Complete chloroplast genome sequence of a subtropical tree, Parasassafras confertiflorum (Lauranceae)

Abstract

Parasassafras confertiflorum (Meisn.) D.G. Long is the single tree species of the genus Parasassafras D.G. Long in the family Lauraceae. To better determine its phylogenetic location with respect to the related Lauraceae species, the complete chloroplast genome of P. confertiflorum was sequenced. The whole plastome is 152,555 bp in length, consisting of a pair of inverted repeat (IR) regions of 20,079 bp, one large single copy (LSC) region of 93,604 bp, and one small single copy (SSC) region of 18,793 bp. The genome contains 127 genes, including 83 protein-coding genes, 8 ribosomal RNA genes, and 36 transfer RNA genes. The overall GC content of the whole plastome is 39.1%. Further, maximum likelihoodphylogenetic analyses were conducted using 34 complete plastomes of the Lauraceae, which support close relationships between P. confertiflorum and Actinodaphne trichocarpa, Lindera benzoin, L. latifolia, L. metcalfiana, L. robusta, and Neolitsea sericea rather than Laurus nobilis or Sinosassafras flavinervium.

Conflicting phylogenetic signals in plastomes of the tribe Laureae (Lauraceae)

“…Lindera and Litsea were polyphyletic in our analysis, consistent with previous studies (Li et al, 2008b;Fijridiyanto & Murakami, 2009b). The phylogenetic position of P. confertiflorum was unresolved based on ETS and ITS (Li et al, 2008b), and the ambiguity of its position still remains, despite the integration of complete plastid genomes in our analysis and a previous study (Liao, Ye & Song, 2018). Subclade III was sister to subclade I and II in our study, consistent with previous analyses (Zhao et al, 2018;Song et al, 2019;Tian, Ye & Song, 2019).…”

A comparative analysis of complete chloroplast genomes of seven Ocotea species (Lauraceae) confirms low sequence divergence within the Ocotea complex

“…The differences among the counts of genes in the Lauraceae species, except the hemiparasitic Cassytha , may be due to different annotation of genes. Particularly the rpl22 gene has not been annotated in most of the earlier studies 17 , 19 , 23 , 24 , 26 , 27 , 29 , 30 , 33 , 39 – 41 .…”

Phylogeny and Systematics of Sassafras (Lauraceae), an Interesting Genus with Disjunct Distributions in Eastern North America and East Asia

“…However, because of the low genetic divergence and phylogenetic information, the circumscription of Lauraceae and Cinnamomeae cannot be clearly clarified, and Sassafras represented an ambiguous phylogenetic position ( Cinnamomum–Ocotea complex or Lauraceae) [ 1 , 11 , 49 ]. With the application of the whole chloroplast genome in phylogenetic research, many targeted or representative molecular results for Lauraceae were found to support the establishment of Cinnamomeae, Sassafras ’s status as a member of Cinnamomeae and the status of Cinnamomeae as sister to Laureae [ 14 , 50 , 51 , 52 ]. In conclusion, the plastid data revealed that the genus Sassafras had closer genetic relationship with and belonged to the tribe Cinnamomeae [ 14 , 15 , 50 , 51 , 52 ], while nuclear phylogeny [ 1 , 11 , 49 ] showed Sassafras was a sister to the genus Lindera (Laureae).…”

“…Sassafras was classified into the Ocotea–Cinnamomum clade, which was sister to the Laureae clade. Liao et al [ 51 ] sequenced the whole chloroplast genome of Parasassafras conferflorum (Meisn.) D.G Long and reconstructed the phylogenetic relationship of 28 species of the Perseeae–Laureae clade using complete chloroplast sequences, with two Endiandra species as an outgroup, resulting in three major branches similar to those found by Zhao et al [ 50 ], and also found Sassafras belonged to the Ocotea–Cinnamomum clade.…”