Sexual plant reproduction depends on the attraction of sperm-cell delivering pollen tubes (PT) by two synergids, followed by their programmed cell death (PCD) in Arabidopsis. Disruption of the mitogen-activated protein kinase 4 (MPK4) by pathogenic effectors activates the resistance protein (R) SUMM2-mediated immunity and cell death. Here we show that synergid preservation and reactive oxygen species (ROS) homeostasis are intimately linked and maintained by MPK4. In mpk4, ROS levels are increased and synergids prematurely undergo PCD before PT-reception. However, ROS scavengers and the disruption of SUMM2, in mpk4, restore ROS homeostasis, synergid maintenance and PT perception, demonstrating that the guardian of MPK4, SUMM2, triggers synergid-PCD. In mpk4/summ2, PTs show a feronia-like overgrowth phenotype. Our results show that immunity-associated PCD and synergid cell death during plant reproduction are regulated by MPK4 underscoring an underlying molecular mechanism for the suppression of plant reproduction during systemic R-mediated immunity.
Bibliographical noteKAUST Repository Item: Exported on 2022-04-06
Acknowledgements: This work was supported by the National Research Foundation of Korea (NRF) grants funded by the Korea government (MSIT) (2020R1A2B5B03096402, 2018R1A5A1023599, and 2021M3H9A1096935). WH is grateful for a graduate fellowship through the Brain Korea 21 Plus Program.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)