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Abstract
Fruits and vegetables play a very significant role in human nutrition. The percentages of selected nutrients contributed by fruits and vegetables as a group according to the amount consumed per person per year are shown in Fig. 1 (10). Vitamins A and C are supplied in the largest amounts by this food group, however, the other 5 nutrients are also supplied in important amounts by fruits and vegetables. Fruits and vegetables are indeed very low in calories, supplying only 9% of the total. These examples illustrate the 7 nutrients supplied in the greatest amounts from fruits and vegetables according to food disappearance data. Other essential vitamins and minerals contributed by fruits and vegetables are discussed later.
Ethylene is a known causal factor in the decay and senescence of fruits and vegetables. The aim of the present study was to incorporate a gene for control of ethylene biosynthesis in order to prevent or delay the senescence of the cauliflower curds. We first developed a reproducible transformation system using marker genes for beta glucuronidase (GUS) and antibiotic resistance. Brassica oleraceae L. var. botrytis was transformed by inoculating hypocotyl explants with the Agrobacterium tumefaciens strains C58 or EHA101 containing plasmids pAG5110, pAG5420, or pAG5520. The plasmid pAG5110 contains the genes for neomycin phosphotransferase II (NPTII) and GUS. The plasmids pAG5420 and pAG5520 contain a functional gene for S-adenosylmethionine hydrolase (SAMase) under an ethylene or wound inducible promoter, respectively. Hypocotyl explants were screened on regeneration medium with kanamycin for selection of transformants. Shoot regeneration occured within 4-6 weeks and morphologically normal plants developed within 3-4 months. The transgenic nature of the plants was confirmed by histochemical GUS assay, an ELISA based NPTII assay and Southern blot analysis. Transgenic plants outplanted in the greenhouse are being evaluated and selfed to study expression and inheritance pattern of the introduced trait.