Variability of Pyrenophora Teres F. Teres in Hungary as revealed by mating type and RAPD analyses

This study was conducted to investigate for the first time the genetic variability among Hungarian isolates of P. teres f. teres, the causal agent of the net form of net blotch of barley. A total of 68 monoconidial isolates were tested for mating type (MAT) and RAPD profiles using a MAT-specific PCR assay and 30 random decamer primers, respectively. Isolates were derived from symptomatic leaves of barley sampled in commercial fields and experimental plots of four geographical regions from 2006-2010. In total, 29 MAT1 and 39 MAT2 cultures were identified. Both mating types were found on different spatial scales, i.e. the same leaf, the same field or geographical region, and across several years, indicating the potential for sexual reproduction. Of the 188 distinct RAPD bands 171 were polymorphic. All isolates exhibited unique RAPD patterns. UPGMA clustering revealed four main isolate groups, but no general correlation between clusters and mating type or geographical origin of the isolates was detected. Nei's gene diversity analysis showed that genetic diversity within sampling units accounted for most of the total genetic diversity, while that between sampling units represented a small proportion of the total diversity. Genetic differentiation was not observed between MAT1 and MAT2 isolates. Although a low level of allelic differentiation was obtained according to field type (commercial vs. experimental) and geographical origin of the isolates, both UPGMA clustering of multilocus RAPD haplotypes and Nei's gene diversity analysis supported the view that seasonal changes had the greatest effect on the genetic divergence of isolates.