Foliar application of methyl jasmonate does not increase terpenoid accumulation, but weakly elicits terpenoid pathway genes in sandalwood (Santalum album L.) seedlings

The sesquiterpenoid rich essential oils of sandalwood (Santalum album L.) stems and roots are a highly sought commodity in the fragrance industry. Plantations of sandalwood are being established in northern Australia, however the valuable heartwood essential oils do not accumulate in substantial amounts before 10 years, while commercially viable harvests do not normally take place for at least 15 years. Inducing essential oil accumulation at an earlier stage, or increasing oil yield in mature trees, may have the potential to enhance the oil productivity of plantations. In this study, we investigated the effects of foliar application of methyl jasmonate on less than one-year-old sandalwood seedlings. Essential oil accumulation was unaffected in both stems and roots. However, at the gene transcript level, several key genes early in the biosynthesis of sandalwood oil components were induced in both leaves and stems. These results suggest that terpenoid biosynthesis in S. album does indeed respond to foliar application of methyl jasmonate, however the effects are small and the full biosynthesis of santalols is likely to be developmentally regulated.