Divergent abiotic spectral pathways unravel pathogen stress signals across species

Plant pathogens pose increasing threats to global food security, causing yield losses that exceed 30% in food-deficit regions. Xylella fastidiosa (Xf) represents the major transboundary plant pest and one of the world's most damaging pathogens in terms of socioeconomic impact. Spectral screening methods are critical to detect non-visual symptoms of early infection and prevent spread. However, the subtle pathogen-induced physiological alterations that are spectrally detectable are entangled with the dynamics of abiotic stresses. Here, using airborne spectroscopy and thermal scanning of areas covering more than one million trees of different species, infections and water stress levels, we reveal the existence of divergent pathogen- and host-specific spectral pathways that can disentangle biotic-induced symptoms. We demonstrate that uncoupling this biotic-abiotic spectral dynamics diminishes the uncertainty in the Xf detection to below 6% across different hosts. Assessing these deviating pathways against another harmful vascular pathogen that produces analogous symptoms, Verticillium dahliae, the divergent routes remained pathogen- and host-specific, revealing detection accuracies exceeding 92% across pathosystems. These urgently needed hyperspectral methods advance early detection of devastating pathogens to reduce the billions in crop losses worldwide. Spectral screening can be used to monitor plant health. Here via airborne hyperspectral imaging of tree species, the authors show that spectral pathways associated with vascular pathogens can be distinguished from those linked to abiotic stress providing the potential for early detection of threatening diseases.

Automated summary

Plant pathogens, such as Xylella fastidiosa, are increasingly threatening global food security, causing significant yield losses. Spectral screening methods are crucial for early detection of non-visual symptoms of infection and prevention of spread. Using airborne spectroscopy, researchers have identified host-specific spectral pathways that can distinguish biotic-induced symptoms, improving detection accuracy and reducing crop losses worldwide.