Phosphatidic Acid Counteracts S-RNase Signaling in Pollen by Stabilizing the Actin Cytoskeleton. Issue 5 (30th April 2018)

• Record Type: Journal Article
• Authors: Chen, Jianqing; Wang, Peng; de Graaf, Barend H.J.; Zhang, Hao; Jiao, Huijun; Tang, Chao; Zhang, Shaoling; Wu, Juyou
• Is Part Of: The Plant Cell. Volume 30:Issue 5(2018)
• Page Start: 1023
• Page End: 1039
• Publication Date: 2018-04-30
• DOI: 10.1105/tpc.18.00021
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract : In the self-incompatibility response in pear, PbrS-RNase directly depolymerizes the actin cytoskeleton and promotes phosphatidic acid production, which plays a protective role in incompatible pollen tubes. Abstract: S-RNase is the female determinant of self-incompatibility (SI) in pear ( Pyrus bretschneideri ). After translocation to the pollen tube, S-RNase degrades rRNA and induces pollen tube death in an S -haplotype-specific manner. In this study, we found that the actin cytoskeleton is a target of P. bretschneideri S-RNase (PbrS-RNase) and uncovered a mechanism that involves phosphatidic acid (PA) and protects the pollen tube from PbrS-RNase cytotoxicity. PbrS-RNase interacts directly with PbrActin1 in an S -haplotype-independent manner, causing the actin cytoskeleton to depolymerize and promoting programmed cell death in the self-incompatible pollen tube. Pro-156 of PbrS-RNase is essential for the PbrS-RNase-PbrActin1 interaction, and the actin cytoskeleton-depolymerizing function of PbrS-RNase does not require its RNase activity. PbrS-RNase cytotoxicity enhances the expression of phospholipase D (PbrPLDΔ1), resulting in increased PA levels in the incompatible pollen tube. PbrPLDΔ1-derived PA initially prevents depolymerization of the actin cytoskeleton elicited by PbrS-RNase and delays the SI signaling that leads to pollen tube death. This work provides insights into the orchestration of the S-RNase-based SI response, in which increased PA levels initially play a protective role in incompatible pollen, until sustained PbrS-RNase activity reaches the point of no return and pollen tube growth ceases.