Wheat nuclear factor Y (NF-Y) B subfamily gene TaNF-YB3;l confers critical drought tolerance through modulation of the ABA-associated signaling pathway

Acting as an indispensible subunit of nuclear factor-Y (NF-Y), a heterotrimeric transcription factor in eukaryotes, NF-YB proteins play important roles in regulating plant responses to abiotic stresses. In this study, a wheat (Triticum aestivum) NY-YB gene referred to as NtNF-YB3;l was functionally characterized for mediation of the drought stress. NtNF-YB3;l shares a high similarity to its counterparts across various plant species. The transcript abundance of TaNF-YB3;l was significantly up-regulated in roots and leaves upon drought and exogenous abiscisic acid (ABA), suggesting its role in regulating drought response possibly through an ABA-associated pathway. The TaNF-YB3;l overexpression lines exhibited improved growth under drought, which is consistent with behaviors of the transgenic lines with promoted stomata closure rate, enhanced leaf water retention capacity, and increased antioxidant enzyme activities and osmolyte accumulation. The genes encoding peroxidase (POD) genes (i.e., NtPOD1;3, NtPOD1;5, and NtPOD2;1) showed up-regulated expression in TaNF-YB3;l -overexpressing plants treated by simulated drought, suggesting their contribution to the TaNF-YB3;l-mediated POD activities. Transcripts of the ABA receptor gene NtPYL4 and PIN-FORMed (PIN) gene NtPIN4 were up-regulated in TaNF-YB3;l overexpression lines; overexpression or knockdown of them validated their roles in regulating plant drought response and modifying root system architecture (RSA) establishment, respectively. Our investigation indicates that TaNF-YB3;l is crucial for plant drought tolerance largely through its function in modulating an ABA-associated signaling pathway, which impacts on the physiological processes associated with stomata movement, reactive oxygen species (ROS) metabolsim, osmolyte accumulation, and RSA establishment.