The variability of a Pyrenophora tritici-repentis population as revealed by inter-retrotransposon amplified polymorphism with regard to the Ptr ToxA gene.

摘要

Pyrenophora tritici-repentis (PTR) is one of the pathogens causing leaf spots in wheat. It occurs everywhere wheat is grown and forms populations with a high genetic variability. The aim of this study was to find a key to explain the relation between PTR population variability and its race spectrum. We studied the variability of a P. tritici-repentis population by analysing the retroelements Pyggy, TfoI, and MITE using two approaches: SSAP and IRAP. By analysing all 122 Pyrenophora spp. with four SSAP primer combinations and two IRAP markers, 186 polymorphic bands were detected. Cluster analysis based on molecular data showed that the variability of P. tritici-repentis isolates established by retrotransposon analysis cannot be explained by the race spectrum, except for race 4, or by geographic origin. A significant correlation was found, with two SSAP, three TfoI, and two MITE markers, between the presence or absence of the marker and the presence or absence of the Ptr ToxA gene, which is considered to be the main pathogenicity factor of this fungus. We found retrotransposons a powerful tool for the study of fungal population-genetic variability.