Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/10/2000
Publication Date: N/A
Citation: Interpretive Summary: DNA markers genetically linked to traits of economic importance can be an efficient way of selecting for those traits. Our research was designed to identify a specific type of DNA markers (Random Amplified Polymorphic DNA or RAPD) linked to resistance to soybean mosaic virus (SMV) resistance. This type of marker is easy and relatively inexpensive to produce. Using DNA markers could identify resistant plants faster than by inoculating with the virus and would be very useful for identifying which specific gene or genes is present when selection is occurring for more than one gene. We did find a RAPD marker that was linked very closely to Rsv1, one of the genes known to confer resistance to SMV. This marker would correctly select for SMV resistance in a segregating population over 95% of the time. In all previous research RAPD markers have only existed in two forms, present or absent. This particular RAPD marker was found to exist in three forms, present, weak, and absent. The weak form represents the state where an individual has two different alleles or is heterozygous. This is the first time that a RAPD marker has been shown to exist in a heterozygous state and greatly increases the usefulness of this marker to soybean breeders. By using this marker they can determine which individuals in a segregating population will produce all SMV resistant progeny and which ones will produce both resistant and susceptible progeny. Actual inoculation with the virus will not provide this information.
Technical Abstract: Williams and three near-isogenic lines (isolines) with soybean mosaic virus (SMV) resistance were used to identify a random amplified polymorphic DNA (RAPD) marker linked to the locus conferring resistance to SMV. A RAPD marker was found to be present in Williams and absent in three isolines of Williams with SMV resistance. Three F2 populations developed from the crosses of Williams x L81-4420, Williams x L92-8151, and Marshall x Kanro were produced to verify the linkage between the fragment and the SMV resistance gene. L81-4420 is an isoline of Williams that has Rps1-k from the cultivar Kingwa in addition to Rsv1 from PI 96983. L92-8151 is an isoline of Williams with PI 486355 as the donor parent. A 1,000 base pair fragment, designated OPN-11(1000), generated by the primer OPN-11 was located approximately 1.17 +/ 1.18 cM in repulsion phase and 1.79 +/ 1.29 cM in coupling phase from Rsv1, a gene for resistance to SMV. In a survey of other germplasm, OPN-11(1000) was found linked with either Rsv1 or rsv1. F3 families derived from F2 resistant plants were used to confirm the F2 genotypes. Using this marker, homozygous and heterozygous SMV resistant plants could be easily distinguished based on the fragment intensity.