Genetic diversity of Pyrenophora teres in Algeria

Barley net blotch is one of the most widespread and destructive foliar diseases of barley crops worldwide. The causal fungal agent, Pyrenophora teres (anamorphic stage: Drechslera teres) occurs in two forms, P. teres f. maculata (Ptm) and P. teres f. teres (Ptt) exhibiting the spot and net type symptoms, respectively. In this study, sixty-one P. teres single conidia isolates were obtained from different cereal-growing areas in Algeria. Fungal isolates of net and spot forms were identified using appropriate form-specific SNP primers. The results indicated that 57.38% of the isolates were Ptm, while 42.62% were identified as Ptt. Mating-type assessments of P. teres isolates were conducted using MAT-specific single nucleotide polymorphism primers. Among the tested strains of Ptt, 19 were found as MAT1-2 and only 7 were determined as MAT 1-1; while 27 were identified as MAT 1-1, and 8 were found as MAT1-2 for the Ptm population. Inter-simple sequence repeat markers (ISSR) were used to examine genetic variation and relationships within the P. teres population. The similarity rates were found as 0.60 and 0.63 within Ptt and Ptm populations, respectively. Our results suggested that both populations are reproducing sexually. It appears that P. teres f. teres population is reproducing exclusively sexually and P. teres f. maculata population is reproducing mostly sexually, but asexual reproduction is also occurring. Obviously, ascospore production is a key epidemiological aspect, but in the case of P. teres f. maculata, conidia may also be playing a role.