Poulation genetic structure of Pyrenophora tritici-repentis isolates collected from wheat under zero tillage in Argentina

MORENO, V; STEINGLEIN S; PERELLÓ, A

CROP & PASTURE SCIENCE

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2012

1836-5795

Tan spot, caused by Pyrenophora tritici-repentis, is a common disease of wheat. In this study the pathogenic and the presence of Tox genes of 65 isolates collected from different regions of Argentina were analyzed. Pathogenic tests were conducted on the wheat cultivars and lines recommended for race determination, Glenlea, Salomouni, Katepwa, M-3, 6B365, and 6B662, and based on this test only 33 isolates were assigned in races. One isolate was classified as race 1, four isolates as race 2 and one as race 3, 11 isolates as race 4, one as race 5, one as race 6, and 13 isolates were classified as race 8. The remaining isolates could not be classified in races. The presence/absence of the Tox A, Tox B and tox b genes using PCR specific-primers revealed that 57 isolates have the fragment that corresponds to the Tox A gene, one isolate to the Tox A and Tox B, and the remaining seven isolates lacked amplifications. We did not observe correlation between phenotypic races and presence/absence of the toxin amplification products. Although some isolates amplified for the Tox A gene, they did not express it through the production of necrosis. On the other hand, most of the isolates produced chlorosis on different cultivars but only one of them amplified for the Tox B gene. These results indicated that different races of P. tritici-repentis were determined for Argentina, and the isolates of P. tritici-repentis that induce necrosis and chlorosis may produce a novel toxin(s) on wheat. Keywords Tan spot ? Triticum aestivum ? Pyrenophora tritici-repentis ? races - Tox genes