TY - JOUR

T1 - Algal diversity in Paramecium bursaria: species identification, detection of Choricystis parasitica, and assessment of the interaction specificity

AU - Flemming, Felicitas

AU - Potekhin, Alexey

AU - Pröschold, Thomas

AU - Schrallhammer, Martina

N1 - Publisher Copyright: © 2020 by the authors.

PY - 2020/8

Y1 - 2020/8

N2 - The ‘green’ ciliate Paramecium bursaria lives in mutualistic symbiosis with green algae belonging to the species Chlorella variabilis or Micractinium conductrix. We analysed the diversity of algal endosymbionts and their P. bursaria hosts in nine strains from geographically diverse origins. Therefore, their phylogenies using different molecular markers were inferred. The green paramecia belong to different syngens of P. bursaria. The intracellular algae were assigned to Chl. variabilis, M. conductrix or, surprisingly, Choricystis parasitica. This usually free-living alga co-occurs with M. conductrix in the host’s cytoplasm. Addressing the potential status of Chor. parasitica as second additional endosymbiont, we determined if it is capable of symbiosis establishment and replication within a host cell. Symbiont-free P. bursaria were generated by cycloheximid treatment. Those aposymbiotic P. bursaria were used for experimental infections to investigate the symbiosis specificity not only between P. bursaria and Chor. parasitica but including also Chl. variabilis and M. conductrix. For each algae we observed the uptake and incorporation in individual perialgal vacuoles. These host-symbiont associations are stable since more than five months. Thus, Chor. parasitica and P. bursaria can form an intimate and long-term interaction. This study provides new insights into the diversity of P. bursaria algal symbionts.

AB - The ‘green’ ciliate Paramecium bursaria lives in mutualistic symbiosis with green algae belonging to the species Chlorella variabilis or Micractinium conductrix. We analysed the diversity of algal endosymbionts and their P. bursaria hosts in nine strains from geographically diverse origins. Therefore, their phylogenies using different molecular markers were inferred. The green paramecia belong to different syngens of P. bursaria. The intracellular algae were assigned to Chl. variabilis, M. conductrix or, surprisingly, Choricystis parasitica. This usually free-living alga co-occurs with M. conductrix in the host’s cytoplasm. Addressing the potential status of Chor. parasitica as second additional endosymbiont, we determined if it is capable of symbiosis establishment and replication within a host cell. Symbiont-free P. bursaria were generated by cycloheximid treatment. Those aposymbiotic P. bursaria were used for experimental infections to investigate the symbiosis specificity not only between P. bursaria and Chor. parasitica but including also Chl. variabilis and M. conductrix. For each algae we observed the uptake and incorporation in individual perialgal vacuoles. These host-symbiont associations are stable since more than five months. Thus, Chor. parasitica and P. bursaria can form an intimate and long-term interaction. This study provides new insights into the diversity of P. bursaria algal symbionts.

KW - Chlorella

KW - Endosymbiosis

KW - intracellular algae

KW - Micractinium

KW - photobiont

KW - infection

KW - syngen

KW - Infection

KW - Syngen

KW - Photobiont

KW - Intracellular algae

UR - https://www.mdpi.com/1424-2818/12/8/287

UR - http://www.scopus.com/inward/record.url?scp=85089537340&partnerID=8YFLogxK

U2 - 10.3390/D12080287

DO - 10.3390/D12080287

M3 - Article

VL - 12

JO - Diversity

JF - Diversity

SN - 1424-2818

IS - 8

M1 - 287

ER -