Cross-Kingdom RNA Interference
Botrytis and Hyaloperonospora release small RNA effectors during host colonization that enter plant cells and hijack the plant Argonaute (AGO)/RNA-induced gene silencing complex (RISC) to induce host gene silencing for infection. This infection strategy is called cross-kingdom RNA interference (RNAi). We are using Botrytis and Hyaloperonopsora pathogens to elucidate the molecular mechanisms and functions of cross-kingdom RNAi in fungal and oomycete pathogens.
We employ a diverse set of genomics, transcriptomics, bioinformatics, molecular genetics, biochemical and cell biological approaches to gain fundamental knowledge of the underlying mechanisms of cross-kingdom RNAi. Understanding these molecular mechanisms and factors that determine cross-kingdom RNAi bears enormous potential in its application for RNA-based biotechnology approaches.
Finding cross-kingdom small RNAs
Our research group addresses the fundamental question of how cross-kingdom small RNAs shape disease phenotypic outcomes. On the one hand, we systematically compare plant or pathogen small RNA biogenesis loss-of-function mutants to investigate alternation of disease phenotypes. On the other hand, we apply state-of-the-art Next-Gen sequencing methods to identify candidate cross-kingdom small RNAs at action. Ultimately, we collect functional data by using cross-kingdom RNAi assays and reporters to validate the impact of cross-kingdom small RNAs in plant-pathogen interactions.
A fundamental question of the cross-kingdom RNAi phenomenon is the transport of small RNAs between filamentous pathogens and their host plants. Extracellular vesicles (EVs) have become famous to mediate cell-to-cell communication in mammals; with small RNAs are important cargoes in EV function. We have established protocols to study EV RNAs and are investigating the role of pathogen EVs and their cargoes in the context of plant-microbe interactions.
Molecular Diversity of small RNA Effectors
Since small RNA effectors seem to be a common theme among pathogenic microbes, the question arises what is the origin of small RNA effectors and whether there is any selective pressure on the sequence level of small RNA effectors. We are taking comparative genomics and transcriptomics approaches combining Illumina and Nanopore technologies to study small RNA sequence populations in wild Botrytis field isolates.
Cysteine-rich protein effectors
We have also started investigation protein effectors of the powdery mildew pathogen, H. arabidopsidis. We use host-induced gene silencing as a method of choice for functional gene studies in this non-transformable, obligate biotrophic plant parasite. The apoplastic cysteine-rich effector HaCR1 was found to suppress pathogen-induced plant cell death to support biotroph pathogen infection. We are interested in understanding the interplay of small RNAs and protein effectors in plant-pathogen interactions.