A high throughput gas exchange screen for determining rates of photorespiration or regulation of C4 activity

Chandra Bellasio, Steven J. Burgess, Howard Griffiths, Julian M. Hibberd

Research output: Contribution to journalArticlepeer-review


Large-scale research programmes seeking to characterize the C4 pathway have a requirement for a simple, high throughput screen that quantifies photorespiratory activity in C3 and C4 model systems. At present, approaches rely on model-fitting to assimilatory responses (A/Ci curves, PSII quantum yield) or real-time carbon isotope discrimination, which are complicated and time-consuming. Here we present a method, and the associated theory, to determine the effectiveness of the C4 carboxylation, carbon concentration mechanism (CCM) by assessing the responsiveness of V O/VC, the ratio of RuBisCO oxygenase to carboxylase activity, upon transfer to low O2. This determination compares concurrent gas exchange and pulse-modulated chlorophyll fluorescence under ambient and low O2, using widely available equipment. Run time for the procedure can take as little as 6 minutes if plants are pre-adapted. The responsiveness of VO/VC is derived for typical C 3 (tobacco, rice, wheat) and C4 (maize, Miscanthus, cleome) plants, and compared with full C3 and C4 model systems. We also undertake sensitivity analyses to determine the impact of RLIGHT (respiration in the light) and the effectiveness of the light saturating pulse used by fluorescence systems. The results show that the method can readily resolve variations in photorespiratory activity between C3 and C4 plants and could be used to rapidly screen large numbers of mutants or transformants in high throughput studies.

Original languageEnglish (US)
Pages (from-to)3769-3779
Number of pages11
JournalJournal of experimental botany
Issue number13
StatePublished - Jul 2014
Externally publishedYes


  • Carbon concentration mechanism (CCM)
  • Carboxylation
  • Cleome gynandra
  • Maize
  • Miscanthus
  • Oxygenation
  • Photosynthesis
  • Rice
  • RuBisCO
  • Wheat

ASJC Scopus subject areas

  • Physiology
  • Plant Science


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