Day and night patterns of gene activity in agave reveal key genes involved in a type of photosynthesis that maximizes water-use efficiency.
Crassulacean acid metabolism (CAM) is a specialized mode of photosynthesis found in plants adapted to hot and arid conditions. CAM photosynthesis differs from the more common C3 and C4 photosynthesis types in that it inverts the day and night pattern of stomata opening to capture carbon dioxide (CO2) at night and avoid water evaporation through stomata opening during the day. Researchers at the University of Nevada and Oak Ridge National Laboratory conducted metabolomics, proteomics, and transcriptomics analyses of the desert plant agave across a diel cycle to identify genes involved in the CAM photosynthesis process and its higher water-use efficiency.
As the photosynthetic machinery of most bioenergy crops is adapted to temperate and humid environments, carbon fixation and, therefore, biomass accumulation are less efficient and require more water than CAM plants adapted to hot and dry conditions. For that reason, introducing CAM photosynthesis into bioenergy crops would enable them to grow in marginal environments, but the molecular and genetic basis of CAM photosynthesis are not well enough understood to do this. This research identified candidate genes responsible for several aspects of the CAM process that can be used to design bioenergy crops with increased water-use efficiency and tolerance to extreme environmental conditions.
A comparison of diel metabolic profiles of the CAM photosynthesis plant agave and the C3 photosynthesis plant Arabidopsis showed that metabolites involved in the redox reactions required for photosynthesis are found at different times of the day in each plant. Consistent with those results, transcription and protein profiling confirmed that the expression patterns of genes necessary for redox balance were shifted between agave and Arabidopsis through the day and night cycle. Furthermore, cell signaling genes in the guard cells that form the stomata, as well as CO2-sensing genes responsible for the closing of stomata and ion channels that participate in stomata opening, also showed the same opposite expression patterns between the two photosynthetic modes. This research provides strong evidence that bioengineering CAM in a C3 plant will require temporal reprogramming and identifies potential key targets for engineering this mode of photosynthesis in C3 plants, such as poplar and other selected bioenergy crops.
Contacts (BER PM)
DOE Office of Biological and Environmental Research
Oak Ridge National Laboratory, Oak Ridge, TN
Department of Biochemistry and Molecular Biology
University of Nevada, Reno, NV
This work was supported by the Office of Biological and Environmental Research within the U.S. Department of Energy’s Office of Science award DE-SC0008834.
Abraham, P. E., H. Yin, A. M. Borland, D. Weighill, S. D. Lim, H. C. De Paoli, N. Engle, P.C. Jones, R. Agh, D. J. Weston, S. D. Wullschleger, T. Tschaplinski, D. Jacobson, J. C. Cushman, R. L. Hettich, G. A. Tuskan, and X. Yang. 2016. “Transcript, Protein, and Metabolite Temporal Dynamics in the CAM Plant Agave,” Nature Plants 2(16178), DOI: 10.1038/nplants.2016.178. (Reference link)
SC-23.2 Biological Systems Science Division, BER
BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER
May 10, 2019
Quantifying Decision Uncertainty in Water Management via a Coupled Agent-Based Model
Considering risk perception can improve the representation of human decision-making processes in age [more...]
May 09, 2019
Projecting Global Urban Area Growth Through 2100 Based on Historical Time Series Data and Future Scenarios
Study provides country-specific urban area growth models and the first dataset on country-level urba [more...]
May 05, 2019
Calibrating Building Energy Demand Models to Refine Long-Term Energy Planning
A new, flexible calibration approach improved model accuracy in capturing year-to-year changes in bu [more...]
May 03, 2019
Calibration and Uncertainty Analysis of Demeter for Better Downscaling of Global Land Use and Land Cover Projections
Researchers improved the Demeter model’s performance by calibrating key parameters and establi [more...]
Apr 22, 2019
Representation of U.S. Warm Temperature Extremes in Global Climate Model Ensembles
Representation of warm temperature events varies considerably among global climate models, which has [more...]
List all highlights (possible long download time)