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Using multirate rapid A / C i curves as a tool to explore new questions in the photosynthetic physiology of plants
Author(s) -
Stinziano Joseph R.,
Adamson Rachael K.,
Hanson David T.
Publication year - 2019
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15657
Subject(s) - photorespiration , photosynthesis , respiration , steady state (chemistry) , biology , carbon dioxide , biological system , botany , biophysics , chemistry , ecology
Summary Steady‐state photosynthetic CO 2 responses ( A / C i curves) are used to assess environmental responses of photosynthetic traits and to predict future vegetative carbon uptake through modeling. The recent development of rapid A / C i curves ( RAC iRs) permits faster assessment of these traits by continuously changing [ CO 2 ] around the leaf, and may reveal additional photosynthetic properties beyond what is practical or possible with steady‐state methods. Gas exchange necessarily incorporates photosynthesis and (photo)respiration. Each process was expected to respond on different timescales due to differences in metabolite compartmentation, biochemistry and diffusive pathways. We hypothesized that metabolic lags in photorespiration relative to photosynthesis/respiration and CO 2 diffusional limitations can be detected by varying the rate of change in [ CO 2 ] during RAC iR assays. We tested these hypotheses through modeling and experiments at ambient and 2% oxygen. Our data show that photorespiratory delays cause offsets in predicted CO 2 compensation points that are dependent on the rate of change in [ CO 2 ]. Diffusional limitations may reduce the rate of change in chloroplastic [ CO 2 ], causing a reduction in apparent RAC iR slopes under high CO 2 ramp rates. Multirate RAC iRs may prove useful in assessing diffusional limitations to gas exchange and photorespiratory rates.