Fig. 4

Each single homozygous S-RNase induces alterations in the actin cytoskeleton and DNA degradation in self-pollen and pollen tubes in vitro. A Typical images of actin cytoskeletal configuration in cross-incompatible and cross-incompatible pollen tubes after 30 min of various treatments. Bar = 20 mm. B Quantification of pollen tubes showing F-actin depolymerization in response to 30 min of various treatments. Different letters indicate significant differences, as determined by ANOVA followed by Tukey’s multiple comparison test (P < 0.05; n = 10); error bars indicate standard error. C TUNEL-based detection of programmed cell death (PCD) in pollen tubes. Typical images of TUNEL signals in pollen tubes during cross-compatible (CC, left) and cross-incompatible (CI, right) responses. DAPI staining results indicate that the TUNEL-CI signals are localized in the nuclear DNA. “Positive” indicates that PCD has occurred in the pollen tube, “negative” indicates no PCD. Bar = 10 μm. D Number of pollen undergoing PCD among cross and self-pollinations in ‘S1S2’, ‘S1S1’ and ‘S2S2’. Samples were processed for TUNEL staining, followed by statistical analysis. Experiment was repeated three times; each experiment included at least 100 measurements. Asterisk indicates significant statistical difference between CC treatment and CI as evaluated by ANOVA and Tukey’s test: P < 0.05; n = 10; error bars indicate standard error