Chloroplast genome sequence of triploid Toxicodendron vernicifluum and comparative analyses with other lacquer chloroplast genomes

AbstractBackground:Toxicodendron vernicifluum, belonging to the family Anacardiaceae, is an important commercial arbor species, which can provide us with the raw lacquer, an excellent adhesive and painting material used to make lacquer ware. Compared with diploid, triploid lacquer tree has a higher yield of raw lacquer and stronger resistance to stress.TriploidT. vernicifluumwas a newly discovered natural triploid lacquer tree. However, the taxonomy of triploidT. vernicifluumhas remained uncertain. Here, we sequenced and analyzed the complete chloroplast (cp) genome of triploidT. vernicifluumand compared withT. vernicifluumcv. Dahongpao,T. vernicifluumcv. Hongpigaobachi,T. vernicifluumandT. succedaneumbased on chloroplast genome and SSR markers.Results:The plastome of triploidT. vernicifluumis 158,221 bp in length, including a pair of inverted repeats (IRs) of 26,462 bp, separated by a large single-copy region of 86,951 bp and a small single-copy region of 18,346 bp. In total, 116 unique genes including 82 protein-coding genes, 30 tRNA genes and 4 rRNA genes were identified in the triploidT. vernicifluum. After nucleotide substitutions, small inversions were analyzed in the chloroplast genomes, five hotspot regions were found, which could be useful molecular genetic markers for future population genetics. Phylogenetic analyses showed that triploidT. vernicifluumwas a sister toT. vernicifluumcv. Dahongpao andT. vernicifluumcv. Hongpigaobachi.Moreover, phylogenetic clustering based on the SSR markers showed that all the individuals of triploidT. vernicifluum,T. vernicifluumcv. Dahongpao andT. vernicifluumcv. Hongpigaobachi in one group, while the individuals ofT. vernicifluumandT. succedaneumin another group.Conclusions:The current genomic datasets provide pivotal genetic resources to determine the phylogenetic relationships, variety identification, breeding and resource exploitation, and future genetic diversity-related studies ofT. vernicifluum.