Comparative chloroplast genomics and phylogenetics of nine Lindera species (Lauraceae)

Lindera, a core genus of the Lauraceae family, has important economic uses in eastern Asia and North America. However, its historical diversification has not been clarified. In this study, we report nine newly sequenced Lindera plastomes. The plastomes of these nine Lindera species range from 152,211 (L. nacusua) to 152,968 bp (L. metcalfiana) in length, similar to that of another Lauraceae species, Litsea glutinosa (152,618 bp). The length variation of these plastomes derived from the length variation in the loci ycf1, ycf2, ψycf1, and ndhF-ψycf1. Comparing our sequences with other available plastomes in the Lauraceae indicated that eight hypervariable loci, ihbA-trnG, ndhA, ndhF-rpl32, petA-psbJ, psbK-psbI, rps16, trnS-trnG, and ycf1, could serve as DNA barcodes for species delineation, and that the inverted repeats (IRs) showed contraction/expansion. Further phylogenetic analyses were performed using 32 complete plastomes of Lauraceae and seven barcodes from 14 additional species of Lindera and related species in the core Lauraceae. The results showed that these Lindera species grouped into two or four sub-clades, and that two Litsea species and Laurus nobilis were located in the same sub-clade as five Lindera species. These data support a close relationship between the genera Laurus, Lindera, and Litsea, and suggest that Lindera is polyphyletic.