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Three New Zealand grown tomato (Lycopersicon esculentum L.) cultivars, Aranka, Encore, and Flavourine, were analysed for colour (CIELAB L(*) a(*) b(*) values), ascorbic acid, total phenolics, lycopene, and total antioxidant activity (ABTS assay). Colour analyses of the air-dried tomatoes showed that the colour degradation as measured by the L(*) a(*) b(*) values was minimal, and the colour was not significantly different (p < 0.05) between each of the dried cultivars. In general, there was no significant difference (p < 0.01) between the fresh cultivars in terms of antioxidant components or total antioxidant activity. The average values obtained for antioxidant components in the three fresh cultivars were: ascorbic acid, 276 mg/100 g DM, total phenolics, 613 mg gallic acid equivalents (GAE)/100 g dry matter (DM) and lycopene 38 mg/100 g DM. Total antioxidant activity of the fresh cultivars was 2917 micromole Trolox equivalent antioxidant capacity (TEAC)/100 g DM. Following forced air-drying treatment at 42 degrees C for 48 hr, all cultivars showed significant decreases in ascorbic acid, total phenolics and total antioxidant activity, and increases in extractable lycopene contents. This study was undertaken to identify cultivars that would provide the best colour and nutrient contents after commercial air drying.

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The objective of this study was to compare the antioxidant activities, total phenolics, lycopene and ascorbic acid content of four commercial tomato cultivars (Excell, Tradiro, Flavourine and Campari) of New Zealand, grown under similar hydroponic conditions. The mean antioxidant activity of the four cultivars, as measured with the ABTS radical decolourization assay, ranged from 2329 to 3268 micromole TEAC/100 g dry matter (DM) in the hydrophilic extracts and from 178 to 303 micromole TEAC/100 g DM in the lipophilic extracts. The major antioxidant components per 100 g DM were phenolics (343-451 mg gallic acid equivalents in hydrophilic extract and 53-74 mg gallic acid equivalents in lipophilic extract), flavonoids (175-204 mg rutin equivalents), ascorbic acid (153-195 mg) and lycopene (33-54 mg). Ascorbic acid and flavonoids were found to contribute 28-38% and 29-34%, respectively, to the antioxidant activity of the hydrophilic extract of tomatoes. The results showed that the smallest cultivar (Campari) had significantly (P < 0.05) higher antioxidant activities, total phenolics and flavonoids than the larger sized cultivars (Excell, Tradiro and Flavourine). This could be attributed to the significantly (P < 0.05) higher surface area/volume ratio of the small cultivar (0.15) when compared with the large-sized cultivars (0.10-0.12). The tomato cultivar (Flavourine) with a brighter red colour (higher a*/b* value), had a higher lycopene content as well, which suggests that the a*/b* value of tomatoes can be used as an indicator of their lycopene content. The phenolics (r = 0.84**) and flavonoids (r = 0.88**) were significantly related to the antioxidant activity of the hydrophilic extract, which suggests that measurement of total phenolics or flavonoids can be used as indicators of the antioxidant activity of tomatoes.

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An Agrobacterium tumefaciens-mediated transformation method has been developed for onions (Allium cepa L.) using immature embryos as the explant source. Transgenic plants were recovered from the open-pollinated onion cultivar Canterbury Longkeeper at a maximum transformation frequency from immature embryos of 2.7%. The method takes between 3-5 months from explant to primary regenerant entering the glasshouse. Multiple-shoot formation from primary transgenic material made possible the clonal multiplication of transformants. The binary vector used carried the nptII antibiotic resistance gene and the m-gfp5-ER reporter gene. Transgenic cultures were initially screened for their ability to fluoresce and to grow in the presence of geneticin (5-25 mg/l). The transgenic nature of individual plants was confirmed by Southern blot analysis.

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Particle bombardment and Agrobacterium-mediated DNA delivery into immature embryos and microbulbs were used to investigate the expression of the uidA gene in in vitro onion cultures. Both methods were successful in delivering DNA and subsequent uidA expression was observed. Optimal transient ß-glucuronidase activity was observed in immature embryos that had been pre-cultured for three days and bombarded at a distance of 3 cm from the stopping plate, under 25 in Hg vacuum, using 900-1300 psi rupture discs. The CaMV35S-uidA gene construct gave five fold higher transient ß-glucuronidase activity than the uidA gene construct regulated by any of four other promoters initially chosen for high experession in monocotyledonous tissues.