Pomology Department, Aula Dei Experimental Station CSIC, Apdo 13034, 50080 Zaragoza, Spain.
BMC Plant Biol. 2014 Jan 3;14:1. doi: 10.1186/1471-2229-14-1.
The characteristics of pollen tube growth are not constant, but display distinct patterns of growth within the different tissues of the pistil. In the stigma, the growth rate is slow and autotrophic, whereas in the style, it is rapid and heterotrophic. Very little is known about the interactions between these distinct maternal tissues and the traversing pollen tube and the role of this interaction on the observed metabolism. In this work we characterise pollen tube growth in the apple flower and look for differences in glycoprotein epitope localization between two different maternal tissues, the stigma and the style.
While immunocytochemically-detected arabinogalactan proteins were present at high levels in the stigma, they were not detected in the transmitting tissue of the style, where extensins were abundant. Whereas extensins remained at high levels in unpollinated pistils, they were no longer present in the style following pollen tube passage. Similarily, while abundant in unpollinated styles, insoluble polysaccharides such as β-glucans, were depleted in pollinated pistils.
The switch from autotropic to heterotrophic pollen tube growth correlates spatially with a change of glycoprotein epitopes between the stigma and the style. The depletion of extensins and polysaccharides following pollen tube passage in the style suggest a possible contribution to the acceleration of heterotrophic pollen tube growth, which would imply an active contribution of female tissues on prezygotic male-female crosstalk.
花粉管生长的特点并非一成不变，而是在雌蕊的不同组织中呈现出明显的生长模式。在柱头中，生长速度缓慢且为自养型，而在花柱中，生长速度较快且为异养型。关于这些不同的母体组织与穿越花粉管之间的相互作用以及这种相互作用对观察到的代谢的影响，人们知之甚少。在这项工作中，我们对苹果花中的花粉管生长进行了描述，并寻找了两个不同的母体组织（柱头和花柱）之间糖蛋白表位定位的差异。
虽然柱头中阿拉伯半乳聚糖蛋白的免疫细胞化学检测水平较高，但在花柱的传递组织中并未检测到，而伸展蛋白在那里含量丰富。虽然在未授粉的雌蕊中伸展蛋白含量较高，但在花粉管通过后，它们不再存在于花柱中。同样，在未授粉的花柱中丰富存在的不可溶性多糖，如β-葡聚糖，在授粉的雌蕊中耗尽。
从自养型到异养型花粉管生长的转变与柱头和花柱之间糖蛋白表位的空间变化相关。花粉管通过花柱后，伸展蛋白和多糖的耗竭表明它们可能有助于异养型花粉管的加速生长，这意味着雌性组织对雌雄配子前相互作用的积极贡献。
