Universidade Federal de Viçosa, Avenida Peter Henry Rolfs, s/n, Viçosa, MG, 36570-900, Brazil.
Embrapa Milho e Sorgo, Rodovia MG 424 km 65, Sete Lagoas, MG, 35701-970, Brazil.
Theor Appl Genet. 2021 Jan;134(1):295-312. doi: 10.1007/s00122-020-03697-8. Epub 2020 Oct 14.
A multiparental random mating population used in sorghum breeding is amenable for the detection of QTLs related to tropical soil adaptation, fine mapping of underlying genes and genomic selection approaches. Tropical soils where low phosphorus (P) and aluminum (Al) toxicity limit sorghum [Sorghum bicolor (L.) Moench] production are widespread in the developing world. We report on BRP13R, a multiparental random mating population (MP-RMP), which is commonly used in sorghum recurrent selection targeting tropical soil adaptation. Recombination dissipated much of BRP13R's likely original population structure and average linkage disequilibrium (LD) persisted up to 2.5 Mb, establishing BRP13R as a middle ground between biparental populations and sorghum association panels. Genome-wide association mapping (GWAS) identified conserved QTL from previous studies, such as for root morphology and grain yield under low-P, and indicated the importance of dominance in the genetic architecture of grain yield. By overlapping consensus QTL regions, we mapped two candidate P efficiency genes to a ~ 5 Mb region on chromosomes 6 (ALMT) and 9 (PHO2). Remarkably, we find that only 200 progeny genotyped with ~ 45,000 markers in BRP13R can lead to GWAS-based positional cloning of naturally rare, subpopulation-specific alleles, such as for SbMATE-conditioned Al tolerance. Genomic selection was found to be useful in such MP-RMP, particularly if markers in LD with major genes are fitted as fixed effects into GBLUP models accommodating dominance. Shifts in allele frequencies in progeny contrasting for grain yield indicated that intermediate to minor-effect genes on P efficiency, such as SbPSTOL1 genes, can be employed in pre-breeding via allele mining in the base population. Therefore, MP-RMPs such as BRP13R emerge as multipurpose resources for efficient gene discovery and deployment for breeding sorghum cultivars adapted to tropical soils.
一个用于高粱育种的多亲本随机交配群体适合检测与热带土壤适应性相关的 QTL，对潜在基因进行精细定位，并采用基因组选择方法。在发展中国家，低磷（P）和铝（Al）毒性限制高粱[高粱（L.）莫恩]生产的热带土壤很普遍。我们报告了 BRP13R，这是一种多亲本随机交配群体（MP-RMP），常用于针对热带土壤适应性的高粱轮回选择。重组消耗了 BRP13R 可能的原始群体结构的大部分，平均连锁不平衡（LD）持续到 2.5 Mb，使 BRP13R 成为双亲群体和高粱关联面板之间的中间地带。全基因组关联作图（GWAS）从以前的研究中鉴定出保守的 QTL，例如在低 P 下的根系形态和粒产量，并且表明在粒产量的遗传结构中显性的重要性。通过重叠共识 QTL 区域，我们将两个候选 P 效率基因映射到染色体 6（ALMT）和 9（PHO2）上的一个约 5 Mb 区域。值得注意的是，我们发现仅在 BRP13R 中用大约 45000 个标记对 200 个后代进行基因型检测，就可以导致基于 GWAS 的位置克隆自然稀有、亚群特异性等位基因，例如 SbMATE 条件下的 Al 耐受性。发现基因组选择在这种多亲本随机交配群体中很有用，特别是如果与主基因 LD 的标记被拟合为固定效应，以适应容纳显性的 GBLUP 模型。在粒产量上有差异的后代中，等位基因频率的变化表明，SbPSTOL1 等 P 效率的中等至次要效应基因可以通过在基础群体中挖掘等位基因，在预育种中使用。因此，BRP13R 等多亲本随机交配群体成为用于发现和部署适应热带土壤的高粱品种的高效基因的多用途资源。
