Figure 4: ROS induce pollen tube rupture in vitro.
(a) H2O2-induced tube rupture. The entire sample immediately prior to application of ROS (0 s) and when a majority of the pollen tubes has ruptured (3 m 40 s) (arrowheads point to cytoplasmic discharges) is shown in full. Magnified views of the first two rupturing pollen tubes (1, 2) are shown in between. * and Δ are reference points for tubes 1,2. Supplementary Movie 1 shows the entire time series in real time. (b) FeSO4 induced RFP-labelled sperm cell (Sp) discharge. The image was captured in a single 250 ms exposure. Supplementary Movie 2 shows a time series of ROS-induced sperm release. Scale bars (a,b), 50 μm. (c) Quantification of superoxide (generated by X/XO), H2O2 and hydroxyl free radicals (generated by FeSO4-mediated Fenton reaction) induced pollen tube rupture. (d–f) Hydroxyl free radical scavengers suppressed ROS-induced tube rupture. Data=average±s.e.m. from at least triplicate from an analysis representative of three independent experiments; n=total number of pollen tubes examined. **P≤0.01 by Student’s t-tests.
