Mesophyll conductance in two cultivars of wheat grown in glacial to super-elevated CO2 concentrations. (7th July 2021)

• Record Type: Journal Article
• Authors: Jahan, Eisrat; Thomson, Peter C; Tissue, David T
• Editors: Lawson, Tracy
• Is Part Of: Journal of experimental botany. Volume 72:Number 20(2021)
• Page Start: 7191
• Page End: 7202
• Publication Date: 2021-07-07
• Subjects: Elevated CO2 -- genotype -- leaf internal conductance -- photosynthesis -- Triticum aestivum -- water stress; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erab320
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract : Mesophyll conductance increased with increasing [CO2 ] from glacial to ambient CO2 levels, then declined at super-elevated CO2 for both well-watered and water-limited treatments. These responses may have a structural basis. Abstract: Mesophyll conductance ( g m ) is an important factor limiting photosynthesis. However, g m response to long-term growth in variable [CO2 ] is not well understood, particularly in crop plants. Here, we grew two cultivars of wheat (Halberd and Cranbrook), known to differ in g m under current environmental conditions, in four [CO2 ] treatments: glacial (206 μmol mol −1 ), pre-industrial (344 μmol mol −1 ), current ambient (489 μmol mol −1 ), and super-elevated (1085 μmol mol −1 ), and two water treatments (well-watered and moderate water limitation), to develop an evolutionary and future climate perspective on g m control of photosynthesis and water-use efficiency (WUE). In the two wheat genotypes, g m increased with rising [CO2 ] from glacial to ambient [CO2 ], but declined at super-elevated [CO2 ]. The responses of g m to different growth [CO2 ] also depend on water stress; however, the specific mechanism of g m response to [CO2 ] remains unclear. Although g m and g m / g sc (mesophyll conductance/stomatal conductance) were strongly associated with the variability of photosynthetic rates ( A ) and WUE, we found that plants with higher g m may increase A without increasing g sc, which increased WUE. These results may be useful to inform plant breeding programmes and cultivar selection for Australian wheat under future environmental conditions.