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Environ Microbiol. 2018 Aug;20(8):3069-3082. doi: 10.1111/1462-2920.14361. Epub 2018 Sep 10.

Divergent gene expression among phytoplankton taxa in response to upwelling.

Author information

1
Department of Marine Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
2
Department of Ocean Sciences, University of California, Santa Cruz, CA, USA.
3
Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada.
4
Institute of Environmental Health, Oregon Health & Science University, Portland, OR, USA.
5
Department of Chemistry, Humboldt State University, Arcata, CA, USA.
6
The Marine Science Institute and the Department of Ecology Evolution and Marine Biology, University of California, Santa Barbara, CA, USA.
7
Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, Baton Rouge, LA, USA.
8
Department of Marine and Coastal Sciences, Rutgers, the State University of New Jersey, New Brunswick, NJ, USA.
9
Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, USA.

Abstract

Frequent blooms of phytoplankton occur in coastal upwelling zones creating hotspots of biological productivity in the ocean. As cold, nutrient-rich water is brought up to sunlit layers from depth, phytoplankton are also transported upwards to seed surface blooms that are often dominated by diatoms. The physiological response of phytoplankton to this process, commonly referred to as shift-up, is characterized by increases in nitrate assimilation and rapid growth rates. To examine the molecular underpinnings behind this phenomenon, metatranscriptomics was applied to a simulated upwelling experiment using natural phytoplankton communities from the California Upwelling Zone. An increase in diatom growth following 5 days of incubation was attributed to the genera Chaetoceros and Pseudo-nitzschia. Here, we show that certain bloom-forming diatoms exhibit a distinct transcriptional response that coordinates shift-up where diatoms exhibited the greatest transcriptional change following upwelling; however, comparison of co-expressed genes exposed overrepresentation of distinct sets within each of the dominant phytoplankton groups. The analysis revealed that diatoms frontload genes involved in nitrogen assimilation likely in order to outcompete other groups for available nitrogen during upwelling events. We speculate that the evolutionary success of diatoms may be due, in part, to this proactive response to frequently encountered changes in their environment.

PMID:
30043484
DOI:
10.1111/1462-2920.14361
[Indexed for MEDLINE]

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