Biology subjects

Thynne, E.

Publications and source records attributed to Thynne, E..

3 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↗

bioRxiv2024

An array of Zymoseptoria tritici effectors suppress plant immune responses

Zymoseptoria tritici is the most economically significant fungal pathogen of wheat in Europe. However, despite the importance of this pathogen, the molecular interactions between pathogen and host during infection are not well understood. Herein, we describe the use of two libraries of cloned Z. tritici effectors that were screened to identify effector candidates with putative pathogen associated molecular pattern (PAMP) triggered immunity (PTI)-suppressing activity. The effectors from each library were transiently expressed in Nicotiana benthamiana, and expressing leaves were treated with bacterial or fungal PAMPs to assess the effectors ability to suppress reactive oxygen species (ROS) production. From these screens, numerous effectors were identified with PTI-suppressing activity. In addition, some effectors were able to suppress cell death responses induced by other Z. tritici secreted proteins. We used structural prediction tools to predict the putative structures of all of the Z. tritici effectors, and used these predictions to examine whether there was enrichment of specific structural signatures among the PTI-suppressing effectors. From among the libraries, multiple members of the killer protein-like 4 (KP4) and killer protein-like 6 (KP6) effector families were identified as PTI-suppressors. This observation is intriguing, as these protein families were previously associated with antimicrobial activity rather than virulence or host manipulation. This data provides mechanistic insight into immune suppression by Z. tritici during infection, and suggests that similar to biotrophic pathogens, this fungus relies on a battery of secreted effectors to suppress host immunity during early phases of colonisation.

plant biology↗

bioRxiv2018

Acquisition and loss of secondary metabolite clusters shaped the evolutionary path of three recently emerged phytopathogens of wheat

O_LIWhite grain disorder is a recently emerged wheat disease in Australia, caused by three Botryosphaeriaceae spp.; Eutiarosporella darliae, E. pseudodarliae, and E. tritici-australis. The disease cycle of these pathogens and the molecular basis of their interaction with wheat are poorly understood. To address this, we undertook a comparative genomics approach to identify potential pathogenicity factors.\nC_LIO_LISubsequent genome analysis revealed that each of the white grain disorder species harbour modular polyketide synthase genes. To our knowledge, this is the first report of fungi harbouring such genes. Further comparative analysis using the modular polyketide synthase genes discovered their presence in the closely related Macrophomina phaseolina. Phylogenetic analysis implicates horizontal acquisition of these genes from a bacterial or a protist species.\nC_LIO_LIBoth E. darliae and E. pseudodarliae possess a secondary metabolite cluster with multiple polyketide/non-ribosomal peptide synthase genes (Hybrid-1, -2, and -3). In contrast, only remnant and partial genes homologous to this cluster were identified at a syntenic locus in E. tritici-australis suggesting loss of this cluster. Homologues of Hybrid-2 in other fungi have been proposed to facilitate disease induction in woody plants. Subsequent assays confirmed that E. darliae and E. pseudodarliae were both pathogenic on woody plant hosts, but E. tritici-australis was not, implicating woody plants as potential host reservoirs for the fungi. We hypothesise that loss of the cluster in E. tritici-australis represents a committed lifestyle jump to grasses.\nC_LIO_LICombined, our observations relating to the secondary metabolite potential of the WGD Eutiarosporella spp. have contributed novel data to the field by expanding the range of known fungal secondary metabolite genes, and helped develop our understanding of the lifestyle and potential host-range of a recently emerged pathogen of wheat.\nC_LI

plant biology↗