Systematic analysis of the F3H family in maize reveals a role for ZmF3H6 in salt stress tolerance

Abstract

Flavanone 3-hydroxylase (F3H) plays a pivotal role in the biosynthesis of flavonoid compounds, which are involved in growth and development processes, as well as stress responses in plants. However, little information has been uncovered about the F3H gene family in maize (Zea mays) to date. In this study, 15 ZmF3H genes were identified in the maize genome and clustered into four phylogenetic groups with homologs from other plant species. Expression profile analysis revealed that most ZmF3H genes exhibited differential expression patterns across various maize tissues. qRT-PCR expression analysis of ZmF3H genes under salt treatment identified ZmF3H6 as an excellent candidate gene for salt resistance. Overexpression of ZmF3H6 in Arabidopsis led to increased tolerance to salt stress, possibly by enhancing flavonol accumulation and antioxidant capacity. Conversely, a mutation in the sequence of ZmF3H6 resulted in compromised salt tolerance of maize seedlings. Molecular docking identified that ZmF3H6 binds to naringenin at specific amino acid residues necessary for hydroxylation. Dual-luciferase reporter and electrophoretic mobility shift assays demonstrated that the transcription factor ZmMYB33 activates ZmF3H6 expression by binding to the MBS domains in the ZmF3H6 promoter. Our findings provide a foundation for further investigation into the roles of the ZmF3H genes in plant abiotic stress responses and present a novel genetic resource for creating salt-resistant maize.