A stigmatic gene confers interspecies incompatibility in the Brassicaceae

First author: Sota Fujii; Affiliations: The University of Tokyo (东京大学): Tokyo, Japan

Corresponding author: Seiji Takayama

Pre-zygotic interspecies incompatibility in angiosperms is a male–female relationship that inhibits the formation of hybrids between two species. Here, we report on the identification of STIGMATIC PRIVACY 1 (SPRI1), an interspecies barrier gene in Arabidopsis thaliana. We show that the rejection activity of this stigma-specific plasma membrane protein is effective against distantly related Brassicaceae pollen tubes and is independent of self-incompatibility. Point-mutation experiments and functional tests of synthesized hypothetical ancestral forms of SPRI1 suggest evolutionary decay of SPRI1-controlled interspecies incompatibility in self-compatible A. thaliana. Hetero-pollination experiments indicate that SPRI1 ensures intraspecific fertilization in the pistil when pollen from other species are present. Our study supports the idea that SPRI1 functions as a barrier mechanism that permits entrance of pollen with an intrinsic signal from self species.

被子植物在合子前的种间不相容性是一种抑制种间杂交的雌雄关系。本文中，作者在拟南芥中鉴定到了一个作用于种间杂交障碍的基因SPRI1。作者的研究显示该柱头特异性质膜蛋白能够有效拒绝远缘芸苔科物种的花粉管，并且与拟南芥的自交不亲和无关。SPRI1蛋白点突变试验以及合成的祖先蛋白功能测试表明在自交植物拟南芥中由SPRI1基因控制的种间不亲和出现了演化上的衰退。异源花粉试验显示SPRI1能够在其它物种花粉存在的情况下保证雌蕊上的种内受精。本文的研究表明SPRI1蛋白作为一种花粉屏障机制，只允许自身花粉进行受精作用。

通讯：高山誠司 (http://park.itc.u-tokyo.ac.jp/seiyu/)

研究方向：植物细胞间的通信。

doi: https://doi.org/10.1038/s41477-019-0444-6

Journal: Nature Plants

Published date: July 01, 2019