High Resolution Assessment of Spatio-Temporal Changes in O2 Concentration in Root-Pathogen Interaction

Abstract

Fusarium wilt, caused by the fungus Fusarium oxysporum f. sp. lycopersici (Fol), is one of the most destructive soil-borne diseases of tomatoes. Infection takes place on the roots and the process starts with contact between the fungus and the roots hairs. To date, no detailed studies are available on metabolic activity in the early stages of the Fol and tomato root interaction. Spatial and temporal patterns of oxygen consumption could provide new insights into the dynamics of early colonization. Here, we combined planar optodes and spatial analysis to assess how tomato roots influence the metabolic activity and growth patterns of Fol. The results shows that the fungal metabolism, measured as oxygen consumption, increases within a few hours after the inoculation. Statistical analysis revealed that the fungus tends to growth toward the root, whereas, when the root is not present, the single elements of the fungus move with a Brownian motion (random). The combination of planar optodes and spatial analysis is a powerful new tool for assessing temporal and spatial dynamics in the early stages of root-pathogen interaction.

A starting guide to root ecology: strengthening ecological concepts and standardising root classification, sampling, processing and trait measurements

“…Although the methodology has not yet been used to determine RR S (e.g. related to surface area), it has a large potential to resolve spatial and temporal complex respiration patterns at root–soil (rhizosphere) interfaces and to relate RR to root growth, nutrient uptake and exudation (Tschiersch et al ., 2012 ; Blossfeld et al ., 2013 ; Rodeghiero et al ., 2018 ).…”

Hypoxia: A Double-Edged Sword During Fungal Pathogenesis?

“…Using non-invasive planar optode technology and geostatistical spatial analysis, it has been recently investigated that behavior patterns of F. oxysporum f. sp. lycopersici depending on presence and absence of tomato root by visualizing and quantifying the dynamics of O 2 consumption ( Rodeghiero et al, 2018 ). The air saturation of the pathogen decreased first by the increase in fungal respiration, and then the air saturation of the inner core (root) peaked and decreased during root-pathogen interaction.…”

“…F. oxysporum f. sp. lycopersici tended to grow toward tomato root, in contrast, the fungus moved with a Brownian motion (random) when the root was absent ( Rodeghiero et al, 2018 ). More direct evidences of hypoxia emergence within hosts during fungal infection have been reported in the hemibiotrophic fungus M. oryzae causing rice blast ( Chung et al, 2019 ) and the necrotrophic fungus Botrytis cinerea causing gray mold ( Valeri et al, 2020 ).…”