Alexander Mandel

Plants recognize microbial effectors by intracellular Toll-like/interleukin nucleotide-binding leucine-rich repeat immune receptors (TIR-NLRs), leading to a strong immune output. Upon effector binding, TIR-NLRs form tetrameric resistosomes, displaying NADase activity to produce nucleotide-based immunostimulatory small molecules (SMs) such as pRib-AMP/ADP, ADPR-ATP or di-ADPR (Huang et al., 2022; Jia et al., 2022). By binding of SMs to the EDS1-heterodimers EDS1-PAD4 (resistance signalling) or EDS1-SAG101 (cell death signalling) they allow association of helper NLRs ADR1 or NRG1, demonstrating the importance of those nucleotides for a refined immune response. 

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Recent studies in prokaryotes demonstrated that TIR-derived small molecule signalling in immunity is not restricted to plants but conserved across kingdoms (Wein & Sorek, 2022). Furthermore, a recent study indicates that SMs can be utilized to stimulate immune responses upon exogenous application (Yu et al., 2024), paving the way for new treatment strategies to gain broad spectrum resistance in the field. Taken together, exogenous application of small molecules to stimulate plant immunity might have impacts on the complex root microbiome consisting of bacteria and fungi. With my project, I want to elucidate the role of immunostimulatory small molecules in plants in association with beneficial but also pathogenic microbes regarding in planta molecular signalling and cross-kingdom effects.