Cloning and Expression Analysis of the Protease Inhibitor StPIa3 Gene from Potato

Cloning and Expression Analysis of the Protease Inhibitor StPIa3 Gene from Potato

Proteinase inhibitor (PI) is one class of small molecule protein involved in disease resistance and defense stress reaction in plants and belongs to a kind of pathogen related protein (PR protein), and thereof includes potato (Solanum tuberosum) protease inhibitor family. PI mainly participates in the disease resistance and the regulation of endogenous protease. In this study, we cloned the overall length cDNA of the PI gene StPIa3 from potato cultivar, ‘Middle potato No.3’ by means of the RACE method after inoculating Ralstonia solanacearum. The analysis to the sequence demonstrated that the gene consisted of 661bp of nucleotides, contained complete open reading frame which coded 152 amino acids. The amino acid sequence coded by StPIa3 gene was highly homologous with the other members of the type PI-II of potato and the PI of tomato (Solanum lycopersicum). The analysis to the induced expression of this gene by means of RT-PCR and Real-time PCR revealed that the StPIa3 gene can be induced to express at high level by R. solanacearum. The tissue location analysis showed that this gene expression was with tissue specificity, which mainly occured at the vascular system in the stem and leaf.