Regulates Maize Growth and Development and Mycorrhizal Symbiosis.

Hydroxyproline O-arabinosyltransferase (HPAT), a critical enzyme in plant glycosylation pathways, catalyzes the transfer of arabinose to the hydroxyl group of hydroxyproline residues. This enzyme contains a canonical GT95 glycosyltransferase, a structural hallmark of this carbohydrate-active enzyme family. HPAT mediates arabinosylation of diverse cellular targets, including cell wall extension and small signaling peptides. Emerging evidence has shown that HPAT orthologs regulate plant development and symbiotic interactions through post-translational modification of /LRR Extracellular (CLE) peptides. Although the molecular functions of genes have been characterized in model plants such as and , their roles remain unexplored in L. In this study, we used homozygous mutants to explore the function of the maize gene. Sequence analysis identified a N-terminal signal peptide targeting the Golgi apparatus and promoter elements responsive to AM fungal colonization. Phenotypic analysis revealed its negative regulatory role: promotes vegetative growth (increased plant height and accelerated flowering) and enhances AM symbiosis (increased colonization rate). Mechanistic studies demonstrated that possesses dual regulatory functions-the activation of auxin signaling and repression of -mediated arbuscular degradation pathways. In addition, overexpression of in inhibits growth (reduced plant height) and impairs symbiotic interactions. Our findings establish as a critical node to regulate auxin and symbiotic signaling, providing novel insights into plant glycosylation-mediated development. This work not only advances our understanding of maize growth regulation but also identifies potential targets for crop improvement through arabinosylation pathway manipulation.