A Preliminary Study On DNA Barcode In Lauraceae And Phylogeography Of Cinnamomum Camphora

DNA barcode is a diagnostic technique for species-level identification using a short,standardized DNA region.It aims to use the information of one or a few genes to identify all species of life.DNA barcode will allow users to efficiently recognize known species,speed the discovery of species yet to be found in nature and contribute to biodiversity research.Using the mitochondrial coxâ… gene(COI)as a DNA barcode region,is now well established for animals,whereas the universal DNA barcode for plants is still heated disputed.In this paper,the utility of the so-called two most potential DNA barcode plastid regions for land plants-psbA-trnH spacer and portion of matK exon was evaluated in 34 Lauraceae species(including many closely related species),and phylogeography of Cinnamomum camphora was analyzed by sequencing 2 cpDNA intergenic spacer(psbA-tmH and trnS-trnG).Conclusions were made as follows:(1)Both psbA-trnH and matK regions amplified successfully in all the 34 species of Lauraceae in this study,psbA-trnH region totally found 26 different sequences,whereas matK obtained 22 different sequences,taking up 76.47%and 64.71%of total sequences respectively.But neither psbA-trnH nor matK region could identify all closely related species.When psbA-trnH and matK regions were combined together,no more different sequences were found.(2)Compared with matK region,psbA-trnH had a much higher interspecific sequence divergence among closely related species,with a figure of 2.45%and 0.36%respectively.So psbA-trnH locus is recommended as the first choice of DNA barcode plastid region for flowering plants.(3)Using our DNA barcode data of Lauraceae,we surprisingly found that the Accession Number of AB331294 in NCBI Database which corresponds to Cinnamomum camphora as it had labeled,actually is a corresponding sequence to Cinnamomum septentrionale-a closely related species to C.camphora or one of its intraspecific haplotypes from psbA-trnH region analysis.(4)The genetic diversity of Cinnamomum camphora populations in mainland China is extremely low.