Development of specific barcodes for identification of Aloe species based on chloroplast DNA barcoding

Abstract

DNA barcoding is a widely used taxonomic tool for correctly identifying plant species. The chloroplast matK and rbcL are some of the most extensively studied variable coding genes of angiosperms and have been recommended as a universal barcode for terrestrial plants. Genus Aloe contains around 500 species, and most Aloe species have extensive traditional medicinal usage worldwide, viz., A. arborescens, A. ferox, A. maculate, and A. vera. This study evaluated the two chloroplast DNA barcodes (matK and rbcL) to develop a theoretical base for species identification and germplasm conservation of Aloe species. The Maximum Parsimony analysis was conducted to study the evolutionary relatedness of Aloe sequences using matK and rbcL sequences obtained from the NCBI nucleotide database. The results revealed that 49 Aloe accessions were segregated into four major clades using matK phylogenetic analysis. Likewise, the 29 Aloe accessions were allocated into two clades based on the rbcL phylogeny. Additionally, specific barcodes have been developed for the following species: A. vera, A. boylei, A. ciliaris, A. karasbergensis, and A. sinkatana based on SNP (Single Nucleotide Polymorphism) site analysis of barcode sequences and the corresponding DNA QR (quick response) code of each sequence was generated. This study provides a unique method for species identification of the genus Aloe and indicates the possibility of correctly identifying, discriminating, and documenting the Aloe species.