Promotion of tomato growth and suppression of plant parasitic nematodes by Trichoderma atroviride: alterations in root metabolomics and soil C/N ratio

Abstract

Several species of Trichoderma are plant beneficial fungi with nematicidal properties. However, the underlying mechanisms involved in this biocontrol trait need to be further explored. The main aim of this work was to examine the effects of inoculation with T. atroviride on tomato growth, metabolomics and nutrition, and soil C:N ratio in a soil naturally infested with plant parasitic nematodes. Inoculation with T. atroviride promoted shoot and root dry weight in tomato plants. This plant growth promoting effect by the fungus coincided with a reduction in the population density of plant parasitic nematodes and modulation of sucrose concentrations in plant tissues, accumulating this disaccharide mainly in the root. On the other hand, T. atroviride had no effect on bacterivorous and frugivorous nematodes. Additionally, the decrease in plant parasitic nematodes was correlated with alterations in the emissions of volatile compounds emitted by the root system. In sterile soil, the fungus increased the emission of m-cymene and methyl salicylate (Me-SA), whereas in non-sterile soil T. atroviride reduced the emission of these volatiles, which indicates that the fungus modulates the chemical defense in tomato. Finally, inoculation with T. atroviride caused a reduction in the soil C:N ratio, probably due to the decomposition of organic compounds deposited and/or previously present in the rhizosphere. Our results highlight novel aspects of the mechanism involved in biocontrol traits of T. atroviride against plant parasitic nematodes in agricultural soils.