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ARS Home » Midwest Area » Urbana, Illinois » Global Change and Photosynthesis Research » Research » Publications at this Location » Publication #323455
Title: An improved approach for measuring the impact of multiple CO2 conductances on the apparent photorespiratory CO2 compensation point through slope-intercept regression

Author
item Walker, Berkley
item SKABELUND, DANE - University Of Illinois
item BUSCH, FLORIAN - Australian National University
item Ort, Donald

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/2016
Publication Date: 4/1/2016
Citation: Walker, B.J., Skabelund, D.C., Busch, F., Ort, D.R. 2016. An improved approach for measuring the impact of multiple CO2 conductances on the apparent photorespiratory CO2 compensation point through slope-intercept regression. Plant Cell and Environment. 39:1109-1203.

Interpretive Summary: Biochemical models of leaf photosynthesis are important to understand how plants respond to current and future climate conditions. These models rely extensively on a parameter called the CO2 photocompensation point to determine how much carbon dioxide they will take from the atmosphere for growth and crop production. This paper presents an improved framework to better understand what measurements of the CO2 photocompensation point mean.

Technical Abstract: Biochemical models of leaf photosynthesis, which are essential for understanding the impact of photosynthesis to changing environments, depend on accurate parameterizations. The CO2 photocompensation point can be especially difficult to determine accurately but can be measured from the intersection of several CO2 response curves measured under sub-saturating illumination. However, determining the actual intersection while accounting for experimental noise can be challenging. Leaf photosynthesis model outcomes are also sensitive to the diffusion path and resistances of CO2 released from the mitochondria that are used. This diffusion path of CO2 includes both chloroplastic as well as cell wall resistances to CO2, which are not readily measurable. Both the difficulties of determining the photocompensation point and the impact of multiple intercellular resistances to CO2 can be assayed through application of slope-intercept regression. This technical report summarizes an improved theoretical framework for implementing slope-intercept regression to evaluate measurements of the photocompensation point. This theoretical framework extends past work to include the cases of both Rubisco and RuBP-limited photosynthesis. This report further presents two interactive graphical applications and a spreadsheet-based tool to allow users to apply slope-intercept theory to their data. These applications also serve as an example for how technical models in general can be presented and used by the non-specialist.