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Quantitative variation in effector activity of ToxA isoforms from Stagonospora nodorum and Pyrenophora tritici-repentis.

Permanent URL:
http://handle.nal.usda.gov/10113/58112
Abstract:
ToxA is a proteinaceous necrotrophic effector produced by Stagonospora nodorum and Pyrenophora tritici-repentis. In this study, all eight mature isoforms of the ToxA protein were purified and compared. Circular dichroism spectra indicated that all isoforms were structurally intact and had indistinguishable secondary structural features. ToxA isoforms were infiltrated into wheat lines that carry the sensitivity gene Tsn1. It was observed that different wheat lines carrying identical Tsn1 alleles varied in sensitivity to ToxA. All ToxA isoforms induced necrosis when introduced into any Tsn1 wheat line, but we observed quantitative variation in effector activity, with the least active version found in isolates of P. tritici-repentis. Pathogen sporulation increased with higher doses of ToxA. The isoforms that induced the most rapid necrosis also induced the most sporulation, indicating that pathogen fitness is affected by differences in ToxA activity. We show that differences in toxin activity encoded by a single gene can contribute to the quantitative inheritance of necrotrophic virulence. Our findings support the hypothesis that the variation at ToxA results from selection that favors increased toxin activity.
Author(s):
Kar-Chun Tan , Margo Ferguson-Hunt , Kasia Rybak , Ormonde D.C. Waters , Will A. Stanley , Charles S. Bond , Eva H. Stukenbrock , Timothy L. Friesen , Justin D. Faris , Bruce A. McDonald , Richard P. Oliver
Subject(s):
Leptosphaeria nodorum , Pyrenophora tritici-repentis , Triticum aestivum , alleles , fungal diseases of plants , host-pathogen relationships , inheritance (genetics) , mycotoxins , necrosis , pathogens , protein secondary structure , sporulation , virulence , wheat
Source:
Molecular plant-microbe interactions 2012 v.25 no.4
Language:
English
Year:
2012
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
File:
Download [PDF File]
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.