Mating-Type Analysis in Diaporthe Isolates from Soybean in Central Europe

Species of the genus <i>Diaporthe</i> have a mating-type system with the two mating types MAT1-1 and MAT1-2, like other ascomycetes. They can either be heterothallic, which means that any isolate only possesses one of the two mating types and needs a mating partner for sexual reproduction, or homothallic, which means that they possess both mating types and are self-fertile. For several <i>Diaporthe</i> species, no sexual reproduction has been observed so far. Using PCR with primers specific to the defining genes <i>MAT1-1-1</i> and <i>MAT1-2-1</i>, we determined the mating types of 33 isolates of <i>Diaporthe caulivora</i>, <i>D. eres</i>, <i>D. longicolla</i>, and <i>D. novem</i> from central Europe. In addition, we partially sequenced the mating-type genes of 25 isolates. We found that different <i>D. longicolla</i> isolates either possess <i>MAT1-1-1</i> or <i>MAT1-2-1,</i> making the species heterothallic, which is in contrast to previous studies and the general assumption that <i>D. longicolla</i> only reproduces asexually. <i>D. eres</i> and <i>D. novem</i> were also found to be heterothallic. Using genomic sequence information and re-sequencing of DNA and RNA, we identified the <i>MAT1-1-1</i> gene in <i>D. caulivora</i> and present here the full sequence of the mating-type locus of this homothallic species. Finally, we used sequence information from <i>MAT1-1-1</i> and <i>MAT1-2-1</i>, respectively, for improved phylogenetic resolution of our isolates.