Independent origins of self-compatibility in Arabidopsis thaliana
Independent origins of self-compatibility in Arabidopsis thaliana
复制标题
DOI：
10.1111/j.1365-294x.2007.03605.x
复制
发表时间：
2008-01-01
影响因子：
4.9
通讯作者：
Purugganan, Michael D.
中科院分区：
文献类型：
--
作者：
Shimizu, Kentaro K.;Shimizu-Inatsugi, Rie;Purugganan, Michael D.
从基于自交不亲和性（SI）的异型杂交到自交系统的进化是开花植物中最普遍的转变之一。有人提出，拟南芥中 SI 的缺失与 S 基因座 SCR 雄性部分假基因的形成有关。然而，最近的研究表明，S 基因座上存在大量缺失的替代等位基因也存在，并且可能是该物种自交亲和性进化的原因。我们证明，大多数这些缺失等位基因是从已经拥有 SCR 假基因的 S 单倍型（单倍群 A）进化而来的。这种单倍型及其缺失变体在欧洲几乎是固定的。结合之前的转基因数据，这些结果表明 Psi SCR1 基因的假基因化改变了大多数拟南芥种质的 SI 表型，并且是该物种自交进化的关键一步。还鉴定出另外两个单倍群（B 和 C），其中前者包含一个新颖且可能具有功能的 SCR 等位基因。与单倍群 A 不同，这两个单倍群主要发现于非洲和亚洲。这些结果表明，在该物种中似乎是固定的自相容性，在不同的遗传基础上多次出现，并表明物种特异性特征与分子水平上的平行进化相关。
The evolution from outcrossing based on self-incompatibility (SI) to a selfing system is one of the most prevalent transitions in flowering plants. It has been suggested that the loss of SI in Arabidopsis thaliana is associated with pseudogene formation at the SCR male component of the S locus. Recent work, however, suggests that alternative alleles with large deletions at the S locus are also present and may be responsible for the evolution of self-compatibility in this species. We demonstrate that most of these deletion alleles are evolutionarily derived from an S haplotype (haplogroups A) that already possessed the SCR pseudogene. This haplotype and its deletion variants are nearly fixed in Europe. Together with previous transgenic data, these results suggest that the pseudogenization of Psi SCR1 gene changed the SI phenotype in the majority of A. thaliana accessions, and was a critical step in the evolution of selfing in this species. Two other haplogroups (B and C) were also identified, the former of which contains a novel and possibly functional SCR allele. In contrast to haplogroups A, these two haplogroups are found primarily in Africa and Asia. These results suggest that self-compatibility, which appears to be fixed in this species, arose multiple times with different genetic bases, and indicates that a species-specific trait is associated with parallel evolution at the molecular level.