Genome-Wide Identification of the Trihelix Transcription Factor Family and Functional Analysis of ZmTHX15 in Maize

The trihelix transcription factor, which is a plant-specific family, play a critical role in plant growth and development and stress responses. Drought is the main limiting factor affecting yield of maize (Zea mays). However, the identification and characterization of this gene family in maize and its biological functions in response to drought stress have not been reported. Here, 46 Zea mays trihelix genes (ZmTHXs) were identified in the genome. Phylogenetic analysis of the ZmTHXs revealed that the genes were clustered into five subfamilies: GT-1, GT-2, GTγ, SH4, and SIP1. Chromosomal localization analysis showed that the 46 ZmTHXs were unevenly distributed across 10 chromosomes in maize. Cis-acting elements related to abiotic stress in ZmTHXs were found. Most ZmTHXs genes showed significant changes in expression levels under drought treatment. In addition, ZmTHX15-overexpressing Arabidopsis exhibited stronger drought tolerance with less secondary oxidative damage and higher photosynthetic rate. These findings could serve as a basis for future studies on the roles of ZmTHXs and the potential genetic markers for breeding stress-resistant and high-yielding maize varieties.