微生物在维持土壤生态系统和农业方面发挥着核心作用,这些功能通常与他们复杂的生活史有关。然而,生活史的调节和进化仍然是神秘和知之甚少,尤其是在原生动物中,土壤中第三丰富的生物群。这里,我们探索一个世界性物种——Colpodasteinii的生活史。我们的分析为C.steinii产生了高质量的大核基因组,大小为155Mbp和37,123个蛋白质编码基因,以及平均内含子长度约93bp,比大多数其他研究纤毛虫长。值得注意的是,我们在C.steinii中确定了两个可能的全基因组复制事件,这可能解释了它的基因组大约是C.inflata的两倍,另一个共存的物种。我们进一步解析了C.steinii不同生命阶段的基因表达谱,这在C.inflata中也得到了证实。在囊肿静止期,与细胞死亡和液泡形成相关的基因上调,和翻译相关的基因下调。而翻译相关基因在静息囊肿的分泌过程中上调。生殖囊肿表现出细胞粘附的显着降低。我们还证明,在特定生命阶段表达的大多数基因都处于强纯化选择下。这项研究提供了对生活史演变的更深入的了解,这些生活史是土壤生态系统中微生物非凡成功和生态功能的基础。重要物种,作为分布最广泛和最丰富的土壤微生物中的一个突出群体,在维持土壤生态系统和促进植物生长方面发挥着至关重要的作用。这项调查揭示了他们特殊的大核基因组特征,包括相当大的基因组大小,长内含子,和大量的基因复制。还阐明了与各个生命阶段之间的转换相关的基因表达谱和特定生物学功能。绝大多数与生命阶段转换相关的基因都受到强烈的净化选择,从新分离和深度测序的多个天然菌株推断。这证实了科尔波达的生活史的持久和保守的性质,在土壤中这些非常成功的原生动物的广泛进化史中一直存在。这些发现揭示了不断波动的土壤环境中微生物真核生物的进化动力学。这项综合研究在理解这些未被研究的单细胞真核生物的生活史方面取得了重大进展。
Microorganisms play a central role in sustaining soil ecosystems and agriculture, and these functions are usually associated with their complex life history. Yet, the regulation and evolution of life history have remained enigmatic and poorly understood, especially in protozoa, the third most abundant group of organisms in the soil. Here, we explore the life history of a cosmopolitan species-Colpoda steinii. Our analysis has yielded a high-quality macronuclear genome for C. steinii, with size of 155 Mbp and 37,123 protein-coding genes, as well as mean intron length of ~93 bp, longer than most other studied ciliates. Notably, we identify two possible whole-genome duplication events in C. steinii, which may account for its genome being about twice the size of C. inflata\'s, another co-existing species. We further resolve the gene expression profiles in diverse life stages of C. steinii, which are also corroborated in C. inflata. During the resting cyst stage, genes associated with cell death and vacuole formation are upregulated, and translation-related genes are downregulated. While the translation-related genes are upregulated during the excystment of resting cysts. Reproductive cysts exhibit a significant reduction in cell adhesion. We also demonstrate that most genes expressed in specific life stages are under strong purifying selection. This study offers a deeper understanding of the life history evolution that underpins the extraordinary success and ecological functions of microorganisms in soil ecosystems.IMPORTANCEColpoda species, as a prominent group among the most widely distributed and abundant soil microorganisms, play a crucial role in sustaining soil ecosystems and promoting plant growth. This investigation reveals their exceptional macronuclear genomic features, including significantly large genome size, long introns, and numerous gene duplications. The gene expression profiles and the specific biological functions associated with the transitions between various life stages are also elucidated. The vast majority of genes linked to life stage transitions are subject to strong purifying selection, as inferred from multiple natural strains newly isolated and deeply sequenced. This substantiates the enduring and conservative nature of Colpoda\'s life history, which has persisted throughout the extensive evolutionary history of these highly successful protozoa in soil. These findings shed light on the evolutionary dynamics of microbial eukaryotes in the ever-fluctuating soil environments. This integrative research represents a significant advancement in understanding the life histories of these understudied single-celled eukaryotes.