Magic Spot Nucleotides (p)ppGpp in response to pathogen invasion in plants.

• Applicant: Dr. Esther Lange
• Subject Area: Plant Physiology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 540272966

In nature, plants are exposed to several biotic stresses such as pathogen and insect invasion. To cope with those attacks, immune responses are activated, enabling the plant to overcome infections. Here, putative candidates of signaling molecules involved in biotic stress responses are the Magic Spot Nucleotides ppGpp and pppGpp, further abbreviated as (p)ppGpp. The metabolites are synthesized and hydrolyzed by four plastid localized RSH homologs and known to be important for the stringent response as primary stress reaction. Previous studies suggest that RSH homologs play essential roles in the adaption to wounding, insect invasion, nitrogen and phosphorus starvation. Additionally, (p)ppGpp were also shown to protect plants against overaccumulation of reactive-oxigen species (ROS). Furthermore, low (p)ppGpp Arabidopsis thaliana mutants indicated increased production of the phytohormone salicylic acid, which plays important roles in the defense against bacterial pathogens, together with an enhanced resistance against the turnip mosaic virus compared to wild-type plants. These studies strengthen the importance of RSH homologs and (p)ppGpp in regulating stress responses, especially towards herbivory and pathogen attacks. In this project, I aim to unravel the role of RSHs and (p)ppGpp in plant-pathogen/pest interactions. I will approach this aim by firstly describing the biochemical functions of synthase and hydrolase domains of the bifuctional homologs RSH2 and RSH3. Secondary, I will determine the physiological function of (p)ppGpp in plants exposed to pathogens/pests and phosphate starvation. Lastly, I will investigate the role of (p)ppGpp in the generation of ROS and ROS scavenging in plants.

• DFG Programme: Research Grants