Olena Zamora, supervised by Prof. Hannes Kollist and Assoc. Prof. Dmitry Yarmolinsky, will defend her thesis ‘Impacts of plant hormones on controlling stomatal conductance’.
The defence can be followed on Zoom: https://ut-ee.zoom.us/j/9530588152?pwd=ZzgzMjY4YytzUkZ5aVRCd2pOdVNQQT09 (meeting ID: 953 058 8152, passcode: kaitsmine).
A summary of her thesis
To survive and adapt to the ever-changing environment, plants must recognize various stimuli and ensure the rapid activation of corresponding protective mechanisms. The list of biotic and abiotic stresses influencing plants includes drought, dry air, temperature extremes, air pollutants, pathogen attacks, etc. Stomata, microscopic pores on plant surfaces, constitute one of the central points in plant adaptation to environmental conditions as they balance CO2 uptake for photosynthesis with the evaporation of water from plants. Stomatal opening and closure can be initiated by changes in illumination conditions, air humidity, and CO2 levels as well as by exposure to ozone or a pathogen attack. In addition, stomata react to a number of endogenous stimuli, including phytohormones acting in minute concentrations. Abscisic acid (ABA) is a plant hormone well known for its involvement in drought resistance and promoting stomatal closure. At the same time, stomatal regulation by other phytohormones is significantly less understood. In our study, we used a genetic approach and gas exchange measurements under various conditions to compare the roles of jasmonic acid, salicylic acid, ethylene, and strigolactones in controlling whole-plant stomatal conductance. We found that, although jasmonic acid, salicylic acid, and ethylene influence steady-state stomatal conductance significantly less than ABA, stomatal responsiveness to some environmental stimuli and ABA can be modulated by these hormones. Furthermore, we showed that strigolactones control stomatal conductance independently of ABA. Our results demonstrate the impacts of various hormones on controlling stomatal conductance and stomatal reactions to environmental cues, expanding our understanding of stomatal regulation under ever-changing environmental conditions.