Heinzelmann Renate, Rigling Daniel, Sipos György, Münsterkötter Martin, Croll Daniel
Swiss Federal Research Institute WSL, Zürcherstrasse 111, CH-8903, Birmensdorf, Switzerland.
Department of Forest and Conservation Sciences, The University of British Columbia, 2424 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
Heredity (Edinb). 2020 Jun;124(6):699-713. doi: 10.1038/s41437-020-0306-z. Epub 2020 Mar 13.
Recombination shapes the evolutionary trajectory of populations and plays an important role in the faithful transmission of chromosomes during meiosis. Levels of sexual reproduction and recombination are important properties of host-pathogen interactions because the speed of antagonistic co-evolution depends on the ability of hosts and pathogens to generate genetic variation. However, our understanding of the importance of recombination is limited because large taxonomic groups remain poorly investigated. Here, we analyze recombination rate variation in the basidiomycete fungus Armillaria ostoyae, which is an aggressive pathogen on a broad range of conifers and other trees. We analyzed a previously constructed, dense genetic map based on 198 single basidiospore progeny from a cross. Progeny were genotyped at a genome-wide set of single-nucleotide polymorphism (SNP) markers using double digest restriction site associated DNA sequencing. Based on a linkage map of on 11,700 SNPs spanning 1007.5 cM, we assembled genomic scaffolds into 11 putative chromosomes of a total genome size of 56.6 Mb. We identified 1984 crossover events among all progeny and found that recombination rates were highly variable along chromosomes. Recombination hotspots tended to be in regions close to the telomeres and were more gene-poor than the genomic background. Genes in proximity to recombination hotspots were encoding on average shorter proteins and were enriched for pectin degrading enzymes. Our analyses enable more powerful population and genome-scale studies of a major tree pathogen.
重组塑造了种群的进化轨迹，并在减数分裂过程中染色体的忠实传递中发挥重要作用。有性生殖和重组水平是宿主 - 病原体相互作用的重要特性，因为对抗性协同进化的速度取决于宿主和病原体产生遗传变异的能力。然而，由于大型分类群体的研究仍然不足，我们对重组重要性的理解有限。在这里，我们分析了蜜环菌（Armillaria ostoyae）的重组率变异，蜜环菌是一种侵袭多种针叶树和其他树木的病原体。我们分析了之前构建的基于一次杂交产生的198个单担子孢子后代的密集遗传图谱。使用双酶切限制性位点相关DNA测序，对后代在全基因组范围内的单核苷酸多态性（SNP）标记进行基因分型。基于跨越1007.5 cM的11,700个SNP的连锁图谱，我们将基因组支架组装成11条假定染色体，总基因组大小为56.6 Mb。我们在所有后代中鉴定出1984个交叉事件，发现重组率沿染色体高度可变。重组热点倾向于位于靠近端粒的区域，并且比基因组背景的基因贫乏。靠近重组热点的基因平均编码较短的蛋白质，并且富含果胶降解酶。我们的分析能够对一种主要的树木病原体进行更强大的种群和基因组规模研究。
