AUTHOR=Claessen Hanne , Palmers Han , Keulemans Wannes , Van de Poel Bram , De Storme Nico 

TITLE=The influence of the pollination compatibility type on the pistil S-RNase expression in European pear (Pyrus communis)

JOURNAL=Frontiers in Genetics

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2024.1360332

DOI=10.3389/fgene.2024.1360332

ISSN=1664-8021

ABSTRACT=<p>The <italic>S-RNase</italic> gene plays an essential role in the gametophytic self-incompatibility (GSI) system of <italic>Pyrus</italic>. 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 <italic>Pyrus</italic> GSI system has primarily focused on the <italic>S-RNase</italic> gene, there is still a lack of insight into its spatiotemporal expression profile and the factors that regulate it. Previous studies have suggested that <italic>S-RNase</italic> 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 <italic>S-RNase</italic> alleles in <italic>Pyrus communis</italic> “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 <italic>S-RNase</italic> expression are influenced by the pollen’s compatibility type, indicating the presence of a signaling mechanism between pollen and style to control <italic>S-RNase</italic> production during pollen tube growth. In our experiment, <italic>S-RNase</italic> expression continuously decreased after cross-pollination and in the unpollinated control. However, after a fully incompatible pollination, <italic>S-RNase</italic> expression remained constant. Finally, semi-compatible pollination showed a initially constant <italic>S-RNase</italic> 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 <italic>S-RNase</italic> expression in the style. This proposed mechanism could be used as a starting point for future research.</p>