V 730 spectrophotometer

250 mg of leaf sample was homogenized with 5 mL of Trichloroacetic acid (TCA) 0.1%. The supernatant was taken after centrifugation (10 000 rpm/5 min) and considered as the extract of H₂O₂ and malondialdehyde (MDA).
To quantify H₂O₂ content, 0.2 mL of extract was added to 0.8 mL of phosphate potassium buffer (10 mM, pH7), then, 1 mL of KI (1 M) was added to the mixture. The set was incubated 10 min at room temperature, and the absorbance was measured at 390 nm (Spectrophotometer JASCO V-730, made in Japan). H₂O₂ content was measured using a standard curve of H₂O₂ [33 (link)].
Lipids peroxidation was evaluated by quantifying leaf MDA content. It was estimated using the method described by Sarker and Oba [33 (link)]. Briefly, 1 mL of the extract was added to 4 mL 20% TCA containing Thiobarbituric acid 0.5%. The set was heated at 95 °C for 10 min. After centrifugation (10 000 rpm/5 min), the absorbance was noted at 532 nm and 600 nm (Spectrophotometer JASCO V-730, made in Japan). MDA content was estimated using the extinction coefficient of MDA at 532 nm which is 155 mM⁻¹ cm⁻¹.

The bacterial strains and plasmids used in this study are described in Table 1. Pseudomonas cannabina pv. alisarensis (Pcal) strain KB211 was used as the pathogenic strain to inoculate cabbage and oat. Pcal strains were grown on mannitol-glutamate (MG; Keane, Kerr & New, 1970 (link)) medium, Luria-Bertani (LB; Sambrook, Fritsch & Maniatis, 1989 ) medium, or King’s B (KB; King, Ward & Raney, 1954 (link)) medium at 28 °C, and E. coli strains were grown on LB medium at 37 °C. Antibiotics used for selection of Pcal strains and E. coli strains included (in µl/ml): rifampicin, 50; kanamycin, 50; ampicillin, 50; chloramphenicol, 10. Before Pcal inoculation, bacteria were suspended in sterile distilled H₂O, and the bacterial cell densities at 600 nm (OD₆₀₀) were measured using a JASCO V-730 spectrophotometer (JASCO, Tokyo, Japan).

All bacterial strains and plasmids used in this study are shown in Table 1. Pseudomonas syringae pv. actinidiae biovar 1 (Psa1; MAFF 613022), biovar 3 (Psa3; MAFF 212115), biovar 3 (Psa3-07; MAFF 212107), biovar 5 (Psa5; MAFF 212056), and biovar 6 (Psa6; MAFF 212133) were a gift from NARO Genebank, Ibaraki, Japan. Psa biovars were used as the pathogenic strains to inoculate kiwifruit plants. All Psa strains were grown at 28 °C on King’s B (KB) [67 (link)] agar. For inoculation, Luria–Bertani (LB) [68 ] broth was used to grow bacterial cultures from plates for 18 h at 28 °C. Before inoculation, bacteria were suspended in sterile distilled H₂O, and the bacterial cell densities at 600 nm (OD₆₀₀) were measured using a JASCO V-730 spectrophotometer (JASCO, Tokyo, Japan).