Impact of abiotic stresses on the protection efficacy of defence elicitors and on metabolic regulation in tomato leaves infected by Botrytis cinerea

Finding sustainable plant protection strategies is a major challenge for agriculture. Taking advantage of the plant natural immune system by using plant defence elicitors is an interesting avenue to explore. However, transfer to field application is often difficult, mostly due to the complexity of interactions between plants and their environment, involving biotic and abiotic stresses. The protection efficacy against gray mold and the modes of action of potential elicitors were studied on tomato. Modulation of plant defense was studied using both global and targeted metabolic profiling. We identified seven potential elicitors showing good plant protection efficacy and able to trigger the oxylipin pathway, including jasmonic acid production, after inoculation with Botrytis cinerea. Following preliminary assays, seven elicitors including two well-studied elicitors (Bion 50WGA (R) and BABA) showing good plant protection efficacy and low fungitoxic effect were selected to assay the effect of abiotic stresses (wounding, water stress and nitrogen deficiency) on their protection efficacy. Our results showed that the protection efficacy of all products was reduced when plants were exposed to abiotic stresses, suggesting an antagonistic interaction between the tomato responses to abiotic stresses and product treatments. We found that responses to leaf cuttings and product treatments induced metabolic changes in a time-dependent manner, and that both of which mainly activated the oxylipin and JA pathway. However, the negative effects of wounding on tomato protection efficacy of defence elicitors suggest that interplay with other antagonistic signalling pathways is also involved in the tomato responses to this combination of stress.