There is a growing interest in producing food plants with increased amounts of antioxidants because of their potential health benefits. In particular polyphenolic secondary metabolites, such as flavonoids and stilbenes, have been investigated for their ignificant antioxidant activity, important both for plant physiology and human nutrition. With the aim of generating plants and fruits with increased antioxidant capability and a wider health benefits, the tomato flavonoid route was modified through the over-expression of the grape stilbene synthase cDNA under a constitutive promoter (Giovinazzo et al., 2005) and a tissue specific, TomLoxB, promoter (D'Introno et al., 2009). The expression of the StS gene in tomato tissues resulted in the synthesis of new compounds, identified as trans-resveratrol and trans-resveratrol-glucopyranoside with a different tissue specificity, both depending on the promoter and the availability of precursors in ripening tissues (Nicoletti et al., 2007). The level synthesis of compounds belonging to different class of polyphenols (i.e. chlorogenic acid, naringenin, rutin, and quercetin), were monitored in both transgenic and wild type fruits tissues at different stages of maturity. Furthermore, we wanted to analyse whether the synthesis of resveratrol in tomato fruit affected the redox status of transformed tomato tissues. The results indicated that the stilbenes and the flavonoids found in transgenic plants were mainly detected as conjugates. This could increase the bioavailability of these compounds. Hence, the structure of the stilbenes synthesized in the transformed tomato plants is of considerable interest from a nutritional point of view. Moreover, the synthesis of resveratrol affected the levels of other antioxidants. In particular, ascorbate and glutathione pool increased in the transformed tissues, proportionally to the amount of the resveratrol. Noteworthy, the transformed fruits also showed increased activities of different enzymes involved in redox homeostasis, (such as ASC - redox enzymes and catalase) which finally resulted in a lower levels of lipid peroxidation. The alteration induced by the presence of resveratrol on cell metabolism will be discussed.
Changes in oxidative processes and antioxidant systems during ripening in resveratrol producing tomato fruit
G Giovinazzo;A Paradiso;I Nicoletti;A Santino;
2011
Abstract
There is a growing interest in producing food plants with increased amounts of antioxidants because of their potential health benefits. In particular polyphenolic secondary metabolites, such as flavonoids and stilbenes, have been investigated for their ignificant antioxidant activity, important both for plant physiology and human nutrition. With the aim of generating plants and fruits with increased antioxidant capability and a wider health benefits, the tomato flavonoid route was modified through the over-expression of the grape stilbene synthase cDNA under a constitutive promoter (Giovinazzo et al., 2005) and a tissue specific, TomLoxB, promoter (D'Introno et al., 2009). The expression of the StS gene in tomato tissues resulted in the synthesis of new compounds, identified as trans-resveratrol and trans-resveratrol-glucopyranoside with a different tissue specificity, both depending on the promoter and the availability of precursors in ripening tissues (Nicoletti et al., 2007). The level synthesis of compounds belonging to different class of polyphenols (i.e. chlorogenic acid, naringenin, rutin, and quercetin), were monitored in both transgenic and wild type fruits tissues at different stages of maturity. Furthermore, we wanted to analyse whether the synthesis of resveratrol in tomato fruit affected the redox status of transformed tomato tissues. The results indicated that the stilbenes and the flavonoids found in transgenic plants were mainly detected as conjugates. This could increase the bioavailability of these compounds. Hence, the structure of the stilbenes synthesized in the transformed tomato plants is of considerable interest from a nutritional point of view. Moreover, the synthesis of resveratrol affected the levels of other antioxidants. In particular, ascorbate and glutathione pool increased in the transformed tissues, proportionally to the amount of the resveratrol. Noteworthy, the transformed fruits also showed increased activities of different enzymes involved in redox homeostasis, (such as ASC - redox enzymes and catalase) which finally resulted in a lower levels of lipid peroxidation. The alteration induced by the presence of resveratrol on cell metabolism will be discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
