Abstract Detail

Host/Plant Pathogen Interactions and Plant Health Management

Aboukhaddour, Reem [1], Strelkov, Stephen. E. [1].

Pyrenophora tritic-repentis and barley: a subtle compatibility.

Pyrenophora tritici-repentis (Ptr) is a necrotrophic fungal pathogen that causes tan spot disease of wheat. The fungus produces several host selective toxins (HSTs) or necrotrophic effectors. Ptr ToxB is a proteinaceous HST that selectively induces chlorosis only on specific wheat genotypes having a corresponding toxin-sensitivity gene. In this study, isolates of Ptr that produce Ptr ToxB were found to induce extensive chlorosis specifically on certain barley genotypes. Seventy four different barley genotypes that were developed or grown in Canada were evaluated for their reaction to a Ptr ToxB-producing isolate of Ptr and rated for disease development. Ten (13.5%) of these genotypes were found to be susceptible to the fungus. Different concentrations of Ptr ToxB (1 µM - 100 µM) were infiltrated into the leaves of the susceptible and resistant barley genotypes; chlorosis developed only in the susceptible genotypes, confirming the specific activity of Ptr ToxB on barley. To assess the effects of temperature on disease development in barley, inoculated plants were incubated under different temperatures. When temperature settings were (18/20)ËšC (night/day), all susceptible lines developed clear chlorosis and rated highly susceptible, but when the temperature was set for 15ËšC or 25ËšC constant day and night, these lines fail to develop the chlorotic symptoms and the reaction shifted from susceptible to resistant. Quantitative PCR analysis revealed considerable differences in the in planta accumulation of fungal biomass in resistant and susceptible barley genotypes starting at 12 h after inoculation. This study demonstrates the ability of Ptr to infect barley in a highly specific manner similar to infection of wheat. However, Ptr-barley specificity can be broken even by slight changes in temperature.

1 - University of Alberta, Faculty of Agriculture, food and nutritional Science, 410 Agriculture Forestry Centre, Edmonton, Alberta, T6G 2P5, Canada

Keywords:
Pyrenophora tritici-repentis
host selective toxin
specificity.

Presentation Type: Oral Paper:Papers for Topics
Session: 46
Location: Salon 2/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 2:00 PM
Number: 46003
Abstract ID:772
Candidate for Awards:None