DOI: 10.1007/s00338-011-0833-4Online First™
Report
Transcriptomic responses to darkness stress point to
common coral bleaching mechanisms
M.
K. DeSalvo, A.
Estrada, S.
Sunagawa and Mónica
Medina
Abstract
Coral
bleaching occurs in response to numerous abiotic stressors, the ecologically
most relevant of which is hyperthermic stress due to increasing seawater
temperatures. Bleaching events can span large geographic areas and are
currently a salient threat to coral reefs worldwide. Much effort has been
focused on understanding the molecular and cellular events underlying
bleaching, and these studies have mainly utilized heat and light stress
regimes. In an effort to determine whether different stressors share common
bleaching mechanisms, we used complementary DNA (cDNA) microarrays for the
corals Acropora palmata and Montastraea faveolata (containing
>10,000 features) to measure differential gene expression during darkness
stress. Our results reveal a striking transcriptomic response to darkness in A.
palmata involving chaperone and antioxidant up-regulation, growth arrest,
and metabolic modifications. As these responses were previously measured during
thermal stress, our results suggest that different stressors may share common
bleaching mechanisms. Furthermore, our results point to hypoxia and endoplasmic
reticulum stress as critical cellular events involved in molecular bleaching
mechanisms. On the other hand, we identified a meager transcriptomic response
to darkness in M. faveolata where gene expression differences between
host colonies and sampling locations were greater than differences between
control and stressed fragments. This and previous coral microarray studies
reveal the immense range of transcriptomic responses that are possible when
studying two coral species that differ greatly in their ecophysiology, thus
pointing to the importance of comparative approaches in forecasting how corals
will respond to future environmental change.
Keywords Coral
bleaching – Microarrays – Transcriptomics – Darkness stress – Symbiosis – Coral
reefs
Communicated
by Environment Editor Prof. Rob van Woesik.