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Transcription factor Zfp1 required for full pathogenesis in Ustilago maydis.
H. K. Cheung (1), K. L. Spence (1), B. J. SAVILLE (2). (1) Trent University, Peterborough, ON, Canada; (2) Trent University, Ennismore, ON, Canada

Smut fungi are biotrophs- obtaining nutrients from the plant host to complete their life cycles. To facilitate this they produce effectors, secreted proteins which alter the host to favour fungal growth. While effector function is investigated by many researchers, the control of effector expression has received little attention. The characterization of a putative transcription factor conserved in smut fungi has revealed a potential link to the control of effector expression. This transcription factor, zinc finger protein 1 (Zfp1), is being investigated in <i>Ustilago maydis</i>, the causal agent for common smut of corn. The protein contains a GAL4-like Zn(II)2Cys6 binuclear cluster DNA-binding domain, and a fungal specific transcription factor domain. Microscopic investigation of infection with <i>zfp1</i> deletion strain showed fungal development is attenuated and remains mostly in the leaf tissue, corresponding with the production of small leaf tumours and reduced anthocyanin. This phenotype is also observed in the <i>U. maydis</i> effector <i>tin2</i> deletion strains. The transcript level of <i>tin2</i> and three other effectors appears altered in the <i>zfp1</i> deletion mutant strains during <i>in planta</i> growth. Additional alteration in expression over the transcriptome is investigated by RNAseq. Complementation by wildtype <i>zfp1</i> restores pathogenesis and anthocyanin production. This work begins an investigation of the control of effector gene expression in the model fungal pathogen <i>U. maydis</i>.

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