Deciphering Molecular Host-Pathogen Interactions During Ramularia Collo-Cygni Infection on Barley

Area of Science:

• Plant Pathology
• Molecular Biology
• Agricultural Science

Background:

• Ramularia leaf spot (RLS) disease, caused by *Ramularia collo-cygni*, is a growing threat to global barley production.
• Understanding barley's response to RLS is crucial for developing resistant cultivars.

Purpose of the Study:

• To investigate the morphological, transcriptional, and metabolic responses of barley cultivars with differing RLS tolerance to *R. collo-cygni* infection.
• To identify molecular markers for improving barley tolerance to RLS.

Main Methods:

• Comparative analysis of two barley cultivars infected with aggressive and mild *R. collo-cygni* isolates.
• Morphological, transcriptomic (gene expression), and metabolomic analyses.
• Weighted gene co-expression network analysis.

Main Results:

• Fungal biomass did not correlate with barley tolerance to RLS.
• Both cultivars showed cell wall reinforcement and differential gene expression in early colonization stages.
• Key defense compounds like *p*-CHDA and serotonin were identified, correlating with transcriptomic and morphological data.

Conclusions:

• Barley exhibits multifaceted responses to *R. collo-cygni* infection.
• Identified molecular pathways and compounds can aid in developing genetic and physiological markers for enhanced barley RLS tolerance.