MdNF-YB14, an apple NF-Y transcription factor, acts as a positive regulator of drought tolerance

MdNF-YB14 plays a critical role in enhancing drought stress tolerance by activating ROS- scavenging and stress-responsive genes. The nuclear factor Y (NF-Y) plays critical roles in maintaining plant growth, development, and stress tolerance. However, systematic research on the NF-Y gene family in apple remains insufficient. Here, a total of 47 MdNF-Y genes were identified in the apple genome, comprising 11 MdNF-YAs, 25 MdNF-YBs, and 11 MdNF-YCs. Analysis of cis-elements revealed that 30 out of 47 apple NF-Y gene promoters harbored one or more drought-responsive cis-elements, suggesting the potential involvement of NF-Y genes in plant drought tolerance. Among the 39 differentially expressed genes, 14 NF-Y genes were highly expressed in response to drought based on RNA-seq data. Notably, MdNF-YB14 showed significantly higher expression after 4 days of drought stress as confirmed by qRT-PCR analysis. Heterologous overexpression of MdNF-YB14 in transgenic Arabidopsis plants resulted in a higher germination rate, fresh weight, and root length under PEG treatment when compared with the wild-type plants. Similarly, overexpression of MdNF-YB14 positively enhanced drought tolerance in apple, which was associated with improved growth due to reduced electrolyte leakage, malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and superoxide radicals (O₂^-). Furthermore, the transcript levels of genes related to reactive oxygen species (ROS) scavenging and stress response were also significantly up-regulated in MdNF-YB14 transgenic apple plants. Collectively, MdNF-YB14 plays a crucial role in enhancing drought tolerance and can serve as a promising candidate gene for improving plant drought tolerance through biotechnological approaches.