Figure 3.

ALA inhibits pollen germination and pollen tube length in vitro and this process might associate with calcium signaling. Pollens were germinated in simplified culture, containing 10% sucrose and 0.01% H₃BO₃, or with treatment reagent, and incubated at 25°C at 100% humidity, in the dark for 3 h. (A₁, B₁, C₁–C₄) ALA inhibits pollen germination (A₁) and pollen tube length (B₁) in vitro. Images (C₁–C₄) represent pollen germination in simplified culture alone (C₁), or with 5 mg/L ALA (C₂), 10 mg/L ALA (C₃), and 20 mg/L ALA (C₄). (A₂,A₃, B₂,B₃) Effects of CaCl₂ and EGTA at different concentrations on pollen germination (A₂,A₃) and pollen tube length (B₂,B₃). (A₄,B₄,C₅,C₆) Reciprocal effect of 10 mg/L ALA, 10⁻³ M Ca²⁺, and 10⁻³ M EGTA on pollen germination (A₄) and pollen tube length (B₄). (C₅,C₆) represent pollen germination in simplified culture with 10 mg/L ALA + 10⁻³ M Ca²⁺ (C₅), or 10 mg/L ALA + 10⁻³ M Ca²⁺ + 10⁻³ M EGTA (C₆). Images (C) were recorded under a light microscope (Nikon TE100, 400 ×), using a fitted camera (MShot Digital Imaging System), and pollen germination (A) and pollen tube length (B) were determined. Scale bar: 300 μm. More than 250 pollen grains and 45 pollen tubes were measured in each treatment and experiments were repeated three times. Different small letters in each figure represent significant difference between treatments (P < 0.05).