Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826, Korea.
Department of Agricultural Biotechnology, Seoul National University, Seoul, 08826, Korea.
Nat Commun. 2022 Apr 1;13(1):1746. doi: 10.1038/s41467-022-29373-7.
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.
植物有性生殖依赖于花粉管（PT）中精子的吸引力，花粉管由两个助细胞输送，随后两个助细胞程序性细胞死亡（PCD），这在拟南芥中是这样的。病原效应物破坏丝裂原活化蛋白激酶 4（MPK4）会激活抗性蛋白（R）SUMM2 介导的免疫和细胞死亡。在这里，我们表明助细胞的保存和活性氧（ROS）稳态通过 MPK4 紧密联系并维持。在 mpk4 中，ROS 水平增加，并且在 PT 接收之前助细胞过早地经历 PCD。然而，在 mpk4 中，ROS 清除剂和 SUMM2 的破坏恢复了 ROS 稳态、助细胞的维持和 PT 的感知，这表明 MPK4 的守护者 SUMM2 触发了助细胞的 PCD。在 mpk4/summ2 中，PT 表现出类似于 feronia 的过度生长表型。我们的结果表明，植物生殖过程中与免疫相关的 PCD 和助细胞死亡受 MPK4 调控，这突显了系统 R 介导的免疫过程中抑制植物生殖的潜在分子机制。
