#Bio soft sequencher download drivers

The origin of the Ug99 lineage is unknown, although it is genetically distinct from other Pgt races 16, 17. It was first detected in Uganda in 1998 and described in 1999 15, and has since given rise to an asexual lineage that has spread through Africa and the Middle East causing devastating epidemics 14. tritici ( Pgt) presents a significant threat to global wheat production 14. The Ug99 strain (race TTKSK) of the wheat stem rust pathogen Puccinia graminis f.

Recent advances in assembling complete karyon sequences in rust fungi 12, 13 provide the opportunity to definitively detect and discriminate between nuclear exchange and recombination. Mechanisms underlying genetic exchange are unknown, but may involve hyphal anastomosis followed by nuclear exchange and/or nuclear fusion and recombination 11.

Some naturally occurring rust pathotypes have been suggested to have arisen by somatic hybridisation and genetic exchange based on limited molecular evidence of shared isozyme or random amplified polymorphic DNA (RAPD) markers 9, 10. Early researchers speculated that rust fungi can exchange genetic material during the asexual phase 5- 8, but these hypotheses could not be confirmed molecularly. These organisms are obligate parasites with complex life cycles that can include indefinite asexual reproduction through infectious dikaryotic urediniospores. Rust fungi (subphylum Pucciniomycotina) comprise over 8,000 species including many pathogens of major agricultural and ecological significance 4. The role of non-sexual genetic exchange between such dikaryons in generating genetic diversity is not known.īasidiomycetes include many fungi with critical ecosystem functions, such as wood decay and plant symbiosis, as well as agents of important human and plant diseases 1. However, in basidiomycete fungi (34% of described species), the predominant life stage is generally dikaryotic, with two different haploid nuclei maintained within each individual 3. Parasexuality has been described in members of the ascomycete phylum (64% of described fungal species) in which the dominant asexually propagating form is haploid 3. This process involves anastomosis of haploid hyphae and fusion of two nuclei to generate a single diploid nucleus, which subsequently undergoes progressive chromosome loss to generate recombinant haploid offspring. Some fungi can use a parasexual mechanism to exchange genetic material independently of meiosis 2. However, many species in the fungal kingdom can propagate asexually for extended periods and therefore understanding alternative mechanisms contributing to genetic diversity in asexual populations has been of great interest 1, 2.

#Bio soft sequencher download drivers

Generation of genetic diversity is crucial for the evolution of new traits, with mutation and sexual recombination as the main drivers of diversity in most eukaryotes. Generation of genetic variation by nuclear exchange may favour the evolution of dikaryotism by providing an advantage over diploidy. Fully haplotype-resolved genome assembly and DNA proximity analysis revealed that Ug99 shares one haploid nucleus genotype with a much older African lineage of Pgt, with no recombination or reassortment. Here we show that Ug99 arose by somatic hybridisation and nuclear exchange between dikaryons. tritici ( Pgt), such as Ug99, are a major threat to global food security. Newly emerged strains of the wheat stem rust pathogen, Puccinia graminis f. However non-sexual genetic exchange mechanisms are not defined in dikaryotic fungi (containing two distinct haploid nuclei). Parasexuality contributes to diversity and adaptive evolution of haploid (monokaryotic) fungi.