AME 76:163-174 (2015)  -  DOI:

Origin of cryptophyte plastids in Dinophysis from Galician waters: results from field and culture experiments

Pilar Rial1,*, Aitor Laza-Martínez2, Beatriz Reguera1, Nicolás Raho3, Francisco Rodríguez1

1Instituto Español de Oceanografía, Subida a Radio Faro 50, Cabo Estai, Canido, 36390 Vigo, Spain
2Departamento de Biología Vegetal y Ecología, Universidad de País Vasco, Barrio Sarrienea s/n, 48940 Leioa, Bizkaia, Spain
3Departamento de Biología Molecular, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
*Corresponding author:

ABSTRACT: Photosynthetic species of the dinoflagellate genus Dinophysis retain cryptophyte plastids from the Teleaulax/Plagioselmis/Geminigera group via their ciliate prey Mesodinium rubrum, but other cryptophyte and algal sources have occasionally been found. Identifying the specific prey of ciliates fed upon by mixotrophic Dinophysis species is a requisite to improve predictive capabilities of their bloom formation. Here we examined the origin of Dinophysis plastids from Galician waters and their transfer in cross-feeding experiments in the laboratory. Plastid 23S rDNA sequences were obtained from 60 Dinophysis specimens from the Galician Rías Baixas and shelf waters. Most sequences in Dinophysis cells were identical to Teleaulax amphioxeia. Galician shelf samples also yielded T. amphioxeia-type sequences, although one of these was closer to a freshwater cryptophyte, and a few others were related with other taxa (diatoms, red algae and proteobacteria). Mesodinium cf. major, an alternative prey to M. rubrum, was identified. Cross-feeding tests in the laboratory showed that T. amphioxeia, T. minuta, T. gracilis, and Plagioselmis prolonga sustained growth of M. rubrum. D. acuminata cultivated on a M. rubrum–T. amphioxeia system was transferred to M. rubrum fed upon T. minuta, T. gracilis and P. prolonga. After >2 mo of acclimation, T. amphioxeia plastid 23S rDNA and psbA gene sequences from D. acuminata were replaced by those of secondary cryptophytes. Here we confirm 2 cryptophytes, T. minuta and P. prolonga, as suitable prey for M. rubrum. Nevertheless, field and laboratory results show that, at least for D. acuminata, T. amphioxeia represents the main source of plastids.

KEY WORDS: Dinophysis · Kleptoplastids · Cryptophytes · Mesodinium · 23S rDNA · psbA gene

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Cite this article as: Rial P, Laza-Martínez A, Reguera B, Raho N, Rodríguez F (2015) Origin of cryptophyte plastids in Dinophysis from Galician waters: results from field and culture experiments. Aquat Microb Ecol 76:163-174.

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