The moss Physcomitrella patens releases a tetracyclic diterpene

The presence of the tetracyclic diterpene 16alpha-hydroxykaurane (16alpha-hydroxy-ent-kaurane, C20H34O, CAS 5524-17-4) was detected in sterile cell cultures of the moss Physcomitrella patens (Hedw.) B.S.G. using gas chromatography and mass spectrometry. 16alpha-hydroxykaurane was found to be a major lipid compound in P. patens, with an estimated intracellular concentration of up to 0.84 mmol/l and an extracellular concentration of up to 9.3 micromol/l. The overall content of 16alpha-hydroxykaurane (in milligrams) produced per culture reached 0.37-fold that of chlorophyll a+b. In agar cultures with low air exchange, 16alpha-hydroxykaurane forms needle-like crystals on tissue and on the inner surface of the culture vessels, indicating that it is being released into the atmosphere. Solid phase microextraction confirmed the air-bound release of 16alpha-hydroxykaurane. To our knowledge this is the first report on the release of a plant-derived tetracyclic diterpene into the air.