| Popis: |
BackgroundMeiotic recombination is mainly, but not exclusively, initiated by Spo11-induced double strand breaks (DSBs) in some sexual eukaryotes. DSBs are repaired by one or two RecA-like recombinases (ubiquitous Rad51 and meiosis-specific Dmc1). In yeast and mammals, Dmc1 is superior to Rad51 in tolerating mismatched sequences during highly polymorphic hybrid meiosis. The mechanisms underlying Rad51-only meiotic recombination remain less studied.ResultsThe Rad51-only filamentous fungusTrichoderma reeseihas only onespo11gene. Removal ofspo11fromT. reeseigenome does not affect normal sexual development, meiosis or chromosome synapsis, but results in decrease of interhomolog recombination products to 70%, crossover homeostasis and lower genetic interference. Our results also suggest thatT. reeseiRad51, like yeast and mammalian Dmc1 (but not Rad51), can tolerate mismatched sequences during meiotic recombination. Moreover, Topoisomerase II might act redundantly (and predominantly) with Spo11 to initiate meiotic recombination.ConclusionWe suggest thatT. reeseiis an emerging model for studying Spo11-independent and Rad51-only meiosis. |
