Comparative metatranscriptomics identifies molecular bases for the physiological responses of phytoplankton to varying iron availability

被引:228
作者
Marchetti, Adrian [1 ]
Schruth, David M. [1 ]
Durkin, Colleen A. [1 ]
Parker, Micaela S. [1 ]
Kodner, Robin B. [1 ]
Berthiaume, Chris T. [1 ]
Morales, Rhonda [1 ]
Allen, Andrew E. [2 ]
Armbrust, E. Virginia [1 ]
机构
[1] Univ Washington, Sch Oceanog, Seattle, WA 98105 USA
[2] Craig Venter Inst, San Diego, CA 92121 USA
基金
美国国家科学基金会;
关键词
RNA-seq; bloom; geoengineering; climate mitigation; SUB-ARCTIC PACIFIC; DIATOM PHAEODACTYLUM-TRICORNUTUM; ENRICHMENT EXPERIMENTS; MARINE DIATOM; NUTRIENT UTILIZATION; ELECTRON-TRANSPORT; USE EFFICIENCIES; NITROGEN-SOURCES; SOUTHERN-OCEAN; PHOTOSYNTHESIS;
D O I
10.1073/pnas.1118408109
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
In vast expanses of the oceans, growth of large phytoplankton such as diatoms is limited by iron availability. Diatoms respond almost immediately to the delivery of iron and rapidly compose the majority of phytoplankton biomass. The molecular bases underlying the subsistence of diatoms in iron-poor waters and the plankton community dynamics that follow iron resupply remain largely unknown. Here we use comparative metatranscriptomics to identify changes in gene expression associated with iron-stimulated growth of diatoms and other eukaryotic plankton. A microcosm iron-enrichment experiment using mixed-layer waters from the northeastern Pacific Ocean resulted in increased proportions of diatom transcripts and reduced proportions of transcripts from most other taxa within 98 h after iron addition. Hundreds of diatom genes were differentially expressed in the iron-enriched community compared with the iron-limited community; transcripts of diatom genes required for synthesis of photosynthesis and chlorophyll components, nitrate assimilation and the urea cycle, and synthesis of carbohydrate storage compounds were significantly overrepresented. Transcripts of genes encoding rhodopsins in eukaryotic phytoplankton were significantly underrepresented following iron enrichment, suggesting rhodopsins help cells cope with low-iron conditions. Oceanic diatoms appear to display a distinctive transcriptional response to iron enrichment that allows chemical reduction of available nitrogen and carbon sources along with a continued dependence on iron-free photosynthetic proteins rather than substituting for iron-containing functional equivalents present within their gene repertoire. This ability of diatoms to divert their newly acquired iron toward nitrate assimilation may underlie why diatoms consistently dominate iron enrichments in high-nitrate, low-chlorophyll regions.
引用
收藏
页码:E317 / E325
页数:9
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