Cell wall thickness has phylogenetically consistent effects on photosynthetic nitrogen-use efficiency of terrestrial plants: a meta-analysis

Abstract

AbstractLeaf photosynthetic nitrogen-use efficiency (PNUE) diversified significantly among C3species. However, morpho-physiological mechanisms and interrelationships forming PNUE remain unclear on the evolutionary time scale. In this study, we compiled a novel extensive matrix of morpho-anatomical and physiological traits of leaf in 679 C3species ranging from bryophytes to angiosperms to understand the intricacy of interrelationships underlying the variations in PNUE. We found that LMA, mesophyll cell wall thickness (Tcwm), Rubisco N allocation fraction (PR), and mesophyll conductance (gm) together interpreted 83% of variations in PNUE, with PRand gmaccounting for 65% of those variations. However, the PReffects were species-dependent on gm; that is, the contribution of PRon PNUE was extensively significant in high-gmspecies in comparison to low-gmspecies. Standard major analysis (SMA) and path analysis suggested a weak correlation between PNUE and LMA, whereas the SMA correlation for PNUE–Tcwmwas strong. The PRwas inversely proportional to Tcwm, which was similar to the relationship between gmand Tcwm(p-value < 0.01), so that the internal CO2drawdown from intercellular airspace to carboxylaton sites was relatively conservative over a wide range of Tcwm. Collectively, the coordination of changes in PRand gmconnecting Tcwmsuggested the complex physiological mechanisms mediated by Tcwmmodulating PNUE across contrasting plant groups.