Mesophyll conductance: the leaf corridors for photosynthesis. (4th March 2020)

• Record Type: Journal Article
• Authors: Gago, Jorge; Daloso, Danilo M.; Carriquí, Marc; Nadal, Miquel; Morales, Melanie; Araújo, Wagner L.; Nunes-Nesi, Adriano; Flexas, Jaume
• Is Part Of: Biochemical Society transactions. Volume 48:Number 2(2020)
• Page Start: 429
• Page End: 439
• Publication Date: 2020-03-04
• Subjects: cell wall -- chloroplast -- CO2 diffusion pathway -- mesophyll diffusion conductance -- photosynthesis -- stomatal conductance; Biochemistry -- Congresses; 572
• DOI: 10.1042/BST20190312
• Languages: English
• ISSNs: 0300-5127

Abstract

Abstract : Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance ( g m ). Therefore, the g m reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that g m can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the g m determinants to summarize the current knowledge on the mechanisms driving g m from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces ( S c / S ) that significantly constrain g m . However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with g m responses. Thus, considering the main role of g m as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.