In tomato plants, arbuscular mycorrhizal fungus regulate the growth-defense trade-off and mitigate the detrimental effects of drought.

Abstract

A variety of arbuscular mycorrhizal fungi (AMF) may be used as biofertilizers in agricultural soils to boost crop productivity and growth. AMF may boost plant defences against a variety of herbivores and diseases, according to recent study. However, our current incapacity to forecast the performance of various AMF-plant complexes in changing settings has significantly hindered the effective application of AMF in agriculture. For example, AMFs may reduce allocation constraints related to growth vs defences by boosting plant foraging capacity. However, the in situ variables may determine whether this impact takes place. Investigating the context-dependency of AMF's capacity to regulate plant development and resistance against herbivores under varying soil water availability was the primary objective of this work. In order to achieve our objective, we conducted a greenhouse experiment in which we measured the effects of various AMF inocula (Funneliformis mosseae, Rhizophagus irregularis, or both) on the growth and defences of tomato plants (Solanum lycopersicum) against an insect herbivore under two conditions: normal watering regimes and drought conditions. We assessed the plants' physiological, chemical, and functional characteristics. Findings: We discovered that the presence of AMF often reduced plant development while boosting chemical defences and resistance to generalist caterpillars. Nevertheless, the mycorrhizal inoculum's identity and the water content of the soil determined this growth-defense trade-off. Inoculated tomato plants reduced their defensive investment under drought, but noninoculated plants reduced their growth.In conclusion, our work emphasises how fungal identity and abiotic variables affect plant–AMF–herbivore interactions. More broadly, our findings highlight the need to identify AMF species with less context-dependency on climatic parameters in order to increase their usage in organi