Understanding regulation of leaf internal carbon and water transport using online stable isotope techniques

Summary The balance of carbon dioxide (CO2) and water vapour exchange between leaves and the atmosphere is strongly controlled by stomatal conductance. However, the influence of transport processes within leaves has recently been gaining prominence. Stable isotope techniques are at the forefront of understanding transport within leaves and the recent development of online, real‐time optical isotope analysers has paved the way for new questions to be asked. In this insight, I outline these new techniques and the questions they can potentially address, including assessing possible coordination between mesophyll conductance to CO2 and leaf hydraulic conductance. Contents Summary 83 I. Introduction 83 II. Dynamic responses of mesophyll conductance to CO2 84 III. Genotypic variation and genetic control of mesophyll conductance to CO2 84 IV. Estimating chloroplast membrane conductance to CO2 in C3 plants 85 V. Water transport within leaves 86 VI. Coordination of CO2 and water transport 86 VII. Future opportunities 86 Acknowledgements 87 References 87