Genome-wide analysis of poplar VQ gene family and expression profiling under PEG, NaCl, and SA treatments

The past research has demonstrated that the VQ genes in Arabidopsis thaliana, Oryza sativa, and Vitis vinifera L play vital roles in their growth, development, and stress responses. So far, no information available describes the functions of the VQ genes in Populus trichocarpa. In our study, comprehensive analysis of poplar VQ genes were performed including genome-wide identification, characterization, and expression analysis under polyethylene glycerol (PEG), NaCl, and salicylic acid (SA) treatment. Fifty-one VQ genes were identified and classified into seven subfamilies (I-VII), distributed randomly on 17 of the 19 chromosomes in poplar. Moreover, these VQ genes expanded primarily due to segmental duplication. In addition, gene structure and protein motif analysis indicated that these genes were relatively conserved within each subfamily; especially 39 of the 51 VQ genes had no introns. The results of quantitative real-time RT-PCR (qRT-PCR) analysis indicated that the VQ genes were variously expressed under different stresses. Our study provides a comprehensive overview of poplar VQ genes, which will be beneficial to the molecular breeding of poplar to promote its resistance to environment stresses, as well as overall thorough research about VQ gene functions.