Triticale and Barley: New Hosts of Magnaporthe Grisea in São Paulo, Brazil — Relationship with Blast of Rice and Wheat

Abstract

Triticale (X. triticosecale) and barley (Hordeum vulgare) are the most recent crops to be infected by Magnaporthe grisea, the causal agent of blast disease. This is a newly emerging problem in Sao Paulo state where frequent yield losses due to rice and wheat blast already occur. The present work is aimed at examining the relationship among isolates from these four important crops through host range, cross-infectivity and DNA fingerprinting. Data from controlled-environment inoculations revealed that M. grisea from triticale and barley could infect triticale, wheat, barley, oat, and rye but not rice, sorghum, maize, common millet, sugarcane, and Brachiaria brizantha. A positive cross-infection of triticale by wheat and barley isolates was observed. Positive cross-infection was also detected between barley and triticale and wheat. Cross-infection was not possible with rice but rice isolates infected barley, triticale and wheat. Southern hybridization of DNA digested with EcoRI, probed with Pot2 showed similar DNA fingerprints among wheat, triticale, and barley isolates suggesting that the disease on triticale and barley originated from wheat blast pathogen.