Genetic basis for the establishment of endosymbiosis in Paramecium

作者：Ming He, Jinfeng Wang, Xinpeng Fan, Xiaohui Liu, Wenyu Shi, Ning Huang, Fangqing Zhao, Miao Miao · 发表于：The ISME Journal · 年份：2019 · DOI：10.1038/s41396-018-0341-4 · 被引用次数：71 · 研究领域：Protist diversity and phylogeny、Microbial Community Ecology and Physiology、Genomics and Phylogenetic Studies

The single-celled ciliate Paramecium bursaria is an indispensable model for investigating endosymbiosis between protists and green-algal symbionts. To elucidate the mechanism of this type of endosymbiosis, we combined PacBio and Illumina sequencing to assemble a high-quality and near-complete macronuclear genome of P. bursaria. The genomic characteristics and phylogenetic analyses indicate that P. bursaria is the basal clade of the Paramecium genus. Through comparative genomic analyses with its close relatives, we found that P. bursaria encodes more genes related to nitrogen metabolism and mineral absorption, but encodes fewer genes involved in oxygen binding and N-glycan biosynthesis. A comparison of the transcriptomic profiles between P. bursaria with and without endosymbiotic Chlorella showed differential expression of a wide range of metabolic genes. We selected 32 most differentially expressed genes to perform RNA interference experiment in P. bursaria, and found that P. bursaria can regulate the abundance of their symbionts through glutamine supply. This study provides novel insights into Paramecium evolution and will extend our knowledge of the molecular mechanism for the induction of endosymbiosis between P. bursaria and green algae.