Keynote and Oral Papers 54

Basal Cryptophytes. They form a sister clade to photo- Biology, University of Namur, Namur 5000, Belgium; synthetic . These two clades together 5Bezhin Rosko, Santec 29250, France; 6Dipartimento (cryptomonads and basal cryptophytes) are a sister di Scienze della Vita e dell’Ambiente, Università clade to the clade. Goniomonas is aplas- Politecnica delle Marche, Ancona 60131, Italy; tidic, has never acquired a , and is currently 7Botany Department, University of Hawai‘iat considered as an ancestor to plastidic cryptomona- Mānoa, Honolulu HI 96822, United States; 8Biology dales. Upon the discovery of basal cryptophytes, the Department, University of Western Ontario, London question arose whether they constitute the most diver- N6A 5B7, Canada; 9School of BioSciences, University gent plastid-containing clade, or a new of Melbourne, Melbourne 3010, Australia and heterotrophic group at the base of the cryptomonad 10Department of Plant Systems Biology, VIB/Ugent, tree. Here, we combined phylogenetic and environ- Gent B-9052, Belgium mental study to address this question. The maximum likelihood phylogeny of 18S rRNA nuclear genes The trebouxiophycean Prasiola is an excellent confirmed placement of basal cryptophytes at the model for the study of ecological transitions, as it is base of the cryptomonad tree. We designed a specific one of the rare algal genera that includes marine, fresh- oligonucleotide probe, to detect members of this clade water and terrestrial representatives. The generitype in environmental samples by Catalysed Reported Prasiola crispa, an extremophile widely distributed in Deposition-Fluorescence in situ Hybridization cold temperate and polar regions of both hemispheres, (CARD-FISH), and to observe their basic morphol- has strong potential to serve as a good model of the ogy. None of the cells hybridized with the new probe evolution of both green algae and the land plants. We are showed chlorophyll-a autofluorescence at 590 nm, using next-generation sequencing data (Illumina tech- meaning they were aplastidic. The phylogenetic ana- nology) to obtain its complete genome sequence. lysis of 18S rRNA genes did not pro- Additionally, we are testing the Oxford Nannopore’s duced a sister clade to photosynthetic cryptomonads, MinION technology in order to complete the assembly suggesting that Basal had not acquired with ultra-long reads. We are presenting the first results a plastid at all. Altogether, these results indicated that of our project: complete sequences of P. crispa orga- the last aplastidic ancestor of cryptomonads could nelles, the mitochondrion (100,036 nt) and the plastid have been a basal cryptophyte, and that the engulf- genome (211,767 nt). Both have relatively low GC ment of a red algal symbiont might have been a more content (29.3% and 28.8%, respectively), as is usual recent event than when assuming radiation of the among green algae. The gene content corresponds well plastidic cryptomonads directly from Goniomonas.If with other sequenced trebouxiophyte organellar gen- confirmed upon culturing and studying a species from omes, with the only peculiarity being the presence of basal cryptophytes, it will change the view of evolu- the rpl10 gene in the mitochondrion. In the plastid DNA, tion of plastidic cryptophytes and . we discovered highly reduced remnants of the ancestral plastid inverted repeats (IRs, 851 bp) that bear no genes. There are clusters of non-algal mobile elements and fi 5OR.7 unidenti ed open reading frames in both genomes; these elements appear to be organelle-specific. WHOLE GENOME SEQUENCING OF THE ANTARCTIC GREEN ALGA PRASIOLA CRISPA 5OR.8 Marie Pažoutová1 ([email protected]), Olivier De Clerck2 ([email protected]), TACKLING RAPID RADIATIONS WITH Andrea Del Cortona3 ([email protected]), PHYLOGENOMICS IN THE Nicolas Dauchot4 ([email protected]), Jiří RHODOMELACEAE Košnar1 ([email protected]), Akira F Peters5 Pilar Díaz-Tapia1 ([email protected]), Christine A ([email protected]), Fabio Rindi6 Maggs2 ([email protected]), John AWest3 ([email protected]), Alison R Sherwood7 (asher ([email protected]) and Heroen Verbruggen3 [email protected]), David R Smith8 (dsmit242@uwo. ([email protected]) ca), Heroen Verbruggen9 (heroen.verbruggen@gmail. com) and Stephane Rombauts10 ([email protected]) 1BioCost Research Group, University of A Coruña, A Coruña 15071, Spain; 2Faculty of Science and 1Department of Botany, University of South Bohemia, Technology, Bournemouth University, Bournemouth České Budějovice 37005, Czech Republic; BH12 5BB, United and 3School of Botany, 2Phycology Research Group, Biology Department, University of Melbourne, Melbourne 3010, Australia Ghent University, Gent B-9000, Belgium; 3Department of Plant Systems Biology, VIB/Ugent, The family Rhodomelaceae, with about 1000 species, Gent B-9052, Belgium; 4Research Unit in Plant is the most species-rich family of the red algae. Its