Diversity of volatile organic compound emissions from flowering and vegetative branches of Yeheb, Cordeauxia edulis (Caesalpiniaceae), a threatened evergreen desert shrub

摘要

Yeheb is a shrub endemic to the Horn of Africa. It is adapted to hot and xeric environments and known to be resistant to insect herbivores. We analysed volatile organic compounds (VOCs) from the headspace of vegetative branches (VBs) and flowering branches (FBs), stored terpenoids from leaf and bark extracts and foliar total phenolics. Isoprene was the dominant compound in the headspace. In total, 66 VOCs were identified, but only a few stored terpenes were detected. Isoprene and monoterpene emissions from FBs were at levels of 24.0 and 5.12 μg/g dw (dry weight)/h, respectively. A total of 30 compounds were emitted at significantly higher rates from FBs than from VBs. The emission of large quantities of a diverse range of VOCs and the presence of high levels of total phenolics in this plant may be attributed to its defence strategy against both abiotic and biotic stresses in arid environments.