Key message

AGP-rich glycoproteins mediate pollen–ovule interactions and cell patterning in the embryo sac of apple before and after fertilization.

Abstract

Glycoproteins are significant players in the dialog that takes place between growing pollen tubes and the stigma and style in the angiosperms. Yet, information is scarce on their possible involvement in the ovule, a sporophytic organ that hosts the female gametophyte. Apple flowers have a prolonged lapse of time between pollination and fertilization, offering a great system to study the developmental basis of glycoprotein secretion and their putative role during the last stages of the progamic phase and early seed initiation. For this purpose, the sequential pollen tube elongation within the ovary was examined in relation to changes in arabinogalactan proteins (AGPs) in the tissues of the ovule before and after fertilization. To evaluate what of these changes are developmentally regulated, unpollinated and pollinated flowers were compared. AGPs paved the pollen tube pathway in the ovules along the micropylar canal, and the nucellus entrance toward the synergids, which also developmentally accumulated AGPs at the filiform apparatus. Glycoproteins vanished from all these tissues following pollen tube passage, strongly suggesting a role in pollen–ovule interaction. In addition, AGPs marked the primary cell walls of the haploid cells of the female gametophyte, and they further built up in the cell walls of the embryo sac and developing embryo, layering the interactive walls of the three generations hosted in the ovule, the maternal sporophytic tissues, the female gametophyte, and the developing embryo.

中文翻译：

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阿拉伯半乳聚糖蛋白介导苹果花胚珠中的细胞间串扰。

关键信息

AGP -丰富的糖蛋白介导花粉-胚珠的相互作用和细胞图案在苹果的胚囊受精前后。

抽象

糖蛋白在不断增长的花粉管与被子植物的柱头和花柱之间的对话中起着重要作用。然而，关于它们可能参与胚珠的信息很少，胚珠是容纳雌配子体的孢子体器官。苹果花在授粉和受精之间的时间间隔较长，为研究糖蛋白分泌的发育基础及其在孕期最后阶段和种子早期萌发中的假定作用提供了一个强大的系统。为此目的，检查了受精前后卵巢中花粉管的顺序伸长与胚珠组织中阿拉伯半乳聚糖蛋白（AGP）的变化有关。为了评估这些变化中哪些受到发育调节，比较了未授粉和授粉的花。AGP在沿着小孔的小珠子的胚珠中铺有花粉管通道，并向增效剂提供了细胞核入口，这也使AGP逐渐在丝状体中积累。花粉管通过后，糖蛋白从所有这些组织中消失，这强烈暗示了花粉与胚珠相互作用的作用。此外，AGP标记雌配子体单倍体细胞的原代细胞壁，并且它们进一步在胚囊和发育中的胚胎的细胞壁中积累，将孕育在胚珠中的三代人的相互作用壁分层孢子体组织，雌配子体和发育中的胚胎。花粉管通过后，糖蛋白从所有这些组织中消失，这强烈暗示了花粉与胚珠相互作用的作用。此外，AGP标记雌配子体单倍体细胞的原代细胞壁，并且它们进一步在胚囊和发育中的胚胎的细胞壁中积累，将孕育在胚珠中的三代人的相互作用壁分层孢子体组织，雌配子体和发育中的胚胎。花粉管通过后，糖蛋白从所有这些组织中消失，这强烈暗示了花粉与胚珠相互作用的作用。此外，AGP标记雌配子体单倍体细胞的原代细胞壁，并且它们进一步在胚囊和发育中的胚胎的细胞壁中积聚，将孕育在胚珠中的三代人的相互作用壁分层孢子体组织，雌配子体和发育中的胚胎。