Plants exchange gases through tiny leaf pores called stomata, flanked by two guard cellst that control the pore opening and closing. The speed at which stomata open and close largely determines how efficiently plants absorb carbon dioxide while minimizing water loss—an ability that will be increasingly important as the climate changes.
Liisa Kübarsepp writes in her PhD thesis „Context- and scale-dependent anatomical constraints on stomatal kinetics across plant lineages“ that in evolutionarily older species, response speed depends strongly on the environmental factor involved. Stomatal size mainly affects opening in response to light and low CO₂ levels, but the responses to darkness, rising CO₂ concentration, and air humidity do not depend significantly on stomatal size. Based on a broader sample of species, it became clear that response speed is determined more by interactions among traits than by individual parameters. An important factor that has so far received little attention is the distribution of stomata between the different sides of the leaf.
According to Kübarsepp, the results could in the future also be used in plant breeding to breed varieties with faster-responding stomata and therefore better resilience to variable weather conditions. However, a major obstacle is the labor-intensive nature of measuring stomatal traits.
“To reduce the workload, we also evaluated the use of machine learning for analyzing microscope images. The best results came from simple sample preparation, but before processing large datasets, it is definitely necessary to verify them with manual measurements,” says Kübarsepp.
Supervisors: Professor Ülo Niinemets, Associate professor Tiina Tosens
Opponent: Associate professor Dimitri Tolleter, Universite Grenoble Alpes, France
