Steidele, C. E. | Search bioRxiv

bioRxiv2020

The secreted hypersensitive response inducing protein 1 from Botrytis cinerea displays non-canonical PAMP-activity

According to their lifestyle, plant pathogens are divided into biotrophic and necrotrophic organisms. While biotrophic pathogens establish a relationship with living host cells, necrotrophic pathogens rapidly kill host cells and feed on the cell debris. To this end, the necrotrophic ascomycete fungus Botrytis cinerea secretes large amounts of phytotoxic proteins and cell wall degrading enzymes. However, the precise role of these proteins during the infection process is unknown. Here we report on the identification and characterization of the previously unknown toxic protein hypersensitive response inducing protein 1 (Hip1), which induces plant cell death. We found the adoption of a folded protein structure to be a prerequisite for Hip1 to exert its necrosis-inducing activity in Nicotiana benthamiana. Localization and the induction of specific plant responses by Hip1 indicate recognition as pathogen-associated molecular pattern at the plant plasma membrane. Our results demonstrate that recognition of Hip1, even in the absence of obvious enzymatic or poreforming activity, induces strong plant defense reactions eventually leading to plant cell death.

plant biology↗

bioRxiv2020

Multi-omics approach highlights differences between functional RLP classes in Arabidopsis thaliana

The receptor-like protein (RLP) family is a complex gene family with 57 members in Arabidopsis thaliana. Some members of the RLP family are known to be involved in basal developmental processes, whereas others have found to be involved in defence responses. However, functional data is to date, only available for a small subset of RLPs, leaving the remaining ones classified as RLPs of unknown function. Using publicly available datasets, we annotated those RLPs of unknown functions as either likely defence-related or likely fulfilling a more basal function in plants. Using these categories, we can identify important characteristics that differ between the RLP sub classes. We find the two classes differ in abundance on both transcriptome and proteome level, physical clustering in the genome and putative interaction partners. However, the classes do not differ in the genetic diversity of their individual members in accessible pan-genome data. Our work has several implications for work related to functional studies on RLPs as well as for the understanding of RLP gene family evolution. Using our annotations, we can make suggestions of which RLPs can be identified as potential immune receptors using genetics tools, which can be useful for disease studies. The lack of differences in nucleotide diversity between the two RLP subclasses further suggests that non-synonymous diversity of gene sequences alone cannot distinguish defence from developmental genes. By contrast, differences in transcript and protein abundance or clustering at genomic loci might also allow for functional annotations and characterisation in other plant species.

genomics↗