Plastid and mitochondrion genomic sequences from Arctic Chlorella sp. ArM0029B

Abstract

BackgroundChorella is the representative taxon of Chlorellales in Trebouxiophyceae, and its chloroplast (cp) genomic information has been thought to depend only on studies concerning Chlorella vulgaris and GenBank information of C. variablis. Mitochondrial (mt) genomic information regarding Chlorella is currently unavailable. To elucidate the evolution of organelle genomes and genetic information of Chlorella, we have sequenced and characterized the cp and mt genomes of Arctic Chlorella sp. ArM0029B.ResultsThe 119,989-bp cp genome lacking inverted repeats and 65,049-bp mt genome were sequenced. The ArM0029B cp genome contains 114 conserved genes, including 32 tRNA genes, 3 rRNA genes, and 79 genes encoding proteins. Chlorella cp genomes are highly rearranged except for a Chlorella-specific six-gene cluster, and the ArM0029B plastid resembles that of Chlorella variabilis except for a 15-kb gene cluster inversion. In the mt genome, 62 conserved genes, including 27 tRNA genes, 3 rRNA genes, and 32 genes encoding proteins were determined. The mt genome of ArM0029B is similar to that of the non-photosynthetic species Prototheca and Heicosporidium. The ArM0029B mt genome contains a group I intron, with an ORF containing two LAGLIDADG motifs, in cox1. The intronic ORF is shared by C. vulgaris and Prototheca. The phylogeny of the plastid genome reveals that ArM0029B showed a close relationship of Chlorella to Parachlorella and Oocystis within Chlorellales. The distribution of the cox1 intron at 721 support membership in the order Chlorellales. Mitochondrial phylogenomic analyses, however, indicated that ArM0029B shows a greater affinity to MX-AZ01 and Coccomyxa than to the Helicosporidium-Prototheca clade, although the detailed phylogenetic relationships among the three taxa remain to be resolved.ConclusionsThe plastid genome of ArM0029B is similar to that of C. variabilis. The mt sequence of ArM0029B is the first genome to be reported for Chlorella. Chloroplast genome phylogeny supports monophyly of the seven investigated members of Chlorellales. The presence of the cox1 intron at 721 in all four investigated Chlorellales taxa indicates that the cox1 intron had been introduced in early Chorellales as a cis-splice form and that the cis-splicing intron was inherited to recent Chlorellales and was recently trans-spliced in Helicosporidium.

The eurythermal adaptivity and temperature tolerance of a newly isolated psychrotolerant Arctic Chlorella sp.

“…Another Arctic Chlorella sp. (strain ArM0029B) displayed fast growth rates over a broad temperature range of 4-32°C (Ahn et al 2012;Jeong et al 2014). Long-term exposure to the extremely low temperatures may induce the development of adaptive mechanisms to chilling in photosynthesis (Hawes 1990;Anning et al 2001), biochemical composition (Converti et al 2009;Sang et al 2012;Jiang et al 2014), and even in gene expression (Chong et al 2011;An et al 2013).…”

The complete plastid genome of Scopolia parviflora (Dunn.) Nakai (Solanaceae)

“…The Illumina paired-end (PE) genomic library of 200 bp was constructed and sequenced using an Illumina HiSeq 2000 platform. The plastid sequence was obtained using CLC Genomics Workbench version 7.05 as described by Jeong et al (2014). Circular structures of each replicon were confirmed by polymerase chain reaction (PCR) amplification at their ends and by joining of Sanger sequence reads derived from the amplicons.…”

Chlorella species as hosts for genetic engineering and expression of heterologous proteins: Progress, challenge and perspective

“…ArM0029B, and A. protothecoides ( C. protothecoides ) and the mitochondrial genome of Chlorella sp. ArM0029B have been sequenced . At present, full nuclear genomes and/or transcriptomes of three Chlorella species, namely, C. variabilis , C. pyrenoidosa , and A. protothecoides ( C. protothecoides ) , and transcriptomes and proteomics of C. vulgaris are available.…”