ZmRLCK1 modulates secondary cell wall deposition in maize

The secondary cell wall (SCW) is essential for providing mechanical strength to plants, enabling upright growth and facilitating the long-distance transport of water and nutrients through the vascular system. In this study, we generated an EMS-induced mutant library in B73 maize and identified two "drought-sensitive like" mutants, rlck1-1 and rlck1-2, which exhibited impaired function of ZmRLCK1. This gene encodes a predicted receptor-like cytoplasmic kinase with kinase activity. Phenotypic analysis revealed that ZmRLCK1 mutation disrupted metaxylem vessel development, likely compromising upward water transport. Additionally, the mutants displayed aberrant microtubule organization, suggesting a role for ZmRLCK1 in cytoskeletal regulation. Differential phosphoproteomic sequencing identified several microtubule-associated proteins as potential substrates of ZmRLCK1, though the exact molecular mechanisms linking ZmRLCK1-mediated phosphorylation to microtubule dynamics remain to be fully elucidated.