(A–E) Quantitative analysis of pollen tube length (A and C), germination rate (B and D), and bursting rate (E) under different concentrations of exogenously applied SA (A and B) or MeSA (C–E). SA inhibits pollen tube germination and elongation while MeSA promotes pollen tube elongation and causes pollen tubes to burst at 1 mM MeSA or higher.
(F) Representative pollen tube phenotype under different concentrations of SA or MeSA. Pollen tube length and germination rates were normalized to the respective control. Pollen grains were germinated for 3 h at 28°C with pollen germination medium. Scale bar, 100 µm.
Error bars show ±SEM; n > 100. *p < 0.05, **p < 0.01 (Dunnett’s test). ND, no significant difference.