Expression of the Health-Beneficial Stilbenes in Transgenic 'Spadona' Pear (Pyrus communis)

The gene encoding stilbene synthase is responsible for the synthesis of the compound resveratrol. Resveratrol and its glycosides are considered to have beneficial effects on human health, including anti-ageing, anti-inflammatory, antiplatelet and anti-carcinogenic activities. To introduce health-beneficial compounds into 'Spadona', a low chill requiring pear cultivar adapted to hot climates, leaf discs were transformed with grapevine (Vitis vinifera L.) cDNA encoding stilbene synthase, transcriptionally regulated by an enhanced cauliflower mosaic virus (CaMV) 35S promoter. Six transgenic 'Spadona' plants were obtained from 276 infected explants, corresponding to a transformation efficiency of 2.2%. Transgenic plants carrying the stilbene synthase gene were identified via polymerase chain reaction and Southern blot. Stilbene production was monitored in one-year-old rooted transgenic plants. The transgenic plants accumulated several new compounds not present in the non-transformed pear that were identified as stilbenes by highperformance liquid chromatography analysis. The major stilbenes were piceid and resveratroloside. The production of stilbene glucosides by an edible fruit may enhance its functionality as a health-promoting food. The functionality of the resveratrol analogs in the transgenic pear is enhanced by the combination of high concentrations in the transformed tissues and the fulfillment of the mouth-retention requirement due to chewing.