An integrated model of stomatal development and leaf physiology

Abstract

Summary: Stomatal conductance (gs) is constrained by the size and number of stomata on the plant epidermis, and the potential maximum rate of gs can be calculated based on these stomatal traits (Anatomical gsmax). However, the relationship between Anatomical gsmax and operational gs under atmospheric conditions remains undefined. Leaf‐level gas‐exchange measurements were performed for six Arabidopsis thaliana genotypes that have different Anatomical gsmax profiles resulting from mutations or transgene activity in stomatal development. We found that Anatomical gsmax was an accurate prediction of gs under gas‐exchange conditions that maximized stomatal opening, namely high‐intensity light, low [CO2], and high relative humidity. Plants with different Anatomical gsmax had quantitatively similar responses to increasing [CO2] when gs was scaled to Anatomical gsmax. This latter relationship allowed us to produce and test an empirical model derived from the Ball–Woodrow–Berry equation that estimates gs as a function of Anatomical gsmax, relative humidity, and [CO2] at the leaf. The capacity to predict operational gs via Anatomical gsmax and the pore‐specific short‐term response to [CO2] demonstrates a precise link between stomatal development and leaf physiology. This connection should be useful to quantify the gas flux of plants in past, present, and future CO2 regimes based upon the anatomical features of stomata.