HOP1 and HAP2 are conserved components of the meiosis-related machinery required for successful mating in Leishmania

Sexual recombination in Leishmania during development in the sand fly vector has been implicated based on Mendelian parental contributions observed in experimental hybrid genomes. Here, we performed functional analyses using in vitro and in vivo hybridization protocols to assess the importance of conserved meiotic-related genes in recombination and plasmogamy. We report that HOP1 and a HAP2 -paralog ( HAP2-2 ) are essential components of the Leishmania meiosis machinery and cell-to-cell fusion mechanism, respectively, since deletion of either gene in one or both parents significantly reduced or completely abrogated mating competence. This is the first report in a trypanosomatid for the involvement of a meiotic protein homolog in genetic exchange, and the first description of a distinct fusogen mediating non-canonical, bilateral function in the hybridizing cells.