Fly High: Volatile Organic Compounds for the Early Detection of the Seed-Borne Pathogen <i>Curtobacterium flaccumfaciens</i> pv. <i>flaccumfaciens</i>

The global demand for legumes has grown significantly since the 1960s, due to their high protein content and environmental benefits. However, this growth could also facilitate the spread of seed-borne pathogens like <i>Curtobacterium flaccumfaciens</i> pv. <i>flaccumfaciens</i> (<i>Cff</i>). <i>Cff</i> is a Gram-positive bacterium causing bacterial wilt in common beans and poses substantial challenges in regard to its detection and management, due to its long latent period and xylemic nature. Traditional diagnostic methods have proven insufficient, highlighting the need for innovative approaches. This study explores the potential of volatile organic compounds (VOCs) produced by <i>Cff</i> to be used as diagnostic markers to prevent the spread of seed-borne pathogens. First, we analyzed the VOCs emitted by different <i>Cff</i> strains in vitro, identifying a unique blend of five major VOCs. Subsequently, we verified the presence of these VOCs in vivo in artificially infected Cannellino beans. Phenylmethanol and 2-methoxy-4-vinylphenol emerged as key diagnostic markers, differentiating <i>Cff</i> from other bacterial pathogens of beans, such as <i>Pseudomonas savastanoi</i> pv. <i>phaseolicola</i> and <i>Xanthomonas phaseoli</i> pv. <i>phaseoli</i>. Our findings suggest that VOC fingerprinting offers a non-invasive, effective method for the early detection of <i>Cff</i>, even in asymptomatic seeds. This innovative approach holds significant promise for improving seed-borne disease management and supporting the development of practical diagnostic tools for field applications. Further research should aim to enhance the sensitivity and specificity of VOC-based diagnostics, facilitating the rapid and accurate screening of plant materials at ports of entry. This would contribute to the sustainability and health of leguminous crop production.