Abstract

                                Cyanobacteria though traditionally have been distinguished on the basis of phenotypic properties, structure and physiology, employment of molecular biological methods results in greater phylogenetic resolution than the use of morphological data alone. Recently, molecular sequence analyses have been viewed as highly superior to structure-based phylogenies in cyanobacteria. Restriction fragment length polymorphisms (RFLP) analyses have been used to evaluate intergeneric, interspecific and intraspecific variation in algae. Restriction fragment length polymorphisms have been used extensively as an efficient DNA fingerprinting method to identify symbiotic cyanobacteria. The RAPD technique in conjunction with PCR has been employed to identify cyanobacterial groups to the strain level of classification. The choice of primers with high G+C content provided good DNA profiles at a low concentration. Neilan (1995) reported the use of RAPD-PCR to generate uniqueness in phylogenetic analysis of toxic cyanobacteria. Lakshmanan and Kumar (2003) employed RAPD-PCR technology using decamer and tandem repeat primers to identify the cyanobacterial cultures of the composite inoculum upto strain level by detecting the genetic heterogeneity. One area in which a significant application has been developed recently is in the phylogenetic characterization of natural cyanobacterial communities by 16S rRNA sequence analysis. The use of DNA-DNA hybridizations as a tool in cyanobacterial phylogeny was pioneered by Stam (Stam and Venema, 1975 and Stam, 1980). ITS sequencing has been used commonly in intrageneric phylogenetic studies of algae. Peters (1997) used ITS sequences to compare species within the widespread algal family Desmarestiaceae.

Key words : Algae, Cyanobacteria, Morphology, Nucleic acid, Phylogeny, Polymorphism, Taxa.