Genetic diversity of Pyrenophora tritici-repentis isolates as revealed by AFLP analysis.

Abstract

The population structure and genotypic diversity of 100 Pyrenophora tritici-repentis isolates originating mainly from the Czech Republic, but also from the Slovak Republic, Russia, Canada, the USA and Argentina, were studied with molecular markers. As an outgroup, eight isolates of Pyrenophora teres f. teres and 7 isolates of P. teres f. maculata were added into the analysis. A total of 115 single monosporic cultures were subjected to molecular marker analysis using the amplified fragment length polymorphism technique (AFLP). When both species of Pyrenophora were analysed with 21 AFLP primer combinations, 664 polymorphic bands were detected. Considering only P. tritici-repentis isolates, 335 polymorphic bands were detected, which corresponds to an average of 16.0 bands per primer combination. UPGMA cluster analysis based on genetic distances clearly distinguished between P. teres and P. tritici-repentis isolates. Isolates of race 4 and isolates collected from non-wheat host plants grouped into two clusters distinct from a main cluster formed by the rest of P tritici-repentis isolates. Analysis of molecular variance (AMOVA) showed that 98.1% of genetic variance occurred within local populations and 1.9% was found among populations. The occurrence of sexual reproduction and longdistance dispersal of inoculum could contribute to the occurrence of genetic variability independently of race structure or geographic origin.