In vitro cultivation of Arabidopsis wildtype and mutant plants: Seeds were sterilized according to standard lab routines (EtOH, NaOCl/NaOH) prior to aseptical (in vitro) cultivation in 500 ml screw cap jars on MS medium (4.3 g/l; 50 ml/jar) containing Bacto- and Phytoagar (1:2; 6 g/l) and 30 g/l sucrose. Ten seeds were pipetted into each jar and plants grown for 6 weeks until flowering at a temperature of 20 ℃ under a 16/8 h day/ night regime using fluorescent tubes (Osram Lumilux Plus Eco 36 W). Both Arabidopsis thaliana wildtype plants of ecotype Columbia-0 (Col) and 4 Col-derived T-DNA knock-out mutants (homozygous lines) showing deficiencies in the GLS biosynthesis pathway were used in this study (five parallels for wildtype and mutants): TGG1 (Atg526000; Salk_130469), TGG2 (At5g25980; Salk_038730), Cyp83A1 (At4g13770) and Cyp83B1 (At4g31500; Salk_028573). Greenhouse-cultivation of Arabidopsis ecotypes: The following Arabidopsis ecotypes were used in the study: Columbia (Col), Cape Verde Islands (Cvi), Landsberg erecta (Ler) and Wassilewskija (Ws). Single plants were greenhouse-cultivated on fertilized soil (P-Jord; Emmaljunga Torvmull AB) in plug trays (9 × 6 cells) at a temperature of 20 ℃ (three parallels for each ecotype). Due to the 6-weeks growth period (November/December 2003), the plants were cultivated under a 16/8 h day/night regime using metal halide lamps (Osram HQI-T 400 W) placed 130 cm above the trays. Depending on the ecotypical plant development, whole plants were sampled after 3-4 weeks right before bolting for in vivo studies, while investigations of single plant organs (leaf, stem, inflorescence) were carried out after 5-6 weeks of cultivation.

Metabolites from methionine, leucine and phenylalanine-derived glucosinolates were most abundant (4-methylthiobutyl, 4-methylpentyl, 2-phenylethyl). In addition, 24 monoterpenes, 26 sesquiterpenes and 12 aromatic structures, predominantly observed in inflorescenses, are described. Excluding the vast group of straight chain aliphatic structures, a total of 102 volatile compounds were detected, of which 59 are reported in Arabidopsis thaliana for the first time, thus emphasizing the sensitivity and applicability of solid-phase microextraction for volatile profiling of plant secondary metabolites.

Experimental: Two hundred grams of healthy mature intact leaves were harvested from each of the taxa growing on their own rootstocks at the UC South Coast Research and Extension Center. flocc = P. americana var. floccosa from Mexico D-7; stey = P. americana var. steyermarkii from Mexico El Salvador 3-22-16; nubi = P. americana var. nubigena from Guatemala 45-C-1; mex = P. americena var. drymfolia from Tasco, Mexico; guat = P. americana var. guatemalensis cult. Nimlioh from Florida; bwl = P. ameticana var. americana cult. Trapp from Florida.

Analysis of oils showed the presence of over 90 components, of which 76 were identified. P. schiedeana oil was found to contain alpha-pinene (23.7%), beta-pinene (23.2%) and beta-caryophyllene as major components. The major constituents of P. americana var. floccosa and P. americana var. steyermarkii were alpha-pinene (10.9%, 7.6%), beta-pinene (20.6%, 10.4%), alpha-terpineol (9.6%, 7.9%), beta-caryophyllene (12.6%, 8.4%), viridiflorene (0.1%, 10.3%) and globulol (0.1%, 9.2%), respectively. The oils of P. americana var. nubigena and P. americana var. drymifolia contained alpha-terpineol (18.4%, 393%) and methylchavicol (12.4%, 40.2%), as major components, respectively. P. americana var. guatemalensis was found to be rich in beta-caryophyllene (38.3%), while the oils of P. americana var. americana and P. primatogena contained alpha-pinene (27.5%) and beta-pinene (40.9%), and alpha-pinene (24.6%), beta-caryophyllene (20.7%) and germacene D (10.1%).

Grape pomaces and stalks of Nero d'Avola and Frappato were donated by the ''Valle dell'Acate'' wine firm, Acate, RG, Italy - those from Nerello Mascalese and Cabernet Sauvignon were given by the ''Emanuele Scammacca Barone del Murgo'' wine firm, Santa Venerina, CT, Italy. The winemaking procedures were similar for all samples, namely grape clusters were crushed and destemmed using a destemmer-crusher. The crushed grapes were treated with sulphur dioxide (0.2-0.5% total mash) and with selected strains of Saccharomyces cerevisiae to start up the fermentation. After 6-8 days of maceration, when alcoholic fermentation was finished, the mash was pressed. Stalks coming from destemming procedure and grape pomace coming from the maceration procedure were subjected to the distillation procedures within 24 h of their collection. All materials were collected during the 2004 vintage.

On the whole, 38 components have been characterized in the samples of grape pomaces, with Frappato cv. showing the richest composition; instead, 88 components have been detected in the stalks of Frappato, Nero d'Avola, Nerello Mascalese and Cabernet Sauvignon varieties.