Coordination of Leaf Photosynthesis, Transpiration, and Structural Traits in Rice and Wild Relatives (Genus Oryza)

• Published in: Plant physiology (Bethesda) 2013-07, Vol.162 (3), p.1632-1651
• Main Authors: Giuliani, Rita, Koteyeva, Nuria, Voznesenskaya, Elena, Evans, Marc A., Cousins, Asaph B., Edwards, Gerald E.
• Format: Article
• Language: English
• Subjects: Analysis of Variance; carbon dioxide; Carbon Dioxide - metabolism; CELL BIOLOGY; Cell Size; Cell walls; Chloroplasts; Genomes; Leaves; mesophyll; Mesophyll Cells; Multifactorial Inheritance; Oryza; Oryza - anatomy & histology; Oryza - metabolism; Photosynthesis; Plant cells; Plant Leaves - anatomy & histology; Plant Leaves - physiology; Plant Leaves - ultrastructure; Plant Transpiration; Plants; Principal Component Analysis; Surface areas; Transpiration; water use efficiency; wild relatives; wild rice
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.113.217497

The genus Oryza, which includes rice (Oryza sativa and Oryza glaberrima) and wild relatives, is a useful genus to study leaf properties in order to identify structural features that control CO₂ access to chloroplasts, photosynthesis, water use efficiency, and drought tolerance. Traits, 26 structural and 17 functional, associated with photosynthesis and transpiration were quantified on 24 accessions (representatives of 17 species and eight genomes). Hypotheses of associations within, and between, structure, photosynthesis, and transpiration were tested. Two main clusters of positively interrelated leaf traits were identified: in the first cluster were structural features, leaf thickness (Thick leaf ), mesophyll (M) cell surface area exposed to intercellular air space per unit of leaf surface area (S mes ), and M cell size; a second group included functional traits, net photosynthetic rate, transpiration rate, M conductance to CO₂ diffusion (g m ), stomatal conductance to gas diffusion (g s ), and the g m /g s ratio. While net photosynthetic rate was positively correlated with g m , neither was significantly linked with any individual structural traits. The results suggest that changes in g m depend on covariations of multiple leaf (S mes ) and M cell (including cell wall thickness) structural traits. There was an inverse relationship between Thick leaf and transpiration rate and a significant positive association between Thick leaf and leaf transpiration efficiency. Interestingly, high g m together with high g m /g s and a low S mes /g m ratio (M resistance to CO₂ diffusion per unit of cell surface area exposed to intercellular air space) appear to be ideal for supporting leaf photosynthesis while preserving water; in addition, thick M cell walls may be beneficial for plant drought tolerance.