Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba Aobaku, Sendai, Miyagi, 980-8572, Japan.
Plant J. 2022 Jul;111(2):496-507. doi: 10.1111/tpj.15811. Epub 2022 May 23.
Self-incompatibility in the Brassicaceae family is governed by SRK and SCR, which are two highly polymorphic genes located at the S-locus. Previously, the Arabidopsis lyrata SRK and SCR genes were introduced into Arabidopsis thaliana to generate self-incompatible lines. However, there are no reports showing that Brassica SRK and SCR genes confer self-incompatibility in A. thaliana. Doing so would further advance the mechanistic understanding of self-incompatibility in Brassicaceae. Therefore, we attempted to generate A. thaliana transformants showing the self-recognition activity of Brassica rapa by introducing BrSCR along with a chimeric BrSRK (BrSRK chimera, in which the kinase domain of BrSRK was replaced with that of AlSKR-b). We found that the BrSRK chimera and BrSCR of B. rapa S-9 and S-46 haplotypes, but not those of S-29, S-44, and S-60 haplotypes, conferred self-recognition activity in A. thaliana. Analyses of A. thaliana transformants expressing mutant variants of the BrSRK-9 chimera and BrSCR-9 revealed that mutations at the amino acid residues involved in BrSRK9-BrSCR9 interaction caused defects in the self-incompatibility response. The method developed in this study for generating self-incompatible A. thaliana transformants showing B. rapa self-recognition activity will be useful for analysis of self-recognition mechanisms in Brassicaceae.
芸薹属植物的自交不亲和性由 SRK 和 SCR 控制，这两个高度多态性的基因位于 S 位点。先前，将拟南芥 lyrata 的 SRK 和 SCR 基因导入拟南芥中，以产生自交不亲和系。然而，目前尚无报道表明芸薹属的 SRK 和 SCR 基因赋予拟南芥的自交不亲和性。这样做将进一步推进对芸薹科自交不亲和性的机制理解。因此，我们试图通过引入 BrSCR 以及嵌合 BrSRK（BrSRK 嵌合体，其中 BrSRK 的激酶结构域被 AlSKR-b 取代），在拟南芥中产生表现出芸薹属自识别活性的转化体。我们发现，芸薹属 S-9 和 S-46 单倍型的 BrSRK 嵌合体和 BrSCR，但不是 S-29、S-44 和 S-60 单倍型的 BrSRK 嵌合体和 BrSCR，赋予了拟南芥的自识别活性。对表达 BrSRK-9 嵌合体和 BrSCR-9 突变体的拟南芥转化体的分析表明，参与 BrSRK9-BrSCR9 相互作用的氨基酸残基的突变导致自交不亲和反应缺陷。本研究中开发的用于产生表现出芸薹属自识别活性的自交不亲和拟南芥转化体的方法，将有助于分析芸薹科的自识别机制。
