize leaf angle via phytohormone signaling.

key messageZmDRL1 is associated with maize leaf angle regulation, potentially through phytohormone-related pathways and interactions with ARF2. Leaf angle is a key determinant of plant architecture, influencing light interception and grain yield in maize. However, despite significant advances in elucidating the regulatory mechanisms of leaf angle, the number of functionally characterized genes involved in this process remains limited. Here, we characterized ZmDRL1, the maize ortholog of Arabidopsis DRL1 and yeast KTI12, which encodes a conserved KTI12 homolog-like protein. ZmDRL1 is expressed in multiple tissues, with relatively high expression in stems, leaves, and young embryos, and is localized to the nucleus. Loss-of-function mutations and CRISPR/Cas9 knockout lines of ZmDRL1 exhibited increased leaf angles and enlarged cells in the pulvinus region in both B73 and Zong31 genetic backgrounds. Yeast two-hybrid screening identified 16 candidate ZmDRL1-interacting proteins. Transcriptomic and metabolomic analyses revealed differentially expressed genes and metabolites enriched in pathways related to hormone signaling, metabolism, and transcriptional regulation. Integrated analysis further identified common regulatory pathways potentially associated with leaf angle variation. Based on these results, we propose a working model in which ZmDRL1 may be associated with phytohormone-related pathways, including IAA, ABA, and SA, and may interact with proteins such as ARF2. These processes may be linked to cell growth and development in the pulvinus region, thereby contributing to variation in leaf angle. Overall, this study provides new insights into the genetic and molecular basis of maize leaf angle and offers potential targets for the improvement of plant architecture in maize breeding.