Fig. 1

Identification of ABA from the supernatant of the Bl or Bl-cyp strain grown on Nfb. a Comparison of the Cyp expression in pET28a-cyp/BL21, BL21, and pET28a/BL21 cultured with different concentrations of IPTG in LB at 37 °C for 4 h, as shown by SDS-PAGE. M represents the protein marker, 1–2 represent the BL21 and pET28a/BL21 cultured with 0.1 mM IPTG in LB; and 3–6 represent pET28a-cyp/BL21 cultured with 0.1, 0.2, 0.3 or 0.4 mM IPTG in LB, respectively. b Comparison of the mRNA expression of the cyp gene in the Bl and Bl-pET28a strains with that in the Bl-cyp strain grown in Nfb medium based on qRT-PCR. c-d Detection of the ABA from the ABA standard solution (c) and the supernatant of the Bl grown on Nfb (d) or LB medium (e) by typical chromatography. The green circles represent the ABA at 4.54 min and at 5.12 min. f-g Detection of ABA from the supernatants of the Bl grown in Nfb medium (f) and an ABA standard solution (g) based on typical mass spectrometry. The red circles indicate the ABA on the 50-ppm ion trace at m/z 263. h Comparison of the ABA concentrations on the supernatants from the Bl-cyp strain with those from the Bl and Bl-pET28a strains grown in Nfb at the different times according to ELISA. Data represent the means ± SD, n = 6–8 per group. *P < 0.05, ** P < 0.01; NS, not significant. Statistical significance was assessed using a one-way ANOVA, followed by Tukey’s test