Biology subjects

Herger, A. G.

Publications and source records attributed to Herger, A. G..

3 recordsLinked to original sources

bioRxiv2025

An HMA-like integrated domain in the wheat tandem kinase WTK4 recognises an RNase-like pathogen effector

Proteins with a tandem kinase structure have recently emerged as new players in race-specific resistance in cereal crops. However, the molecular understanding of these novel immune receptors resistance mechanisms is limited by the lack of knowledge about the pathogen effectors that they recognise. In this work, we identify AvrWTK4, the wheat powdery mildew RNase-like effector recognised by the wheat tandem kinase immune receptor WTK4, through a combination of bi-parental genetic mapping and mutagenesis. We demonstrate that mutations in the AvrWTK4 gene or a reduction of its expression lead to virulence on WTK4. Transfection of AvrWTK4 specifically induced cell death in WTK4-containing Aegilops tauschii protoplasts. The avirulent AvrWTK4 variant interacts more strongly than the virulent variant with the N-terminal heavy metal-associated (HMA)-like domain of WTK4. These findings further highlight that integrated domains in tandem kinase proteins serve as decoys for pathogen effectors, which could be leveraged to design novel recognition specificities.

molecular biology↗

bioRxiv2025

Virulence on Pm4 kinase-based resistance is determined by two divergent wheat powdery mildew effectors

The wheat resistance gene Pm4 encodes a kinase fusion protein and has gained particular attention as it confers race-specific resistance against two major wheat pathogens: powdery mildew and blast. Here, we describe the identification of AvrPm4, the mildew avirulence effector recognised by Pm4, using UV- mutagenesis, and its functional validation in wheat protoplasts. We show that AvrPm4 directly interacts with and is phosphorylated by Pm4. Using genetic association and QTL mapping, we furthermore demonstrate that evasion of Pm4 resistance by virulent mildew isolates relies on a second fungal component, SvrPm4, which suppresses AvrPm4-induced cell death. Surprisingly, SvrPm4 was previously described as AvrPm1a. We show that SvrPm4, but not its inactive variant svrPm4, is recognised by the NLR immune receptor Pm1a. These multiple roles of a single effector provide a new perspective on fungal (a)virulence proteins and their combinatorial interactions with different types of immune receptors.

genetics↗

bioRxiv2017

LRX Proteins play a crucial role in pollen grain and pollen tube cell wall development

Leucine-rich repeat extensins (LRXs) are chimeric proteins containing an N-terminal leucine-rich repeat (LRR) and a C-terminal extensin domain. LRXs are involved in cell wall formation in vegetative tissues and required for plant growth. However, the nature of their role in these cellular processes remains to be elucidated. Here, we used a combination of molecular techniques, light microscopy, and transmission electron microscopy to characterize mutants of pollen-expressed LRXs in Arabidopsis thaliana. Mutations in multiple pollen-expressed lrx genes causes severe defects in pollen germination and pollen tube (PT) growth, resulting in a reduced seed set. Physiological experiments demonstrate that manipulating Ca2+ availability partially suppresses the PT growth defects, suggesting that LRX proteins influence Ca2+-related processes. Furthermore, we show that LRX protein localizes to the cell wall, and its LRR-domain (which likely mediates protein-protein interactions) is associated with the plasma membrane. Mechanical analyses by cellular force microscopy and finite element method-based modelling revealed significant changes in the material properties of the cell wall and the fine-tuning of cellular biophysical parameters in the mutants compared to the wild type. The results indicate that LRX proteins might play a role in cell wall-plasma membrane communication, influencing cell wall formation and cellular mechanics.

plant biology↗