Evolution of the allergenic potential in peach and nectarine fruits during ripening

According to recent epidemiological studies, in many countries food allergies increased strongly during recent decades. Allergies to fruits represent also an emerging problem and studies should be addressed to identify allergens, evaluate the allergenic potential of different species and varieties and, possibly, produce hypoallergenic fruits. In peach, the major allergen has been identified as a Lipid Transfer Protein (LTP) and in the present research the evolution of the allergenic potential of different peach and nectarine varieties has been monitored throughout ripening and in relation to postharvest treatments. Fruits of peach cv. ‘Royal Gemm’, ‘Zorzi’, of nectarine cv. ‘Rita Star’, ‘Early Giant’ and ‘Maria Dorata’, and of flat type (Platicarpa) were harvested in correspondence of commercial ripeness and allowed to ripen at room temperature or stored at 4°C for 3 weeks. Northern blot analyses were carried out on total RNA extracted from epicarp and mesocarp to study Pp-LTP1 gene expression. Immunological studies were performed by means of a polyclonal antibody raised against the purified protein. Expression analysis showed that Pp-LTP1 transcripts accumulated only in the epicarp. With the exception of cv. ‘Rita Star’ the strongest accumulations have been detected in epicarp of all varieties at harvest. With the exception of Platicarpa, a decreasing trend of expression was observed in fruits kept in air and at 4°C. Western blots revealed the presence of LTP only in epicarp of all studied varieties, but not in ‘Rita Star’, and showed that the protein markedly increased in full ripe fruits maintained in air. This might indicate the presence of a lag between gene transcription and accumulation of secreted functional LTP. According to these results, cv. ‘Rita Star’ appears to be a variety with a reduced allergenic potential.