Genome-wide Classification, Identification and Expression Profile of the C3HC4-type RING Finger Gene Family in Poplar (Populus trichocarpa)

Abstract

C3HC4-type RING finger genes belong to a large gene family in plants and play crucial roles in diverse stress responses. In this study, a comprehensive analysis of the poplar (Populus trichocarpa) C3HC4-type RING finger gene family was performed, including analysis of phylogenetic relationships, chromosomal locations, gene structures, motif compositions, possible cis-elements, and expression profiles. Ninety-one poplar C3HC4-type RING finger genes were identified, which were clustered phylogenetically into seven distinct subfamilies and distributed predominantly across 17 linkage groups. Motif analysis revealed the presence of 15 conserved motifs with unknown functions within the predicted proteins. Promoter cis-element analysis indicated that most of the C3HC4-type RING finger genes contained abiotic stress-related cis-elements. Further, expression profiling showed that a number of genes were expressed differentially across disparate tissues and under various stresses, such as wood formation and drought. Additionally, quantitative real-time RT-PCR was performed on 24 selected C3HC4-type RING finger genes to confirm their responses to drought stress treatment. We found that PtrRHC7, 20 and 70 were not only abundantly transcribed in leaves, but also were upregulated in roots under drought stress. These results represent the foundation for further investigation of the roles of these candidate genes and for future genetic engineering and gene functional studies in Populus.