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.

The aerial parts (~20 cm, 15-100 g) of A. campestris L. from ten different wild populations of Lithuania were gathered at the full flowering stage. Plant material was dried at room temperature (20-25 ℃). Oils (samples 1-10) obtained from Artemisia campestris plants collected at sampling sites (A-I,Y) characterized by locality, city (c.) or district (d.), soil type (Or, ordo; Sn, sand; Sl, sandy loam; Gr, gravel; Lm, loam) and description of natural habitat (Af, abandoned field; Fe, forest edge; Ct, cutting area; Mw, meadow; Rs, roadside; Rv, river valley): A (1) Birstonas c. (Or, Ct); B (2) Palanga c. (Sn, Fe); C (3) Nociunai, Kedainai d. (Or, Mw); D (4) Alytus c. (Sl, Rs); E (5) Moletai c. (Lm, Af); F (6) Kaltanenai, Sencionys d. (Gr, Fe); G (7) Merkine, Alytus d. (Sl, Ct); H (8) Trakai c. (Gr, Af); I (9) Druskininkai c. (Or, Rv); Y (10) Vilnius c. (Gr, Af).

The main chemical profile (ten samples) was characterized by the predominance of germacrene D (9.8-31.2%), while spathulenol, humulene epoxide II and caryophyllene oxide were found as the first major compounds in another three oils. One oil was determined as a mixed chemotype. Some compounds such as gamma-curcumene, alpha-cadinol, (E,E)-alpha-farnesene, beta-ylangene, beta-selinene and humulene epoxide II have been mentioned for the first time among three principal constituents in A. campestris oils. The fifty-six components made up 73.6.1-98.5% of the total content, while the remaining twenty-six volatile compounds were identified in insignificant amounts in the A. campestris essential oils.

Aerial parts of endemic pichana were harvested in December 1996 at different localities of northern Patagonia. Origin: Planicie Banderita, Dept. Confluencia, Province of NeuquCn. Habitat: altitude, 327 m; average temperature in the station, 21.8 ℃; annual precipitation, 125 mm; sandy soils. Aerial parts (5 kg, 2 kg of dried material;humidity, 11%) from four well developed plants at the fullflowering stage (December, 1996). Sample 2 : Origin: RincBn de 10s; Sauces, Dept. of Pehuenclies, Province of Neuqukn. Habitat: altitude, 750 m; average temperature in the station, 20.9 ℃; annual precipitation, 147 mm; sandy and gritty salty soils. Aerial parts (5 kg, 1.85 kg of dried material, humidity, 10%), from two well developed plants at the full flowering stage, and after several days copious rains (December, 1996). Sample 3: Origin: Coronel GBmez, Dept. General Roca, Province of Rio Negro. Habitat: altitude, 242 m; average temperature in the station, 22.5 ℃; annual precipitation, 179 mm; sandy and stony soils. Aerial parts (4.5 kg, 1.3 kg of dried material, humidity, 9%), from 12 young plants at the beginning flowering stage (December, 1996).

Fifty-four components, representing approximately 84.6-97.4% of the oil samples, were identified. The samples consisted mainly of hydrocarbons and oxygenated monoterpenes. The major constituents were limonene (28.7-56.7%), 6R-7R-bisabolone (3.2-9.1%), sabinene (0.1-11.0%) and citronellal (2.4-5.2%). Significant differences among the content of the three samples could be the result of changes in the climatic conditions (sample 2: Rincon de los Sauces, Province of Neuquen, after strong rains) or by translocations in different parts of the plant (sample 3: Coronel Gomez, Province of Rio Negro, more leaves and less stems).

The aerial parts of M. camphoratum were collected at Manaus, Amazonas (type A) and Vigia, Para, (type B).

The plants were collected from two different localities in the Amazon Region and their oils were found to be remarkably different. One oil obtained from the sample collected at Manaus was characterized by a high content of terpinolene (30.3%), limonene (13.8%) and delta-3-carene (13.2%). The main constituents found in the other oil distilled from a sample collected at Vigia were camphor (15.0%), alpha-phellandrene (20.5%) and beta-caryophyllene (8.9%)

Dry leaves of Menlba piperita L. 'Kliment-63' and 'Zefir' of 1997 crop were used.

The oil yield from 'Zefir' was 0.97% and that from 'Kliment-63' was 0.54%. The oil from 'Zefir' was found to be rich in menthol (46.2-50.2%) and menthyl acetate (16.8-22.5%). In the oil from 'Kliment-63,' the content of these components was lower, while the menthone content was higher (20.0-23.1%).

Seeds of Ocimum basilicum cv. keskenylevelu provided from Hungary, were used in this study. Potted seedlings of Ocimum basilicum were subjected to study the effect of different irrigation rigimes on the essential oil content and composition at experimental farm of college of agriculture, Tarbiat Modarres, University, located in Tehran. (1215 m above sea level, latitude 35° 43′ north, altitude 51° 8′ east). The seeds were sown in spring of 2001 in pots. The irrigation regimes to induce of water stress were: 100%, 85%, 70% and 55% of field capacity. This percentage of field capacity kept constant in the soil by daily weighting of pots. The soil was sandy-loam with 22.6% of field capacity. The harvest of whole plants was performed at the beginning of the flowering stage.

The essential oil content of herb increased from 1.12 to 1.26% as plant water deficit increased (till 70% of field capacity). The number of component of the oil of Ocimum basilicum increased as water stress increase. Amount of the main constituents of the oil such as linalool, methyl chavicol, 1,8-cineole and trans alpha-bergamotene significantly affected by water stress.

The 36 'Genovese' and 24 'Foglia di Lattuga' samples preliminarily analysed were grown in Tavazzano (MI), and harvested at flowering, from 5th to 10th August 1998. The breeding program started in 1999, by crossing several selected lines of 'Genovese' with 'Foglia di Lattuga' and 'Compatto'. Selected F1 plants were selfpollinated in 2000. Plants of the F2 (2001), F3 (2002) and F4 (2003) generations were selected on the basis of agronomic and morphologic traits, and self-pollinated. Only the seeds from self pollinated plants with satisfactory essential oil content and composition were used to obtain the next generation. In 2004, some F4 plants were replanted in order to evaluate their stability in relation to environmental variations. All leaf harvests were carried out at flowering.

Genovese' showed higher essential oil and linalool content, with almost total absence of methyl chavicol, very abundant in 'Foglia di Lattuga'.

Plant materials were collected from Chalous Road (north of Tehran province) both at the flowering stage in June and the seed stage in September 2003. The fresh plants were dried at room temperature. Dried stems/leaves (S/L) (collected during flowering stage), seeds (S) were hydrodistilled for 3 h in a Clevenger-type apparatus to produce the oils.

The major constituent in the stem/leaf oil was trans-alpha-bergamotene (77.1%), whereas the major constituent of the seed oil was pregeijerene (87.0%). Nonadecane (8.6%) were the other major constituents in the stem/leaf.

Plant material and isolation procedure: Aerial parts of the plant were collected from two regions, from Kazeroon in southern Iran and Shahr-e-kord in western Iran at the time of flowering in June 2002.

The main components of the oil of S. pilifera collected from Kazeroon, in southern Iran, were spathulenol (15.8%), cis-chrysanthenol (15.3%), beta-caryophyllene (8.4%) and cis-chrysanthenyl acetate (6.9%), while for the plant collected from Shahr-e-kord, in western Iran, they were cis-chrysanthenyl acetate (21.8%), linalool (18.9%), terpinen-4-ol (11.9%) and cis-chrysanthenol (9.2%).

Plant materials were collected during the flowering period in July 2002 from the Dumluca Mountain in the vicinity of Divrigi village of Sivas city at 1900 m altitude and Saksagan Gorge in Saimbeyli village of Adana city at 1900 m altitude.

The flower, stem and root oils of T. cadmeum ssp. orientale collected from the Adana location were characterized with alpha-thujone (25%, 5.2%), cis-linalool oxide (6.8%, 12.8%), trans-chrysanthenyl acetate (5.8%, 8.5%) for flower and stem oils, and beta-eudesmol (10.3%, 6.2%, 13.8%); in addition, stem oil contained 1,8-cineole (6.6%) and root oil contained hexadecanoic acid (6.0%), spathulenol (5.8%) and beta-muurolol (5.3%). The flower and stem oils of T. cadmeum ssp. orientale collected from the Sivas location were characterized with camphor (25.9%, 14.8%), borneol (15.4%, 25.8%) and alpha-thujone (7.8%, 5.5%); in addition, stem oil contained 1,8-cineole (7.4%) and root oil contained nonacosane (16.2%), spathulenol (6.8%) and hexadecanoic acid (5.8%).