Boty, a long-terminal-repeat retroelement in the phytopathogenic fungus Botrytis cinerea

Abstract

The phytopathogenic fungus Botrytis cinerea can infect an extremely wide range of host plants (tomato, grapevine, strawberry, and flax) without apparent specialization. While studying genetic diversity in this fungus, we found an element which is present in multiple copies and dispersed throughout the genome of some of its isolates. DNA sequence analysis revealed that the element contained direct, long-terminal repeats (LTRs) of 596 bp whose features were characteristic of retroviral and retrotransposon LTRs. Within the element, we identified an open reading frame with sequences homologous to the reverse transcriptase and RNase H domains of retroelement pol genes. We concluded that the element we had identified was a retroelement and named it Boty. By comparing its open reading frame with sequences from other retroelements, we found that Boty is related to the gypsy family of retrotransposons. Boty was present in numerous strains isolated from grapes and tomatoes but not in isolates from lentils. We propose that Boty-containing and Boty-deficient groups represent two lineages in the population of B. cinerea.