Molecular characterization and induction of a peach beta-1,3-glucanase gene

Abstract

A peach genomic library of cultivar Stark Earligo was screened using a pea $\beta$-1,3-glucanase gene as a probe. Five clones containing $\beta$-1,3-glucanase sequence were isolated and characterized. A 3.85 Kb DNA fragment of one of the genomic clones, containing peach $\beta$-1,3-glucanase gene was sequenced in both the directions. The peach $\beta$-1,3-glucanase gene, PpGns1, encodes a proenzyme of 350 amino acids, which consists of a 38 amino acid signal peptide and a 312 amino acid mature peptide. This is the longest signal peptide of all plant $\beta$-1,3-glucanase genes so far reported. Putative TATA and CAAT boxes in the 5$\prime$ flanking region and two polyadenylation signals in the 3$\prime$ flanking region were identified. The PpGns1 was induced in in vitro-grown peach shoot cultures following treatment with a culture filtrate of Xanthomonas campestris pv. pruni and ethephon within 12-18 h. However, it was not induced following treatment with mercuric chloride. Characterization of four additional clones revealed two other different types of $\beta$-1,3-glucanase genes in peach. Southern blot analysis of total genomic DNA also indicated that $\beta$-1,3-glucanase gene belongs to a multigene family in peach.