Genome-Wide Identification of the ZmNF-Y Transcription Factor Family in Maize and Functional Characterization of ZmNF-YA7 in Drought Tolerance.

The nuclear factor Y (NF-Y) transcription factor family plays crucial roles in plant growth, development, and stress responses. However, studies on the NF-Y family in maize remain relatively limited. In this study, we identified 53 NF-Ys in the maize genome, which were classified into ZmNF-YA, ZmNF-YB, and ZmNF-YC subfamilies. These genes exhibited diverse physicochemical properties and were unevenly distributed across the 10 chromosomes. Synteny analysis revealed 48 collinear gene pairs between maize and rice, indicating close evolutionary relationships. Gene structure and conserved motif analyses showed both conservation and divergence within the family. Promoter analysis identified abundant cis-acting elements related to hormone response, abiotic stress, light response, and growth regulation. Expression profiling under drought stress revealed that ZmNF-Ys respond differentially, with some showing strong induction. Functional characterization demonstrated that ZmNF-YA7 positively regulates drought tolerance in maize. Overexpression of ZmNF-YA7 enhanced drought tolerance through multiple mechanisms: reducing oxidative damage by increasing antioxidant enzyme activities, accumulating osmoprotectants, and modulating xylem vessel anatomy (larger diameter and lower density under drought). These findings provide comprehensive insights into the ZmNF-Y gene family and highlight ZmNF-YA7 as a promising candidate for improving drought tolerance in maize breeding programs.