Flowers are the most vulnerable plant organ to infection by the necrotrophic fungus, Botrytis cinerea. Here we show that pre-treatment of chrysanthemum flowers with phenylalanine (Phe) significantly reduces their susceptibility to B. cinerea. To comprehend how Phe-treatment induces resistance, we monitored the dynamics of metabolites (GC/LC-MS) and transcriptomes (RNAseq) in flowers post Phe-treatment and B. cinerea infection. Phe treatment resulted in accumulation of 3-phenyllactate and benzaldehyde, and in particular induced genes related to Ca2+ signaling and receptor kinases, implicating a defense response perception. Interestingly, the foremost response of Phe-treatment was in flowers exposed to B. cinerea infection, stabilizing the global fluctuations in the levels of metabolites and transcripts while reducing susceptibility to the fungus. We suggest that Phe-induced resistance is associated to cells priming, enabling rapid and targeted reprogramming of cellular defense responses to resist disease development. Phe pre-treatment maintained the levels of anti-fungal volatiles i.e. phenylacetaldehyde and eugenol, and strongly accumulated the levels of coniferin, a plausible monolignol precursor in cell wall lignification. In addition, Phe pre-treatment lessened the ROS generation, prevented the ethylene emission, and caused changes in expression of a minor number of genes with transcriptional reprogramming related to cell wall biogenesis, RLKs (THESEUS 1), Ca2+ and hormonal signaling processes. Our findings point to Phe pre-treatment as a potential orchestrator of a broad-spectrum defense response which may not only provide an ecological friendly control but also offers a promising way of priming plants to induce defense responses against B. cinerea.
Flowers are the most vulnerable plant organ to infection by the necrotrophic fungus, Botrytis cinerea. Here we show that pre-treatment of chrysanthemum flowers with phenylalanine (Phe) significantly reduces their susceptibility to B. cinerea. To comprehend how Phe-treatment induces resistance, we monitored the dynamics of metabolites (GC/LC-MS) and transcriptomes (RNAseq) in flowers post Phe-treatment and B. cinerea infection. Phe treatment resulted in accumulation of 3-phenyllactate and benzaldehyde, and in particular induced genes related to Ca2+ signaling and receptor kinases, implicating a defense response perception. Interestingly, the foremost response of Phe-treatment was in flowers exposed to B. cinerea infection, stabilizing the global fluctuations in the levels of metabolites and transcripts while reducing susceptibility to the fungus. We suggest that Phe-induced resistance is associated to cells priming, enabling rapid and targeted reprogramming of cellular defense responses to resist disease development. Phe pre-treatment maintained the levels of anti-fungal volatiles i.e. phenylacetaldehyde and eugenol, and strongly accumulated the levels of coniferin, a plausible monolignol precursor in cell wall lignification. In addition, Phe pre-treatment lessened the ROS generation, prevented the ethylene emission, and caused changes in expression of a minor number of genes with transcriptional reprogramming related to cell wall biogenesis, RLKs (THESEUS 1), Ca2+ and hormonal signaling processes. Our findings point to Phe pre-treatment as a potential orchestrator of a broad-spectrum defense response which may not only provide an ecological friendly control but also offers a promising way of priming plants to induce defense responses against B. cinerea.