Genome-Wide Analysis of the YUCCA Gene Family in Wheat and the Potential Roles of TaYUCCA19 and Its Homologs in Male Reproductive Development

YUCCA belongs to the flavin-containing monooxygenas and catalyzes the rate-limiting step in endogenous auxin biosynthesis, thereby regulating local auxin homeostasis and participating in diverse aspects of plant growth, development, and physiological processes. However, the relationship between the <i>YUCCA</i> genes and male fertility regulation in wheat remains unclear. In this study, we identified 64 <i>TaYUCCA</i> genes through whole-genome analysis and classified them into three clades, each of which is conserved in motif composition and gene structure. A synteny analysis indicated that family expansion was primarily driven by segmental duplication and tandem duplication, and Ka/Ks analysis suggested that all members are under purifying selection. An analysis of the expression patterns showed that the <i>TaYUCCA</i> genes displayed differential expression across various tissues and reproductive developmental stages. In the temperature-sensitive male-sterile wheat line YS3038, <i>TaYUCCA19</i>, <i>TaYUCCA22</i>, and <i>TaYUCCA25</i> were specifically highly expressed at the uninucleate pollen stage under fertile conditions. The silencing of <i>TaYUCCA19</i> resulted in abnormal pollen morphology and a significant reduction in the seed set rate, indicating that it is a key gene required for normal pollen development in wheat. Overall, this study systematically characterizes the wheat <i>YUCCA</i> gene family and provides the first functional evidence of <i>TaYUCCA</i> genes in male reproductive development, offering an important foundation for studies on wheat male sterility mechanisms and the exploitation of heterosis.