Ksenia V Krasileva | bioRxiv Science

bioRxiv2020

Intraspecies diversity reveals a subset of highly variable plant immune receptors and predicts their binding sites

Evolution of recognition specificities by the immune system depends on the generation of receptor diversity, and connecting binding of new antigens with initiation of downstream signalling. In plant immunity, these functions are enabled by the family of innate Nucleotide-Binding Leucine Rich Repeat (NLR) receptors. In this paper we surveyed the NLR complements of 62 ecotypes of Arabidopsis thaliana and 54 lines of Brachypodium distachyon and identified a limited number of NLR subfamilies responsible for generation of new receptor specificities. We show that the predicted specificity-determining residues cluster on the surfaces of Leucine Rich Repeat domains, but the location of the clusters varies between NLR subfamilies. By comparing NLR phylogeny, allelic diversity, and known functions of the Arabidopsis NLRs, we formulate a hypothesis for emergence of direct and indirect pathogen sensing receptors, and of the autoimmune NLRs. These findings reveal the recurring patterns of evolution of innate immunity and inform NLR engineering efforts.

plant biology↗

bioRxiv2015

In planta expression screens of candidate effector proteins from the wheat yellow rust fungus reveal processing bodies as a pathogen-targeted plant cell compartment

Rust fungal pathogens of wheat (Triticum spp.) affect crop yields worldwide. The molecular mechanisms underlying the virulence of these pathogens remain elusive, due to the limited availability of suitable molecular genetic research tools. Notably, the inability to perform high-throughput analyses of candidate virulence proteins (also known as effectors) impairs progress. We previously established a pipeline for the fast-forward screens of rust fungal effectors in the model plant Nicotiana benthamiana. This pipeline involves selecting candidate effectors in silico and performing cell biology and protein-protein interaction assays in planta to gain insight into the putative functions of candidate effectors. In this study, we used this pipeline to identify and characterize sixteen candidate effectors from the wheat yellow rust fungal pathogen Puccinia striiformis f sp tritici. Nine candidate effectors targeted a specific plant subcellular compartment or protein complex, providing valuable information on their putative functions in plant cells. One candidate effector, PST02549, accumulated in processing bodies (P-bodies), protein complexes involved in mRNA decapping, degradation, and storage. PST02549 also associates with the P-body-resident ENHANCER OF mRNA DECAPPING PROTEIN 4 (EDC4) from N. benthamiana and wheat. Our work identifies P-bodies as a novel plant cell compartment targeted by pathogen effectors.

Plant Biology↗