Increased adaxial stomatal density is associated with greater mesophyll surface area exposed to intercellular air spaces and mesophyll conductance in diverse C4 grasses. Issue 1 (4th September 2019)

• Record Type: Journal Article
• Authors: Pathare, Varsha S.; Koteyeva, Nuria; Cousins, Asaph B.
• Is Part Of: New phytologist. Volume 225:Issue 1(2020)
• Page Start: 169
• Page End: 182
• Publication Date: 2019-09-04
• Subjects: C4 grasses -- intrinsic water‐use efficiency -- leaf thickness -- mesophyll conductance -- mesophyll surface area exposed to intercellular air space (Smes) -- stomatal densities -- stomatal ratio; Botany -- Periodicals; 580
• DOI: 10.1111/nph.16106
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Mesophyll conductance ( g m ) is the diffusion of CO2 from intercellular air spaces (IAS) to the first site of carboxylation in the mesophyll cells. In C3 species, g m is influenced by diverse leaf structural and anatomical traits; however, little is known about traits affecting g m in C4 species. To address this knowledge gap, we used online oxygen isotope discrimination measurements to estimate g m and microscopy techniques to measure leaf structural and anatomical traits potentially related to g m in 18 C4 grasses. In this study, g m scaled positively with photosynthesis and intrinsic water‐use efficiency (TEi ), but not with stomatal conductance. Also, g m was not determined by a single trait but was positively correlated with adaxial stomatal densities (SDada ), stomatal ratio (SR), mesophyll surface area exposed to IAS ( S mes ) and leaf thickness. However, g m was not related to abaxial stomatal densities (SDaba ) and mesophyll cell wall thickness ( T CW ). Our study suggests that greater SDada and SR increased g m by increasing S mes and creating additional parallel pathways for CO2 diffusion inside mesophyll cells. Thus, SDada, SR and S mes are important determinants of C4 ‐ g m and could be the target traits selected or modified for achieving greater g m and TEi in C4 species.