Stomatal response to high VPD: Insights from Arabidopsis Molecular Signaling

K. Samantara, H. Hõrak, E. Merilo
Nooruse 1, Institute of Technology, University of Tartu, Tartu 50411, Estonia

Elevated atmospheric dryness, driven by increased air temperature and reduced relative air-humidity, causes rise in vapour pressure deficit (VPD), reduced stomatal conductance(Gs) and photosynthesis ultimately limits plant-productivity. Understanding the complex-mechanisms of stomatal VPD sensitivity is important. This study aims at filling gaps in stomatal molecular pathway involved in Arabidopsis' VPD sensing and regulation. Genetic-screens are crucial for finding components in stomatal-regulation pathways, e.g. under elevated atmospheric CO2, reduced air humidity and ozone. Here, we used HEMs (Homozygous-EMS-Mutants) obtained from Versailles Arabidopsis Stock Center and measured 100 of 897 lines to assess any impaired response towards VPD-induced stomatal closure respective to control lines, Col-0 (wild-type) and ost1-3 mutant (insensitive to high VPD). Initial screening with Li-600 porometer determined total (abaxial+adaxial) Gs under both low and high VPD levels and enabled to calculate VPD-sensitivity. Selected mutants, showing reduced VPD-sensitivity, were again measured with a custom-made Arabidopsis specific gas exchange device to verify impaired VPD-responses. Verified mutants will be further be analysed to reveal genes behind reduced response. For this, database provided for HEM line whole genome sequences are used, several candidate genes identified and next, single gene mutants of these genes were ordered and measured. This study will serve to identify further new genes linked to Arabidopsis' stomatal VPD-resistance.