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.

中文翻译：

---

异交禾本科多年生黑麦草（Lolium perenne）自交亲和的新遗传位点

背景自交不亲和性(SI)是许多开花植物用来防止自体受精和保持杂合性的生理机制。在草科中，这被称为由双位点 (SZ) 系统控制；然而，SI 系统本质上是有泄漏的。已知 S 和 Z 基因座以及另一个基因座 T 的修饰基因会覆盖 SI，导致自我受精和自我种子生产。这对生态和进化的成功以及草的商业育种都有影响。在这里，我们报告了一项研究，其中自交亲和性 (SC) 的遗传控制是根据自花授粉 F2 多年生黑麦草种群的结果确定的，该种群来自两个独立衍生的自交系，这些自交系由单种子后代产生。方法 分析了 73 株可育植物的体外自花授粉。使用通过基因型测序方法生成的一组 1863 个单核苷酸多态性 (SNP) 标记进行了遗传关联分析。将标记放置在使用 Joinmap v.5 创建的七个连锁群 (LG) 的重组图谱上。在 143 株植物上测定了自花授粉和开放授粉花序上的种子，包括分析自花授粉反应的 73 株植物。主要结果 自花授粉显示 SC 百分比呈双峰分布，峰值分别为 50% 和 100%。单个数量性状基因座 (QTL) 被鉴定为标记 6S14665z17875_11873 的峰值关联，映射到 LG 6。峰值位置与最大标记分离失真相关。自交和开放授粉后，自交植物同样多产。