Objective Genome-wide identification, biological functions, and expressions under heat stress of the LBD family in Rhus chinensis Mill were studied.

Methods Based on the whole genome of R. chinensis, bioinformatics methods were applied to identify the LBD family members and analyze their physicochemical properties, conserved motifs, chromosomal localization, phylogeny, and collinearity. Transcriptomes were used to determine the expressions of RcLBDs in tissues and predict the key cis-acting elements on the promoters from online database. Subcellular localizations of the genes were examined by GFP fused expression in tobacco leaves, and expressions under heat stress by qRT-PCR.

Results Thirty-two members in the LBD family were identified from the whole genome of R. chinensis and classified into 5 subfamilies based on the genetic distance. Structurally, they were mainly GAS glycine conserved domains, CX2CX6CX3C zinc fingers, and leucine zippers, and expressed significantly higher in the non-embryonic callus tissues than in the others. The promoter regions of RcLBDs were rich in various cis-acting components that responded to abiotic stress, hormones, growth, and development. Based on the analysis of promoter cis-acting components, 3 members were selected that included the pan-localized RcLBD16 and the nuclear-localized RcLBD19 and RcLBD23 with expressions significantly upregulated by heat stress.

Conclusion Of the 32 RcLBDs identified in R. chinensis, RcLBD16, RcLBD19, and RcLBD23 were presumably associated with the response to heat stress.