Figure 1.

Pollen tube growth was observed under UV fluorescent microscopy. (A–E) Self-pollinated pistils at 5 min, 10 min, 30 min, 1 h, and 2 h, respectively. Pollen grains germinated normally, but the pollen tubes were soon inhibited at or near the stigma surface and may block with callose. Subsequently, pollen tubes nearly stopped growth at 30 min, and few pollen tubes reached into the style. (F–J) Cross-pollinated pistils at 5 min, 10 min, 30 min, 1 h, and 2 h, respectively. Pollen grains and pollen tubes germinated and grew normally. A majority of pollen tubes reached the style base at 1–2 h after cross-pollination. Bars: A–H, 100 μm; I–J, 200 μm.