Genome-Wide Identification and Characterization of the NF-YA Gene Family and Its Expression in Response to Different Nitrogen Forms in Populus × canescens

The NF-YA gene family is a class of conserved transcription factors that play important roles in plant growth and development and the response to abiotic stress. Poplar is a model organism for studying the rapid growth of woody plants that need to consume many nutrients. However, studies on the response of the NF-YA gene family to nitrogen in woody plants are limited. In this study, we conducted a systematic and comprehensive bioinformatic analysis of the NF-YA gene family based on Populus × canescens genomic data. A total of 13 PcNF-YA genes were identified and mapped to 6 chromosomes. According to the amino acid sequence characteristics and genetic structure of the NF-YA domains, the PcNF-YAs were divided into five clades. Gene duplication analysis revealed five pairs of replicated fragments and one pair of tandem duplicates in 13 PcNF-YA genes. The PcNF-YA gene promoter region is rich in different cis-acting regulatory elements, among which MYB and MYC elements are the most abundant. Among the 13 PcNF-YA genes, 9 contained binding sites for P. × canescens miR169s. In addition, RT-qPCR data from the roots, wood, leaves and bark of P. × canescens showed different spatial expression profiles of PcNF-YA genes. Transcriptome data and RT-qPCR analysis showed that the expression of PcNF-YA genes was altered by treatment with different nitrogen forms. Furthermore, the functions of PcNF-YA genes in transgenic poplar were analyzed, and the potential roles of PcNF-YA genes in the response of poplar roots to different nitrogen forms were revealed, indicating that these genes regulate root growth and development.