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Identifying oxalic acid independent compatibility factors from Sclerotinia sclerotiorum

Pei-Ling Yu: University of Florida

<div>Previous studies have shown that oxalic acid (OA) accumulation is required for <em>Sclerotinia sclerotiorum </em>to fully<em> </em>colonize and produce symptoms in a broad range of hosts. We hypothesize that limited lesion-causing OA-minus mutants (<em>oah1</em>) are able to establish a basic compatibility with their hosts but are unable to transition to the OA-dependent colonization phase of compatibility. To test this hypothesis we are seeking to identify and characterize genes important for the establishment of primary lesions independent of OA accumulation. We have approached this experimentally by comparing transcriptome expression profiles from the wild type and OA-minus mutants during pre-penetration, penetration, and colonization phases of disease development. Of specific interest, cyanide hydratase genes (<em>chn1</em> and<em> chn2</em>) are highly expressed by both wild type and the OA-minus mutant during the infection of Brassicaceae and strongly up-regulated in the OA-minus mutant relative to the wild type. As glucosinolates are major phytoanticipins in Brassicaceae, these enzymes, through breakdown of toxic glucosinulate hydrolysis products, are candidates for the establishment of basic compatibility in Brassicaceae. From functional analyses, we have observed that <em>chn1 </em>mutants retain wild type virulence and <em>chn2, chn1-chn2</em>, and <em>chn-oah1 </em>mutants are being developed to further test the role of cyanide hydratases in establishment of basic compatibility in this broad host range necrotrophic pathogen.</div>