the general transcriptional repressor tup1 is required for dimorphism and virulence in a fungal plant pathogen所需的通用转录阻遏tup1二态性和毒性的真菌植物病原体.pdf

The General Transcriptional Repressor Tup1 Is Required for Dimorphism and Virulence in a Fungal Plant Pathogen ´ ´ ´ ´ Alberto Elıas-Villalobos, Alfonso Fernandez-Alvarez, Jose I. Ibeas* ´ ´ Centro Andaluz de Biologıa del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Cientıficas, Sevilla, Spain Abstract A critical step in the life cycle of many fungal pathogens is the transition between yeast-like growth and the formation of filamentous structures, a process known as dimorphism. This morphological shift, typically triggered by multiple environmental signals, is tightly controlled by complex genetic pathways to ensure successful pathogenic development. In animal pathogenic fungi, one of the best known regulators of dimorphism is the general transcriptional repressor, Tup1. However, the role of Tup1 in fungal dimorphism is completely unknown in plant pathogens. Here we show that Tup1 plays a key role in orchestrating the yeast to hypha transition in the maize pathogen Ustilago maydis. Deletion of the tup1 gene causes a drastic reduction in the mating and filamentation capacity of the fungus, in turn leading to a reduced virulence phenotype. In U. maydis, these processes are controlled by the a and b mating-type loci, whose expression depends on the Prf1 transcription factor. Interestingly, Dtup1 strains show a critical reduction in the expression of prf1 and that of Prf1 target genes at both loci. Moreover, we observed that Tup1 appears to regulate Prf1 activity by controlling the expression of the prf1 transcripti