Trees make their own bug-alarm scent when caterpillars attack
Panagoulias M, Bäsmann J, Strassburg S, Bach M, Fernández-Giro Muñoz M
Plant Signaling
The next time you spot chewed leaves on a tree in the park, the plant may already be broadcasting a chemical distress call that recruits wasps and other predators to fight back on its behalf.
When caterpillars munch on the leaves of a tree called Idesia polycarpa, the tree releases a special airborne scent called DMNT that can call in the caterpillars' natural enemies for help. Researchers found the exact pair of plant enzymes that work together to build this scent from scratch, something that had only been well understood in small herbs before, not trees. It turns out this particular tree makes only the short-range version of the alarm scent and lacks the machinery to make a longer-range version that other plants use.
Key Findings
Caterpillar feeding on Idesia polycarpa leaves triggered strong emission of the homoterpene DMNT along with a rise in jasmonic acid defense hormones, while the related compound TMTT was never detected
Two enzymes were identified as responsible: the terpene synthase IpTPS15 makes (E)-nerolidol, and the P450 enzyme IpCYP82L45 converts that nerolidol into DMNT
Co-expressing IpTPS15 and IpCYP82L45 together in tobacco plants successfully reconstituted DMNT production, and no enzyme capable of making the TMTT precursor was found in the tree, explaining why TMTT is absent
chevron_right Technical Summary
Scientists discovered the specific plant enzyme that lets a tree release an alarm-scent when caterpillars start chewing on it, a signal that can attract the caterpillars' predators. This is one of the first times this defense chemistry has been mapped out in a woody tree rather than a garden herb.
Abstract Preview
Original paper
A herbivore-inducible CYP82 catalyzes DMNT formation in Idesia polycarpa leaves.
Herbivore-induced volatile organic compounds (HIPVs) are important components of plant defense, but the molecular basis of their biosynthesis in woody plants remains poorly understood. Among HIPVs,...
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Idesia is a genus of flowering plants in the family Salicaceae, comprising the single species Idesia polycarpa. It is native to eastern Asia in China, Japan, Korea, and Taiwan.