# De Novo Terpenes Emitted from Juvenile Leaves of Eucalyptus globulus Labill. subsp. globulus

## TL;DR

This study shows that certain terpenes in Eucalyptus globulus leaves are newly synthesized and emitted, not just from stored oils.

## Contribution

The study identifies specific terpenes synthesized de novo in Eucalyptus globulus leaves using 13CO2 labeling.

## Key findings

- Isoprene, iso-valeraldehyde, cis-ocimene, and trans-caryophyllene were synthesized de novo in Eucalyptus leaves.
- 13C labeling showed up to 82% incorporation in isoprene and iso-valeraldehyde within 2.5 hours.
- Terpene emissions occurred independently of oil glands.

## Abstract

The contributions of de novo synthesis to terpene emissions from Eucalyptus globulus subsp. globulus were determined by fumigating branchlets with 13CO2 in a gas exchange system. Of more than thirty-four terpenes emitted by this species, only four, i.e., isoprene, iso-valeraldehyde, cis-ocimene, and trans-caryophyllene, incorporated 13C into the terpene carbon skeleton during the ~5–6 h experiment. 13C incorporation into isoprene and iso-valeraldehyde reached a maximum of ca. 82% of the carbon skeleton, similar to cis-ocimene, with a maximum of 77% 13C incorporation after ~2.5 h exposure to 13CO2. Only ca. 20% of carbon was labelled in trans-caryophyllene after 5–6 h. the incorporation of 13C was observed only in compounds emitted from leaves, and was not detected in either individual oil glands or in bulk leaf tissue. The results suggest the de novo synthesis of some terpenes (isoprene, cis-ocimene, trans-caryophyllene, and iso-valeraldehyde) and their emission is independent of emissions of terpenes stored in oil glands.