Application Of DNA Barcoding In Plants From Malvaceae Family And Ardisia Genus

Traditional plant taxonomy is based on the analysis of character which is the phenotype closely related to the environment. From the molecular genetics perspective, the differences of species phenotype, in the final analysis, should be traced back to the differences of genotype, namely variations of DNA genomic sequences. So, comparative studies on the differences of DNA genomic sequences provide essential basis to the classification and identification of plants. DNA barcoding technology is a new method of species identification which provides digital, informationized classification standard and more sensitive model of molecular differences. It can identify species fast and accurately by comparing the differences of one or several short DNA fragments in various species. This technology uses some biological population gene fragments with high genetic conservation to identify species, determine genetic relationship, obtain the evolutionary origin and even infer the evolutionary trend, which make this technology a hot spot in recent years.To pick out the best candidate sequence which can be used as a universal DNA barcode to identify species in Malvaceae family and Ardisia genus by testing and evaluating the ability for several hotspot DNA barcode sequences, five hot regions (ITS, ITS2, rbcL, matK and psbA-trnH) were amplified and sequenced using universal primers. PCR amplification and sequencing, differential intra-and interspecific divergences, DNA barcoding gap and identification (using BLAST1and nearest Distance methods) were used to evaluate the discrimination ability of these candidate sequences.For collected26plant samples belonging to11species in Malvaceae family, ITS region had fairly high amplification efficiency, better intra-and interspecific divergences and DNA barcoding gap than any other region tested. In addition, after1228plant samples from GenBank database of the Malvaceae belonging to316species from60different genera the rate of successful identification using ITS region was89.9%at the species level for after added1228plant samples from GenBank database of the Malvaceae belonging to316species from60distinct genera. The psbA-trnH region had the best amplification efficiency and sequencing efficiency; the rate of successful identification using psbA-trnH region was63.2%, but it can discriminate some species which can’t be successfully discriminated by ITS region.The PCR amplification efficiency of matK region was88.9%for collected54plant samples belonging to24species of Ardisia. MatK region exhibited significant difference between intra-and interspecific divergences and DNA barcoding gap, meanwhile it produced the highest rate of successful identification at the species level.According to the result, it was suggested that ITS and psbA-trnH are an appropriate DNA barcode sequence combination for identifying the Malvaceae species. The matK region is a promising DNA barcode for the genus Ardisia.