Inter- and intra-isolate rRNA large subunit variation in Glomus coronatum spores

Area of Science:

• Mycology
• Molecular Biology
• Ecology

Background:

• Arbuscular mycorrhizal fungi (AMF) are crucial soil symbionts.
• High variability in the large subunit (LSU) rRNA gene's D2 region of Glomus coronatum has been reported.
• Understanding genetic diversity within AMF is vital for ecological studies.

Purpose of the Study:

• To investigate the extent of intra- and inter-isolate sequence variation in the LSU rRNA D2 region of Glomus coronatum.
• To compare this variation with closely related AMF species (G. mosseae, G. constrictum, G. geosporum).
• To discuss the implications for AMF species concepts and biodiversity assessment.

Main Methods:

• PCR-single-strand conformational polymorphism (PCR-SSCP) was used as a prescreening method.
• 435 clones containing the D2 region from 7 G. coronatum isolates were analyzed.
• 138 representative sequences were analyzed using neighbour-joining analysis.

Main Results:

• Most analyzed LSU rRNA D2 sequences from G. coronatum were unique, with variation not attributed to artifacts.
• Only 13 sequences were shared among isolates.
• Sequences from G. mosseae and G. constrictum clustered with G. coronatum, indicating potential genetic overlap.

Conclusions:

• Significant, unexpected variation exists in the LSU D2 region of G. coronatum.
• The four studied Glomus species may represent a genetic continuum.
• Findings impact species delineation, biodiversity estimation, and in situ detection of AMF.