Gallardo Jimena, Gallo Cristian Andrés, Quevedo Martín, Carballo José, Echenique Viviana, Zappacosta Diego
Centro de Recursos Naturales Renovables de La Zona Semiárida (CERZOS-CONICET, CCT Bahía Blanca), Bahía Blanca, Argentina.
Departamento de Agronomía, Universidad Nacional del Sur, Bahía Blanca, Argentina.
BMC Plant Biol. 2025 May 17;25(1):658. doi: 10.1186/s12870-025-06676-7.
Apomixis is an asexual reproduction process that allows plants to bypass meiosis and fertilization, resulting in clonal seeds that are genetically identical to the maternal genotype. Eragrostis curvula is a grass species used as model to disclose the mechanism associated to diplosporous apomixis. Previously, the first E. curvula linkage maps were developed using a F1 population derived from a cross between a sexual female parent (cv. OTA-S) and a facultative apomictic pollen donor (cv. Don Walter). Even though this work allows the identification a markers linked to apomixis in the male parent, the number of hybrids was not enough to produce a consensus map. Here, a new population is presented, increasing the number of genotyped hybrids to 107 which allows the construction of a consensus map and the development of KASP markers.
We constructed a consensus linkage map at the tetraploid level using a mapping population segregating for reproductive mode. Within this map, a region associated with apomeiosis (the APO locus) was identified using maternal and paternal SNP markers, along with three paternal markers that exhibited strong linkage with the trait. KASP markers were developed, one of which demonstrated 100% concordance with the cytoembryological phenotype of individuals in both the mapping population and other E. curvula genotypes. Through synteny analysis, the APO locus was mapped onto the E. curvula reference genome, and two genes that could be part of molecular pathways involved in apomeiosis were proposed.
This study presents the first consensus genetic map and the development of KASP markers for phenotyping reproductive modes in E. curvula. This map enables the association of the apomixis-determining region with molecular markers from both parental genotypes, including the reference sexual tetraploid genotype of the species (OTA-S). The development and validation of co-dominant molecular KASP markers linked to the APO locus provide a crucial tool for future research and breeding.
无融合生殖是一种无性繁殖过程，使植物能够绕过减数分裂和受精，产生与母本基因型基因相同的克隆种子。弯叶画眉草是一种用于揭示二倍体孢子生殖无融合生殖相关机制的禾本科植物。此前，利用有性雌性亲本（cv. OTA-S）与兼性无融合生殖花粉供体（cv. Don Walter）杂交产生的F1群体构建了首张弯叶画眉草连锁图谱。尽管这项工作能够鉴定出与雄性亲本无融合生殖相关的标记，但杂种数量不足以构建一张共识图谱。在此，我们展示了一个新的群体，将基因分型杂种数量增加到107个，这使得构建共识图谱和开发竞争性等位基因特异性PCR（KASP）标记成为可能。
我们利用一个因生殖模式而分离的作图群体构建了四倍体水平的共识连锁图谱。在这张图谱中，利用母本和父本单核苷酸多态性（SNP）标记以及三个与该性状表现出强连锁的父本标记，鉴定出了一个与无孢子生殖（APO位点）相关的区域。开发了KASP标记，其中一个与作图群体及其他弯叶画眉草基因型个体的细胞胚胎学表型100%一致。通过共线性分析，将APO位点定位到弯叶画眉草参考基因组上，并提出了两个可能参与无孢子生殖分子途径的基因。
本研究展示了首张弯叶画眉草用于生殖模式表型分析的共识遗传图谱及KASP标记的开发。该图谱能够将无融合生殖决定区域与来自双亲基因型的分子标记关联起来，包括该物种的参考有性四倍体基因型（OTA-S）。与APO位点连锁的共显性分子KASP标记的开发和验证为未来的研究和育种提供了关键工具。
