Diversity of transcripts and transcript processing forms in plastids of the dinoflagellate alga Karenia mikimotoi
Dorrell, Richard G
Hinksman, George A
Plant Molecular Biology
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Dorrell, R. G., Hinksman, G. A., & Howe, C. (2016). Diversity of transcripts and transcript processing forms in plastids of the dinoflagellate alga Karenia mikimotoi. Plant Molecular Biology, 90 233-247. https://doi.org/10.1007/s11103-015-0408-9
Plastids produce a vast diversity of transcripts. These include mature transcripts containing coding sequences, and their processing precursors, as well as transcripts that lack direct coding functions, such as antisense transcripts. Although plastid transcriptomes have been characterised in many plant species, less is known about the transcripts produced in other plastid lineages. We characterised the transcripts produced in the fucoxanthin-containing plastids of the dinoflagellate alga Karenia mikimotoi. This plastid lineage, acquired through tertiary endosymbiosis, utilises transcript processing pathways that are very different from those found in plants and green algae, including 3’ poly(U) tail addition, and extensive substitutional editing of transcript sequences. We have sequenced the plastid transcriptome of K. mikimotoi, and have detected evidence for divergent evolution of fucoxanthin plastid genome sequences. We have additionally characterised polycistronic and monocistronic transcripts from two plastid loci, psbD-tRNA Met-ycf4 and rpl36-rps13-rps11. We find evidence for a range of transcripts produced from each locus that differ in terms of editing state, 5’ end cleavage position, and poly(U) tail addition. Finally, we identify antisense transcripts in Karenia mikimotoi, which appear to undergo different processing events from the corresponding sense transcripts. Overall, our study provides insights into the diversity of transcripts and processing intermediates found in plastid lineages across the eukaryotes.
RNA processing, haptophytes, transcript processing, endosymbiotic gene transfer, chloroplast evolution
This work was supported by a BBSRC doctoral training grant [BB/F017464/1, to RGD], and a British Phycological Society summer undergraduate studentship [to GAH].
External DOI: https://doi.org/10.1007/s11103-015-0408-9
This record's URL: https://www.repository.cam.ac.uk/handle/1810/252726
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