Genetic analysis and comparative virulence of isolates of Pyrenophora tritici-repentis from wheat in Argentina

PERELLÓ, A.; YANNICARI, M; MORENO, V; CASTRO, A

AFRICAN JOURNAL OF MICROBIOLOGY RESEARCH

ACADEMIC JOURNALS

Lugar: New York; Año: 2012 vol. 6 p. 5558 - 5567

1996-0808

Tan spot caused by the fungus Pyrenophora tritici-repentis, occurs in many wheat¬13 growing regions worldwide and is considered among the major diseases of wheat in 14 Argentina. In nature, this pathogen reproduces both sexually and asexually, but the extent 15 of genetic variability in the P. tritici-repentis argentinian population is unknown. The 16 genetic structure of P. tritici-repentis populations was assessed with amplified polymorphic 17 markers with sequence data from the internal transcribed spacer region of the ribosomal 18 DNA (ITS) analysis. Eighty-nine P. tritici-repentis isolates were collected from 14 19 geographically distinct regions of the wheat growing areas in Argentina. Clustered analysis 20 of RAPDs showed seven different groups of isolates at 43% similarity. Analysis of the 21 ITS1 and ITS4 primers grouped the isolates in fifteen separated clusters and resulted in a 22 sensible method by providing valuable information on the genotypic diversity detected in 23 the populations. Additionally, diversity was assayed by analysis of severity and type of 24 symptoms reaction indicating significant differences between cultivars and isolates. The utility of cleaved amplified polymorphic sequence analysis for molecular differentiation of 2 pathotypes was demonstrated. It appears that the P. tritici-repentis population in Argentina 3 is fairly diverse, and caution should be used taken in any breeding strategy, since rare 4 pathotypes may quickly become predominant if susceptible host genotypes are 5 continuously grown.