A cDNA from the arbuscular mycorrhizal fungus Glomus versiforme with homology to a cruciform DNA-binding protein from Ustilago maydis

A cDNA clone (Gv1) was isolated from a Medicago truncatula/Glomus versiforme root cDNA library by a differential screening technique. Gv1 represents a full-length G. versiforme mRNA encoding a 99-amino-acid polypeptide. This shares regions of identity with HMP1: a non-histone, cruciform DNA-binding protein from Ustilago maydis. Northern blot analysis indicated that Gv1 transcripts were present in mycorrhizal roots of M. truncatula and M. sativa (alfalfa), but absent in uncolonized roots of both species. A reverse transcription/polymerase chain reaction (RT-PCR) technique detected transcripts in the roots of the M. sativa non-mycorrhizal genotype MN NN-1008 colonized with G. versiforme, as well as in external hyphae collected from the roots of M. sativa colonized with G. versiforme. A genomic copy of Gvl was detected by PCR in DNA isolated from the roots of M. truncatula colonized with G. versiforme and in DNA isolated from spores of G. versiforme. The PCR product identified in the mycorrhizal DNA preparation was identical in sequence to the cDNA, except for the presence of two introns. A homologue of Gv1 was detected in a second arbuscular mycorrhizal fungus, Glomus intraradices.