The Lauraceae family comprises nearly 3500 species in over 50 genera worldwide. The genus Machilus in the family Lauraceae includes nearly 100 tree species distributed in tropical and subtropical East and South Asia. Machilus (with two misplaced species of Phoebe) forms a distinct, monophyletic, Asian clade. Are there any useful sequences for the phylogenetic classification of Machilus species in the chloroplast genome?

   Prof. Rechard Corlett and his team of Xishuangbanna Tropical Botanical Garden (XTBG) selected two species (Machilus yunnanensis and Machilus yunnanensis) to determine the entire chloroplast genome sequences. By comparing those two complete chloroplast genomes, the researchers wanted to see the size range of chloroplast genomes in Machilus and types of mutation events occurred in chloroplast genomes of Machilus. They also asked whether there was any highly variable region in the in the chloroplast genomes of Machilus. They also compared the chloroplast genomes with the recently published chloroplast genome of Cinnamomum kanehirae.

The plastomes of Machilus yunnanensis and M. balansae were 152, 622 and 152, 721 bp, respectively. Seven highly variable regions between the two Machilus species were identified and 297 mutation events, including one micro-inversion in the ccsA-ndhD region, 65 indels, and 231 substitutions, were accurately located. Thirty-six microsatellite sites were found for use in species identification and 95 single-nucleotide changes were identified in gene coding regions.

The study produced two complete chloroplast genomes for species in the Lauraceae. For species identification and population structure analysis in the family, the rapidly developed molecular markers such as indels and SNPs have been proved to have significant potential.

The study entitled “Comparative analysis of complete chloroplast genome sequences of two tropical trees Machilus yunnanensisand Machilus balansae in the family Lauraceae” has been published online in Frontiers in Plant Science.