Volatile terpenes

Elucidating the Metabolism of Plant Terpene Volatiles Alternative Tools for Engineering Plant Defenses ... 

This observation led us to examine whether Arabidopsis flowers emit terpene volatiles. However, standard volatile collection and analysis techniques did not result in readily detectable levels of terpenes. We, therefore, adapted a closed loop stripping method developed initially by Donath and Boland for the detection of Arabidopsis volatiles. This method (Fig. 1.3A) is based on a continuous circulation of air in the headspace of whole plants or plant parts placed in a 1-3 liter glass bell... 

Using these methods in combination with gas chromatography-mass spectrometry (GC-MS), we were able to detect the emission of a number of monoterpenes as well as a large group of sesquiterpenes from whole Arabidopsis Columbia plants (Fig. 1.4). In total, 3 monoterpenes (P-myrcene, linalool, and limonene) and over 20 sesquiterpene hydrocarbons were detected with E- -caryophyllene as the predominant terpene volatile. The sesquiterpene volatiles showed a high structural diversity including acyclic, mono-, di- and tricyclic compounds. All monoterpenes and 19 sesquiterpenes were identified with certainty by mass spectra and comparison with authentic standards. 

Lee S, Badieyan S, Bevan DR, Herde M, Gatz C, Tholl D (2010) Herbivore-induced and floral homo-terpene volatiles are biosynthesized by a single P450 enzyme CYY 2G ) vaArabidopsis. Proe Natl Aead Sci U S A 107 21205-21210... 

Keywords Climate aerosols defense herbivory pollination pollutants storage terpenes volatiles... 

Terpenes volatilization can be sensed by herbivores as they approach a potential host plant with imphcations for the defense strategies of plants. Volatile compounds can repel most potential generalist herbivores at some distance from the plant, but the same emitted VOCs have an opposite function in attracting host plant-specific herbivores. Terpenes secreted on plant surfaces as waxes or resins or deposited in... 

Several terpene synthases appear to be multi-functional. For example, a sesquiterpene synthase from Zea mays produces a complex mixture of terpene volatiles. The closely related TPS4 and TPS5 from different maize varieties each synthesize the same complements of sesquiterpenes from FPP, but in different proportions as a result of the different ratios of S)- versus (il)-bisabolyl cation formation. This difference in stereoselectivity is determined by four amino acid residues in the active site [35]. 

Tyson et al. (1974) took the work a step further when they conducted studies of the rate of terpene volatilization from foliage of S. mellifera. The calculated rate of volatilization was 13.3 Lig/dm per day. Total loss of photosynthate was estimated at 0.06%. On an area basis, it was calculated that 3.1 kg/km were released daily. The total terpene content of the leaves was more than 1000 times the amount volatilized. 

Muller, C.H. 1965. Inhibitory terpenes volatilized from Salvia shrubs. Bull. Torrey Bot. Club 92 38-45. 

---