Mesophyll diffusion conductance to CO2: an unappreciated central player in photosynthesis

Jaume Flexas (1) , Margaret Barbour (2) , Oliver Brendel (3) , Hernan Cabrera (1) , Marc Carriqui (1) , Antonio Diaz-Espejo (4) , Cyril Douthe (3, 5) , Erwin Dreyer (3) , Juan-P. Ferrio (6) , Jorge Gago (1) , Alexander Gallé (1) , Jeroni Galmes (1) , Naomi Kodama (7) , Hippolito Medrano (1) , Jose-J. Peguero-Pina (1) , Alicia Pou (1) , Miquel Ribas-Carbo (1) , Magdalena Tomas (1) , Tina Tosens (8) , Charles-R. Warren (5)

1 Research Group in Plant Biology under Mediterranean Conditions
2 Faculty of Agriculture, Food and Natural Resources
3 EEF - Ecologie et Ecophysiologie Forestières [devient SILVA en 2018]
4 Instituto de Recursos Naturales y Agrobiología
5 School of Biological Sciences
6 Department of Crop and Forest Sciences, AGROTECNIO Center
7 NIAES - National Institute of Agro-Environmental Sciences
8 Institute of Agricultural and Environmental Sciences

Mesophyll diffusion conductance to CO2 is a key photosynthetic trait that has been studied intensively in the past years. The intention of the present review is to update knowledge of g(m), and highlight the important unknown and controversial aspects that require future work. The photosynthetic limitation imposed by mesophyll conductance is large, and under certain conditions can be the most significant photosynthetic limitation. New evidence shows that anatomical traits, such as cell wall thickness and chloroplast distribution are amongst the stronger determinants of mesophyll conductance, although rapid variations in response to environmental changes might be regulated by other factors such as aquaporin conductance. Gaps in knowledge that should be research priorities for the near future include: how different is mesophyll conductance among phylogenetically distant groups and how has it evolved? Can mesophyll conductance be uncoupled from regulation of the water path? What are the main drivers of mesophyll conductance? The need for mechanistic and phenomenological models of mesophyll conductance and its incorporation in process-based photosynthesis models is also highlighted.

Mots clés: Aquaporins; Climate change; Conductance; Diffusion; Leaf anatomy; Plant hydraulics; Photosynthesis

Domaines: Sciences du Vivant [q-bio]

Jaume Flexas, Margaret Barbour, Oliver Brendel, Hernan Cabrera, Marc Carriqui, et al.. Mesophyll diffusion conductance to CO2: an unappreciated central player in photosynthesis. Plant Science, 2012, 193-194, pp.70-84. ⟨10.1016/j.plantsci.2012.05.009⟩. ⟨hal-01268007⟩