N-decanoyl-homoserine lactone alleviates elevated CO2-induced defense suppression to Botrytis cinerea in tomato

Abstract Tropospheric CO2 concentrations were remarkably increasing, especially since the Industrial Revolution. The CO2 fertilization technology was increasingly used in greenhouse agriculture cultivation because of its benefit to crop quality and yield. But, as a consequence of elevated CO2, the plant-pathogen interactions in natural or agricultural ecosystems have large potential to be affected. So far, the effects of elevated CO2 on plant defense against pathogen are complicated and the underlying mechanism remained poorly understood. Here, using tomato plants, we found that elevated CO2 significantly suppressed the plant defense against necrotrophic pathogen Botrytis cinerea, which is accompanied by the disturbed homeostasis between defense-related salicylic acid- and jasmonic acid- (JA-) signaling. But, exogenous application of bacterial secreta N-decanoyl-homoserine lactone (DHL) drastically rescued B. cinerea disease susceptibility under elevated CO2 condition. Moreover, JA biosynthesis mutant spr2 and JA signaling gene-silenced plants blocked DHL-induced plant defense under elevated CO2 condition, which suggested JA signaling was indispensable to the alleviated effect of DHL on plant susceptibility to B. cinerea under elevated CO2 condition. Overall, this information will be benefit to manipulate DHL as an attractive disease management strategy in agriculture cultivation under changing CO2 conditions.