Arabidopsis volatiles

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... 

Arabidopsis A Small Weed and Its Genetic Resources for Volatile Terpene Biosynthesis... 

How Does Arabidopsis Assemble Homoterpene Volatiles 11.4.1 Formation of Alcohol Precursors... 

The phenotypic effects observed under the constitutive expression of GES may also be avoided by the use of inducible promoters. Transgenic Arabidopsis expressing GES controlled by the alcohol-inducible Ale A promoter did not show the lesion phenotype observed under constitutive expression of GES [58]. Recent experiments with wound- and insect-inducible promoters such as that of the potato proteinase inhibitor 11 have been reported [78]. The use of strong inducible promoters that respond to herbivore-feeding may not only minimize toxic effects or costs associated with the constitutive formation of a volatile compound but can also provide the advantage that parasitoids associate volatiles only with the presence of feeding damage by the respective host. 

Chen E, ThoU D, D Auria JC, Earooq A, Pichersky E, Gershenzon J (2003) Biosynthesis and emission of terpenoid volatiles from Arabidopsis flowers. Plant Cell 15 481 94... 

Ealdt J, Arimura G, Gershenzon J, Takabayashi J, Bohlmann J (2003) Functional identification of AtTPSOS as ( )-P-ocimene synthase a monoterpene synthase catalyzing jasmonate- and wound-induced volatile formation in Arabidopsis thaliana. Planta 216 745-751... 

ThoU D, Chen F, Gershenzon J, Pichersky E, Romeo JT (2004) Arabidopsis thaliana, a model system for investigating volatile terpene biosynthesis, regulation, and function. In Romeo JT (ed) Secondary metaboUsm in model systems. Elsevier, Amsterdam, pp 1-18... 

Chen F, Ro DK, Petri J, Gershenzon J, Bohhnann J, Pichersky E, Tholl D (2004) Characterization of a root-specific Arabidopsis terpene synthase responsible for the formation of the volatile monoterpene 1,8-cineole. Plant Physiol 135 1956-1966... 

Steeghs M, Bais HP, de Gouw J, Goldan P, Kuster W, Northway M, Fall R, Vivanco JM (2004) Proton-transfer-reaction mass spectrometry as a new tool for real time analysis of root-secreted volatile organic compounds in arabidopsis. Plant Physiol 135 47-58... 

Van Poecke RMP, Posthumus MA, Dicke M (2001) Herbivore-induced volatile production by Arabidopsis thaliana leads to attraction of the parasitoid Cotesia rubecula Chemical, behavioral, and gene-expression analysis. J Chem Ecol 27 1911-1928... 

The transformation of Arabidopsis thaliana with a cDNA from strawberry fruits encoding a dual (S)-linalool/(S)-nerolidol synthase also led to the production of both (S)-linalool and its glycosylated and hydroxylated derivatives in the leaves [14]. Surprisingly, the formation and emission of (S)-nerolidol was detected as well, suggesting that a small pool of its precursor farnesyl diphosphate is present in the plastids. The newly emitted (S)-linalool and (S)-nerolidol showed the same diurnal emission pattern as the pristine volatiles. 

Methyl ethers and esters are also found as volatile constituents in a wide range of flowers and fragrant herbs. For example, methyleugenol is found in the essential oil of herbs such as sweet basil and in the floral headspace of a wide range of flowers.7"10 Defense compounds and phytoalexins are commonly O-methylated as well. These compounds include the 3 -O-methylated form of the flavonoid quercetin as well as the 7-O-methyl ester of the flavone apigenin (Fig. ll.l).11,12 While not within the scope of this paper, it should be noted that protein O-methylation is common.13,14 One interesting protein modification known to occur in Arabidopsis thaliana is the a-carboxyl methylation of prenylated proteins.15 This modification has been shown in mammals and yeast to be important in protein targeting and membrane association.16,17... 

In many recent studies, the role of terpenoids in indirect defense has been studied. A broad range of plant species such as Arabidopsis, com, lima bean, cucumber, tomato, tobacco, apple, and poplar serves as models for studies on the genetic, biochemical, physiological, and ecological aspects of these tritrophic interactions between plants, herbivores, and natural enemies (e.g.. Reference 10). Plants have been shown to respond with quantitatively and qualitatively different volatile blends to different herbivore species, and predators can exploit this behavior to respond specifically to their prey (Fig. 3)... 

ARABIDOPSIS THALIANA, A MODEL SYSTEM FOR INVESTIGATING VOLATILE TERPENE BIOSYNTHESIS, REGULATION, AND FUNCTION... 

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. 

Arabidopsis Thaliana, a Model System for Investigating Volatile Terpene... 

Alternaria brassicola) did lead to a change in the root volatile emissions. Also, when root was treated with aphids (Diuraphis noxia), specific VOCs were released, indicating that this aphid may be a compatible pest for Arabidopsis roots. 

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