Different expression of Pp-LTP1 and accumulation of Pru p 3 in fruits of two Prunus persica L. Batsch genotypes

The full-length cDNAs of Pp-LTP1 and Pp-LTP2, two members of the lipid transfer protein (LTP) multigene family in peach (Prunus persica L. Batsch), have been isolated along with the proximal promoter and the complete genomic sequence of Pp-LTP1. As observed in other plant species, Pp-LTP1 is organized in two exons and, according to the deduced amino acid sequence of the secreted protein, it encodes the 9 kDa allergenic protein Pru p 3. Pp-LTP1 transcripts and Pru p 3 protein markedly accumulate in epicarp of ripe fruit in all of the peach and nectarine varieties examined (including 'Royal Gem') with the exception of 'Rita Star' that shows weak specific mRNA hybridization signal and no Pru p 3 accumulation. SDS-PAGE clearly displays a different banding pattern in correspondence of 9 kDa between 'Rita Star' and 'Royal Gem'. In immunoblotting analysis, performed using sera of eight LTP pos+ patients, a strong band is present when using 'Royal Gem' epicarp extract but not in the case of 'Rita Star'. According to these data, 'Rita Star' appears an interesting model to better elucidate the role of LTP in fruit development and allergenic reactions.