Botrytis hypersensitive response inducing protein 1 triggers noncanonical PTI to induce plant cell death

Abstract

According to their lifestyle, plant pathogens are divided into biotrophic and necrotrophic organisms. Biotrophic pathogens exclusively nourish on living host cells, whereas necrotrophic pathogens rapidly kill host cells and nourish on cell walls and cell contents. To this end, the necrotrophic fungus Botrytis cinerea secretes large amounts of phytotoxic proteins and cell wall degrading enzymes. However, the precise role of these proteins during infection 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 structurally conserved folded Alternaria alternata Alt a 1 protein structure to be a prerequisite for Hip1 to exert its necrosis-inducing activity in a host-specific manner. Localization and the induction of typical plant defense responses by Hip1 indicate recognition as a pathogen-associated molecular pattern at the plant plasma membrane. In contrast to other secreted toxic Botrytis proteins, activity of Hip1 does not depend on the presence of the receptor-associated kinases BRI1-ASSOCIATED KINASE 1 (BAK1) and SUPPRESSOR OF BIR1-1 (SOBIR1) Our results demonstrate that recognition of Hip1, even in the absence of obvious enzymatic or pore-forming activity, induces strong plant defense reactions eventually leading to plant cell death. Botrytis hip1 overexpression strains generated by CRISPR/Cas9 displayed enhanced infection, indicating the virulence-promoting potential of Hip1. Taken together, Hip1 induces a non-canonical defence response which might be a common feature of structurally conserved fungal proteins from the Alt a 1 family.

Pulsed Thermography as a Reliable Tool to Detect Presymptomatic Stages of Botrytis cinerea Infection in Plants

“…cinerea. The HR in Botrytis infection has been extensively described in many plant species. , Interestingly, leaf areas producing ROI appear 6 h after B. cinerea inoculation of spores and spread fast with the progress of infection in Arabidopsis thaliana.…”

Botrytis cinerea BcCDI1 protein triggers both plant cell death and immune response

“…Plant pathogens can secrete effectors to promote host colonization through diverse molecular mechanisms. In B. cinerea , many predicted secreted proteins have been mined through comparative transcriptomics, secreted proteomics, or genomics approaches ( Zhu et al., 2017 ; Mousavi-Derazmahalleh et al., 2019 ; Valero-Jiménez et al., 2019 ; Denton-Giles et al., 2020 ; Zhang et al., 2020 ; Jeblick et al., 2023 ). However, due to the high functional redundancy of virulence factors, only a limited number of secreted proteins have been confirmed to have a true contribution to the pathogenesis of B. cinerea ( Brito et al., 2006 ; Frías et al., 2011 ; Frías et al., 2016 ; Zhu et al., 2017 ; Bi et al., 2022 ; Leisen et al., 2022 ).…”

Networked proteins redundantly interact with VAP27 and RABG3 to regulate membrane tethering at the vacuole and beyond

“…For generation of stable Arabidopsis plants, A. tumefaciens was transformed as described previously (Jeblick et al, 2023), and floral inoculation performed as described by Narusaka et al, (Narusaka et al, 2010). The lines lifeact-RFP x NET4A-GFP OE , xi-k/1/2 x NET4A-GFP OE , act7-4 x NET4A-GFP OE , act2 act8 x NET4A-GFP OE , NET4A-GFP OE x amiR-vps16 , SRß-mTurquoise x NET4A-GFP OE , RFP-HDEL x NET4A-GFP were generated by crossing the respective parental lines as shown in Supplemental Table S9.…”

“…Transient expression was performed as previously described (Jeblick et al, 2023). Infiltrated areas were marked for easier identification and plants were incubated under reduced light conditions for 48-72 h prior microscopic analysis.…”