Isolation and characterization of mating type genes of Pseudopyrenochaeta lycopersici

Abstract

Pseudopyrenochaeta lycopersici is a soil-borne fungus causing corky root of tomato. The slow growth and poor sporulation of the pathogen make its isolation difficult. Isolates of the fungus are classified into types 1 and 2, with many different physiological and molecular characteristics between both types. In general, mating type genes enable mating ability and sexual development. The type 1 strains CBS267.59 and Oha3-6 of P. lycopersici were utilized to amplify DNA binding domains (HMG box). The MAT1-1-1 gene of CBS267.59 encodes a predicted protein including an alpha box DNA binding domain, while MAT1-2-1 of Oha3-6 encodes a predicted protein including an HMG DNA binding domain. The sequences of the putative P. lycopersici α and HMG boxes were very similar to established α and HMG boxes. ORF1 and the DNA lyase gene were found in the 5ʹ and 3ʹ regions, respectively, of the MAT1-1 locus. Comparison of the mating type genes and flanking regions was carried out between the strains CBS267.59 and Oha3-6 and other Loculoascomycetes, Pyrenomycetes and Discomycetes. The assembled sequences were 2932 bp (nucleotide positions 426–3358) for the MAT1-1 idiomorph and 3410 bp (nucleotide positions 438–3848) for the MAT1-2 idiomorph. Multiplex polymerase chain reaction amplified 432 bp and 786 bp bands in the MAT1-1 and MAT1-2 strains, respectively. The isolation and characterization of the MAT genes of P. lycopersici improve our knowledge and may help to explain the taxonomic differences in types 1 and 2 of this fungus.