Characterization of the Complete Chloroplast Genome of <i>Acer truncatum</i> Bunge (Sapindales: Aceraceae): A New Woody Oil Tree Species Producing Nervonic Acid

Abstract

<i>Acer truncatum</i>, which is a new woody oil tree species, is an important ornamental and medicinal plant in China. To assess the genetic diversity and relationships of <i>A. truncatum</i>, we analyzed its complete chloroplast (cp) genome sequence. The <i>A. truncatum</i> cp genome comprises 156,492 bp, with the large single-copy, small single-copy, and inverted repeat (IR) regions consisting of 86,010, 18,050, and 26,216 bp, respectively. The <i>A. truncatum</i> cp genome contains 112 unique functional genes (i.e., 4 rRNA, 30 tRNA, and 78 protein-coding genes) as well as 78 simple sequence repeats, 9 forward repeats, 1 reverse repeat, 5 palindromic repeats, and 7 tandem repeats. We analyzed the expansion/contraction of the IR regions in the cp genomes of six <i>Acer</i> species. A comparison of these cp genomes indicated the noncoding regions were more diverse than the coding regions. A phylogenetic analysis revealed that <i>A. truncatum</i> is closely related to <i>A. miaotaiense</i>. Moreover, a novel <i>ycf4-cemA</i> indel marker was developed for distinguishing several <i>Acer</i> species (i.e., <i>A. buergerianum</i>, <i>A. truncatum</i>, <i>A. henryi</i>, <i>A. negundo</i>, <i>A. ginnala</i>, and <i>A. tonkinense</i>). The results of the current study provide valuable information for future evolutionary studies and the molecular barcoding of <i>Acer</i> species.