Determining of Mating Type Alleles in Cercospora beticola, the Causal Agent of Cercospora Leaf Spot on Sugar Beet Using Specific Primers and Induction of Sexual Phase Under Laboratory and Greenhouse Conditions

Sexual stage of Cercospora beticola has not yet been discovered; however, high levels of phenotypic and genetic diversity as well as resistance against fungicides have been reported in different populations of C. beticola. In present study, mating types of 70 Iranian isolates of C. beticola were determined using specific primer sets and formation of sexual reproduction cycle was evaluated under laboratory and greenhouse conditions. For this purpose, C. beticola isolates were recovered directly from sugar beet plants showing leaf spot disease symptoms in fields of Moghan region, Ardabil province. Pure cultures were established using a single spore technique and subsequently subjected to DNA extraction. Mating types were determined by a modification made in the already designed protocol using a multiplex PCR assay. Analysis of PCR products revealed a 400 bp amplicon specific only for Mat1-2 and an 800 bp amplicon specific for Mat1-1 isolates only. Six different methods were used to induce sexual structures by crossing opposite mating type strians under laboratory and greenhouse conditions. The results for the induction of sexual stage using different crossing protocols were unsuccessful. It seems that some unknown factors are involved in sexual induction or failure in other genes involved in sexual reproduction result in lack of sexual reproduction under field or controlled conditions.