Pest recognition and differentiation by plant immunity

Plants detect pest-associated molecular patterns through surface immune receptors, which bind extracellular ligands and initiate defense signal transduction. Many well-characterized receptors detect pathogen-associated molecular patterns (PAMPs) such as flg22, but receptors for other pest classes such as chewing herbivores are not well understood. How do plants initiate differential signal transduction downstream of receptors for herbivores and pathogens, potentially upstream of hormonal antagonisms?

We recently identified inceptin receptor INR (Steinbrenner et al. 2019, bioRxiv, a receptor for inceptin peptides found in oral secretions of Lepidopteran larval herbivores (caterpillars). We hope to study INR activation as a model for early signaling in response to herbivores.

​Herbivore resistance in legumes

Species in the the legume family (Fabaceae) are uniquely able to respond to inceptin, a family of small peptides present in all studied Lepidopteran larval oral secretions. How do inceptin responses vary across populations and species? Does this matter for resistance and tolerance to herbivores in nature?

Evolution of immune receptor function

Only a subset of surface receptors have immune functions; others serve critical roles in growth and development. How do new immune functions emerge from ancestral roles for receptors? Can we identify immune receptors from genome sequence data?

The INR receptor is restricted to certain legume species, but its function is idiosyncratic across species. Soybean, for example, cannot respond to inceptin despite the presence of receptor homologs. Common bean, on the other hand, displays novel inceptin recognition capability relative to cowpea. Long-read sequencing may allow rapid interrogation of the INR receptor locus across populations and species to better understand evolution of herbivore recognition in legumes. Advancing technologies in legumes will also facilitate reverse genetics to understand how INR contributes to herbivore resistance in nature.