Project description:Branching coral species like the Caribbean Acroporids are long lived and reproduce asexually via breakage of branches. Fragmentation is the dominant mode of local population maintenance for these corals across much of their range. Thus, large genets with many member ramets (colonies) are common. Each of the ramets experiences different microenvironments, especially with respect to light and water flow. Here, we investigate whether colonies that are members of the same genet have different epigenomes because of differences in their microenvironments. The Florida Keys experienced a large- scale coral bleaching event in 2014-2015 caused by high water temperatures. During the event, ramets of the same coral genet bleached differently. Previous work had shown that this was unlikely to be due to their eukaryotic algal symbionts (Symbiodinium ‘fitti’) because each genet of this coral species typically harbors a single strain of S. ‘fitti’. Characterization of the microbiome via 16S tag sequencing did not provide evidence for a central role of microbiome variation in determining bleaching response. Instead, epigenetic changes were significantly correlated with the host’s genetic background, the position of the sampled polyps within the colonies (e.g. tip versus base of colony), and differences in the colonies’ condition during the bleaching event. We conclude that microenvironmental differences in growing conditions led to long-term changes in the way the ramets methylated their genomes and thus to a differential bleaching response.
Project description:Branching coral species like the Caribbean Acroporids are long lived and reproduce asexually via breakage of branches. Fragmentation is the dominant mode of local population maintenance for these corals across much of their range. Thus, large genets with many member ramets (colonies) are common. Each of the ramets experiences different microenvironments, especially with respect to light and water flow. Here, we investigate whether colonies that are members of the same genet have different epigenomes because of differences in their microenvironments. The Florida Keys experienced a large- scale coral bleaching event in 2014-2015 caused by high water temperatures. During the event, ramets of the same coral genet bleached differently. Previous work had shown that this was unlikely to be due to their eukaryotic algal symbionts (Symbiodinium ‘fitti’) because each genet of this coral species typically harbors a single strain of S. ‘fitti’. Characterization of the microbiome via 16S tag sequencing did not provide evidence for a central role of microbiome variation in determining bleaching response. Instead, epigenetic changes were significantly correlated with the host’s genetic background, the position of the sampled polyps within the colonies (e.g. tip versus base of colony), and differences in the colonies’ condition during the bleaching event. We conclude that microenvironmental differences in growing conditions led to long-term changes in the way the ramets methylated their genomes and thus to a differential bleaching response.
Project description:Salinity stress is one of the serious factors, limiting production of major agricultural crops; especially, in sodic soils. A number of approaches are being applied to mitigate the salt-induced adverse effects in agricultural crops through implying different halotolerant microbes. In this aspect, a halotolerant, Exiguobacterium profundum PHM11 was evaluated under eight different salinity regimes; 100, 250, 500, 1000, 1500, 2000, 2500, and 3000 mM to know its inherent salt tolerance limits and salt-induced consequences affecting its natural metabolism. Based on the stoichiometric growth kinetics; 100 and 1500 mM concentrations were selected as optimal and minimal performance limits for PHM11. To know, how salt stress affects the expression profiles of regulatory genes of its key metabolic pathways, and total production of important metabolites; biomass, carotenoids, beta-carotene production, IAA and proline contents, and expression profiles of key genes affecting the protein folding, structural adaptations, transportation across the cell membrane, stress tolerance, carotenoids, IAA and mannitol production in PHM11 were studied under 100 and 1500 mM salinity. E. profundum PHM11 showed maximum and minimum growth, biomass and metabolite production at 100 and 1500 mM salinity respectively. Salt-induced fine-tuning of expression profiles of key genes of stress pathways was determined in halotolerant bacterium PHM11.
Project description:Florida’s coral reefs are currently experiencing a multi-year disease-related mortality event, that has resulted in massive die-offs in multiple coral species. Approximately 21 species of coral, including both Endangered Species Act-listed and the primary reef-building species, have displayed tissue loss lesions which often result in whole colony mortality [Stony Coral Tissue Loss Disease (SCTLD)]. Determining the causative agent(s) of coral disease relies on a multidisciplinary approach since the causation may be a combination of abiotic, microbial or viral agents. Metaproteomics was used to survey changes in the molecular landscape in the coral holobiont with the goal of providing useful information not only in diagnosis, but for prediction and prognosis. Specifically, in the case of SCTLD, defining molecular changes in the coral holobiont will help define disease progression and aid in identifying the causative agent by clearly defining traits of disease progression shared across affected species. Using samples from nine coral species (46 samples total; those appearing healthy, n = 23, and diseased, n = 23), analysis of the coral and its associated microbiome were performed using bottom-up proteomics. Ongoing analysis (including improving coral holobiont genome-based search space) will demonstrate the utility of this approach and help define improved future experiments.