Study on mating types and sensitivity to strobilurin fungicide in fungal wheat pathogen Mycosphaerella graminicola

Mycosphaerella graminicola, the causal agent of septoria tritici blotch (STB), is a widespread and significant pathogen of wheat. To determine mating types, 89 isolates were collected randomly from wheat fields of Khuzestan, East Azerbaijan, Ardebil, Kermanshah and Golestan provinces of Iran, during 2006-7. DNA was extracted based on standard protocols. Multiplex PCR was conducted using two pairs of mating type-specific primers for MAT1-1 and MAT1-2. Sensitivity to strobilurin fungicide was determined using strobSNPrc7 and strobSNPrc1 primers. The results showed that in 35 isolates, a fragment of 340 bp amplified with MAT1-1 idiomorph specific primers and in 54 isolates a fragment of 660 bp was amplified with MAT1-2 idiomorph specific primers. While the mating type frequencies were highly unequal, the MAT1-1 was predominant. All isolates were sensitive to strobilurin and amplified a fragment of 639 bp. It is concluded that both mating types are present in Iran, although with different frequencies, which may affect genetic variation through sexual cycle. Meanwhile the studied isolates were not resistant to strobilurin fungicides which may be due to growing wheat cultivars resistant to STB rather than using strobilurin fungicides as a dominant control method.