Hitchcock Megan, Thorn Veronica, Samarasinghe Himeshi, Sun Sheng, Heitman Joseph, Xu Jianping
bioRxiv. 2025 Aug 20:2025.08.20.671223. doi: 10.1101/2025.08.20.671223.
is a human fungal pathogen capable of both -α and α-α mating and sexual reproduction in laboratory settings. However, the extent of -α and α-α sexual reproductions in natural populations remain unexplored. Here we analyzed the whole-genome sequences of 24 environmental strains of from western Saudi Arabia, including one and 23 α isolates, with 15 α isolates belonging to multi-locus sequence type ST160 as defined by their combined DNA sequences at seven loci. To identify signatures for -α and α-α reproduction, three samples were analyzed: total, α, and ST160. For each subpopulation, single nucleotide polymorphisms (SNPs) were identified for both the nuclear and mitochondrial genomes and subjected to four-gamete tests. In the total population and the α subpopulation, variable proportions of SNP pairs within as well as between the nuclear and the mitochondrial genomes showed evidence for recombination. Though no mitogenome SNPs were found among the 15 strains of ST160, the nuclear genome showed clear evidence for recombination, including among SNPs within the mating type region. In addition, the nuclear genome SNP pairs located further apart on the same chromosome showed a greater frequency of recombination in all three sample types. In contrast, mitogenome recombination breakpoints were mainly located in two genomic regions. Together, these results provide robust evidence for both -α and α-α sexual reproduction within this environmental population of .
This study compares conclusions drawn from multilocus sequence data and whole-genome SNP data regarding genetic diversity and reproduction in an environmental population of . By analyzing bi-allelic SNPs across 24 strains isolated from western Saudi Arabian soils, evidence of both -α and α-α recombination was found, suggesting the occurrence of both -α and α-α sexual reproduction in nature. This provides strong support for these reproductive modes and indicates diverse mechanisms of genetic exchange in fungal pathogens in nature. Additionally, our results suggest that multi-locus sequence typing underestimates genetic diversity, potentially confounding interpretations of population structure and evolutionary history.
是一种人类真菌病原体，在实验室环境中能够进行 -α 和 α-α 交配以及有性生殖。然而，自然种群中 -α 和 α-α 有性生殖的程度仍未得到探索。在这里，我们分析了来自沙特阿拉伯西部的24株环境菌株的全基因组序列，包括1株 和23株α分离株，其中15株α分离株属于多基因座序列类型ST160，这是根据它们在7个基因座的组合DNA序列定义的。为了识别 -α 和 α-α 繁殖的特征，分析了三个样本：总体、α 和 ST160。对于每个亚群，鉴定了核基因组和线粒体基因组的单核苷酸多态性（SNP），并进行了四配子测试。在总体种群和α亚群中，核基因组和线粒体基因组内部以及之间不同比例的SNP对显示出重组的证据。虽然在15株ST160菌株中未发现线粒体基因组SNP，但核基因组显示出明显的重组证据，包括交配型区域内的SNP之间。此外，在所有三种样本类型中，位于同一条染色体上距离更远的核基因组SNP对显示出更高的重组频率。相比之下，线粒体基因组重组断点主要位于两个基因组区域。总之，这些结果为该环境种群中的 -α 和 α-α 有性生殖提供了有力证据。
本研究比较了从多基因座序列数据和全基因组SNP数据得出的关于环境种群中遗传多样性和繁殖的结论。通过分析从沙特阿拉伯西部土壤中分离出的24株菌株的双等位基因SNP，发现了 -α 和 α-α 重组的证据，表明在自然界中存在 -α 和 α-α 有性生殖。这为这些生殖模式提供了有力支持，并表明自然界中真菌病原体的遗传交换机制多种多样。此外，我们的结果表明多基因座序列分型低估了遗传多样性，可能会混淆对种群结构和进化历史的解释。
