Department of Biology, Lund University, Sölvegatan 35, 22362 Lund, Sweden.
Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P Bag 16, 00267 Palapye, Botswana.
FEMS Yeast Res. 2017 Sep 1;17(6). doi: 10.1093/femsyr/fox060.
Large-scale chromosomal rearrangements are an important source of evolutionary novelty that may have reshaped the genomes of existing yeast species. They dramatically alter genome organization and gene expression fueling a phenotypic leap in response to environmental constraints. Although the emergence of such signatures of genetic diversity is thought to be associated with human exploitation of yeasts, less is known about the driving forces operating in natural habitats. Here we hypothesize that an ecological battlefield characteristic of every autumn when fruits ripen accounts for the genomic innovations in natural populations. We described a long-term cross-kingdom competition experiment between Lachancea kluyveri and five species of bacteria. Now, we report how we further subjected the same yeast to a sixth species of bacteria, Pseudomonas fluorescens, resulting in the appearance of a fixed and stably inherited large-scale genomic rearrangement in two out of three parallel evolution lines. The 'extra-banded' karyotype, characterized by a higher fitness and an elevated fermentative capacity, conferred the emergence of new metabolic traits in most carbon sources and osmolytes. We tracked down the event to a duplication and translocation event involving a 261-kb segment. Such an experimental setup described here is an attractive method for developing industrial strains without genetic engineering strategies.
大规模染色体重排是进化新颖性的重要来源，可能重塑了现有酵母物种的基因组。它们极大地改变了基因组组织和基因表达，为应对环境限制提供了表型飞跃。尽管这种遗传多样性的特征被认为与人类对酵母的利用有关，但在自然栖息地中，其驱动因素知之甚少。在这里，我们假设每个秋季果实成熟时都会出现的生态战场是自然种群中基因组创新的原因。我们描述了拉氏酵母（Lachancea kluyveri）和五种细菌之间的长期跨物种竞争实验。现在，我们报告了我们如何进一步将同一种酵母暴露于第六种细菌荧光假单胞菌（Pseudomonas fluorescens），导致在三个平行进化系中的两个系中出现了固定且稳定遗传的大规模基因组重排。“额外带型”核型的特征是更高的适应性和更高的发酵能力，赋予了大多数碳源和渗透物中出现新的代谢特征。我们将该事件追溯到涉及 261kb 片段的重复和易位事件。这里描述的这种实验设置是一种无需遗传工程策略即可开发工业菌株的有吸引力的方法。
