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Published on: September 15, 2015
Characterization of Trichodesmium spp. by genetic techniques
K M Orcutt1, U Rasmussen, E A Webb
1Department of Botany, Stockholm University, S-106 91 Stockholm, Sweden. karen.orcutt@maine.edu
Applied and Environmental Microbiology
|April 27, 2002
Summary
Genetic diversity in Trichodesmium cyanobacteria is low in natural populations. DNA fingerprinting and gene sequencing reveal two major clades, with Trichodesmium erythraeum distinct from other species.
Area of Science:
- Marine microbiology
- Cyanobacteria genetics
- Molecular ecology
Background:
- Trichodesmium spp. are vital marine cyanobacteria, playing a significant role in nitrogen fixation in oceanic environments.
- Understanding the genetic diversity of Trichodesmium is crucial for comprehending their ecological roles and evolutionary history.
- Previous studies have indicated potential genetic variation within Trichodesmium, but comprehensive analysis across different populations and species was lacking.
Purpose of the Study:
- To investigate the genetic diversity of Trichodesmium spp. from diverse natural populations and culture isolates.
- To compare genetic variation using multiple molecular techniques.
- To elucidate the phylogenetic relationships among different Trichodesmium species and related genera.
Main Methods:
- DNA fingerprinting using a highly iterated palindrome (HIP1) probe.
- Denaturing gradient gel electrophoresis (DGGE) of a hetR gene fragment.
- Sequencing of the internal transcribed spacer (ITS) region of the 16S-23S rDNA.
Main Results:
- Low genetic diversity was observed in natural populations of Trichodesmium from both hemispheres.
- Culture isolates of several Trichodesmium species and Katagnymene spiralis showed high similarity, suggesting close evolutionary relationships.
- Trichodesmium erythraeum exhibited the greatest genetic variation, distinguishing it from other Trichodesmium species and Katagnymene.
- Two major clades within Trichodesmium spp. were identified using all three molecular techniques.
- HIP1 fingerprinting and ITS sequencing effectively distinguished closely related species.
Conclusions:
- Trichodesmium populations exhibit limited genetic diversity globally.
- The genus Trichodesmium likely comprises two distinct phylogenetic clades.
- Katagnymene spiralis is closely related to the genus Trichodesmium.
- Trichodesmium erythraeum represents a genetically distinct lineage within the Trichodesmium group.
- The study introduces HIP1 fingerprinting as a novel tool for analyzing marine cyanobacteria.
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