Species preferentiality of the pollen tube attractant derived from the synergid cell of Torenia fournieri
Species preferentiality of the pollen tube attractant derived from the synergid cell of Torenia fournieri
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DOI：
10.1104/pp.106.083832
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发表时间：
2006-10-01
期刊：
影响因子：
7.4
通讯作者：
Nakano, Akihiko
中科院分区：
文献类型：
--
作者：
Higashiyama, Tetsuya;Inatsugi, Rie;Nakano, Akihiko
蓝猪耳的助细胞通过一种可扩散但未知的化学引诱剂吸引花粉管。本研究以两属五种近缘种，即拟谷盗、拟谷盗和拟谷盗为材料，研究了拟谷盗引诱剂的种间差异。fournieri、蓝猪耳、蓝猪耳、壳和微花。这5个种的胚囊外露，消融实验证实助细胞能吸引花粉管。T. fournieri和另一种植物的花粉管一起培养时，花粉管对相应植物助细胞的吸引力显著增加。不同种间胚囊的接近程度不影响其吸引力。这表明，引诱剂是一个物种的优先分子，可能是合成的助细胞。钙离子，长期以来被认为是一种潜在的引诱剂，不能作为唯一的引诱剂在这些物种中，因为钙离子浓度的升高并不影响所观察到的吸引力。活体杂交实验还表明，当不同种的花粉管到达胚囊周围时，花粉管对胚囊的吸引力受损，这表明引诱剂的种偏好性可能在定向控制花粉管的最后步骤中充当生殖屏障。
The synergid cell of Torenia fournieri attracts pollen tubes by a diffusible but yet unknown chemical attractant. Here we investigated the species difference of the attractant using five closely related species in two genera, namely T. fournieri, Torenia baillonii, Torenia concolor, Lindernia (Vandellia) crustacea, and Lindernia micrantha. These five species have an exserted embryo sac, and ablation experiments confirmed that their synergid cells attracted the pollen tube. When ovules of T. fournieri and one of the other species were cultivated together with pollen tubes of each species, pollen tubes were significantly more attracted to synergid cells of the corresponding species. The attraction was not affected by the close proximity of embryo sacs of different species. This suggests that the attractant is a species-preferential molecule that is likely synthesized in the synergid cell. The calcium ion, long considered a potential attractant, could not serve as the sole attractant in these species, because elevation of the calcium ion concentration did not affect the observed attraction. In vivo crossing experiments also showed that the attraction of the pollen tube to the embryo sac was impaired when pollen tubes of different species arrived around the embryo sac, suggesting that the species preferentiality of the attractant may serve as a reproductive barrier in the final step of directional control of the pollen tube.