Stomata are formed on the leaf surface by two guard cells and simultaneously regulate and balance water loss with the uptake of carbon dioxide necessary for photosynthesis. Stomata are a primary site of interaction of the plant with its environment and have developed mechanisms to sense and respond to changing conditions. We have shown that the leucine-rich receptor-like kinase (LRR-RLK) GHR1 is a central regulator of stomatal closure. GHR1 is a pseudokinase that activates the guard cell anion channel SLAC1 and acts in stomatal closure through scaffolding functions rather than direct phosphorylation of target proteins.
Given the severity and pervasive nature of stomatal phenotypes in ghr1 mutant plants, GHR1 may be an integration point where diverse endogenous and environmental signals converge to regulate components required for rapid stomatal closure. Through an interactomics approach, we have identified multiple novel interactors of GHR1, including channel proteins, transporters and LRR-RLKs. We aim to characterize these novel components and the mechanistic details of the interactions in order to further our understanding of the signalling networks that regulate stomatal function.
Although stomatal function must be intricately linked to the transport of water at the whole plant level, research combining these two processes, and especially knowledge of the molecular components involved, is lacking. We have shown that GHR1 regulates water transport in the vasculature and identified interactors that may facilitate this function. Further characterization of these molecular interactions will shed light on how stomatal function and regulation of water transport are connected at the level of the whole plant. We conduct this research in Arabidopsis and birch within the Centre of Excellence in tree Biology.
Stomatal molecular mechanisms have been investigated by looking at guard cells as isolated systems. Still, guard cell signalling must be integrated and coordinated at both leaf and whole-plant levels. Therefore, we aim to understand how guard cell signalling is integrated within the leaf epidermis and at the leaf level. By combining transcriptomics and metabolomics approaches with whole-plant gas exchange phenotyping and confocal microscopy, we aim to identify and characterize non-cell autonomous mechanisms involved in the regulation of stomatal function.
Programmed cell death regulates developmental and stress responses in eukaryotes. Golgi anti-apoptotic proteins (GAAPs) are evolutionarily conserved cell death regulators. Human and viral GAAPs inhibit apoptosis and modulate intracellular calcium fluxes, and viral GAAPs form cation-selective channels. Although most mammalian cell death regulators are not conserved at the sequence level in plants, the GAAP gene family shows expansion, with five paralogues in the Arabidopsis genome. We pursue molecular and physiological characterization of AtGAAPs concentrating on their role in regulation of stress tolerance and making use of the advanced knowledge of their human and viral counterparts.