内钙拮抗剂TMB- 8 对白皮松花粉管细胞壁构建的影响

Effects of Intracellular Calcium Antagonist, TMB-8, on the Construction of Pollen Tube Wall in Pinus bungeana

摘要:

应用荧光显微技术、激光共聚焦扫描显微技术、单克隆抗体免疫荧光标记技术以及傅里叶变换显微红外光谱分析(FTIR)等手段,研究了内钙拮抗剂TMB-8对白皮松花粉管胞内Ca²⁺分布、花粉管生长以及细胞壁构建等的影响。结果表明,白皮松花粉管经TMB-8处理后,胞内的Ca²⁺浓度下降,花粉管内典型的Ca²⁺浓度梯度消失,花粉萌发和花粉管生长均受到不同程度的抑制,抑制效果与拮抗剂浓度呈正相关。在对照中,纤维素和胼胝质在花粉管细胞壁上均匀分布,酸性果胶质仅分布在花粉管管壁上,而酯化果胶质仅分布于花粉管顶端;经TMB-8处理后,花粉管顶端纤维素、胼胝质以及酸性果胶质含量增加,而酯化果胶质含量减少。这些表明胞内Ca²⁺对花粉管顶端Ca²⁺浓度梯度的建成具有重要的作用,抑制胞内Ca²⁺释放可以影响花粉管细胞壁的结构组成和物理性质,从而抑制花粉管的生长。

Abstract:

The effects of TMB-8, an intracellular calcium antagonist, on the pollen tube growth and cell wall construction in Pinus bungeana were investigated by means of fluorescence microscopy, laser scanning confocal microscopy, immunofluorescence technique and Fourier transform infra-red (FTIR) microspectroscopy. The results showed that TMB-8 inhibited P. bungeana pollen germination and tube growth in a dose-dependent manner. Normally growing pollen tubes displayed a typical tip-focused cytosolic free Ca²⁺ concentration gradient, while the Ca²⁺ concentration gradient dissipated in TMB-8-treated pollen tubes. Cellulose and callose were distributed uniformly in the wall of pollen tubes; acidic pectin was distributed in the tube wall except for the apex while esterified pectin was present only in the apex. In TMB-8-treated tubes, the content of cellulose, acidic pectin and callose increased while esterified pectin decreased in the apex compared with the normal tube wall. It indicated that the intracellular Ca²⁺ was necessary in the formation of apical cytosolic Ca²⁺ concentration gradient. Inhibition of intracellular Ca²⁺ release resulted in the arrest of pollen tube growth by the modification of cell wall composition in P. bungeana pollen tube.