Abstract
Three bacteria endophytes that colonize flowering dogwood (Cornus florida) suppressed Erysiphe pulchra powdery mildew disease severity. The three bacteria identified as Stenotrophomonas sp. (B17A), Serratia marcescens (B17B), and Bacillus thuringiensis (IMC8) were assessed for plant defense enzymes associated with plant protection. Detached leaves inoculated with powdery mildew were spray treated with the selected bacterial isolates and incubated for 15 h, 26 h, 48 h and 72 h and then analyzed for activation of defense enzymes and Pathogenesis related (PR) proteins associated with induced systemic resistance (ISR) as a potential mode of action against powdery mildew. At each time point post treatment with the bacteria, leaf tissue was ground in liquid nitrogen and stored at -70°C for biochemical assay of enzyme activity. This data set presents the activation of enzyme activity for peroxidase (PO), polyphenol oxidase (PPO) and β -1,3-glucanase at 15 h, 26 h, 48 h and 72 h post treatment with bacteria as indicated by a change in absorbance min -1 mg-1 per gram fresh weight of leaves. The gene expression of the corresponding pathogenesis related (PR) protein for each bacterial treatment compared to the control was also analyzed using Real time PCR and five primers targeting PR1, PR2, and PR5. While changes for PO, PPO, and β -1,3-glucanase enzyme activities were observed at different time points post treatment with all three bacteria, expression of PR protein was detected for PR1, but it was negligible for PR2, and PR5.