Leaf anatomy mediates coordination of leaf hydraulic conductance and mesophyll conductance to CO2 in Oryza

Abstract

Leaf hydraulic conductance (Kleaf) and mesophyll conductance (gm) both represent major constraints to photosynthetic rate (A), and previous studies have suggested that Kleaf and gm is correlated in leaves. However, there is scarce empirical information about their correlation. In this study, Kleaf, leaf hydraulic conductance inside xylem (Kx), leaf hydraulic conductance outside xylem (Kox), A, stomatal conductance (gs), gm, and anatomical and structural leaf traits in 11 Oryza genotypes were investigated to elucidate the correlation of H2O and CO2 diffusion inside leaves. All of the leaf functional and anatomical traits varied significantly among genotypes. Kleaf was not correlated with the maximum theoretical stomatal conductance calculated from stomatal dimensions (gsmax), and neither gs nor gsmax were correlated with Kx. Moreover, Kox was linearly correlated with gm and both were closely related to mesophyll structural traits. These results suggest that Kleaf and gm are related to leaf anatomical and structural features, which may explain the mechanism for correlation between gm and Kleaf.