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 (<i>Zea mays</i>). 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 <i>Zea mays</i> trihelix genes (<i>ZmTHXs</i>) were identified in the genome. Phylogenetic analysis of the <i>ZmTHXs</i> revealed that the genes were clustered into five subfamilies: GT-1, GT-2, GTγ, SH4, and SIP1. Chromosomal localization analysis showed that the 46 <i>ZmTHXs</i> were unevenly distributed across 10 chromosomes in maize. Cis-acting elements related to abiotic stress in <i>ZmTHXs</i> were found. Most <i>ZmTHXs</i> genes showed significant changes in expression levels under drought treatment. In addition, <i>ZmTHX15</i>-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 <i>ZmTHXs</i> and the potential genetic markers for breeding stress-resistant and high-yielding maize varieties.