Figure 4.

Effects of SA biosynthesis on the senescence of tulip petals and 35S:TgNAP transgenic Arabidopsis. A, The phenotypes of TgNAP-silenced petals and the TRV control treated with 30 μM AIP. The samples in each boxed area were photographed at the same time. B and C, The total anthocyanin content (B) and expression level of TgSAG6 (C) of TRV control and TgNAP-silenced petals treated with AIP. The expression levels of the samples at the indicated time point were normalized to a TgUBQ10-like gene. Relative gene expression was calculated using the 2^–ΔΔCt method. Error bars indicate SE (n = 3). Asterisks indicate significant difference between WT and two transgenic lines based on the LSD values (**P < 0.01). Different letters denote significant differences at P < 0.05 analyzed by Tukey’s test. D, In situ detection of H₂O₂ in TRV control and TgNAP-silenced plants after AIP treatment, as revealed by histochemical staining with DAB. The samples in each boxed area were photographed at the same time and are part of a single image. E, H₂O₂ content in TRV control and TgNAP-silenced plants before and after AIP treatment. Error bars indicate SE (n = 3). Asterisks indicate significant difference between WT and two transgenic lines based on the LSD values (*P < 0.05). F, The phenotypes of 2-week-old WT and transgenic lines (#2 and #3) sprayed with or without 30 μM AIP and 200 μM SA for 5 d. G–I, Measurement of chlorophyll contents (G), DAB staining (H), and H₂O₂ contents (H) in the leaves shown in (F) on Day 5. Error bars indicate SE (n = 3). Asterisks indicate significant difference between WT and two transgenic lines based on the LSD values (*P < 0.05, **P < 0.01). Scale bar, 1.0 cm.