## 4 Discussion
This makes it difficult to isolate VOCs that are specific to a single pathogen. As a result, a more reliable diagnostic framework would be a specific complex VOC profile, which is a broader VOC signature, that can consistently associate the presence of a pathogen with the host context, i.e., the host commodity subject to official testing. Benzaldehyde is an aromatic flavor compound, which is responsible for the taste and odor of bitter almonds [48]. All the tested bacteria are capable of metabolizing benzaldehyde, either by degrading it or by producing it from precursor compounds, such as phenylalanine, an amino acid involved in the biosynthesis of aromatic derivatives [49]. The use of benzaldehyde as a marker for the identification of dried beans is well-documented in the literature [37]. Phenylmethanol is highlighted as a promising compound for use as a diagnostic marker for _Cff_, based on the results presented. Neither _Xpp_ nor _Psp_ produces phenylmethanol in naturalized media. As an antiseptic, it physiologically prevents secondary infections due to its bacteriostatic effects, which enhance membrane fluidity and destabilize its structural integrity [50; 51]. The data supporting this compound's diagnostic potential appears robust in regard to all naturalized media and comparatively weaker in regard to synthetic media. In addition, 6,10-dimethyl-5,9-undecadien-2-one exhibits a broad spectrum of bioactivity, including germicidal and antimicrobial properties [52]. This terpenoid demonstrates potential in regard to legume-based naturalized media, but lacks diagnostic significance as an individual compound for _Cff_ detection. Moreover, 2-methoxy-4-vinylphenol is an aromatic substance used as a flavoring agent and its antimicrobial activities have been reported [53, 54]. The production of this VOC by some microorganisms, such as _Saccharomyces cerevisiae_ and _Pseudomonas fluorescens_, is known to involve trans-ferulic acid as a precursor [55, 56]. It is interesting to note that 2-methoxy-4-vinylphenol has strain specificity within _Cff_. In fact, it is not substantially produced by _Cff_ 50R, as well as by _Xpp_ and _Psp_. The greatest variations occur in naturalized media, which mimic the actual host-pathogen molecular interaction. Overall, four representative _Cff_ isolates were tested here, and a specific VOC signature was demonstrated for bean seeds infected by _Cff_, as well as for _Cff_ strains growing in vitro on legume-based media, but not for the other two bacterial seed-borne pathogens of beans. Therefore, this study provides initial evidence of a specific VOC fingerprint associated with the presence of _Cff_ in its major hosts. However, further validation with a broader range of isolates and in diverse environmental conditions is necessary to ensure reliability across different contexts and confirm the reproducibility of this approach. Further investigations will establish the sensitivity of VOCs as biomarkers for _Cff_, particularly in distinguishing infected seeds in natural and artificial conditions, by comparing and combining VOC detection with other methodologies, such as molecular approaches. Ongoing experiments aim to compare VOC flux rates with symptom progression and _Cff_ growth in plants, assessed using PCR analysis [28, 29, 30], to investigate the applicability of VOC profiling across different infection stages. Additionally, exploring the integration of VOC detection with portable analytical tools, such as electronic noses, could significantly enhance the feasibility of using these biomarkers in agricultural diagnostics. Such advancements could provide rapid, non-invasive tools for monitoring asymptomatic infections directly in the field.