Coevolution between a family of parasite virulence effectors and a class of LINE-1 retrotransposons

• Published in: PloS one 2009-10, Vol.4 (10), p.e7463-e7463
• Main Authors: Sacristán, Soledad, Vigouroux, Marielle, Pedersen, Carsten, Skamnioti, Pari, Thordal-Christensen, Hans, Micali, Cristina, Brown, James K M, Ridout, Christopher J
• Format: Article
• Language: English
• Subjects: Accuracy; Adaptation; Agriculture; Airborne microorganisms; Amino acids; Ascomycota - genetics; Ascomycota - pathogenicity; Ascomycota - physiology; Barley; Coevolution; Defense mechanisms; Effectors; Evolution & development; Evolution, Molecular; Evolutionary Biology/Microbial Evolution and Genomics; Fungi; Fungi - genetics; Fungi - metabolism; Gene Library; Gene loci; Gene sequencing; Genes; Genes, Fungal; Genetics; Genome, Fungal; Genomes; Genomics; Haustoria; Host plants; Life sciences; Long Interspersed Nucleotide Elements - genetics; Microbiology/Cellular Microbiology and Pathogenesis; Microbiology/Microbial Evolution and Genomics; Microbiology/Plant-Biotic Interactions; Models, Genetic; Molecular biology; Molecular Biology/Molecular Evolution; Nutrients; Parasites; Phylogenetics; Phylogeny; Physiology; Plant Biology/Plant-Biotic Interactions; Plant Diseases - microbiology; Plants (botany); Plants - microbiology; Powdery mildew; Proteins; Retroelements - genetics; Statistical methods; Studies; Transposons; Trends; Virulence; Virulence (Microbiology)
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0007463

Parasites are able to evolve rapidly and overcome host defense mechanisms, but the molecular basis of this adaptation is poorly understood. Powdery mildew fungi (Erysiphales, Ascomycota) are obligate biotrophic parasites infecting nearly 10,000 plant genera. They obtain their nutrients from host plants through specialized feeding structures known as haustoria. We previously identified the AVR(k1) powdery mildew-specific gene family encoding effectors that contribute to the successful establishment of haustoria. Here, we report the extensive proliferation of the AVR(k1) gene family throughout the genome of B. graminis, with sequences diverging in formae speciales adapted to infect different hosts. Also, importantly, we have discovered that the effectors have coevolved with a particular family of LINE-1 retrotransposons, named TE1a. The coevolution of these two entities indicates a mutual benefit to the association, which could ultimately contribute to parasite adaptation and success. We propose that the association would benefit 1) the powdery mildew fungus, by providing a mechanism for amplifying and diversifying effectors and 2) the associated retrotransposons, by providing a basis for their maintenance through selection in the fungal genome.