Plant Genome Mapping Laboratory, College of Agricultural and Environmental Sciences, University of Georgia, Athens, Georgia.
Kayada 2069-6, Yachiyo, Chiba, Japan.
PLoS One. 2020 Jul 30;15(7):e0235896. doi: 10.1371/journal.pone.0235896. eCollection 2020.
Mature sorghum herbage is known to contain several water-soluble secondary metabolites (allelochemicals). In this study, we investigated quantitative trait loci (QTLs) associated with allelochemical characteristics in sorghum using linkage mapping and linkage disequilibrium (LD)-based association mapping. A sorghum diversity research set (SDRS) of 107 accessions was used in LD mapping whereas, F2:3 lines derived from a cross between Japanese and African landraces were used in linkage mapping. The QTLs were further confirmed by positional (targeted) association mapping with Q+K model. The inhibitory effect of water-soluble extracts (WSE) was tested on germination and root length of lettuce seedlings in four concentrations (25%, 50%, 75% and 100%). A Significant range of variations was observed among genotypes in both types of mapping populations (P < 0.05). A total of 181 simple sequence repeats (SSRs) derived from antecedently reported map have been used for genotyping of SDRS. A genetic linkage map of 151 sorghum SSR markers was also developed on 134 F2 individuals. The total map length was 1359.3 cM, with an average distance of 8.2 cM between adjacent markers. LD mapping identified three QTLs for inhibition effect on germination and seven QTLs for root length of lettuce seedlings. Whereas, a total of six QTLs for inhibition of germination and ten QTLs for root length were detected in linkage mapping approach. The percent phenotypic variation explained by individual QTL ranged from 6.9% to 27.3% in SDRS and 9.9% to 35.6% in F2:3 lines. Regional association analysis identified four QTLs, three of them are common in other methods too. No QTL was identified in the region where major gene for sorgoleone (SOR1) has been cloned previously on chromosome 5.
成熟的高粱草被认为含有几种水溶性次生代谢物（化感物质）。在这项研究中，我们使用连锁图谱和连锁不平衡（LD）关联图谱，研究高粱草中与化感物质特征相关的数量性状位点（QTLs）。利用 LD 图谱，我们使用了一个由 107 个品系组成的高粱草多样性研究组（SDRS），而通过日本和非洲地方品种杂交得到的 F2:3 系则用于连锁图谱。通过 Q+K 模型的靶向关联图谱进一步验证了 QTLs。在四个浓度（25%、50%、75%和 100%）下，测试了水溶性提取物（WSE）对生菜幼苗发芽和根长的抑制作用。在两种图谱群体中（P<0.05），基因型之间观察到显著的变异范围。总共使用了 181 个来自先前报道图谱的简单序列重复（SSR）对 SDRS 进行基因分型。还对 134 个 F2 个体进行了 151 个高粱 SSR 标记的遗传连锁图谱开发。总图谱长度为 1359.3cM，相邻标记之间的平均距离为 8.2cM。LD 图谱鉴定出三个与发芽抑制相关的 QTL 和七个与生菜幼苗根长相关的 QTL。而在连锁图谱方法中，共检测到六个与发芽抑制相关的 QTL 和十个与根长相关的 QTL。单个 QTL 解释的表型变异百分比在 SDRS 中从 6.9%到 27.3%不等，在 F2:3 系中从 9.9%到 35.6%不等。区域关联分析确定了四个 QTL，其中三个在其他方法中也很常见。在先前已克隆在 5 号染色体上的 sorgoleone（SOR1）主基因所在区域没有鉴定到 QTL。
