Table 3. Field performance and squalene accumulation by select, segregating transgenic lines.

Plant line	Height (cm)	Weight (kg)	Leaf area (cm2)	Photosynthesis (μmol CO2/m2•sec)	Conductance (mol H2O/m2•sec)	Ci (μmol CO2/mol air)	Squalene (μg/g fw)
Wild type (control)	46.8 ± 13.6	1.0 ± 0.4	13,887 ± 4,586	23.4 ± 2.2	0.6 ± 0.1	254.0 ± 8.6	nd
32–	50.2 ± 12.9	1.0 ± 0.3	11,313 ± 3,356	21.5 ± 3.1	0.5 ± 0.1	249.3 ± 19.0	nd
32+	18.9 ± 5.8	0.2 ± 0.1	2,398 ± 1,128	6.9 ± 2.2	0.6 ± 0.2	327.8 ± 11.2	79.9 ± 36.6
42−	58.4 ± 8.1	1.1 ± 0.3	11,704 ± 2,956	21.3 ± 2.1	0.5 ± 0.1	249.6 ± 15.6	nd
42+	39.5 ± 6.3	0.6 ± 0.1	7,776 ± 1,650	21.4 ± 2.5	0.4 ± 0.1	243.2 ± 20.5	112.0 ± 27.8

Segregating (T₁ generation) seed for transgenic lines targeting SQS and FPS to the chloroplast under the direction of trichome-specific promoters (line 32) or constitutive promoters (line 42) were grown under greenhouse conditions for approximately 6 weeks prior to transplanting them to the field. Plants were chosen randomly for field planting and the plants grown for a total of 60 days, which is approximately two-thirds of a full growth cycle. The plants were screened several times throughout the growing season, but the data shown are for the final data collection at the end of the field season. For squalene determinations, two leaf discs of 2 cm diameter collected from the first fully expanded leaf from the top of each plant were extracted with organic solvent and their squalene content determined by GC–MS. For line 32, 6 plants accumulated significant squalene (denoted as +), while18 others did not (−). For line 42, 14 plants accumulated squalene (+) and 8 did not (−). Six control plants were evaluated. nd no squalene detected, below the detection limit of ∼ 0.5 μg/g fw. Measurements of photosynthetic gas exchanges were conducted between 10AM and 12PM on a cloudless day with light intensity of 1,500 μmol/m²•sec with a LI-COR 6400 portable instrument