Cloning, characterization, and expression of the gene encoding polygalacturonase- inhibiting proteins from strawberry

Polygalacturonase-inhibiting proteins (PGIP) play important roles in the defense against plant pathogens, especially fungi. The sequence of strawberry PGIP gene was obtained using reverse transcription PCR (RT-PCR) and its expression in different tissues was studied by semi-quantitative RT-PCR. A cDNA fragment of FaPGIP gene was cloned and the sequence analysis shows that the fragment contains a full ORF of 999 bp encoding 332 amino acids. The FaPGIP gene from genomic DNA shows a single 168bp intron that is efficiently spliced out of the FaPGIP pre-mRNA transcript. The FaPGIP has a high degree of identity with previously isolated PGIP genes and the encoded polypeptide shows all the characteristic features of PGIP peptides. The 3 dimensional model of the protein contains 12 \alpha-helices and 21 \beta-sheets, and the center LRR structural domain is composed of 10 tandem LRR motifs. The semi-quantitative RT-PCR revealed FaPGIP gene displaying high expression levels in fruit and leaf, middle expression in flower and root, and weak expression in stem. The expression level of FaPGIP gene is particular to tissues.