Dataset Information

Expression of major photosynthetic and salt-resistance genes in invasive reed lineages grown under elevated CO2 and temperature.

ABSTRACT: It is important to investigate the molecular causes of the variation in ecologically important traits to fully understand phenotypic responses to climate change. In the Mississippi River Delta, two distinct, sympatric invasive lineages of common reed (Phragmites australis) are known to differ in several ecophysiological characteristics and are expected to become more salt resistant due to increasing atmospheric CO2 and temperature. We investigated whether different patterns of gene expression can explain their ecophysiological differences and increased vigor under future climatic conditions. We compared the transcript abundance of photosynthetic genes of the Calvin cycle (Rubisco small subunit, RbcS; Phosphoglycerate kinase, PGK; Phosphoribulokinase, PRK), genes related with salt transport (Na(+)/H(+) antiporter, PhaNHA) and oxidative stress response genes (Manganese Superoxide dismutase, MnSOD; Glutathione peroxidase, GPX), and the total aboveground biomass production between two genotypes representing the two lineages. The two genotypes (Delta-type, Mediterranean lineage, and EU-type, Eurasian lineage) were grown under an ambient and a future climate scenario with simultaneously elevated CO2 and temperature, and under two different soil salinities (0‰ or 20‰). We found neither differences in the aboveground biomass production nor the transcript abundances of the two genotypes, but soil salinity significantly affected all the investigated parameters, often interacting with the climatic conditions. At 20‰ salinity, most genes were higher expressed in the future than in the ambient climatic conditions. Higher transcription of the genes suggests higher abundance of the protein they code for, and consequently increased photosynthate production, improved stress responses, and salt exclusion. Therefore, the higher expression of these genes most likely contributed to the significantly ameliorated salinity impact on the aboveground biomass production of both P. australis genotypes under elevated temperature and CO2. Although transcript abundances did not explain differences between the lineages, they correlated with the increased vigor of both lineages under anticipated future climatic conditions.

SUBMITTER: Eller F

PROVIDER: S-EPMC4242567 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature

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Expression of major photosynthetic and salt-resistance genes in invasive reed lineages grown under elevated CO2 and temperature.

Eller Franziska F Lambertini Carla C Nielsen Mette W MW Radutoiu Simona S Brix Hans H

Ecology and evolution 20141012 21

It is important to investigate the molecular causes of the variation in ecologically important traits to fully understand phenotypic responses to climate change. In the Mississippi River Delta, two distinct, sympatric invasive lineages of common reed (Phragmites australis) are known to differ in several ecophysiological characteristics and are expected to become more salt resistant due to increasing atmospheric CO2 and temperature. We investigated whether different patterns of gene expression ca ...[more]

PMID: 25505541

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Project description:Background and aimsPlants growing under elevated atmospheric CO2 concentrations often have reduced stomatal conductance and subsequently increased leaf temperature. This study therefore tested the hypothesis that under long-term elevated CO2 the temperature optima of photosynthetic processes will shift towards higher temperatures and the thermostability of the photosynthetic apparatus will increase.MethodsThe hypothesis was tested for saplings of broadleaved Fagus sylvatica and coniferous Picea abies exposed for 4-5 years to either ambient (AC; 385 µmol mol(-1)) or elevated (EC; 700 µmol mol(-1)) CO2 concentrations. Temperature response curves of photosynthetic processes were determined by gas-exchange and chlorophyll fluorescence techniques.Key resultsInitial assumptions of reduced light-saturated stomatal conductance and increased leaf temperatures for EC plants were confirmed. Temperature response curves revealed stimulation of light-saturated rates of CO2 assimilation (Amax) and a decline in photorespiration (RL) as a result of EC within a wide temperature range. However, these effects were negligible or reduced at low and high temperatures. Higher temperature optima (Topt) of Amax, Rubisco carboxylation rates (VCmax) and RL were found for EC saplings compared with AC saplings. However, the shifts in Topt of Amax were instantaneous, and disappeared when measured at identical CO2 concentrations. Higher values of Topt at elevated CO2 were attributed particularly to reduced photorespiration and prevailing limitation of photosynthesis by ribulose-1,5-bisphosphate (RuBP) regeneration. Temperature response curves of fluorescence parameters suggested a negligible effect of EC on enhancement of thermostability of photosystem II photochemistry.ConclusionsElevated CO2 instantaneously increases temperature optima of Amax due to reduced photorespiration and limitation of photosynthesis by RuBP regeneration. However, this increase disappears when plants are exposed to identical CO2 concentrations. In addition, increased heat-stress tolerance of primary photochemistry in plants grown at elevated CO2 is unlikely. The hypothesis that long-term cultivation at elevated CO2 leads to acclimation of photosynthesis to higher temperatures is therefore rejected. Nevertheless, incorporating acclimation mechanisms into models simulating carbon flux between the atmosphere and vegetation is necessary.

Project description:Sand lances of the genus Ammodytes are keystone forage fish in coastal ecosystems across the northern hemisphere. Because they directly support populations of higher trophic organisms such as whales, seabirds or tuna, the current lack of empirical data and, therefore, understanding about the climate sensitivity of sand lances represent a serious knowledge gap. Sand lances could be particularly susceptible to ocean warming and acidification because, in contrast to other tested fish species, they reproduce during boreal winter months, and their offspring develop slowly under relatively low and stable pCO2 conditions. Over the course of 2 years, we conducted factorial pCO2 × temperature exposure experiments on offspring of the northern sand lance Ammodytes dubius, a key forage species on the northwest Atlantic shelf. Wild, spawning-ripe adults were collected from Stellwagen Bank National Marine Sanctuary (Cape Cod, USA), and fertilized embryos were reared at three pCO2 conditions (400, 1000 and 2100 μatm) crossed with three temperatures (5, 7 and 10 ˚C). Exposure to future pCO2 conditions consistently resulted in severely reduced embryo survival. Sensitivity to elevated pCO2 was highest at 10 ˚C, resulting in up to an 89% reduction in hatching success between control and predicted end-of-century pCO2 conditions. Moreover, elevated pCO2 conditions delayed hatching, reduced remaining endogenous energy reserves at hatch and reduced embryonic growth. Our results suggest that the northern sand lance is exceptionally CO2-sensitive compared to other fish species. Whether other sand lance species with similar life history characteristics are equally CO2-sensitive is currently unknown. But the possibility is a conservation concern, because many boreal shelf ecosystems rely on sand lances and might therefore be more vulnerable to climate change than currently recognized. Our findings indicate that life history, spawning habitat, phenology and developmental rates mediate the divergent early life CO2 sensitivities among fish species.

Dataset Information

Expression of major photosynthetic and salt-resistance genes in invasive reed lineages grown under elevated CO2 and temperature.

Publications

Expression of major photosynthetic and salt-resistance genes in invasive reed lineages grown under elevated CO2 and temperature.

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