Changes in pathogenesis-related proteins in pepper plants with regard to biological control of phytophthora blight with <Emphasis Type="Italic">Paenibacillus illinoisensis</Emphasis>

To evaluate the biocontrol effectiveness of chitinase-producing bacterium, Paenibacillus illinoisensis strain KJA-424 against pathogenic strain of Phytophthora capsici in pepper plants, growth response and kinetics of pathogen related (PR) proteins were estimated after inoculation with P. capsici (P), and with a combination of P. capsici and strain KJA-424 cell culture (P+A). Fresh weight and chlorophyll content in shoots at P+A-treated plants significantly increased by 23.4 and 34.2%, respectively after 7days of inoculation, compared to P-treated plants. Root mortality in P+A-treated plants was significantly reduced compared to P-treated plants. Seven days after inoculation, the activities of -1,3-glucanase, cellulase and chitinase in P-treated roots had decreased by 54.8, 36.5 and 52.8%, respectively, compared to P+A-treated roots, while those in P-treated leaves increased by 22.8, 36.3 and 23.8%, respectively, compared to those in P+A-treated leaves. The activities of -1,3-glucanase, cellulase and chitinase in roots are negatively correlated with root mortality. All these results suggest that the inoculation of an antagonist, P. illinoisensis alleviates root mortality, reduction of PR proteins in roots, and activates of PR proteins in leaves infected by P. capsici.