Fig. 4

Pharmaceutical application of biologically produced BVC 2,3-butanediol to improve cucumber growth and elicit induced resistance. a Schematic diagram showing the experimental design to observe plant responses to different concentrations of 2,3-butanediol (2,3-BDO). The 2,3-BDO solution (1000, 10, and 0.1 μM; 5 mL total) was dispensed into plates (90 mm diameter) containing filter paper (5 × 5 cm). A total of six plates containing one piece of filter paper per plate were prepared for each concentration and placed in the miniature greenhouse together with the plants. 2,3-BDO-containing plates were placed on three different position and placed in the miniature greenhouse. b Shoot fresh weight (g) assessed at 14 days after 2,3-butanediol exposure. c Disease symptom severity (0–5) in BVC-treated cucumber plants recorded at 7 days after infection with P. syringae pv. lachrymans (10⁶ CFU/mL). Photographs of the lesions were taken at 7 days after infection with P. syringae pv. lachrymans. d Pathogen population measured at 0 and 7 days after challenge with P. syringae pv. lachrymans. Air and 1 mM BTH were used as negative and positive controls, respectively. Different letters indicate significant differences between treatments (P = 0.05 according to least significant difference). Error bars indicate the standard error (n = 6). The experiments were repeated three times with six replications