Genetic heterogeneity of the marine cyanobacterium Leptolyngbya valderiana (Pseudanabaenaceae) evidenced by RAPD molecularn markers and 16S rDNA sequence data

摘要

The distribution and diversity patterns of the cosmopolitan marine cyanobacterium Leptolyngbya valderiana (Pseudanabaenaceae, Cyanobacteria) were studied. To asses the level of genetic diversity, morphotypes from different geographical locations (Coast of south India and Andaman) were subjected to randomly amplified polymorphic DNA (RAPD) analysis and partial 16S rRNA gene sequence studies. Morphologically and ecologically, all strains fit the currently circumscribed L. valderiana. However, RAPD primers yielded 100% polymorphism among the studied strains, indicating a considerable degree of intra-specific genomic heterogeneity, with percent similarity between 13 and 82%. Partial 16S rDNA sequence similarity values ranged from 91 to 99%. In conclusion, the genetic variability observed within the marine strains of L. valderiana indicates the presence of cryptic species. Thus, future investigations combining well-characterized ultra-structural morphology with additional molecular markers are essential to characterize and clarify the patterns in the evolution and biogeography.