Cloning, characterization and expression of the gene encoding polygalacturonase-inhibiting proteins (PGIPs) of peach [prunus persica (L.) Batch]

Polygalacturonase-inhibiting Proteins (PGIPs) are plant proteins that counteract fungal Polygalacturonases (PGs), which are important virulence factors. As defense proteins, PGIP can efficiently limit fungal invasion. In this study, a full-length cDNA of PPGIP1 gene (peach PGIP gene copy no.1) has been cloned from peach [prunus persica (L.) Batch] variety 'Okubo', which is resistant to fungal diseases such as peach scab. Sequence analysis revealed that the cDNA of PPGIP1 is 1380 bp in length and that its containing open reading frame (ORF) encodes for a polypeptide of 330 amino acids. The PPGIP1 gene from genomic DNA shows a single 147 bp intron that is efficiently spliced out of the PPGIP1 pre-mRNA transcript. The PPGIP1 has a high degree of identify with previously isolated PGIP genes and the encoded polypeptide shows all the characteristic features of PGIP peptides. Analysis of genomic organization and expression indicate that the PPGIP1 gene is one of a low copy number gene family with three copies in peach genome and its expression can be induced by exogenous salicylic acid (SA).