Genetic diversity and classification of cyanobacteria in different Azolla species by the use of PCR fingerprinting
ABSTRACT Symbiotically associated cyanobacteria from 18 accessions within all known species in the genus Azolla were examined and classified by the use of polymerase chain reaction (PCR)-fingerprinting. A repetitive sequence specific
for cyanobacteria, the short tandemly repeated repetitive (STRR) sequence, was used as a primer in the reaction. Cyanobacterial
filaments isolated directly from the Azolla leaf cavity or contained within homogenised symbiotic Azolla tissue were used as templates. Based on the fingerprint pattern, distinct differences were demonstrated between cyanobacteria
isolated from the Euazolla and Rhizosperma sections. In addition, individual fingerprints were obtained from all cyanobacteria isolated from the different Azolla species. The fingerprints were used to generate a phylogenetic tree. Three clusters were distinguished: one contained the
four isolates from the section Euazolla, a second the isolate from Azolla filiculoides, and a third the three isolates from the section Rhizosperma. By the use of STRR-PCR fingerprinting, new data on the taxonomy of cyanobacteria in Azolla were obtained, which have been difficult to generate by other classification methods. PCR-fingerprinting may, therefore,
be a valuable tool for diversity and classification studies of symbiotic cyanobateria from Azolla and, as co-evolution between the cyanobacteria and its corresponding host exists the method may also be useful for the taxonomy
- Acta Botanica Hungarica 01/2004; 46(1):211-223.
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ABSTRACT: Members of the genus Nostoc are the most commonly encountered cyanobacterial partners in terrestrial symbiotic systems. The objective of this study was to determine the taxonomic position of the various symbionts within the genus Nostoc, in addition to examining the evolutionary relationships between symbiont and free-living strains within the genus by analyzing the complete sequences of the nitrogen fixation (nif) genes. NifD was sequenced from thirty-two representative strains, and phylogenetically analyzed using the Maximum likelihood and Bayesian criteria. Such analyses indicate at least three well-supported clusters exist within the genus, with moderate bootstrap support for the differentiation between symbiont and free-living strains. Our analysis suggests 2 major patterns for the evolution of symbiosis within the genus Nostoc. The first resulting in the symbiosis with a broad range of plant groups, while the second exclusively leads to a symbiotic relationship with the aquatic water fern, Azolla.
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ABSTRACT: The diversity of cyanobacteria in the North-Eastern region of India has not been studied except for a few sporadic and inconclusive reports. Loktak Lake is a huge reservoir for various kinds of organisms, including cyanobacteria. The present study describes the isolation and molecular diversity of 72 filamentous, heterocystous cyanobacterial strains isolated from samples collected from Loktak Lake, its adjoining rice fields and rice fields in Indian Council of Agricultural Research (ICAR) complex, Shillong, Meghalaya, India. The isolated strains belonged to the genera Anabaena, Nostoc, Calothrix, Cylindrospermum and Mastigocladus. The molecular analysis of isolates revealed the occurrence of certain strains being present in the sample collected from the rice fields falling in the catchment area of Loktak Lake, Manipur and rice fields in ICAR complex, Shillong, Meghalaya both. A polyphasic approach based on morphological features and PCR based molecular polymorphism revealed enormous level of molecular diversity. Out of three primers targeted regions used for determining genetic polymorphism, STRR1A produced best fingerprint profile of cyanobacterial strains. The morphological diversity of isolates was assured by light microscope whereas PCR based multiple fingerprint profile was used for molecular characterization. Molecular typing using short tandemly repeated repetitive STRR1A sequences as primer provided strain specific fingerprint profiles of the isolates.World Journal of Microbiology and Biotechnology · 1.35 Impact Factor