Sexual Recombination and Genetic Diversity in Iranian Populations of Pyrenophora Teres

Pyrenophora teres is an economically important pathogen of barley worldwide causing net blotch diseases. In this study, the frequency and mating-type alleles's distribution as well as genetic diversity of P. teres were assessed on micro-spatial scale and also on macro-geographical scale to find out whether a sexual cycle is possible within its Iranian populations. A multiplex PCR assay was developed for simultaneous identification and recognition of P. teres f. teres and P. teres f. maculata and to screen their mating-type alleles. 118 isolates of P. teres were procured from barley fields of East Azerbaijan province during 2017-2018. Among 89 isolates of P. teres f. teres examined, 39 isolates were found as MAT1-1 and 50 isolates were found to be MAT1-2. Among 29 isolates of P. teres f. maculata examined, 17 isolates were found as MAT1-1 and 12 isolates were found to be MAT1-2 with the dominancy belonging to MAT1-1. Nearly same mating-type alleles distribution within and between various populations of P. teres f. teres (1:1 ratio; chi(2) = 1.36) and P. teres f. maculata (1:1 ratio; chi(2) = 0.862) was observed. Genetic diversity assessment of 118 P. teres isolates was carried out through inter-simple sequence repeat (ISSR) analysis and results revealed that there was 70.83% and 63.89% polymorphism among the isolates of P. teres f. teres and P. teres f. maculata, respectively. No relation was observed between the isolates and their mating as well as geographical type. Among collected isolates (89 P. teres f. teres and 29 P. teres f. maculata isolates), the gene diversity was generally similar (h = 0.280 and h = 0.238 for P. teres f. teres and P. teres f. maculata, respectively). Based on our findings and referring to the prior data on the structure of P. teres population, we conclude that in the majority of tested areas, this fungal species might have the potential to undergo regular sexual recombination cycles.