Isolation of the 3-phosphoglycerate kinase gene of the arbuscular mycorrhizal fungus Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe

The 3-phosphoglycerate kinase (PGK) gene of the arbuscular mycorrhizal fungus Glomus mosseae has been isolated by differential RNA display (DD). Experimentally, the technique of DD was utilized to simultaneously compare the mRNA transcript populations from Lycopersicon esculentum root systems colonized by the arbuscular mycorrhizal fungus G. mosseae and non-mycorrhizal plants. A differentially expressed band was isolated and cloned from mycorrhizal tissue. The isolated DD fragment was screened and sequenced. A reverse transcription-PCR (RT-PCR) technique detected transcripts in germinated spores and G. mosseae-colonized root systems but not in uncolonised root systems. The full-length cDNA was isolated by RACE and corresponded to the 3-phosphoglycerate kinase gene of G. mosseae. The cDNA encodes a polypeptide of 416 amino acids, with a predicted molecular weight of 44 764 Da. The PGK proteins shows high homology to those PGKs of other fungi and the phylogenetic relationship among 14 isolated fungal PGK sequences is illustrated.