Preliminary characterization of the Pp-endoPG gene promoter region in NMF, MF and Slow Melting peach genotypes

In peach, different texture characteristics (NMF, MF, Slow Melting) are linked to different expression of an endopolygalacluronase (Pp-endoPG) gene [1]. To individuate regulatory motifs correlated to the different expression of Pp-endoPG, the promoter regions of Pp-endoPG were studied in NMF 'Oro A', MF 'Bolero' and SM 'Big Top'. The 5'-UTR regions of the 'Oro A' and 'Bolero' m Pp-endoPG clones (m-O and m-B) and of the 'Big Top' Bt one were isolated by Genome Walking (GW). In 'Bolero' (heterozygous at the endoPG locus), by PAMSA analysis on GW products, the M clone was isolated and discriminated from m-B. The m and Bt promoter sequences were very similar and different from that of M PLACE analysis individuated putative Regulatory Elements linked to the responses to hormones (ABA), light and stresses, and a microsatellite (GAn) of different length in the different clones possibly usable as a MAS marker. An Ethylene Responsive Element was present in the promoter sequences of m-B, M and Bt Pp-endoPG but not in that of m-O, suggesting a possible relationship with diminished expression of Pp-endoPG in NMF 'Oro A' despite the observed higher ethylene production. [1] Ghiani et al. (2011) J. Am. Soc. Hortic. Sci. 136, 61-68