Tomato (Lycopersicon esculentumMill.) tissues were transformed with a grape (Vitis vinifera L.) stilbene synthase cDNA, transcriptionally regulated by the cauliflower mosaic virus (CaMV) 35S promoter. Transgenic plants accumulated new compounds, not present in either wild-type or vector-transformed plants. These were identified, by high-pressure liquid chromatography, as trans-resveratrol and trans-resveratrol-glucopyranoside. The amounts oftrans-resveratrol and its piceid form were evaluated in the transgenic fruit. It was found that the content of the metabolite varied during fruit maturation to up to 53µg/g fresh weight of totaltrans-resveratrol at the red stage of ripening. This metabolite accumulation was possibly dependent on a combination of sufficiently high levels of stilbene synthase and the availability of substrates. With the aim of verifing the metabolic impairment, the amounts of chlorogenic acid and naringenin in both transgenic andwild-type ripening fruit were compared and no dramatic variation in the synthesis profile of the two metabolites was noted. To our knowledge, no data are available on the assessment of the effects of the expression of the StSy gene on other antioxidant compounds present in tomato fruit. To establish whether the presence of a novel antioxidant molecule affected the redox regulation in transgenic tomato fruit cells, the effect of resveratrol accumulation on the naturally present antioxidant pool was analysed. We showed that, in transgenic fruit which accumulate trans-resveratrol, there is an increase in the levels of ascorbate and glutathione, the soluble antioxidants of primary metabolism, as well as in the totalantioxidant activity. Conversely, the content of tocopherol and lycopene, which are membrane-located antioxidants, is not affected. Consistent with the increased antioxidant properties, the lipid peroxidation was lower in transformed than in wild-type fruit.
Antioxidant metabolite profiles in tomato fruits constitutively expressing the grapevine stilbene synthase gene
Giovinazzo G;D'Amico L;Bollini R;Sparvoli F;
2005
Abstract
Tomato (Lycopersicon esculentumMill.) tissues were transformed with a grape (Vitis vinifera L.) stilbene synthase cDNA, transcriptionally regulated by the cauliflower mosaic virus (CaMV) 35S promoter. Transgenic plants accumulated new compounds, not present in either wild-type or vector-transformed plants. These were identified, by high-pressure liquid chromatography, as trans-resveratrol and trans-resveratrol-glucopyranoside. The amounts oftrans-resveratrol and its piceid form were evaluated in the transgenic fruit. It was found that the content of the metabolite varied during fruit maturation to up to 53µg/g fresh weight of totaltrans-resveratrol at the red stage of ripening. This metabolite accumulation was possibly dependent on a combination of sufficiently high levels of stilbene synthase and the availability of substrates. With the aim of verifing the metabolic impairment, the amounts of chlorogenic acid and naringenin in both transgenic andwild-type ripening fruit were compared and no dramatic variation in the synthesis profile of the two metabolites was noted. To our knowledge, no data are available on the assessment of the effects of the expression of the StSy gene on other antioxidant compounds present in tomato fruit. To establish whether the presence of a novel antioxidant molecule affected the redox regulation in transgenic tomato fruit cells, the effect of resveratrol accumulation on the naturally present antioxidant pool was analysed. We showed that, in transgenic fruit which accumulate trans-resveratrol, there is an increase in the levels of ascorbate and glutathione, the soluble antioxidants of primary metabolism, as well as in the totalantioxidant activity. Conversely, the content of tocopherol and lycopene, which are membrane-located antioxidants, is not affected. Consistent with the increased antioxidant properties, the lipid peroxidation was lower in transformed than in wild-type fruit.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
