Journal article
pH dependency of sclerotial development and pathogenicity revealed by using genetically defined oxalate-minus mutants of Sclerotinia sclerotiorum
Environmental microbiology, Vol.17(8), pp.2896-2909
08/2015
Handle:
https://hdl.handle.net/2376/113174
PMID: 25720941
Abstract
The devastating plant pathogen Sclerotinia sclerotiorum produces copious (up to 50 mM) amounts of oxalic acid, which, for over a quarter century, has been claimed as the pathogenicity determinant based on UV-induced mutants that concomitantly lost oxalate production and pathogenicity. Such a claim was made without fulfilling the molecular Koch's postulates because the UV mutants are genetically undefined and harbour a developmental defect in sclerotial production. Here, we generated oxalate-minus mutants of S. sclerotiorum using two independent mutagenesis techniques, and tested the resulting mutants for growth at different pHs and for pathogenicity on four host plants. The oxalate-minus mutants accumulated fumaric acid, produced functional sclerotia and have reduced ability to acidify the environment. The oxalate-minus mutants retained pathogenicity on plants, but their virulence varied depending on the pH and buffering capacity of host tissue. Acidifying the host tissue enhanced virulence of the oxalate-minus mutants, whereas supplementing with oxalate did not. These results suggest that it is low pH, not oxalic acid itself, that establishes the optimum conditions for growth, reproduction, pathogenicity and virulence expression of S. sclerotiorum. Exonerating oxalic acid as the primary pathogenicity determinant will stimulate research into identifying additional candidates as pathogenicity factors towards better understanding and managing Sclerotinia diseases.
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Details
- Title
- pH dependency of sclerotial development and pathogenicity revealed by using genetically defined oxalate-minus mutants of Sclerotinia sclerotiorum
- Creators
- Liangsheng Xu - Department of Plant Pathology, Washington State University, Pullman, WA, 99164, USAMeichun Xiang - Department of Plant Pathology, Washington State University, Pullman, WA, 99164, USADavid White - Department of Plant Pathology, Washington State University, Pullman, WA, 99164, USAWeidong Chen - USDA-ARS, Grain Legume Genetics and Physiology Research Unit, Washington State University, Pullman, WA, 99164, USA
- Publication Details
- Environmental microbiology, Vol.17(8), pp.2896-2909
- Academic Unit
- Plant Pathology, Department of
- Publisher
- England
- Identifiers
- 99900547554201842
- Language
- English
- Resource Type
- Journal article