Convergence of powdery mildew AVRA virulence functions in the barley host

• Applicant: Isabel Marie-Luise Saur, Ph.D.
• Subject Area: Organismic Interactions, Chemical Ecology and Microbiomes of Plant Systems
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 444847662

Pathogenic fungi pose serious threats to agricultural productivity. The Blumeria graminis forma specialis hordei (Bgh) fungus is the causal agent of the powdery mildew disease on barley (Hordeum vulgare). This project will investigate the molecular mechanisms underlying powdery mildew development on barley and resolve some long-standing bottlenecks through the employment of innovative molecular - biochemical tools. The results will enhance our ability to combat crop diseases in a rational, predictable and sustainable manner. The long-term impact of the technology will be new crop varieties that are less susceptible to pathogens. Such new varieties offer an alternative to chemical disease control, are more productive to growers and will thus have both economic and social benefits.Fungal pathogens encode hundreds of virulence factors that are secreted from the fungus during infection of the host. Virulence factors facilitate a pathogen’s proliferation on the host ultimately leading to disease development and pathogen spread. It remains unclear, however, if all the small-secreted proteins annotated in the Bgh genome actually function as virulence factors. Further, while an understanding of the molecular mechanisms employed by Bgh virulence factors are crucial in order to understand barley powdery mildew disease development, to date these mechanisms remain largely uncharacterized. This project will investigate the virulence function of multiple Bgh avirulence (AVR) proteins that were recently molecularly characterised. Bgh AVRA proteins are recognised by the barley mildew locus A (Mla) nucleotide-binding oligomerization domain-like receptors (NLRs). Based on the evolutionary concept that host NLRs recognise crucial pathogen virulence factors inside the host cell, AVRA effectors can be defined as true virulence factors, and thus, the characterisation of Bgh AVRA virulence function is a particularly promising approach for understanding Bgh pathogenesis. Because AVRs from unrelated fungal pathogens are also recognised by Mla NLRs or their orthologs in wheat, the project holds the potential to identify core processes that not only Bgh but also other devastating fungal phytopathogens manipulate in plant hosts.

• DFG Programme: Independent Junior Research Groups
• Major Instrumentation: Klimakammer
• Instrumentation Group: 4400 Pflanzenwuchskammern und -schränke, Klimaversuchsanlagen für Biologie und Medizin