My research focusses on how organic nitrogen such as amino acids influence plant development, symbiotic interactions with microbes as well as susceptibility to plant pathogens. I use the well-studied symbiosis between legumes and rhizobacteria as a model system to analyze the impact of organic nitrogen on a plant’s ability to form and maintain this interaction, and to fix nitrogen from the air. In addition, I aim to understand the molecular role of different nitrogen sources on a plant’s ability to interact with the mutualistic or pathogenic microbes. Here, the role of amino acid transporters is of interest. This is why a collaboration centered around artificial intelligence and machine learning has been established, in order to predict molecular properties of amino acid transport proteins. By using the model plant Arabidopsis thaliana, we are able to test the predicted properties directly in vivo. Understanding not only the molecular underpinnings of amino acid transporters but also the relationship between amino acid transport and microbial interactions will open avenues to improved fertilization strategies that are less detrimental to the environment.
Dr. Tobias Link, University of Hohenheim, Germany
Project: Molecular Soybean-Pathogen Interactions
Dr. Tommy Löfstedt, Umeå University, Sweden
Project: AI for Life Sciences - Using Deep Semantic Embeddings to Predict Protein Properties to Improve Plant Nutrient Uptake
Dr. Rumen Ivanov, Heinrich-Heine University, Germany
Project: Characterization of the amino acid transporter PtrLHT1.2 in hybrid aspen
Since 2022 Researcher, Department of Forest Genetics and Plant Physiology, SLU
2018 – 2022 Postdoc, Department of Forest Ecology and Management, SLU
2018 PhD in Botany, Institute of Botany, Heinrich – Heine University, Germany
2013 MSc in Human- and Molecular Biology, Saarland University, Germany
Abel Chandra (2021 – present)
Justine Colou (2021 – present)
Laura Tuennermann (2021 – present, Assistant supervisor)
Tinkara Bizjak (2021 – present, Assistant supervisor)
Johan Lundberg (2022, Assistant supervisor)
Laura Tuennermann (2019 - 2020)
Tinkara Bizjak (2019 - 2020, Assistant supervisor)
Bachelor and Internship Students:
Mélissa Fenelon (2022)
Yannik Diethelm (2021)
Laura Tuennermann (2017)
Dana Wiebel (2016)
Christopher Endres (2016 – 2017)
Bianca Castaneda (2016)
Hristina Gyurova (2015)
Lukas Becker (2014 – 2015)
Tünnermann L, Colou J, Näsholm T and Gratz R, 2022. To have or not to have: expression of amino acid transporters during pathogen infection. Plant Molecular Biology.
Gratz R, Ahmad I, Svennerstam H, et al., 2021. Organic nitrogen nutrition: LHT1.2 protein from hybrid aspen (Populus tremula L. x tremuloides Michx) is a functional amino acid transporter and a homolog of Arabidopsis LHT1. Tree Physiology.
Gratz R, Von Der Mark C, Ivanov R, Brumbarova T, 2021. Fe acquisition at the crossroad of calcium and reactive oxygen species signaling. Current Opinion in Plant Biology 63, 102048.
Gratz R, Brumbarova T, Ivanov R, et al., 2020. Phospho‐mutant activity assays provide evidence for alternative phospho‐regulation pathways of the transcription factor FER‐LIKE IRON DEFICIENCY‐INDUCED TRANSCRIPTION FACTOR. New Phytologist 225, 250-67.
Gratz R, Manishankar P, Ivanov R, et al., 2019. CIPK11-dependent phosphorylation modulates FIT activity to promote Arabidopsis iron acquisition in response to calcium signaling. Dev Cell 48, 726-40. e10.
Khan I, Gratz R, Denezhkin P, et al., 2019. Calcium-Promoted Interaction between the C2-Domain Protein EHB1 and Metal Transporter IRT1 Inhibits Arabidopsis Iron Acquisition. Plant Physiol 180, 1564-81.