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Abstract Despite the severe impacts of the
Deepwater Horizon oil spill, the foundation plant speciesSpartina alterniflora proved resilient to heavy oiling, providing an opportunity to identify mechanisms of response to the anthropogenic stress of crude oil exposure. We assessed plants from oil‐affected and unaffected populations using a custom DNA microarray to identify genomewide transcription patterns and gene expression networks that respond to crude oil exposure. In addition, we used T‐DNA insertion lines of the model grassBrachypodium distachyon to assess the contribution of four novel candidate genes to crude oil response. Responses inS. alterniflora to hydrocarbon exposure across the transcriptome as well as xenobiotic specific response pathways had little overlap with those previously identified in the model plantArabidopsis thaliana . Among T‐DNA insertion lines ofB. distachyon , we found additional support for two candidate genes, one (ATTPS21) involved in volatile production, and the other (SUVH5) involved in epigenetic regulation of gene expression, that may be important in the response to crude oil. The architecture of crude oil response inS. alterniflora is unique from that of the model speciesA. thaliana, suggesting that xenobiotic response may be highly variable across plant species. In addition, further investigations of regulatory networks may benefit from more information about epigenetic response pathways. -
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Abstract Spartina alterniflora has a distinct flood‐adapted morphology, and its physiological responses are likely to vary with differences in tidal submergence. To understand these responses, we examined the impacts of tidal inundation on the efficiency of Photosystem II (φPSII) photochemistry and leaf‐level photosynthesis at different canopy heights through a combination of in situ chlorophyll fluorescence (ChlF), incident photosynthetically active radiation, and tide levels. Our result showed small declines (7%–8.3%) in φPSII for air‐exposed leaves when the bottom canopies were tidally submerged. Submerged leaves produced large reductions (30.3%–41%) in φPSII. Our results suggest that when submerged, PSII reaction centers inS. alterniflora leaves are still active and able to transfer electrons, but only at ∼20% of the typical daily rate. We attribute this reduction in φPSII to the decrease in the fraction of “open” PSII reaction centers (10% of the total) and the stomatal conductance rate caused by the tidal submergence. To our knowledge, this flooding induced leaf‐level reduction of φPSII forS. alterniflora in field settings has not been reported before. Our findings suggest that canopy‐level φPSII is dependent on the proportion of submerged versus emerged leaves and highlight the complexities involved in estimating the photosynthetic efficiency of tidal marshes.
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/ecy.2863
