NF-YB Family Genes Identified in a Poplar Genome-wide Analysis and Expressed in Populus euphratica Are Responsive to Drought Stress

Some members of the nuclear transcription factor Y subunit B (NF-YB) have been newly reported to regulate a variety of functions in annual plant development and drought tolerance. The overall goal of this study was to identify and characterize the NF-YB genes in the model tree Populus trichocarpa, with the expectation of determining which orthologs in P. euphratica, naturally distributed in semiarid regions, were involved in drought response. A total of 20 NF-YB genes in the P. trichocarpa genome were identified and annotated. The examination on their phylogenetic relationships and ortholog predictions showed that Populus has an expanded set of NF-YB genes within unknown functional groups in comparison to Arabidopsis. Four members of the PeNF-YB gene family in P. euphratica were found to be up-regulated in expression during PEG-6000 (polyethylene glycol 6000) drought treatment based on RT-qPCR analyses. The increased knowledge on the phylogenetic relationships, predicted orthologs, and expression patterns of the poplar NF-YB genes during drought stress can be expected to promote the future study of woody plants.