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

Moisés Roberto Vallejo-Pérez1,2, Jesús Antonio Sosa-Herrera3, Hugo Ricardo Navarro-Contreras2

  • 1Consejo Nacional de Ciencia y Tecnología-Universidad Autónoma de San Luis Potosí, CIACYT, Alvaro Obregon 64, Col. Centro, San Luis Potosí 78000, Mexico.

Insights

Early detection of bacterial canker in tomato plants is possible using Raman spectroscopy. This non-invasive method identifies biochemical changes in asymptomatic plants, enabling rapid disease diagnosis.

Area of Science:

  • Plant Pathology
  • Biochemistry
  • Spectroscopy
  • Machine Learning

Background:

  • Bacterial canker of tomato, caused by *Clavibacter michiganensis* subsp. *michiganensis* (Cmm), is a destructive disease.
  • Cmm infections often remain asymptomatic, facilitating disease spread.
  • Early detection is crucial for effective management of tomato bacterial canker.

Purpose of the Study:

  • To implement Raman spectroscopy (RS) and machine learning for early detection of Cmm in tomato plants.
  • To identify specific biochemical markers indicative of asymptomatic Cmm infection.
  • To evaluate the efficacy of RS combined with spectral analysis for differentiating healthy and infected plants.

Main Methods:

  • Raman spectra were acquired from asymptomatic infected tomato plants (BCTo) and healthy controls (HTo) using a micro-Raman spectrometer.
  • Spectral data were normalized and processed using Principal Component Analysis (PCA).
  • Machine learning classifiers, Multilayer Perceptron (MLP) and Linear Discriminant Analysis (LDA), were applied to PCA-processed data (PCA + MLP, PCA + LDA).

Main Results:

  • Raman spectra revealed distinct peaks associated with cellular components, including carbohydrates, carotenoids, chlorophyll, and phenolic compounds in both healthy and infected plants.
  • Significant biochemical alterations were detected in infected plants, with specific Raman bands linked to triterpenoids and flavonoids identified as potential indicators of asymptomatic Cmm infection.
  • The analytical method demonstrated high performance, including sensitivity, specificity, and accuracy, in differentiating between BCTo and HTo.

Conclusions:

  • Raman spectroscopy is an efficient, rapid, and reliable technology for assessing tomato plant health status.
  • The developed RS and machine learning approach enables accurate differentiation of healthy and Cmm-infected asymptomatic tomato plants.
  • This method holds significant potential for early and non-invasive diagnosis of bacterial canker in tomatoes.