Table_1_Identification of Candidate Genes for Self-Compatibility in Perennial Ryegrass (Lolium perenne L.).xlsx

Self-incompatibility (SI) is a genetic mechanism preventing self-pollination in ~40% of plant species. Two multiallelic loci, called S and Z, control the gametophytic SI system of the grass family (Poaceae), which contains all major forage grasses. Loci independent from S and Z have been reported to disrupt SI and lead to self-compatibility (SC). A locus causing SC in perennial ryegrass (Lolium perenne L.) was previously mapped on linkage group (LG) 5 in an F2 population segregating for SC. Using a subset of the same population (n = 68), we first performed low-resolution quantitative trait locus (QTL) mapping to exclude the presence of additional, previously undetected contributors to SC. The previously reported QTL on LG 5 explained 38.4% of the phenotypic variation, and no significant contribution from other genomic regions was found. This was verified by the presence of significantly distorted markers in the region overlapping with the QTL. Second, we fine mapped the QTL to 0.26 centimorgan (cM) using additional 2,056 plants and 23 novel sequence-based markers. Using Italian ryegrass (Lolium multiflorum Lam.) genome assembly as a reference, the markers flanking SC were estimated to span a ~3 Mb region encoding for 57 predicted genes. Among these, seven genes were proposed as relevant candidate genes based on their annotation and function described in previous studies. Our study is a step forward to identify SC genes in forage grasses and provides diagnostic markers for marker-assisted introgression of SC into elite germplasm.

自交不亲和性（Self-incompatibility，SI）是一类存在于约40%植物物种中的遗传调控机制，可有效阻止自花授粉。禾本科（Poaceae）包含所有主流饲用禾草，其配子体型自交不亲和系统由两个命名为S和Z的多等位基因位点共同调控。已有研究报道，独立于S和Z的基因位点可破坏自交不亲和性，进而导致自交亲和性（Self-compatibility，SC）。此前，科研人员在一个发生自交亲和性分离的F2群体中，将多年生黑麦草（Lolium perenne L.）中导致自交亲和性的位点定位至连锁群（Linkage group，LG）5上。本研究利用该群体的一个亚群（样本量n=68），首先开展低分辨率数量性状基因座（Quantitative trait locus，QTL）定位分析，以排除存在此前未被发现的其他自交亲和性调控因子。结果显示，此前报道的位于连锁群5上的QTL可解释38.4%的表型变异，未检测到其他基因组区域存在显著贡献。该结论通过QTL重叠区域内存在显著偏分离标记得到了验证。随后，研究团队借助额外的2056株植株与23个新型序列标记，将该QTL精细定位至0.26厘摩（centimorgan，cM）区间内。以意大利黑麦草（Lolium multiflorum Lam.）基因组组装版本作为参考基因组，侧翼标记覆盖的自交亲和性区间被估算为约3 Mb，共编码57个预测基因。其中，基于基因注释及既往研究报道的功能，有7个基因被认定为相关候选基因。本研究为饲用禾草中自交亲和性基因的鉴定迈出了重要一步，并为通过标记辅助导入技术将自交亲和性性状转育至优良种质资源提供了诊断性分子标记。