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Asaph Cousins

Asaph Cousins

Field of Study: Plant Metabolism and Physiology
Title: Professor
Degrees: Ph.D., Plant Biology, Arizona State University
Homepage: Homepage/Lab Web Site Link
Google Scholar:  Google Scholar
Office: 406 BA Abelson Hall
Phone: 509-335-7218; Lab 509-335-8243
Fax: 509-335-3184
Mailing Address: School of Biological Sciences
Washington State University
PO Box 644236
Pullman,WA 99164-4236


The ability to monitor and predict how plants both influence and are influenced by future climatic conditions is critical for the health of our planet and for future food production. My research couples molecular biology techniques with plant physiology and mathematical modeling of photosynthesis to understand the mechanistic processes dictating plant-environment interactions. This research uses a variety of experimental techniques, including field experiments, leaf and whole plant gas exchange, recombinant DNA techniques, biochemistry, and metabolite analysis to elucidate how the interactions of plant light utilization, carbon and nutrient assimilation, and isotope discrimination are influenced by changing environmental conditions.

The two main areas my research is focusing on are:

1) Plant energy metabolism

Understanding the flow of energy between metabolic pathways and organelles is important for determining how plants will respond to environmental stress and future climatic conditions. This research uses gas exchange, mass spectrometry and metabolite analysis to understand the key steps in photosynthesis, photorespiration and nitrogen metabolism that coordinate the energy flow between these competing processes.

2) Carbon and oxygen isotope exchange in plants

Isotope analysis of atmospheric CO2 is an important tool for monitoring ecosystem changes in plant metabolism in response to climate change. However, to interpret the atmospheric CO2isotopic signature requires an understanding of the fractionation steps associated with specific processes during leaf gas exchange. This research uses molecular tools coupled with stable isotope analysis and mathematical modeling of photosynthesis and isotope exchange to understand how leaf metabolism and anatomy influence the exchange of carbon and water between plants and their environment.

I am excited to discuss research and graduate student opportunities. Please contact me at if you are interested in joining the lab.

Representative Publications:

  • Feldman M., Ellsworth P.Z., Fahlgren N., Gehan M.A.,Cousins A.B., Baxter I.R. (2018) Components of water use efficiency have unique genetic signatures in the model C4grass Setaria. Plant Physiol. doi: 10.1104/pp.18.00146.
  • Alonso-Cantabrana H., Cousins A.B., Danila F.R., Ryan T., Sharwood R.E., von Caemmerer S., Furbank R.T. (2018) Diffusion of CO2 across the mesophyll-bundle sheath cell interface in a C4 plant with genetically reduced PEP carboxylase activity. Plant Physiol. doi: 10.1104/pp.18.00618.
  • Kolbe A.R., Brutnell T.P.,Cousins A.B., Studer A.J. (2018) Carbonic Anhydrase Mutants in Zea mays Have Altered Stomatal Responses to Environmental Signals. Plant Physiol. 177: 980-989
  • Ellsworth P.V., #Ellsworth P.Z., Cousins A.B.(2018) Cell wall properties in Oryza sativainfluence mesophyll CO2conductance. New Phytiologist219, 66-76
  • Ubierna N., Gandin A., Cousins A.B.(2018) The response of mesophyll conductance to short-term variation in CO2in three C4species. Journal of Exp Botany69,1159-1170
  • Kolbe A.R., Cousins A.B.(2018) Mesophyll conductance in Zea mays responds transiently to CO2 availability: implications for transpiration efficiency in C4 crops. NewPhytologistDOI:10.1111/nph.14942
  • Kolbe A.R., Studer A.J., Cousins A.B.(2018) Biochemical and transcriptomic analysis of maize diversity to elucidate drivers of leaf carbon isotope composition Functional Plant Biology
  • Ellsworth P.Z., Ellsworth P.V., Cousins A.B.(2017) Measurements of Leaf Oxygen and Carbon Isotopic Signatures to estimate Transpiration Efficiency in the C4 Grasses Setaria viridis andSetaria italica.Journal of Exp BotanyJournal of Exp Botany68,3513-3528
  • Ubierna N., Gandin A., Boyd R.A., Cousins A.B.(2017) Temperature response of mesophyll conductance in three C4species calculated with two methods: 18O discrimination and in-vitroVpmaxNew PhytologistDoi: 214,66-80