Meeting Abstract

12.3  Saturday, Jan. 4 10:45  Interacting effects of light and temperature on the transcriptome of Madracis auretenra GUERMOND, SM*; BEAZLEY, M; MEYER, E; Oregon State University; Oregon State University; Oregon State University sarah.guermond@science.oregonstate.edu

Coral reefs are in decline globally, in part because of bleaching-induced mortality resulting from multiple stressors including temperature and light. To enable studies of gene expression in Madracis auretenra, a Caribbean coral for which no sequence resources were previously available, we sequenced, assembled, and annotated the transcriptome using RNA from a colony collected at Flower Garden Banks (FGB) in the Gulf of Mexico. We prepared both normalized and non-normalized cDNA libraries, and found that normalized cDNA provided more complete gene representation and contained less contamination from the algal symbiont. Although interacting effects of elevated temperatures and light are important for coral bleaching, most gene expression studies of bleaching have profiled their combined effects. To disentangle the effects of each factor, we profiled gene expression in factorial combinations of temperature and light intensity. To simulate environmentally relevant conditions, we slowly increased temperatures from 28°C to a final temperature (31°) only one degree higher than the average annual maximum temperature encountered by corals at FGB. Bleaching occurred at approximately 4 degree heating weeks in the high light, high temperature treatment. To quantify these effects, we measured symbiont density using qPCR. We then profiled gene expression in all treatments to identify transcriptional responses specific to each factor and to their interaction. Our findings suggest that responses to warming sea water temperatures may depend on factors such as depth and turbidity that affect light intensity, and identify different genes and physiological processes affected by each factor separately and in combination.