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Updated: Aug 19, 2026

Genetic Manipulation of the Plant Pathogen Ustilago maydis to Study Fungal Biology and Plant Microbe Interactions
Published on: September 30, 2016
The biallelic a mating type locus of Ustilago maydis: remnants of an additional pheromone gene indicate evolution
1Institut für Genetik und Mikrobiologie der Universität München, München, Germany.
Abstract:
The a mating type locus of Ustilago maydis contains the structural genes for a pheromone-based cell recognition system that governs fusion of haploid cells. The locus exists in two alleles, termed a1 and a2. We have completed the analysis of the nucleotide sequences unique to a1 and a2. Within these dissimilar regions we find two short patches of DNA sequence similarity. Interestingly, one of these segments corresponds to the transcribed region of the a1 pheromone precursor. As a result of multiple nucleotide exchanges this sequence does not code for a functional product. The existence of a second pheromone gene in the a2 allele suggests that the present locus had a multiallelic ancestor. In addition, we describe the presence of two additional genes in the a2 allele. We have investigated the role of these genes during mating and pathogenic development and speculate that they might affect mitochondrial inheritance.
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