Abstract：Chitinase (Chi) which is an important pathogenesis-related protein can degrade cell wall components of fungal pathogens, and be induced by salicylic acid (SA), ethylene, plant pathogenic fungi, bacteria and virus. To explore the function of chitinaseⅢ (ChiⅢ) gene in Pyrus bretschneideri Yali, the CDS of ChiⅢ was cloned from Yali which was named PbChiⅢ (GenBank accession No. KJ872675), and the CDS length of PbChiⅢ was 897 bp. Homology analysis showed that the amino acid sequence of PbChiⅢ was highly homologous with Pyrus Huangguan (ACM45715.1), and the nucleotide acid sequence had the closest relationship with Huangguan (FJ589785.1). Quantitative Real-time PCR (qRT-PCR) analysis revealed that PbChiⅢ highly expressed in root and fruit, and its expression had extremely significant difference compared with stem and leave (P＜0.01). Expression of PbChiⅢ was regulated by SA, and enhanced up to the peak at 12 h after treatment with SA during 96 h, and had extremely significant difference compared with control (P＜0.01). PbChiⅢ protein successfully expressed by prokaryotic expression system and a specific protein band of 31 kD was successfully induced. The CDS sequence of PbChiⅢ gene was firstly obtained from Yali and researched the expression of PbChiⅢ in different tissues and the expression characteristic after treatment with SA. This study provided informative references for further study of the function of PbChiⅢ.
