MOLECULAR PHYLOGENY OF ANGIOSPERMIC PLANT FAMILIES USING RBCL GENE SEQUENCES

Abstract

The present study was undertaken to assess the role of plastid-rbcL (ribulose-1, 5-bisphosphate carboxylase large-subunit) gene sequences in addressing the evolutionary relationships within the angiosperms at inter and intra-familial levels using computational experiment. In order to elucidate the relationships, a set of 92 chloroplast rbcL sequences representing from 90 taxa of 12 genera and 10 angiospermic plant families (dicot and monocots) were withdrawn from the GenBank database. The multiple sequence alignment was performed using Genebee-ClustalW service to findout the regions of conserved or indels among the sequences. The phylogenetic tree was inferred from these sequences by employing Bootstrap method of UPGMA (Unweighted Pair Group Method with Arithmetic Mean) using MEGA (Molecular Evolutionary Genetics Analysis) software. The consistency of these generic-wise groupings was further confirmed by the MP (Maximum-Parsimony), ME (Minimum-Evolution) and NJ (Neighbor-Joining) methods. The analysis of these studies strongly indicates that, out of the 12 selected genera Trichosanthes (Cucurbitaceae), Phyllanthus (Phyllanthaceae), Austrobryonia (Cucurbitaceae), Solanum (Solanaceae), Piper (Piperaceae) and Saxifraga (Saxifragaceae) are grouped into separate clusters and exhibiting monophyletic conditions. Where as, Drypetes (Putranjivaceae), Asparagus (Asparagaceae), Cassia (Caesalpinioideae, sub-family), Canna (Cannaceae), Mentha (Lamiaceae), are paraphyletic and the members of the Salvia (Lamiaceae) are distributed throughout these hiraeoid clades, confirming the polyphyly of this large genus. Similar observations were noticed in all four methods. Thus, chloroplast rbcL gene sequences can unambiguously resolve the relationships, as well as provided a good indication of major supra-generic groupings among the selected angiospermic plant families and also gave many clues for future studies.