Bacterial wilt and canker of tomato: fundamentals of a complex biological system

Raman Spectroscopy and Machine-Learning for Early Detection of Bacterial Canker of Tomato: The Asymptomatic Disease Condition

“…The Raman spectra obtained from tomato leaves of healthy (HTo) and infected plants (BCTo) exhibited peaks associated to cellular components, and the most prominent vibrational bands were associated to monomeric and polymeric carbohydrates, carotenoids, chlorophyll, and phenolic compounds ( Table 1 ). The compatible pathogen-plant interaction (Cmm-tomato) is an extremely complex biological system, because Cmm can manipulate the plant metabolism and evade defense responses allowing the bacteria to multiply and to shift from an endophytic to a pathogenic state, the process induce latent asymptomatic infections [ 10 ]. Biochemical alterations induced during the tomato-Cmm interaction were also detectable in the Raman spectral patterns ( Figure 1 ).…”

“…The 1112 cm −1 wavenumber showed a higher relative intensity, the band is associated to carbohydrates monomer [ 18 ]; which suggests possible degradation processes on cell walls [ 4 ]. Different enzymes produced by Cmm take part in the degradation of cell walls during the infection process and these are responsible for the virulence of the pathogen [ 9 , 10 ].…”

“…Previous works [ 28 , 29 ] proposed to normalize Raman spectra to specific vibrational bands, because spectral intensities can vary with coloration of each specimen, and symptoms induced by biotic (phytopathogens) or abiotic (nutrient deficiencies) factors [ 30 ]. However, BCTo disease is characterized by the lack of symptoms during early disease stages, so we use SNV normalization due to the particularities of the analyzed pathosystem [ 10 ].…”

“…The transition from endophyte to pathogen is governed by the expression of putative virulence factors and the evasion or suppression of plant defense reactions. The phenomenon is modulated by bacterial population density (quorum-sensing), plant age, genetic diversity and the prevalent environmental conditions [ 4 , 8 , 9 , 10 ].…”

Detection of Clavibacter michiganensis subsp. michiganensis Assisted by Micro-Raman Spectroscopy under Laboratory Conditions

“…At the moment, there are no genetic materials showing resistance or tolerance to the Cmm bacterium ( Sen et al, 2013 ). BCT occurrence is usually erratic, the disease is asymptomatic at its early stages, and the compatible interaction between Cmm and tomato is an extremely complex and multi-faceted biological system, one of whose facets is the level of genetic variability in each organism ( Martínez-Castro et al, 2018 ).…”