Biology subjects

Crean, E. E.

Publications and source records attributed to Crean, E. E..

2 recordsLinked to original sources

bioRxiv2025

Molecular mimicry of plant cell-surface immune receptors by fungal secreted leucine-rich repeat proteins

O_LILeucine-rich repeat (LRR) receptor-like kinases (LRR-RLKs) are important plant immunity proteins. The wheat pathogen Zymoseptoria tritici produces many virulence effectors during infection; however, most remain uncharacterised. We identified a secreted protein from Z. tritici (ZtLRR) that consists of a single LRR domain and hypothesised that it mimics host LRR-RLKs to suppress plant immunity. C_LIO_LIWe used transient expression to probe ZtLRR function related to production of reactive oxygen species (ROS) and cell death, two important immune processes. We used AlphaFold structural predictions with targeted yeast two-hybrid to demonstrate protein-protein interactions. Transgenic wheat allowed assessment of effector function in the natural host. C_LIO_LIZtLRR suppressed ROS production and cell death in N. benthamiana with high potency. Structural predictions suggested high similarity to several plant LRR-RLKs and interaction with TaBAK1 was confirmed by targeted yeast two-hybrid. Transgenic wheat expressing ZtLRR was impaired in PAMP-triggered immunity (PTI) and had increased susceptibility to infection with compatible Z. tritici. We identified structural orthologs of ZtLRR in diverse fungal lineages and demonstrated that several of these proteins have similar immune-suppressing properties as ZtLRR. C_LIO_LIOur work demonstrates that molecular mimicry of host LRR-RLKs by phytopathogen sLRR effectors is effective at disrupting host immune pathways. C_LI

molecular biology↗

bioRxiv2023

A dominant-negative avirulence effector of the barley powdery mildew fungus provides mechanistic insight to barley MLA immune receptor activation

Nucleotide-binding leucine-rich repeat receptors (NLRs) recognize pathogen effectors to mediate plant disease resistance, which is often accompanied by a localized host cell death response. Effectors can escape NLR recognition through various polymorphisms, allowing the pathogen to proliferate on previously resistant host plants. The powdery mildew effector AVRA13-1 is recognized by the barley NLR MLA13 and activates host cell death. We demonstrate here that a virulent form of AVRA13, called AVRA13-V2, escapes MLA13 recognition by substituting a serine for a leucine residue at the C-terminus. Counterintuitively, this substitution in AVRA13-V2 resulted in an enhanced MLA13 association and prevented the detection of AVRA13-1 by MLA13. Therefore, AVRA13-V2 is a dominant-negative form of AVRA13 and has likely contributed to the breakdown of Mla13 resistance. Despite this dominant-negative activity, AVRA13-V2 failed to suppress host cell death mediated by the MLA13 auto-active "MHD" variant. Neither AVRA13-1 nor AVRA13-V2 interacted with the MLA13 auto-active variant, implying that the binding moiety in MLA13 that mediates association with AVRA13-1 is altered after receptor activation. We also show that mutations in the MLA13 coiled-coil signalling domain, which were thought to impair Ca2+-channel activity and NLR function, instead resulted in MLA13 auto-active cell death. The data constitute an important step to define intermediate receptor conformations during NLR activation.

plant biology↗