Four Petal-Specific TPS Drive Nocturnal Terpene Scent in <em>Jasminum sambac</em>

Floral volatile terpenoids are known to play important roles in plant pollination biology by attracting animal pollinators and repelling antagonists, as well as enhancing resistance to potential microbial pathogens. Terpenoid blend emitted by a flower is usually plant-lineage specific and mostly determined by a set of versatile terpene synthases (TPSs) which catalyze the final step of diverse terpenoid synthesis. The strongly scented flower of Jasminum sambac emits linalool and α-farnesene dominating the nocturnal floral VOC, yet the corresponding TPSs have not been identified. Here, we show that four TPS enzymes are responsible for the synthesis of the mixtures of volatile terpenoids in the flower, based on their highly-correlated and almost-exclusive expression in the petal, and on their enzymatic characterizations in vitro and in Nicotiana benthamiana. JsTPS01 (TPS-a) acts as a sesquiterpene synthase, producing τ-cadinol in yeast at levels that mirror its rhythmic expression in petals. JsTPS02 (TPS-b) carries a plastid-transit peptide, localizes to chloroplasts/plastids, and converts GPP to linalool with high affinity (Km = 28.2 ± 3.4 µM). JsTPS03 is a TPS-b clade member that is able to convert FPP to farnesol with a Km of 14.4 ± 5.9 μM in an in vitro assay using isolated yeast vehicles. JsTPS04 (TPS-e/f) exhibits dual targeting—cytosolic in Arabidopsis protoplasts but plastidic in J. sambac petals—and functions as a bifunctional mono-/sesqui-TPS, forming linalool from GPP (Km = 2.5 ± 0.3 µM) and trans-nerolidol from FPP (Km = 7.6 ± 0.6 µM). Transient expression in Nicotiana benthamiana leaves further confirmed its in-planta linalool production. collectively, we identified four preferentially expressed terpene synthases contribute to linalool, τ-cadinol, tans-nerolidol, and farnesol in Jasminum sambac.