title: Site-specific variation in gene expression from Symbiodinium spp. associated with offshore and inshore Porites astreoides in the lower Florida Keys is lost with bleaching and disease stress.
abstract: Scleractinian coral are experiencing unprecedented rates of mortality due to increases in sea surface temperatures in response to global climate change. Some coral species however, survive high temperature events due to a reduced susceptibility to bleaching. We investigated the relationship between bleaching susceptibility and expression of five metabolically related genes of Symbiodinium spp. from the coral Porites astreoides originating from an inshore and offshore reef in the Florida Keys. The acclimatization potential of Symbiodinium spp. to changing temperature regimes was also measured via a two-year reciprocal transplant between the sites. Offshore coral fragments displayed significantly higher expression in Symbiodinium spp. genes PCNA, SCP2, G3PDH, PCP and psaE than their inshore counterparts (p<0.05), a pattern consistent with increased bleaching susceptibility in offshore corals. Additionally, gene expression patterns in Symbiodinium spp. from site of origin were conserved throughout the two-year reciprocal transplant, indicating acclimatization did not occur within this multi-season time frame. Further, laboratory experiments were used to investigate the influence of acute high temperature (32°C for eight hours) and disease (lipopolysaccharide of Serratia marcescens) on the five metabolically related symbiont genes from the same offshore and inshore P. astreoides fragments. Gene expression did not differ between reef fragments, or as a consequence of acute exposure to heat or heat and disease, contrasting to results found in the field. Gene expression reported here indicates functional variation in populations of Symbiodinium spp. associated with P. astreoides in the Florida Keys, and is likely a result of localized adaptation. However, gene expression patterns observed in the lab imply that functional variation in zooxanthellae observed under conditions of chronic moderate stress is lost under the acute extreme conditions studied here.
authors.affiliation: University of Texas School of Medicine, San Antonio, TX, United States of America.
authors.forename: Briana Hauff
authors.identifier: http://orcid.org/0000-0002-4156-3278
authors.initials: BH
authors.lastname: Salas
authors.affiliation: Michigan State University, Department of Integrative Biology, East Lansing, MI, United States of America.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Haslun
authors.affiliation: Annis Water Resources Institute-Grand Valley State University, Muskegon, MI, United States of America.
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Strychar
authors.affiliation: Michigan State University, Department of Integrative Biology, East Lansing, MI, United States of America.
authors.forename: Peggy H
authors.initials: PH
authors.lastname: Ostrom
authors.affiliation: Woods Hole Oceanographic Institute, Department of Marine Chemistry & Geochemistry, Woods Hole, MA, United States of America.
authors.forename: James M
authors.initials: JM
authors.lastname: Cervino
mesh_terms: D000064:Acclimatization / Q000235:genetics*; D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D061146:Chlorophyll Binding Proteins / Q000235:genetics / Q000378:metabolism; D057231:Climate Change; D057894:Coral Reefs; D004141:Dinoflagellida / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005431:Florida; D005786:Gene Expression Regulation; D014644:Genetic Variation; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+) / Q000235:genetics / Q000378:metabolism; D045331:Photosystem I Protein Complex / Q000235:genetics / Q000378:metabolism; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D012621:Seasons; D013559:Symbiosis / Q000502:physiology*; D013696:Temperature
chemical_list: D002135:Calcium-Binding Proteins; D061146:Chlorophyll Binding Proteins; D045331:Photosystem I Protein Complex; D018809:Proliferating Cell Nuclear Antigen; D015800:Protozoan Proteins; C079741:photosystem I, psaE subunit; D024601:Glyceraldehyde 3-Phosphate Dehydrogenase (NADP+)