Eaves Deborah J, Flores-Ortiz Carlos, Haque Tamanna, Lin Zongcheng, Teng Nianjun, Franklin-Tong Vernonica E
*School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
Biochem Soc Trans. 2014 Apr;42(2):370-6. doi: 10.1042/BST20130248.
Self-fertilization, which results in reduced fitness of offspring, is a common problem in hermaphrodite angiosperms. To prevent this, many plants utilize SI (self-incompatibility), which is determined by the multi-allelic S-locus, that allows discrimination between self (incompatible) and non-self (compatible) pollen by the pistil. In poppy (Papaver rhoeas), the pistil S-determinant (PrsS) is a small secreted protein which interacts with the pollen S-determinant PrpS, a ~20 kDa novel transmembrane protein. Interaction of matching pollen and pistil S-determinants results in self-recognition, initiating a Ca²⁺-dependent signalling network in incompatible pollen. This triggers several downstream events, including alterations to the cytoskeleton, phosphorylation of sPPases (soluble inorganic pyrophosphatases) and an MAPK (mitogen-activated protein kinase), increases in ROS (reactive oxygen species) and nitric oxide (NO), and activation of several caspase-like activities. This results in the inhibition of pollen tube growth, prevention of self-fertilization and ultimately PCD (programmed cell death) in incompatible pollen. The present review focuses on our current understanding of the integration of these signals with their targets in the SI/PCD network. We also discuss our recent functional expression of PrpS in Arabidopsis thaliana pollen.
自体受精会导致后代适应性降低，这是雌雄同体被子植物中常见的问题。为了避免这种情况，许多植物利用自交不亲和性（SI），它由多等位基因的S位点决定，使雌蕊能够区分自体（不亲和）和非自体（亲和）花粉。在罂粟中，雌蕊S决定因子（PrsS）是一种小的分泌蛋白，它与花粉S决定因子PrpS相互作用，PrpS是一种约20 kDa的新型跨膜蛋白。匹配的花粉和雌蕊S决定因子相互作用导致自我识别，在不亲和花粉中启动一个依赖Ca²⁺的信号网络。这触发了几个下游事件，包括细胞骨架的改变、可溶性无机焦磷酸酶（sPPases）和丝裂原活化蛋白激酶（MAPK）的磷酸化、活性氧（ROS）和一氧化氮（NO）的增加以及几种半胱天冬酶样活性的激活。这导致花粉管生长受到抑制，防止自体受精，并最终导致不亲和花粉中的程序性细胞死亡（PCD）。本综述重点关注我们目前对这些信号在SI/PCD网络中与其靶标的整合的理解。我们还讨论了我们最近在拟南芥花粉中对PrpS的功能表达。
