Genes under positive selection in a model plant pathogenic fungus, Botrytis

Ecologie, Systématique et Evolution, Université Paris-Sud UMR8079, F-91405 Orsay Cedex, France.
Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases (Impact Factor: 3.02). 03/2012; 12(5):987-96. DOI: 10.1016/j.meegid.2012.02.012
Source: PubMed


The rapid evolution of particular genes is essential for the adaptation of pathogens to new hosts and new environments. Powerful methods have been developed for detecting targets of selection in the genome. Here we used divergence data to compare genes among four closely related fungal pathogens adapted to different hosts to elucidate the functions putatively involved in adaptive processes. For this goal, ESTs were sequenced in the specialist fungal pathogens Botrytis tulipae and Botrytis ficariarum, and compared with genome sequences of Botrytis cinerea and Sclerotinia sclerotiorum, responsible for diseases on over 200 plant species. A maximum likelihood-based analysis of 642 predicted orthologs detected 21 genes showing footprints of positive selection. These results were validated by resequencing nine of these genes in additional Botrytis species, showing they have also been rapidly evolving in other related species. Twenty of the 21 genes had not previously been identified as pathogenicity factors in B. cinerea, but some had functions related to plant-fungus interactions. The putative functions were involved in respiratory and energy metabolism, protein and RNA metabolism, signal transduction or virulence, similarly to what was detected in previous studies using the same approach in other pathogens. Mutants of B. cinerea were generated for four of these genes as a first attempt to elucidate their functions.

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    • "This approach has been used to reveal ECs in several filamentous plant pathogen lineages [29–34]. Positive selection has been detected in B. cinerea genome [35] suggesting that it may be used to mine S. sclerotiorum genome for ECs. Second, gene duplication is another hallmark of several known fungal effector genes, such as the ToxB host specific toxin of Pyrenophora tritici-repentis [36, 37]. "
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