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The Ustilago maydis transcription factor, Zfp1 influences pathogenic development through the control of effector gene expression.

Barry Saville: Trent University

<div>Control of the pathogenic/sexual cycle in the corn smut pathogen <em>Ustilago maydis</em> was investigated through functional characterization of meiosis gene orthologs. <em>zfp1</em>, encoding a Zn(II)<sub>2</sub>Cys<sub>6</sub> transcription factor, was identified as an ortholog to <em>Saccharomyces cerevisiae</em> Ume6. Deleting <em>zfp1</em> in compatible haploid <em>U. maydis</em> strains did not affect meiosis, but altered pathogenesis. Deletion in a solopathogenic strain, SG200, reduced anthocyanin production, inhibited <em>in planta</em> growth, and blocked the progression of pathogenesis. Zfp1 localizes to the nucleus and comparative transcriptome analysis of plants infected with SG200 and SG200Δ<em>zfp1 </em>identified 1870 <em>U. maydis</em> genes with altered transcript levels. 83 of these genes were down-regulated effectors, including <em>tin2</em> which induces anthocyanin production during infection. The sub-cellular location, pattern of transcript level changes and results of complementation experiments support a hypothesis that Zfp1 differentially controls effector gene expression by interacting with distinct binding partners. Transcription factor gene transcript levels were also altered in SG200Δ<em>zfp1</em> suggesting Zfp1 is part of a regulatory cascade. GO analysis of <em>Zea mays</em> genes that were differentially represented in SG200Δ<em>zfp1 </em>infections, identified plant processes potentially influenced by Zfp1 controlled <em>U. maydis </em>effectors. This study advances the molecular knowledge of smut pathogenesis to aid control measure development.</div>