Wilkins Katie A, Poulter Natalie S, Franklin-Tong Vernonica E
School of Biosciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK.
J Exp Bot. 2014 Mar;65(5):1331-42. doi: 10.1093/jxb/ert468. Epub 2014 Jan 21.
Self-incompatibility (SI) is an important genetically controlled mechanism used by many angiosperms to prevent self-fertilization and inbreeding. A multiallelic S-locus allows discrimination between 'self' (incompatible) pollen from 'nonself' pollen at the pistil. Interaction of matching pollen and pistil S-determinants allows 'self' recognition and triggers rejection of incompatible pollen. The S-determinants for Papaver rhoeas (poppy) are PrsS and PrpS. PrsS is a small secreted protein that acts as a signalling ligand to interact with its cognate pollen S-determinant PrpS, a small novel transmembrane protein. Interaction of PrsS with incompatible pollen stimulates increases in cytosolic free Ca(2+) and involves influx of Ca(2+) and K(+). Data implicate involvement of reactive oxygen species and nitric oxide signalling in the SI response. Downstream targets include the cytoskeleton, a soluble inorganic pyrophosphatase, Pr-p26.1, and a MAP kinase, PrMPK9-1. A major focus for SI-induced signalling is to initiate programmed cell death (PCD). In this review we provide an overview of our understanding of SI, with focus on how the signals and components are integrated, in particular, how reactive oxygen species, nitric oxide, and the actin cytoskeleton feed into a PCD network. We also discuss our recent functional expression of PrpS in Arabidopsis thaliana pollen in the context of understanding how PCD signalling systems may have evolved.
自交不亲和性（SI）是许多被子植物用来防止自花受精和近亲繁殖的一种重要的遗传控制机制。一个多等位基因的S位点能够在雌蕊处区分“自身”（不亲和）花粉和“非自身”花粉。匹配的花粉和雌蕊S决定簇之间的相互作用使得能够识别“自身”，并触发对不亲和花粉的排斥。虞美人（罂粟）的S决定簇是PrsS和PrpS。PrsS是一种小的分泌蛋白，作为信号配体与其同源花粉S决定簇PrpS相互作用，PrpS是一种新型的小跨膜蛋白。PrsS与不亲和花粉的相互作用会刺激胞质游离Ca2+增加，并涉及Ca2+和K+的内流。数据表明活性氧和一氧化氮信号参与了自交不亲和反应。下游靶点包括细胞骨架、一种可溶性无机焦磷酸酶Pr-p26.1和一种丝裂原活化蛋白激酶PrMPK9-1。自交不亲和诱导信号的一个主要焦点是启动程序性细胞死亡（PCD）。在本综述中，我们概述了我们对自交不亲和性的理解，重点关注信号和成分是如何整合的，特别是活性氧、一氧化氮和肌动蛋白细胞骨架如何融入PCD网络。我们还在理解PCD信号系统可能如何进化的背景下，讨论了我们最近在拟南芥花粉中对PrpS的功能表达。
