Fig. 1. PbrRALFs inhibit pollen tube growth.

A Pollen tubes from pear were treated with 1μM recombinant PbrRALFs, and pollen tube growth was measured. Selected PbrRALFs were expressed in pollen by RT-PCR (Supplementary Fig. S1A). Different letters indicate significant differences, as determined by one-way ANOVA (P < 0.05, n = 3). Three independent experiments were conducted. Data points are presented as the means ± s.e.m., with those significantly different from the control (CK) shown in red. B Recombinant or synthetic PbrRALF2 at different concentrations (0.025 μM, 0.05 μM, 0.075 μM, 0.1 μM, 0.25 μM, 0.5 μM, and 1 μM) was added to precultured pollen tubes. Images shown were acquired 10 h after treatment without or with purified recombinant PbrRALF2. Scale bars = 0.1 mm. Data points are presented as the means ± s.e.m. (IC₅₀ = 58 ± 20 nM for synthetic PbrRALF2 and 92 ± 12 nM for recombinant PbrRALF2). C Knockdown (antisense oligodeoxynucleotide; as-ODN) of the expression of PbrRALF2 promoted pollen tube growth (P < 0.05, n = 3), whereas s-ODN (sense ODN) and cytofection control had no function. UT indicates no treatment controls. Different letters indicate significant differences, as determined by one-way ANOVA (P < 0.05, n = 3). Three independent experiments were conducted