Does insect's salivary enzyme activate the defense response in wiild tomato species?

Plant domestication has altered the defenses in plants because breeders have selectively chosen some desirable traits (taste, size, color) from wild species to improve the cultivated ones. In the literatures, some authors claimed that cultivated plants performed worse than their wild ancestors while others pointed that some cultivated plants had higher defenses when attacked by pathogens. Induced defenses in plant-insect interaction system can be initiated through the recognition of insect oral secretions (Glucose Oxidase; GOX) and signals from injured plants leading to activation of defensive protein production (anti-nutritive and anti-oxidative enzymes).
Despite studies on how GOX acts to modulate plants defenses especially cultivated plants, little information is known on how wild relatives respond to GOX. In this study, we examined the induced defenses in some accessions of Solanum pennellii (wild tomato species) against insects’ infestation using a generalist caterpillar (Helicoverpa zea; tomato fruitworm). Solanum pennellii has been widely studied for its drought tolerant ability and used in introgression of cultivated varieties. However, there are limited studies on how it responds to herbivory. From this study, our findings revealed that GOX does not induce anti-nutritive enzymes in S. pennellii but activated anti-oxidative enzyme indicating that factors like edema (a physiological response that happens when plant roots absorb too much water than it could transpire) might be involved. Further studies on this showed that, edema was a contributory factor of plant defenses.
This research aims to provide baseline information to breed for resistant plant varieties against insect pests and enhancing agricultural sustainability.