Duplicated pollen-pistil recognition loci control intraspecific unilateral incompatibility in Brassica rapa
Duplicated pollen-pistil recognition loci control intraspecific unilateral incompatibility in Brassica rapa
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DOI：
10.1038/nplants.2017.96
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发表时间：
2017-07-01
期刊：
影响因子：
18
通讯作者：
Watanabe, Masao
中科院分区：
文献类型：
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作者：
Takada, Yoshinobu;Murase, Kohji;Watanabe, Masao
在植物中，细胞-细胞识别是选择最佳配子对以实现后代成功繁殖的关键步骤。有花植物已经进化出各种遗传机制，通过细胞-细胞识别介导，使它们的雌蕊能够拒绝自交花粉，从而防止近亲繁殖和随之而来的后代适应性降低（自交不亲和性，SI），并拒绝来自其他物种的外来花粉，从而保持物种身份（种间不亲和性）。在芸苔属中，SI系统由柱头表达的雌性受体（S受体激酶，SRK）和绒毡层细胞表达的雄性配体（S位点蛋白11，SP11）之间的S-单倍型特异性相互作用调节，所述S-单倍型特异性相互作用由它们各自在S位点的多态性基因编码2 -6。然而，识别外来花粉，导致生殖不亲和的分子机制尚未确定。在这里，我们表明，一种新的蛋白质，雌蕊受体SUI 1（柱头单面不相容1）和花粉配体PUI 1（花粉单面不相容1）之间的识别，触发单方面的生殖不相容植物之间的两个地理上遥远的自交不亲和的芜菁线，即使杂交将被预测为兼容的基础上的S单倍型的花粉和柱头。有趣的是，SUI 1和PUI 1分别与SI基因SRK和SP11相似，并且在这两个群体中保持为隐藏的不亲和基因。SRK和SP11基因的重复以及在不同种群中的相互丢失可能为异地繁殖障碍的出现提供了分子机制。
In plants, cell-cell recognition is a crucial step in the selection of optimal pairs of gametes to achieve successful propagation of progeny. Flowering plants have evolved various genetic mechanisms, mediated by cell-cell recognition, to enable their pistils to reject self-pollen, thus preventing inbreeding and the consequent reduced fitness of progeny (self-incompatibility, SI), and to reject foreign pollen from other species, thus maintaining species identity (interspecific incompatibility) 1. In the genus Brassica, the SI system is regulated by an S-haplotype-specific interaction between a stigma-expressed female receptor (S receptor kinase, SRK) and a tapetum cell-expressed male ligand (S locus protein 11, SP11), encoded by their respective polymorphic genes at the S locus2-6. However, the molecular mechanism for recognition of foreign pollen, leading to reproductive incompatibility, has not yet been identified. Here, we show that recognition between a novel pair of proteins, a pistil receptor SUI1 (STIGMATIC UNILATERAL INCOMPATIBILITY 1) and a pollen ligand PUI1 (POLLEN UNILATERAL INCOMPATIBILITY 1), triggers unilateral reproductive incompatibility between plants of two geographically distant self-incompatible Brassica rapa lines, even though crosses would be predicted to be compatible based on the S haplotypes of pollen and stigma. Interestingly, SUI1 and PUI1 are similar to the SI genes, SRK and SP11, respectively, and are maintained as cryptic incompatibility genes in these two populations. The duplication of the SRK and SP11 followed by reciprocal loss in different populations would provide a molecular mechanism of the emergence of a reproductive barrier in allopatry.