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

Abstract

Acer truncatum, 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 A. truncatum, we analyzed its complete chloroplast (cp) genome sequence. The A. truncatum 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 A. truncatum 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 Acer species. A comparison of these cp genomes indicated the noncoding regions were more diverse than the coding regions. A phylogenetic analysis revealed that A. truncatum is closely related to A. miaotaiense. Moreover, a novel ycf4-cemA indel marker was developed for distinguishing several Acer species (i.e., A. buergerianum, A. truncatum, A. henryi, A. negundo, A. ginnala, and A. tonkinense). The results of the current study provide valuable information for future evolutionary studies and the molecular barcoding of Acer species.

The Acer truncatum genome provides insights into nervonic acid biosynthesis

“…(2019) and Ma et al . (2019) proved that A. truncatum and A. miaotaiense are closely related. In our study, we found that A. truncatum was not only closely related to A. miaotaiense , but also to A. catalpifolium , based on phylogeny of the chloroplast genomes.…”

A Review of Nervonic Acid Production in Plants: Prospects for the Genetic Engineering of High Nervonic Acid Cultivars Plants

“…Eight to ten years to maturity Appelqvist, 1976;Jart, 1978;Taylor et al, 2009;Qiao et al, 2018;Ma et al, 2019Ma et al, , 2020 Xanthoceras its development and industrialization (Wang et al, 2006;Tang et al, 2013;Xu et al, 2019). T. speciosum, a unique perennial herbaceous plant species from Chile, has a seed oil content in the range of 12.3∼26.0%, with NA remarkably constituting 40.0∼45.4% of the total FA content.…”

“…Third, some seed oils require the removal of erucic or lignoceric acid by distillation or other expensive methods before they can be used in health applications. Therefore, although a number of species present excellent oil or NA contents, only L. annua and A. truncatum are considered niche species in practice (Ma et al, 2019(Ma et al, , 2020, and the other plant species must be further researched to address the current NA extraction inefficiencies. Genetic modification may thus be an excellent approach for the mass production of NA.…”

“…A weighted gene co-expression network analysis in Acer truncatum Bunge ( A. truncatum ) showed that MYB and bZIP transcription factors were involved in regulating NA biosynthesis ( Ma et al, 2020 ). Recent genome sequencing or transcriptome analysis of A. truncatum , Malania oleifera Chun et S. K. Lee ( M. oleifera ) or Xanthoceras sorbifolia ( X. sorbifolia ) species containing rich NA provides important foundations from which to study the molecular mechanisms influencing the NA production ( Wang et al, 2018 ; Yang et al, 2018 ; Liang et al, 2019 ; Ma et al, 2019 , 2020 ; Xu et al, 2019 ) and serves as a support point of NA production by genetic engineering.…”

“…In the future, numerous KCS proteins for VLCFA biosynthesis need to be identified in plant resources with high NA contents, and their functions, especially the mechanisms by which KCS affects NA production, need to be verified. Since NA is particularly abundant in M. oleifera , T. speciosum , and A. truncatum , new KCS enzymes discovered and identified from these plants may constitute good choices in NA genetic engineering ( Ma et al, 2004 , 2019 , 2020 ; Xu et al, 2019 ).…”