The S-RNase gene plays an essential role in the gametophytic self-incompatibility (GSI) system of Pyrus. It codes for the stylar-expressed S-RNase protein which inhibits the growth of incompatible pollen tubes through cytotoxicity and the induction of programmed cell death in the pollen tube. While research on the Pyrus GSI system has primarily focused on the S-RNase gene, there is still a lack of insight into its spatiotemporal expression profile and the factors that regulate it. Previous studies have suggested that S-RNase expression in the style is influenced by pollination and is dependent on the compatibility type. We here continue on this basic hypothesis by analyzing the spatiotemporal expression of the S-RNase alleles in Pyrus communis “Conference” styles in response to different types of pollination; namely, upon full- and semi-compatible pollination and upon incompatible selfing. The results revealed that temporal dynamics of S-RNase expression are influenced by the pollen’s compatibility type, indicating the presence of a signaling mechanism between pollen and style to control S-RNase production during pollen tube growth. In our experiment, S-RNase expression continuously decreased after cross-pollination and in the unpollinated control. However, after a fully incompatible pollination, S-RNase expression remained constant. Finally, semi-compatible pollination showed a initially constant S-RNase expression for both alleles followed by a strong decrease in expression. Based on these results and previous findings, we propose a regulatory mechanism to explain the effect of pollination and the associated compatibility type on S-RNase expression in the style. This proposed mechanism could be used as a starting point for future research.

中文翻译：

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授粉亲和类型对欧洲梨雌蕊S-RNase表达的影响

这S-RNA酶基因在配子体自交不亲和性（GSI）系统中起着至关重要的作用梨属。它编码花柱表达的 S-RNase 蛋白，该蛋白通过细胞毒性和诱导花粉管中的程序性细胞死亡来抑制不相容花粉管的生长。在研究的同时梨属GSI 系统主要关注S-RNA酶基因，仍然缺乏对其时空表达谱及其调节因素的深入了解。先前的研究表明S-RNA酶风格的表达受到授粉的影响，并且取决于亲和类型。我们在这里通过分析的时空表达来继续这个基本假设S-RNA酶等位基因在梨针对不同授粉类型的“会议”风格；即，在完全和半亲和授粉时以及在不亲和自交时。结果表明，时间动态S-RNA酶表达受花粉亲和类型的影响，表明花粉和花柱之间存在信号机制来控制S-RNA酶花粉管生长期间的产生。在我们的实验中，S-RNA酶异花授粉后和未授粉对照中的表达持续下降。然而，在完全不亲和的授粉之后，S-RNA酶表达保持恒定。最后，半亲和授粉表现出最初的恒定S-RNA酶两个等位基因的表达随后急剧下降。基于这些结果和之前的发现，我们提出了一种调节机制来解释授粉和相关的亲和类型对植物的影响。S-RNA酶表现在风格上。该机制可作为未来研究的起点。