Pathogenicity of isolates of Magnaporthe oryzae from wheat and grasses infecting seedlings and mature wheat plants in Argentina

PERELLO, ANALIA EDITH; MARTINEZ, IVÁN; SANABRIA PAEZ, A; ALTAMIRANO,R; SIBOLE, J

PLANT PATHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2017 vol. 66 p. 1149 - 1161

0032-0862

Wheat Blast (WB) of wheat (Triticum aestivum), caused by Pyricularia oryzae (Magnaporthe oryzae patotype triticum) (MoT) is a destructive disease in the South American countries of Brasil, Paraguay and Bolivia. In Argentina, the fungus was recently mentioned in wheat and barley plants in the northeast part of the country, Buenos Aires and Corrientes Provinces, with a potential for spreading. This work aimed to study for the first time, the morphocultural and pathogenic characteristics of MoT isolates collected from wheat and other herbaceous species in Argentina and three neighbouring countries (Paraguay, Brasil and Bolivia) and determine their virulence on wheat plants. Statistical differences among isolates, culture media, and development conditions were found for conidia color, growth rate, size and sporulation rate. Pathogenicity tests performed on seedling plants with fifteen isolates of MoT under greenhouse conditions showed a maximum disease severity of 55.30% and 66.67 % for the two varieties tested, BIOINTA 3004 and Baguette 18. Weed and grass isolates were infectious on wheat, demonstrating their epidemiological role on the disease. Spike, disease severity was 34.55 % for the host/pathogen interaction of BIOINTA 3004/PY22. Observed symptoms included partial or total spike bleaching, and glume and rachis discoloration. The 1000 grain weight was significantly reduced (38.46 and 63.09 %) for both cultivars, respectively. The disease affected grain germination, which fell to 65.87% for seeds infected with the PYAR22 isolate. Symptoms observed in infected grains were partial spotting, grain softening, and rot symptoms with the presence of a greyish mold.