Texas A&M AgriLife Research Center at Dallas, Texas A&M University System, Dallas, TX, 75252, USA.
Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Plant J. 2015 Jun;82(5):744-57. doi: 10.1111/tpj.12842. Epub 2015 Apr 21.
Zoysiagrass (Zoysia spp.), belonging to the genus Zoysia in the subfamily Chloridoideae, is widely used in domestic lawns, sports fields and as forage. We constructed high-density genetic maps of Zoysia japonica using a restriction site-associated DNA sequencing (RAD-Seq) approach and an F1 mapping population derived from a cross between 'Carrizo' and 'El Toro'. Two linkage maps were constructed, one for each of the parents. A map consisting of 2408 RAD markers distributed on 21 linkage groups was constructed for 'Carrizo'. Another map with 1230 RAD markers mapped on 20 linkage groups was constructed for 'El Toro'. The average distance between adjacent markers of the two maps was at 0.56 and 1.4 cM, respectively. Comparative genomics analysis was carried out among zoysiagrass, rice and sorghum genomes and a highly conserved collinearity in the gene order was observed among the three genomes. Chromosome collinearity was disrupted at centromeric regions for each chromosome pair between zoysiagrass and sorghum genomes. However, no obvious synteny gaps were observed across the centromeric regions between zoysiagrass and rice genomes. Two homologous chromosomes for each of the 10 sorghum chromosomes were found in the zoysiagrass genome, indicating an allotetraploid origin for zoysiagrass. The reduction of the basic chromosome number from 12 to 10 in chloridoids and panicoids took place via independent single-step nested chromosome fusion events after the two subfamilies diverged from a common ancestor. The genetic maps will assist in genome sequence assembly, targeted gene isolation and comparative genomic analyses among grasses.
结缕草（Zoysia 属）属于禾本科画眉草亚科，广泛应用于国内草坪、运动场和饲料。本研究采用限制性位点相关 DNA 测序（RAD-Seq）方法，以‘Carrizo’和‘El Toro’杂交产生的 F1 作图群体为材料，构建了结缕草高密度遗传图谱。构建了两个连锁图谱，分别来自于父本和母本。‘Carrizo’连锁图谱由 2408 个 RAD 标记组成，分布于 21 个连锁群；‘El Toro’连锁图谱由 1230 个 RAD 标记组成，分布于 20 个连锁群。两个图谱的相邻标记平均间距分别为 0.56 和 1.4 cM。对结缕草、水稻和高粱基因组进行了比较基因组学分析，观察到三个基因组中基因顺序具有高度保守的共线性。在结缕草和高粱基因组中，每个染色体对的着丝粒区域都发生了染色体共线性的破坏；然而，在结缕草和水稻基因组中，着丝粒区域没有明显的同线性缺口。在结缕草基因组中发现了 10 条高粱染色体的每一条的两个同源染色体，表明结缕草是异源四倍体起源。在这两个亚科从共同祖先分化后，通过独立的单步嵌套染色体融合事件，将基本染色体数从 12 减少到 10，从而产生了 Chloridoids 和 Panicoids。这些遗传图谱将有助于基因组序列组装、目标基因分离以及禾本科植物的比较基因组分析。
