Proceedings of the XLVI Italian
Society of Agricultural Genetics - SIGA Annual Congress
Giardini
Naxos, Italy - 18/21 September, 2002
ISBN 88-900622-3-1
Poster
Abstract - 2.07
ANALYSIS OF ANTIOXIDANTS IN RIPENING TOMATO
FRUITS SYNTHESIZING RESVERATROL
BELLOMO
M.P.*, D’AMICO L.*, PARADISO A.**, LOSCALZO R.***, MORELLI R.****,
SPARVOLI F.*****, DEGARA L.**, GIOVINAZZO G.*
*)
Istituto di Scienze delle Produzioni Alimentari - CNR, Lecce
**)
Dipartimento di Biologia e Patologia Vegetale - UNI, Bari
***)
Istituto per la
Valorizzazione Tecnologica dei Prodotti Agricoli, Milano
****) Istituto di scienze e tecnologie molecolari - CNR, Milano
*****)
Istituto di Biologia e Biotecnologia Agraria - CNR, Milano
antioxidant, stilbene
synthase, resveratrol, Lycopersicon esculentum Mill.
Many phytochemicals, with
antioxidant activity, have significant consequences for human health and are
thought to prevent some diseases greatly. The manipulation of plant secondary
metabolism offers the opportunity to develop transgenic plants with increased
health-promoting phytochemicals content. One such pathway with potential for
manipulation is flavonoid metabolism where derivatives of cinnamic acid are
converted to a wide array of phenolic compounds with various functions in
plants. Trans-resveratrol is a polyphenolic compound produced from a reaction
catalysed by the enzyme stilbene synthase which is closely related to chalcone
synthase, the first enzyme of the flavonoid pathway. Resveratrol is believed to
play a significant role in the pharmacological property of several plants
through antioxidant, antileukaemic, or chemopreventive activities.
Expression
of stilbene synthase in
heterologous plant species is considered an attractive option because the
synthesis of resveratrol as a foreign antioxidant requires the addition of only
a single gene. A stilbene synthase cDNA from
grape was utilised to transform tomato (Lycopersicon esculentum
Mill., cv Money maker) tissues by A. tumefaciens. Transgenic
plants accumulate new compounds, not present in wild-type or vector transformed
plants, that were identified as trans-resveratrol and
trans-resveratrol-glucopyranoside by RP-HPLC analysis.
The
level synthesis of trans-resveratrol during fruit ripening was evaluated and
the accumulation of the metabolite is likely to be dependent upon a combination
of sufficient stilbene synthase levels and the availability of substrates
(coumaroil-CoA and malonyl CoA).
Fruit ripening is considered an oxidative
phenomenon which requires enzymatic activity together with low-molecular-weight
antioxidant molecules. Here we analyse the consequence of
trans-resveratrol accumulation on
synthesis of ascorbate and glutathione
in transgenic ripening fruits.