THE EFFECTS OF HERBIVORY INTENSITY ON ARBUSCULAR MYCORRHIZAL FUNGI (RHIZOPHAGUS IRREGULARIS) COLONIZATION IN CHERRY TOMATO (SOLANUM LYCOPERSICUM VAR. CERAIFORME) ROOTS

Résumé fourni par la source

With the increase in agricultural intensification leading to the continued degradation of soil quality and belowground biodiversity, arbuscular mycorrhizal fungi (AMF) have emerged as a potential tool for sustainable crop production. AMF form mutualistic associations with plant roots, exchanging nutrients such as phosphorus in return for carbohydrates. However, while many studies have examined how AMF benefits its host plant, less is known about how aboveground plant stress affects its belowground fungal partner. This study investigates whether caterpillar herbivory alters belowground AMF colonization in cherry tomato plants (Solanum lycopersicum) inoculated with Rhizophagus irregularis. In a controlled greenhouse experiment, plants were assigned to none, low, medium, or high herbivory treatments using Manduca sexta caterpillars, then harvested to quantify AMF colonization through ink-vinegar staining and microscopic counts of fungal structures. AMF inoculation successfully established colonization in tomato roots, with arbuscules, vesicles, hyphae, and germinating spores observed across inoculated plants. Mean AMF colonization followed the predicted pattern: no-herbivory plants had the highest average colonization, while high-herbivory plants had the lowest. However, differences among herbivory treatments were not statistically distinguishable, suggesting that short-term caterpillar herbivory did not produce a detectable reduction in AMF colonization under the conditions tested. These findings suggest that R. irregularis colonization may persist under short-term aboveground stress, though herbivory may still limit colonization increases over time. This study contributes to a broader understanding of plant-AMF mutualisms by considering the fungal response to plant stress and highlights the need for future studies with larger sample sizes, longer recovery periods, repeated herbivory events, and direct measurements of carbon allocation.

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