Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, 24061, Blacksburg, VA, USA.
Theor Appl Genet. 1995 Nov;91(6-7):907-14. doi: 10.1007/BF00223899.
Soybean [Glycine max (L.) Merr.] PI486355 is resistant to all the identified strains of soybean mosaic virus (SMV) and possesses two independently inherited resistance genes. To characterize the two genes, PI486355 was crossed with the susceptible cultivars 'Lee 68' and 'Essex' and with cultivars 'Ogden' and 'Marshall', which are resistant to SMV-G1 but systemically necrotic to SMV-G7. The F2 populations and F2∶3 progenies from these crosses were inoculated with SMV-G7 in the greenhouse. The two resistance genes were separated in two F3∶4 lines, 'LR1' and 'LR2', derived from Essex x PI486355. F1 individuals from the crosses of LR1 and LR2 with Lee 68, Ogden, and 'York' were tested with SMV-G7 in the greenhouse; the F2 populations were tested with SMV-G1 and G7. The results revealed that expression of the gene in LR1 is gene-dosage dependent, with the homozygotes conferring resistance but the heterozygotes showing systemic necrosis to SMV-G7. This gene was shown to be an allele of the Rsv1 locus and was designated as Rsv1-s. It is the only allele identified so far at the Rsv1 locus which confers resistance to SMV-G7. Rsv1-s also confers resistance to SMV-G1 through G4, but results in systemic necrosis with SMV-G5 and G6. The gene in LR2 confers resistance to strains SMV-G1 through G7 and exhibits complete dominance. It appears to be epistatic to genes at the Rsv1 locus, inhibiting the expression of the systemic necrosis conditioned by the Rsv1 alleles. SMV-G7 induced a pin-point necrotic reaction on the inoculated primary leaves in LR1 but not in LR2. The unique genetic features of the two resistance genes from PI486355 will facilitate their proper use and identification in breeding and contribute to a better understanding of the interaction of SMV strains with soybean resistance genes.
大豆[ Glycine max (L.) Merr.] PI486355 对所有鉴定的大豆花叶病毒 (SMV) 株系均具有抗性，并且具有两个独立遗传的抗性基因。为了对这两个基因进行特征描述，PI486355 与感病品种 'Lee 68' 和 'Essex' 以及对 SMV-G1 具有抗性但对 SMV-G7 表现系统坏死的品种 'Ogden' 和 'Marshall' 进行了杂交。将这些杂交的 F2 群体和 F2∶3 后代在温室中用 SMV-G7 接种。这两个抗性基因在来自 Essex x PI486355 的两个 F3∶4 系 'LR1' 和 'LR2' 中分离。LR1 和 LR2 与 Lee 68、Ogden 和 'York' 的 F1 个体在温室中用 SMV-G7 进行了测试；F2 群体用 SMV-G1 和 G7 进行了测试。结果表明，LR1 中基因的表达是剂量依赖的，纯合子赋予抗性，但杂合子对 SMV-G7 表现系统坏死。该基因被证明是 Rsv1 基因座的一个等位基因，被命名为 Rsv1-s。它是迄今为止在 Rsv1 基因座上鉴定出的唯一一个赋予 SMV-G7 抗性的等位基因。Rsv1-s 还通过 G4 赋予对 SMV-G1 的抗性，但与 SMV-G5 和 G6 一起导致系统坏死。LR2 中的基因赋予对 SMV-G1 至 G7 的抗性，并表现出完全显性。它似乎与 Rsv1 基因座上的基因是上位的，抑制了由 Rsv1 等位基因引起的系统坏死的表达。SMV-G7 在 LR1 上诱导接种的初生叶片产生针尖状坏死反应，但在 LR2 上则没有。PI486355 中两个抗性基因的独特遗传特征将有助于它们在育种中的正确使用和鉴定，并有助于更好地理解 SMV 株系与大豆抗性基因的相互作用。
