Submitted to: Journal of Crop Science and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2010
Publication Date: 9/30/2010
Citation: Arelli, P.R., Concibido, V.C., Young, L.D. 2010. QTLs associated with resistance in soybean PI567516C to synthetic nematode population infecting cv. Hartwig. Journal of Crop Science and Biotechnology. 13:163-167. Interpretive Summary: Soybean yields worldwide are limited by the soybean cyst nematode, a microscopic size round worm attacking the roots of the soybean plant in infested fields. Resistant cultivars have been the most effective means of controlling the pest. Nematode populations are highly variable and have adapted to reproduce on resistant cultivars of soybean having resistance derived from wild sources, PI88788 and Peking. Soybean cultivar Hartwig was released due to its comprehensive resistance to most populations of the nematodes. However, Hartwig was found susceptible to a synthetic nematode population called as LY1. This nematode population is highly aggressive and overcomes resistance of all known sources except a wild soybean line PI567516C. Similar aggressive nematode populations have been reported from soybean fields but their extent of spread is limited. Soybean line PI567516C has no commercial value to growers but the genes for resistance to the LY1 nematode population can be transferred into the back ground of Hartwig using a traditional breeding program. This will strengthen Hartwig for its comprehensive resistance. More recent technology has provided much better methodology called QTL mapping to identify resistance genes using DNA markers. Hartwig and PI567516C were crossed to develop their progenies and used in mapping. Three DNA markers were associated with resistance in PI567516C and these markers can be used in other crosses as “tags” to select resistant soybean lines for the LY1nematodes. This information will be highly useful to soybean breeders to develop new cultivars with improved resistance to the nematodes especially to the LY1 population using marker assisted breeding method.
Technical Abstract: Worldwide, soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is the most destructive pathogen of soybean [Glycine max (L.) Merr.]. Crop losses are primarily mitigated by the use of resistant cultivars. Nematode populations are variable and have adapted to reproduce on resistant cultivars overtime because resistance primarily traces to two soybean accessions, Plant Introduction (PI) 88788 and Peking. Soybean cultivar Hartwig, derived primarily from PI 437654, was released for its comprehensive resistance to most SCN populations. A virulent nematode population, LY1, was recently selected for its reproduction on Hartwig. The LY1 nematode population infects currently known sources of resistance except soybean PI567516C. However, the inheritance of PI567516C resistance to the LY1 has not been characterized. The objective of this study was to identify quantitative trait loci (QTLs) underlying resistance to the LY1 SCN population in PI567516C, identify diagnostic DNA markers for the LY1 resistance and confirm their utility for marker assisted selection (MAS). Resistant soybean line PI567516C was crossed to susceptible cultivar Hartwig to generate 105 F2- derived F5 families. QTLs were mapped using simple sequence repeats (SSRs) covering 20 Linkage Groups (LGs) and three diagnostic markers, Satt592, Satt331, and Sat_274, were identified on LG O associated with resistance to the LY1. These three markers have a combined efficacy of 90% in identifying resistant lines in a marker assisted selection to the LY1.To confirm the utility of these markers for resistance in a marker assisted selection, another soybean cross was made using cv.5601T (susceptible) with PI 567516C. Resistant lines were identified in F2 -derived F4 population for the LY1 nematodes.