Photosynthesis, the primary determinant of plant biomass depends on light intensity and CO2 availability at the sites of carboxylation. Stomatal conductance (gs), a measure of the ease at which gas diffuses through stomata over the leaf surface is closely correlated with the rate of carbon assimilation (A) under steady state conditions, although the mechanisms co-ordinating the two are not clear. The coordination between A and gs is an unexploited avenue to increase plant productivity (Wu et al., 2019) and is thought to be due in part to the energy requirements of stomatal movements that are fulfilled at different time of the response by mitochondria and/or chloroplasts. Indeed, Mawson (1993) highlighted that the translocation of protons across the guard-cell plasmalemma, the first step of stomatal apperture is an energy-requiring activity. His study suggested that both guard-cell chloroplasts and mitochondria contribute in synergy to supply energy to BL-induced proton pumping by guard-cell protoplasts, as both were inhibited by low [O2]. Preliminary results have highlighted the importance of mitochondrial respiration for rapid stomatal responses in interaction with the circadian clock, and further experiment are required.
In this project, you will perform gas exchange measurements on leaves of tomato/cucumber using a gas exchange chamber (Li-6800/6400). Under low [O2] to inhibit respiration, the stomatal response to step changes in light intensity will enable to quantify the importance of respiration in driving stomatal movements.
- Gas exchange measurements
- Data analysis
Wu A, Hammer GL, Doherty A, von Caemmerer S, Farquhar GD. 2019. Quantifying impacts of enhancing photosynthesis on crop yield. Nature Plants 5: 380–388.
Mawson BT. 1993. Regulation of blue-light-induced proton pumping by Vicia faba L. guard-cell protoplasts: Energetic contributions by chloroplastic and mitochondrial activities. Planta 191.
Interested in doing a BSc or MSc thesis at HPP? Please contact the HPP student coordinator Katharina Hanika.