Mechanical wounding impacts the growth versus defence balance in tomato (Solanum lycopersicum)

Abstract

Plants have evolved elaborate surveillance systems that allow them to perceive the attack by pests and pathogens and activate the appropriate defences. Mechanical stimulation, such as mechanical wounding, represents one of the most reliable cues for the perception of potential herbivore aggressors. Here we demonstrate that mechanical wounding disturbs the growth versus defence balance in tomato, a physiological condition where growth reduction arises as a pleiotropic consequence of the activation of defence responses (or vice-versa). We observed that consecutive lesions on tomato leaves impairs the formation of several growth-related traits, including shoot elongation, leaf expansion and time for flowering set, while concomitantly activating the production of defence responses such as trichome formation and the upregulation of defence-related genes. We also provide genetic evidence that this wound-induced growth repression is a consequence of tomato plants sensing the injuries via jasmonates (JAs), a class of plant hormones known to be master regulators of the plant growth versus defence balance. Besides providing a mechanistic explanation on how the growth and defence balance is shifted when plants are subjected to a specific type of mechanical stimulus, our results may offer a practical explanation for why tomato productivity is so negatively impacted by herbivore attack.