DNA barcoding of Indian Alysicarpus (Fabaceae): ITS alone distinguishes species

Abstract

In India, the genus Alysicarpus (Fabaceae) is represented by approximately 18 species and seven varieties. It includes some species of considerable economic importance, including two of therapeutic value. The species of this genus are difficult to identify because of overlapping morphological characters. Moreover, it becomes difficult to establish the botanical identity of a herbal medicine available in powdered/fragmented form. In the present study, DNA barcoding was used to identify 42 accessions belonging to 15 species of Alysicarpus and two varieties. The DNA regions that were tested as potential barcodes were matK (Maturase K), rbcL (Rubisco Large Sub-unit), rpoC1 (RNA Polymerase-β subunit, the main catalytic subunit) and nrITS (Nuclear Ribosomal Internal Transcribed Spacer). In BLAST search on National Centre for Biotechnology Information (NCBI), ITS and rpoC1 sequences best matched with the respective sequences of species of other genera belonging to the family Fabaceae with less than 100% similarity, as no corresponding sequences of any Alysicarpus species were available. The rbcL and matK sequences had first match, with the respective sequences of Alysicarpus species, however, with less than 100% similarity. Among the loci tested, ITS alone discriminated all species on the basis of genetic distance as well as phylogenetic tree methods.