在外授粉草本植物多年生黑麦草（Lolium perenne）中，发现一个与自交亲和性相关的新遗传位点。
A new genetic locus for self-compatibility in the outcrossing grass species perennial ryegrass (Lolium perenne).
机构信息
Institute of Biological, Environmental and Rural Sciences, Gogerddan, Aberystwyth University, Aberystwyth, UK.
KWS UK Ltd, Thriplow, Royston, Hertfordshire, UK.
出版信息
Ann Bot. 2021 May 7;127(6):715-722. doi: 10.1093/aob/mcaa140.
BACKGROUND
Self-incompatibility (SI) is a physiological mechanism that many flowering plants employ to prevent self-fertilization and maintain heterozygosity. In the grass family this is known to be controlled by a two locus (S-Z) system; however, the SI system is intrinsically leaky. Modifier genes of both the S and Z loci and a further locus, T, are known to override SI leading to self-fertilization and self-seed production. This has implications for the ecological and evolutionary success as well as the commercial breeding of grasses. Here we report a study where the genetic control of self-compatibility (SC) was determined from the results of self-pollinating an F2 population of perennial ryegrass from two independently derived inbred lines produced by single-seed descent.
METHODS
In vitro self-pollinations of 73 fertile plants were analysed. A genetic association analysis was made with a panel of 1863 single-nucleotide polymorphism (SNP) markers, generated through genotype-by-sequencing methodology. Markers were placed on a recombination map of seven linkage groups (LGs) created using Joinmap v.5. The seed set on self- and open-pollinated inflorescences was determined on 143 plants, including the 73 plants analysed for self-pollination response.
KEY RESULTS
Self-pollinations revealed a bimodal distribution of percentage SC with peaks at 50 and 100 %. A single quantitative trait locus (QTL) was identified with peak association for marker 6S14665z17875_11873 that mapped to LG 6. Peak position was associated with maximum marker segregation distortion. The self-compatible plants were equally fecund after self- and open pollination.
CONCLUSIONS
This is the first report in the Poaceae family of an SC locus located on LG 6. This new SC QTL discovery, as well as indicating the complex nature of the pollen-stigma recognition process and its evolutionary significance, provides an additional source of SC for breeding perennial ryegrass.
背景
自交不亲和（SI）是许多开花植物用来防止自花授粉和保持杂合性的生理机制。在禾本科中，这种机制被认为是由两个基因座（S-Z）系统控制的；然而，SI 系统本质上是有漏洞的。已知 S 和 Z 基因座的修饰基因以及另一个基因座 T 可以覆盖 SI，导致自花授粉和自交种子的产生。这对禾本科的生态和进化成功以及商业育种都有影响。在这里，我们报告了一项研究，该研究从两个由单种子衍生而来的独立近交系的多年生黑麦草 F2 群体的自交结果中确定了自交亲和性（SC）的遗传控制。
方法
分析了 73 株可育植物的离体自交。通过基因型测序方法生成的 1863 个单核苷酸多态性（SNP）标记的遗传关联分析。标记被放置在使用 Joinmap v.5 创建的七个连锁群（LG）的重组图谱上。在 143 株植物上测定了自交和异交花序的结实率，包括对 73 株自交授粉反应进行分析的植物。
主要结果
自交揭示了 SC 百分比的双峰分布，峰值分别为 50%和 100%。鉴定到一个单一的数量性状位点（QTL），与标记 6S14665z17875_11873 的峰关联最大，该标记映射到 LG 6。峰位置与最大标记分离偏度相关。自交亲和植物在自交和异交后的繁殖力相等。
结论
这是禾本科中第一个位于 LG 6 的 SC 基因座的报告。这个新的 SC QTL 发现，以及指示花粉柱头识别过程的复杂性及其进化意义，为多年生黑麦草的育种提供了另一个 SC 来源。
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