Disease resistance conferred by components of essential chrysanthemum oil and the epigenetic regulation of OsTPS1.

The sesquiterpene alpha-bisabolol is the predominant active ingredient in essential oils that are highly valued in the cosmetics industry due to its wound healing, anti-inflammatory, and skin-soothing properties. Alpha-bisabolol was thought to be restricted to Compositae plants. Here we reveal that alpha-bisabolol is also synthesized in rice, a non-Compositae plant, where it acts as a novel sesquiterpene phytoalexin. Overexpressing the gene responsible for the biosynthesis of alpha-bisabolol, OsTPS1, conferred bacterial blight resistance in rice. Phylogenomic analyses revealed that alpha-bisabolol-synthesizing enzymes in rice and Compositae evolved independently. Further experiments demonstrated that the natural variation in the disease resistance level was associated with differential transcription of OsTPS1 due to polymorphisms in its promoter. We demonstrated that OsTPS1 was regulated at the epigenetic level by JMJ705 through the methyl jasmonate pathway. These data reveal the cross-family accumulation and regulatory mechanisms of alpha-bisabolol production.