Triwitayakorn K, Njiti V N, Iqbal M J, Yaegashi S, Town C, Lightfoot D A
Department of Plant, Soil, and Agricultural Systems, Southern Illinois University at Carbondale, IL 62901, USA.
Genome. 2005 Feb;48(1):125-38. doi: 10.1139/g04-103.
Candidate genes were identified for two loci, QRfs2 providing resistance to the leaf scorch called soybean (Glycine max (L.) Merr.) sudden death syndrome (SDS) and QRfs1 providing resistance to root infection by the causal pathogen Fusarium solani f.sp. glycines. The 7.5 +/- 0.5 cM region of chromosome 18 (linkage group G) was shown to encompass a cluster of resistance loci using recombination events from 4 near-isogenic line populations and 9 DNA markers. The DNA markers anchored 9 physical map contigs (7 are shown on the soybean Gbrowse, 2 are unpublished), 45 BAC end sequences (41 in Gbrowse), and contiguous DNA sequences of 315, 127, and 110 kbp. Gene density was high at 1 gene per 7 kbp only around the already sequenced regions. Three to 4 gene-rich islands were inferred to be distributed across the entire 7.5 cM or 3.5 Mbp showing that genes are clustered in the soybean genome. Candidate resistance genes were identified and a molecular basis for interactions among the disease resistance genes in the cluster inferred.
已确定两个位点的候选基因，即赋予大豆（Glycine max (L.) Merr.）对叶焦枯病（称为大豆猝死综合征，SDS）抗性的QRfs2和赋予对致病病原体大豆镰刀菌（Fusarium solani f.sp. glycines）根部感染抗性的QRfs1。利用来自4个近等基因系群体的重组事件和9个DNA标记，显示18号染色体（连锁群G）上7.5±0.5 cM的区域包含一个抗性基因座簇。这些DNA标记定位了9个物理图谱重叠群（大豆基因组浏览器上显示7个，2个未发表）、45个BAC末端序列（基因组浏览器中有41个）以及315、127和110 kbp的连续DNA序列。仅在已测序区域周围基因密度较高，每7 kbp有1个基因。推断3至4个富含基因的岛分布在整个7.5 cM或3.5 Mbp区域，表明基因在大豆基因组中是成簇分布的。已鉴定出候选抗性基因，并推断出该簇中抗病基因之间相互作用的分子基础。
