Comparison of the transcriptomes of different life history stages of the freshwater Rhodophyte Thorea hispida.

Thorea hispida exclusively inhabits freshwater environments and is characterized by a triphasic life history. In this study, the organelle genomes and transcriptomes of different life history stages of T. hispida were examined using next generation sequencing. The chloroplast and mitochondrial genomes of the chantransia stage were 175,747 and 25,411 bp in length, respectively. The chantransia stage was highly similar to the gametophyte stage based on comparisons of organelle genomes and phylogenetic reconstruction. Transcriptomic comparisons of two stages found that ribosome-related genes were the most up-regulated in the gametophyte stage of T. hispida. Seven meiosis-specific genes, including SPO11 initiator of meiotic double-stranded breaks(spo 11), meiotic nuclear divisions 1(mnd 1), RAD51 recombinase(rad 51), mutS homolog 4(msh 4), mutS homolog 5(msh 5), REC8 meiotic recombination protein(rec 8), and DNA helicase Mer3(mer 3), were differentially regulated between the two life history stages. The organelle genomes and transcriptomes from T. hispida provided in this study will be valuable for future studies of freshwater red algae. • Organelle genomes of chantransia stage of T. hispida are provided. • Transcriptomes of chantransia and gametophyte stages of T. hispida are compared. • Organelle genomes are highly conserved between chantransia and gametophyte. • Seven meiosis-specific genes are differentially regulated. [ABSTRACT FROM AUTHOR]