Imaging Mass Spectrometry of Endogenous Polypeptides and Secondary Metabolites from Galls Induced by Root-Knot Nematodes in Tomato Roots

Abstract

Nematodes are devastating pests that infect most cultivated plant species and cause considerable agricultural losses worldwide. The understanding of metabolic adjustments induced during plant-nematode interaction is crucial to generate resistant plants or to select more efficient molecules to fight against this pest. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) has been used herein for in situ detection and mapping endogenous polypeptides and secondary metabolites from nematode-induced gall tissue. One of the major critical features of this technique is sample preparation; mainly, the generation of intact sections of plant cells with their rigid cell walls and vacuolated cytoplasm. Our experimental settings allowed us to obtain sections without contamination of exogenous ions or diffusion of molecules and to map the differential presence of low and high molecular weight ions in uninfected roots compared with nematode-induced galls. We predict the presence of lipids in both uninfected roots and galls, which was validated by MALDI time-of-flight tandem mass spectrometry and high-resolution mass spectrometry analysis of lipid extracts. Based on the isotopic ion distribution profile, both esters and glycerophospholipids were predicted compounds and may be playing an important role in gall development. Our results indicate that the MALDI-MSI technology is a promising tool to identify secondary metabolites as well as peptides and proteins in complex plant tissues like galls to decipher molecular processes responsible for infection and maintenance of these feeding sites during nematode parasitism.

Unravel the Local Complexity of Biological Environments by MALDI Mass Spectrometry Imaging

“…Moreover, all the ions shared the same localization at the level of the granular cells layer [91]. Only the species PI (40:6) was found in the granular cell layer but not in the gray matter, and the grey matter regions were differentiated by PI (38:4) and PC (32:0) as observed in other studies [88,89]. This differential phospholipids localization finds an explanation in the lipid processing, especially at the level of the hypothalamus [92].…”

“…However, a few studies performed on Caenorhabditis elegans and Schistosoma mansoni showed promising results for lipid detection [83,86,87] (Supplementary Table S1). Moreover, a recent study investigated the effect of the parasitism of tomato roots by the nematode Meloidogyne incognita on polypeptides and secondary metabolites, but focused only on the plant side of the interaction [88] (Supplementary Table S1).…”

“…In this context, MSI of brain tissue plays a crucial role not only in neurobiology but also in tissue sample preparation development. Many studies evaluated the performance of a novel MALDI MSI method, e.g., evaluation of a new matrix, or instrumental setup by analyzing animal brain tissue and mapping specific histological regions [28,88,89].…”

Mass spectrometry imaging for direct visualization of components in plants tissues

“…MALDI-MSI was used to analyze peptides, proteins, and secondary metabolites in uninfected tomato roots and nematode-induced galls. It was found that glycerophospholipids were present only in the nematode's feeding site, while other compositions only in the unaffected roots, suggesting that glycerophospholipids may be involved in the process of nematode infection and maintenance of root development [100]. MSI was also used to track the fate and transportation of several secondary plant metabolites in simulated ecosystems [101].…”

Mass spectrometry imaging as a potential technique for diagnostic of Huanglongbing disease using fast and simple sample preparation

“…The technique was used with success to monitor the presence of hesperidin and rutin in the infection site 32 . MSI was also applied to monitor other plant diseases 33 – 35 ; however, this technique has never been applied to understand the infection process of C Las in citrus. Herein, we applied for the first time MSI analyses combined with HPLC–MS/MS to investigate healthy and diseased leaves (both asymptomatic and symptomatic stages) in the search for HLB biomarkers.…”