ZmXYL modulates auxin‐induced maize growth

SUMMARY Plant architecture, lodging resistance, and yield are closely associated with height. In this paper, we report the identification and characterization of two allelic EMS‐induced mutants of Zea mays , xyl‐1 , and xyl‐2 that display dwarf phenotypes. The mutated gene, ZmXYL , encodes an α‐xylosidase which functions in releasing xylosyl residue from a β‐1,4‐linked glucan chain. Total α‐xylosidase activity in the two alleles is significantly decreased compared to wild‐type plants. Loss‐of‐function mutants of ZmXYL resulted in a decreased xylose content, an increased XXXG content in xyloglucan (XyG), and a reduced auxin content. We show that auxin has an antagonistic effect with XXXG in promoting cell divisions within mesocotyl tissue. xyl‐1 and xyl‐2 were less sensitive to IAA compared to B73. Based on our study, a model is proposed that places XXXG, an oligosaccharide derived from XyG and the substrate of ZmXYL, as having a negative impact on auxin homeostasis resulting in the dwarf phenotypes of the xyl mutants. Our results provide a insight into the roles of oligosaccharides released from plant cell walls as signals in mediating plant growth and development.