De novo Assembly and Analysis of Sumac (Toxicodendron vernicifluum (Stokes) F.A. Barkley) Transcriptomes Provides Insights into the Biosynthesis of Urushiol

Sumac is universally known for its abundance of raw lacquer. Toxicodendron vernicifluum (Stokes) F.A. Barkley is one of the widely distributed native sumac cultivars. To accelerate sumac breeding for more prolific, high-quality, and robust cultivars, it is essential to explore its lacquer metabolism. However, transcriptomic and genomic data available for sumac are still limited. In this study, we generated the transcriptomic profiles of triploid Toxicodendron vernicifluum CV. Dahongpao (Dahongpao) and diploid T. vernicifluum and Toxicodendron vernicifluum CV. Huoyanzi (Huoyanzi), with 87856 unigenes. About 53% of these unigenes were annotated using Nr, Swiss-Prot, Kyoto Encyclopedia of Genes and Genomes (KEGG), Cluster of Orthologous Groups (COG) and Gene Ontology (GO). We identified nine differentially expressed candidate genes associated with type III polyketide synthase formation, which is the first step in urushiol biosynthesis. Additionally, a number of simple sequence repeats (EST-SSRs) were identified in T. vernicifluum for further molecular marker-assisted breeding. This study is the first report of Toxicodendron species transcriptome.