Fig. 4.

Transient expression of PwTUA1 improves Picea wilsonii pollen germination and pollen tube growth. (A) The effect of PwTUA1 on pollen germination using microprojectile bombardment. After 12 h and 24 h of incubation, the percentage germination of pollen bombarded with the GFP-only construct showed no significant difference compared with the untreated control pollen (P <0.05). Significant differences were observed in the percentage of germination of pollen bombarded with 2.5 μg and 5 μg of the PwTUA1 gene construct compared with untreated pollen or GFP-transformed pollen (P <0.05). Error bars indicate averages from the number of pollen tubes measured (n≥81). (B) The effect of PwTUA1 on pollen tube length using microprojectile bombardment. After 12 h and 24 h of incubation, no significant differences were detected in the length of pollen tubes bombarded with GFP compared with untreated pollen tubes (P=0.47). Significant differences were seen in the length of pollen tubes bombarded with 5 μg of PwTUA1 compared with untreated pollen or GFP-transformed pollen (P <0.05). Error bars indicate averages from the number of pollen tubes measured (n≥65). (C) Microscopic analysis of pollen tube co-expression 24 h after gene transfer of different doses of PwTUA1 with GUS and GFP. Upper panel: fluorescence images. Lower panel: transmitted light images. The data were obtained from three independent experiments, and every condition was tested three times. Bars=100 μm.