Endopolygalacturonase Gene Polymorphisms : Asset of the Locus in Different Peach Accessions

Endopolygalacturonase (endoPG) plays a pivotal role in determining peach [Prunus persica L. (Batsch)] fruit characteristics. Different Pp-endoPG genes or allelic variants have been described, characterized by different polymorphisms: insertions-deletions (InDels) and single nucleotide polymorphisms (SNPs). Eighty-five peach accessions (comprising commercial cultivars, F1 progenies of selected crosses, and three haploid seedlings) with different flesh softening patterns (Non Melting: NM; Melting: M; Slow Softening: SS; Stony Hard: SH) were screened by exploiting specific polymorphisms, with the aim to characterize their asset at the endoPG locus and evaluate a potential relationship with fruit flesh texture phenotype. The results of InDel analysis allowed to distinguish, by a simple genotyping procedure, NM flesh phenotypes from the others. Further information arose from this analysis, showing that two Pp-endoPG genes, i.e., Pp-endoPGm (Ppa006839m), involved in the determination of the Melting/Non Melting trait, and Pp-endoPG_M (Ppa006857m), involved in the determination of the Clingstone/Freestone trait, always co-segregate, and that SS Big Top possesses a “null” Pp-endoPG allele. Cleaved Amplified Polymorphic Sequence (CAPS) analysis allowed to preliminarily discriminate the Pp-endoPG variants of the SS and SH accessions considered. The integrated use of the considered polymorphisms in a high number of peach accessions proved useful, by individuating the different gene variants and their combinations, to describe the structure of the endoPG locus in different genotypes.