Intersporal Genetic Variation of Gigaspora margarita, a Vesicular Arbuscular Mycorrhizal Fungus, Revealed by M13 Minisatellite-Primed PCR

Abstract

Spores of vesicular arbuscular mycorrhizal (VAM) fungi contain thousands of nuclei. In order to understand the karyotic structure of a VAM fungus spore, the genetic variation of the first generation of spores from a VAM fungus (Gigaspora margarita) was examined. Spores originating from both single-and multispore inoculations of the species G. margarita were analyzed by M13 minisatellite-primed PCR. In both cases, different fingerprints were obtained from individual spores with few spores exhibiting similar fingerprints. These results can be explained only by a heterokaryotic status of the nuclear population within a spore.

A molecular marker diagnostic of a specific isolate of an arbuscular mycorrhizal fungus,Gigaspora margarita

“…If the diagnostic sequence found in this study were located in a 'hot spot', such an 'unstable' genetic marker might disappear after several cycles of DNA replication. Ze ¤ze ¤ et al [7] showed genetic variation in M13 mini-satellite-primed RAPD among spores after a cycle of single-spore cultures of G. margarita BEG34. This could be explained by two putative mechanisms: DNA rearrangement and karyotype shift as predicted by Lanfranco et al [6].…”

“…Therefore, the DNA sequences of the ITS region could not serve as a molecular marker for the identi¢cation of G. margarita isolates. The M13 mini-satellite primer was also tested because it had been found to be e¡ective for the RAPD analysis and produced a diagnostic band (1180 bp) from the sporal DNA of G. margarita BEG34 [7]. The PCR displayed a polymorphism with a major product of about 500 bp among the Japanese isolates tested.…”

Multiple Divergent ITS1 Copies Were Identified in Single Tomato Genome Using DGGE Analysis

“…The abundance of ITS sequence variability within plant species suggests that some plant classes have a long history of duplication, incomplete homogenization, and pseudogenization in their genomes (Bortiri et al 2001;Cronn et al 2002). ITS sequence variations have been also found in other eukaryotes including beetles (Vogler and DeSalle 1994), yellow monkey flowers Mimulus (Ritland and Straus 1993), coral Acropora (Marquez et al 2003;Odorico and Miller 1997), the fungus Fusarium (O'Donnell and Cigelnik 1997), and Trichaptum abietihum (Ko and Jung 2002), Scutellospora (Hijri et al 1999), Gigaspora (Zeze et al 1997), sponges (Wörheide et al 2004), and Ascochyta (Fatehi and Bridge 1998).…”