Cheung A Y, Wang H, Wu H M
Department of Biology, Yale University, New Haven, Connecticut 06520-8104, USA.
Cell. 1995 Aug 11;82(3):383-93. doi: 10.1016/0092-8674(95)90427-1.
Pollen tubes elongate directionally in the extracellular matrix of pistil tissues to transport the male gametes from the apically located stigma to the basally located ovary for fertilization. The molecular mechanisms underlying directional pollen tube growth in the pistil are poorly understood. We have purified a glycoprotein, TTS, from tobacco stylar transmitting tissue, which supports pollen tube growth between the stigma and the ovary. TTS proteins belong to the arabinogalactan protein family, and they polymerize readily in vitro in a head-to-tail fashion into oligomeric forms. TTS proteins stimulate pollen tube growth in vitro and attract pollen tubes grown in a semi-in vivo culture system. In vivo, the pollen tube growth rate is reduced in transgenic plants that have significantly reduced levels of TTS proteins as a result of either antisense suppression or sense cosuppression. These results identify TTS protein as a pistil component that positively contributes to pollen tube growth.
花粉管在雌蕊组织的细胞外基质中定向伸长，将雄配子从顶端的柱头运输到基部的子房进行受精。关于雌蕊中花粉管定向生长的分子机制，目前了解甚少。我们从烟草花柱的传递组织中纯化出一种糖蛋白TTS，它支持花粉管在柱头和子房之间生长。TTS蛋白属于阿拉伯半乳聚糖蛋白家族，它们在体外很容易以头对尾的方式聚合成寡聚体形式。TTS蛋白在体外刺激花粉管生长，并吸引在半体内培养系统中生长的花粉管。在体内，由于反义抑制或正义共抑制导致TTS蛋白水平显著降低的转基因植物中，花粉管生长速率降低。这些结果表明TTS蛋白是一种对花粉管生长有正向作用的雌蕊成分。
