Qiu Yi Lan, Liu Ru Shi, Tian Hui Qiao
School of Life Sciences, Hunan Normal University, Changsha 410081, 2School of Life Sciences, Xiamen University, Xiamen 361005.
Fen Zi Xi Bao Sheng Wu Xue Bao. 2007 Aug;40(4):253-61.
Potassium antimonite was used to locate calcium in the synergids of lettuce (Lactuca sativa L) during their development. The two synergids on 3d before anthesis formed evident polarity with most cytoplasm located in the micropylar end and nucleus in the middle and a big vacuole in the chalazal end. At this time, calcium precipitates were a few in both cells. Calcium precipitates in the two synergids began to increase on 2d before anthesis. Synergid wall in the micropylar end thickened on 1d before anthesis, in which many calcium precipitates located. Near anthesis, synergids formed filiform apparatus in which abundant calcium precipitates accumulated to prepare for attracting pollen tubes entering. At anthesis, the distribution of calcium precipitates between two synergids was the same. At 1h after pollination, calcium precipitates evidently increased in one synergid that seemed to degenerate, the other one was persistent and the distribution of calcium granules did not change. Two synergids kept intact at 1d after emasculated, and the distribution of calcium precipitates did not display difference, suggesting that the degeneration of one synergid was caused by approaching pollen tubes which might give some signal to induce calcium increase of the synergid. Before fusion of sperm cell with egg cell, the cytoplasm of degenerated synergid embraced the egg and formed a thin layer between the egg and the central cell. Calcium precipitates in the different parts of degenerated synergid were closely connected with the fertilization: calcium precipitates accumulated in the near chalazal end of degenerated synergid at 1h after pollination. At 2.5h after pollination, the calcium precipitates increased at the chalazal end, especially abundant in the thin layer between the egg and the central cell. However, at 4h after pollination, the fertilization had finished at this time, the distribution of calcium precipitates in degenerated synergid changed again: the precipitates decreased at the chalazal end and increased at the micropylar end. The above-mentioned results suggested that calcium in the degenerated synergid played an important role during lettuce fertilization.
利用焦锑酸钾定位生菜（Lactuca sativa L）助细胞发育过程中的钙。开花前3天，两个助细胞形成明显极性，大部分细胞质位于珠孔端，细胞核位于中部，合点端有一个大液泡。此时，两个细胞中的钙沉淀都很少。开花前2天，两个助细胞中的钙沉淀开始增加。开花前1天，珠孔端的助细胞壁增厚，其中有许多钙沉淀。接近开花时，助细胞形成丝状器，其中积累了大量钙沉淀，为吸引花粉管进入做准备。开花时，两个助细胞之间的钙沉淀分布相同。授粉后1小时，一个似乎退化的助细胞中的钙沉淀明显增加，另一个保持不变，钙颗粒分布没有变化。去雄后1天，两个助细胞保持完整，钙沉淀分布没有差异，表明一个助细胞的退化是由接近的花粉管引起的，花粉管可能发出一些信号诱导助细胞钙增加。精子细胞与卵细胞融合前，退化助细胞的细胞质包裹卵细胞，在卵细胞和中央细胞之间形成一层薄膜。退化助细胞不同部位的钙沉淀与受精密切相关：授粉后1小时，钙沉淀在退化助细胞合点端附近积累。授粉后2.5小时，合点端的钙沉淀增加，尤其是在卵细胞和中央细胞之间的薄膜中丰富。然而，授粉后4小时，此时受精已经完成，退化助细胞中钙沉淀的分布再次改变：合点端的沉淀减少，珠孔端的沉淀增加。上述结果表明，退化助细胞中的钙在生菜受精过程中起重要作用。
