Whole plant chamber to examine sensitivity of cereal gas exchange to changes in evaporative demand

• Published in: Plant methods Vol. 14; no. 1; pp. 97 - 13
• Main Authors: Jauregui, Iván, Rothwell, Shane A, Taylor, Samuel H, Parry, Martin A J, Carmo-Silva, Elizabete, Dodd, Ian C
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 01-11-2018; BioMed Central; BMC
• Subjects: ABA; Abscisic acid; Barley; Biomass; Carbon dioxide; Carbon isotopes; Carboxylation; Climate change; Crop resilience; Crop yield; Cultivars; Deficient mutant; Demand; Efficiency; Environmental conditions; Evaporation; Gas exchange; Genetic aspects; Genetic diversity; Genetic variation; Humidity; Leaves; Observations; Photosynthesis; Physiological aspects; Plant-water relationships; Ribulose-bisphosphate carboxylase; Spraying; Substrates; Transpiration; VPD; Water shortages; Water use; Water use efficiency; Wheat; ABA; Transpiration; VPD; Water use efficiency; Photosynthesis
• ISSN: 1746-4811; 1746-4811
• DOI: 10.1186/s13007-018-0357-9

Improving plant water use efficiency (WUE) is a major target for improving crop yield resilience to adverse climate change. Identifying genetic variation in WUE usually relies on instantaneous measurements of photosynthesis (An) and transpiration (Tr), or integrative measurements of carbon isotope discrimination, at the leaf level. However, leaf gas exchange measurements alone do not adequately represent whole plant responses, especially if evaporative demand around the plant changes.
Here we describe a whole plant gas exchange system that can rapidly alter evaporative demand when measuring An, Tr and intrinsic WUE (iWUE) and identify genetic variation in this response. An was not limited by VPD under steady-state conditions but some wheat cultivars restricted Tr under high evaporative demand, thereby improving iWUE. These changes may be ABA-dependent, since the barley ABA-deficient mutant (
) failed to restrict Tr under high evaporative demand. Despite higher Tr,
showed lower An than wild-type (WT) barley because of limitations in Rubisco carboxylation activity. Tr and An of
were more sensitive than WT barley to exogenous spraying with ABA, which restricted photosynthesis via substrate limitation and decreasing Rubisco activation.
Examining whole plant gas exchange responses to altered VPD can identify genetic variation in whole plant iWUE, and facilitate an understanding of the underlying mechanism(s).