Metabolomics by NMR Spectroscopy in Plant Disease diagnostic: Huanglongbing as a Case Study

Abstract

Candidatus Liberibacter spp. is the pathogen associated with Huanglongbing (HLB), a disease with an economic impact in the order of billions of dollars to the worldwide citrus industry. A key point to reduce HLB economic losses lies on early detection on asymptomatic stages of the infection by new detection methods as it is still not possible to cultivate Candidatus Liberibacter spp. in vitro, and the polymerase chain reaction (PCR) method used nowadays is not manageable in large scale. In this study, we search for metabolic biomarkers from Citrus sinensis leaves in different disease stages using a combined approach of NMR spectroscopy and chemometrics. Chemometric clustering was observed, providing excellent tools for class discrimination, with high accuracy, therefore enabling metabolic profile differentiation on disease early stages. Around 20 different key biomarkers, metabolites responsible for the clustering of each group, were identified using 2D NMR experimental data.

Twenty Years of 1H NMR Plant Metabolomics: A Way Forward toward Assessment of Plant Metabolites for Constitutive and Inducible Defenses to Biotic Stress

“…decreased in flavones. 96 In response to mosaic viruses, tobacco and tomato increased chlorogenic acid and its derivatives. 38,54 Citrus exocortis viroid also increased gentisic acid glycoside in tomato.…”

Virulence Factors in the Phytopathogen–Host Interactions: An Overview

“…13 Currently, the search for metabolites from Candidatus Liberibacter spp. related to the virulence is based on metabolomics of the different parts of the host 71,74 or analysis of nymphal instars of its vector Diaphorina citri Kuwayama. 75,76 So far, the metabolites identified in this pathogen−host interaction are related to the biochemistry of the host, and it is still unclear if the pathogen has the potential for secondary metabolites production.…”

Fungal Basidiomycete Ceratobasidium theobromae DNA obtained directly from cocoa petioles

“…Therefore, attempts to achieve robust nucleic acid isolates are challenging. This increase in plant chemical compound production is thought to be an active self-defence mechanism, resulting from phytoalexin and phytohormone activation; this mechanism can be triggered in several ways, including pathogen infection, pest infestation, or abiotic stress (Afifah et al 2019;Castro-Moretti, Gentzel et al 2020;Gómez et al 2020;Lima et al 2017;Pontes, Ohashi et al 2016). These defensive compounds can become a significant inhibitory factor when seeking to extract high quality nucleic acids in sufficient quantity for genetic assays such as pathogen identification.…”