Cloning, sequencing and functional analysis of Magnaporthe grisea MVP1 gene, a hex-1 homolog encoding a putative 'woronin body' protein

A hex-1 homolog named MVP1 was isolated from an appressoria cDNA library of the rice blast fungus Magnaporthe grisea. The transcript of ∼1.6 kb contains 546 bp of coding sequence with a 3′ untranslated region about 168 bp long and a 5′ untranslated region about 870 bp long. Southern gel blot analysis of genomic DNA following digestion with three restriction enzymes (BamHI, EcoRI, HindIII) indicated that the gene exists as a single copy in M. grisea genome. RNA gel blot analyses showed that MVP1 was highly expressed in germinating conidia and the mycelial stage compared to appressoria or non-germinated conidia. MVP1 showed a high degree of homology to the hex-1 gene recently described to encode a major protein in the woronin bodies of Neurospora crassa. Double homologous recombination was used to replace MVP1 with the hyg^R gene. MVP1 knockout mutants showed apical swellings when grown on agar plates containing 2% sorbose but they were not impaired in any other vegetative or pathogenic properties evaluated. The pathological and other phenotypic consequences of gene disruption are discussed.