Sensing Disease in Apple Trees: Potential Signature Compounds for European Canker (Neonectria ditissima) Infection

Area of Science:

• Plant pathology
• Mycology
• Agricultural science

Background:

• European Canker (EC) is a destructive apple tree disease caused by the fungus Neonectria ditissima.
• Current detection methods for EC are often destructive and time-consuming.
• Identifying early biochemical markers of infection is crucial for timely disease management.

Purpose of the Study:

• To identify secondary metabolites in apple twigs that indicate early Neonectria ditissima infection.
• To assess the potential of these metabolites as biomarkers for non-destructive disease detection.

Main Methods:

• Experimental inoculation of apple trees with Neonectria ditissima.
• Analysis of infected and healthy apple twigs using microscopy and qPCR.
• Chemical analysis of secondary metabolites via headspace solid-phase microextraction GC-MS and LC-MS.

Main Results:

• Microscopy confirmed extensive fungal hyphal penetration by 8 weeks post-inoculation.
• qPCR confirmed the presence of Neonectria ditissima.
• Significantly elevated levels of styrene were detected at 6 weeks post-inoculation.
• Phloretin, triterpene acids, and 1-benzoyl β-d-glucose concentrations increased after 6 weeks.

Conclusions:

• Styrene, phloretin, triterpene acids, and 1-benzoyl β-d-glucose are potential early biochemical indicators of Neonectria ditissima infection in apple trees.
• These compounds could form the basis for developing non-destructive methods for early EC detection.
• Further research is needed on apple variety, pathogen specificity, and field detection technology.