Genome-Wide Identification of the MADS-Box Family Reveals Transcriptional Regulation Underlying Heat Stress Response in Pearl Millet

Pearl millet, an African-origin crop with exceptional heat tolerance, maintains normal flowering and seed production even under extremely high temperatures. The MADS-box transcription factor family plays a central role not only in floral organs, but also in abiotic stress responses. However, its specific function in pearl millet’s heat stress response remains unclear. In this study, a total of 63 MADS-box genes were identified. These genes were classified into five subfamilies and distributed across seven chromosomes, with chromosome 6 containing the highest number (12 genes). Additionally, expression analysis revealed that 53 MADS-box genes exhibited increased expression levels following heat stress under high-temperature conditions. Differential expression analysis identified five key MADS-box genes responding to heat stress. Further analysis of their expression trends using qRT-PCR revealed that the expression levels of these genes first increased and then decreased after heat stress treatment, with differences in the timing of peak expression among different genes. PMA1G07218.1 was selected for further functional characterization, which exhibited a significant response to heat stress treatment and reached a peak at 6 h. Subcellular localization analysis confirmed that the encoded protein is exclusively nuclear-localized. Through the yeast one-hybrid method (Y1H), we found that PMA1G07218.1 interacts by binding to the AG cis-acting element of F-box gene PMA1G04890.1. These findings provide valuable insight into the role of MADS-box genes in the high-temperature stress response of pearl millet, highlighting PMA1G07218.1 as a promising candidate for enhancing thermotolerance in this species.