Fig. 1.

The effect of H₂O₂ (hydrogen peroxide) levels on fibre elongation. (A) H₂O₂ contents in G. hirsutum ovules and fibres at different development stages (mean±SE, n=3). 0 DPA, 0 days post-anthesis (DPA) ovules; 5–20 DPA, 5–20 DPA fibres. (B) ASA (ascorbic acid) and DHA (dehydroascorbic acid) contents and ASA/DHA ratios in 0 DPA ovules, 5 DPA, 10 DPA, 15 DPA and 20 DPA fibres (mean±SD, n=3). (C) In vivo histochemical staining for ROS in 0 DPA ovules with 10 µM 2′,7′-DCFDA after treatments for 4h with different concentrations of H₂O₂ and DPI. The results were observed using stereo fluorescence microscopy. The upper panel shows the fibre growth after 10 days in culture with the different treatments; the middle panel shows fluorescence images; the lower panel shows bright field images. (D) The ability of H₂O₂ to rescue the 1 µM DPI-induced suppression of fibre elongation. The upper panel shows fibre growth after 7 days in culture with the different treatments; the middle panel shows fluorescence images with in vivo histochemical staining of ROS in 0 DPA ovules with 10 µM 2′,7′-DCFDA after treatments for 4h with different concentrations of DPI and H₂O₂; the lower panel shows bright field images. (E, F) The fibre lengths in response to the different treatments in D and C (n=3; Student’s t test; significant differences compared with the control: *P<0.05, **P<0.01).