Phylogenetic relatedness among Spirulina and related cyanobacterial genera

Abstract

Molecular polymorphisms in a selected set of Spirulina and related genera using random primers based on repetitive sequences along with biochemical parameters, led to the unambiguous differentiation of the strains and understanding of their phylogenetic relationships. A combination of 10 sets of dual primers generated 100% distinct polymorphic bands ranging from 150 to 5,000 bp. Total number of fragments ranged from 68 to 159 whereas polymorphic bands ranged from 13 to 32 for different Random Amplified Polymorphic DNA (RAPD) reactions. Spirulina platensis strains, Sp-2 and Sp-3, possessed quite comparable chlorophyll and protein content besides having maximum similarity coefficient (0.88) between them on the basis of RAPD reactions, thus proved to be closely related. Sp-8 (Spirulina from Loktak Lake) having the highest protein content and protein: chlorophyll ratio, showed close similarity with the mutant of Spirulina platensis (Sp-7) on the basis of RAPD analysis. Duncan’s Multiple Range Test (DMRT) ranking for the biochemical parameters were quite closer for the strains of Spirulina and Arthrospira. This is also supported by the cluster analysis based on RAPD data, as the strains of Spirulina and Arthrospira are placed together in the same subcluster in the dendrogram. The comparative closeness among the strains of Lyngbya, Oscillatoria and Phormidium is reflected by the low content of protein and protein: chlorophyll ratio, which is also supported by the dendrogram based upon RAPD; thus, exhibiting the usefulness of multiplex RAPD along with biochemical parameters for the phylogenetic analysis of Spirulina and related genera.