Contrasting anatomical and biochemical controls on mesophyll conductance across plant functional types. Issue 2 (2nd August 2022)

• Record Type: Journal Article
• Authors: Knauer, Jürgen; Cuntz, Matthias; Evans, John R.; Niinemets, Ülo; Tosens, Tiina; Veromann‐Jürgenson, Linda‐Liisa; Werner, Christiane; Zaehle, Sönke
• Is Part Of: New phytologist. Volume 236:Issue 2(2022)
• Page Start: 357
• Page End: 368
• Publication Date: 2022-08-02
• Subjects: leaf anatomy -- leaf internal CO2 transfer -- leaf gas exchange -- leaf nutrient content -- photosynthetic capacity -- photosynthetic limitation; Botany -- Periodicals; 580
• DOI: 10.1111/nph.18363
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Mesophyll conductance ( g m ) limits photosynthesis by restricting CO2 diffusion between the substomatal cavities and chloroplasts. Although it is known that g m is determined by both leaf anatomical and biochemical traits, their relative contribution across plant functional types (PFTs) is still unclear. We compiled a dataset of g m measurements and concomitant leaf traits in unstressed plants comprising 563 studies and 617 species from all major PFTs. We investigated to what extent g m limits photosynthesis across PFTs, how g m relates to structural, anatomical, biochemical, and physiological leaf properties, and whether these relationships differ among PFTs. We found that g m imposes a significant limitation to photosynthesis in all C3 PFTs, ranging from 10–30% in most herbaceous annuals to 25–50% in woody evergreens. Anatomical leaf traits explained a significant proportion of the variation in g m ( R 2 > 0.3) in all PFTs except annual herbs, in which g m is more strongly related to biochemical factors associated with leaf nitrogen and potassium content. Our results underline the need to elucidate mechanisms underlying the global variability of g m . We emphasise the underestimated potential of g m for improving photosynthesis in crops and identify modifications in leaf biochemistry as the most promising pathway for increasing g m in these species.