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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVEMENT OF PEST RESISTANCE AND QUALITY TRAITS OF SOYBEAN Title: Novel quantitative trait loci for partial resistance to Phytophthora sojae in soybean PI 398841

Authors
item Lee, Sungwoo -
item Mian, Rouf
item Mchale, Leah -
item Wang, Hehe -
item Wijeratne, Asela -
item Sneller, Clay -
item Dorrance, Ann -

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 10, 2012
Publication Date: January 25, 2013
Repository URL: http://handle.nal.usda.gov/10113/58205
Citation: Lee, S., Mian, R.M., Mchale, L.K., Wang, H., Wijeratne, A., Sneller, C., Dorrance, A. 2013. Novel quantitative trait loci for partial resistance to Phytophthora sojae in soybean PI 398841. Theoretical and Applied Genetics. 126(4):1121-1132.

Interpretive Summary: Phytophthora root and stem rot caused by Phytophthora sojae Kaufmann and Gerdmann is one of the most severe diseases of soybean in the USA. Partial resistance or multi-gene resistance can be as effective managing this disease as single-gene (Rps) mediated resistance and is often more durable. The objective of this study was to identify novel loci associated with partial resistance to P. sojae in a soybean plant introduction (PI) 398841, which originated from South Korea. A population of 305 F7:8 recombinant inbred lines (RILs) derived from a cross of OX20-8 × PI 398841 was used to evaluate partial resistance against P. sojae isolate C2S1 using tray test. The genetic linkage map of this population was constructed with 273 single nucleotide polymorphism and simple sequence markers. Composite interval mapping detected three significant quantitative trait loci (QTL) on soybean chromosomes 1, 13, and 18, which accounted for 4 to 16 % of the phenotypic variance. This study also reported six more putative QTL with lower level of significance , each accounting for only 2 to 3% of the variance. Six of the nine loci were novel. Since three QTL on chromosomes 3, 13 and 18 co-localized with known Rps genes PI 398841 was expected to have some Rps genes. However, it was susceptible to all 48 isolates of P. sojae tested in this study. Soybean breeders and pathologists in USA and elsewhere may find this soybean PI useful.

Technical Abstract: Phytophthora root and stem rot caused by Phytophthora sojae Kaufmann and Gerdmann is one of the most severe soybean [Glycine max (L.) Merr] diseases in the US. Partial resistance is as effective in managing this disease as single-gene (Rps) mediated resistance and is more durable. The objective of this study was to identify novel QTL associated with partial resistance to P. sojae in a new genetic source PI 398841, which originated from South Korea. A population of 305 F7:8 recombinant inbred lines (RILs) derived from a cross of OX20-8 × PI 398841 was used to evaluate partial resistance against P. sojae isolate C2S1 using tray test. The genetic linkage map of this population was constructed with 273 single nucleotide polymorphism and simple sequence markers. Composite interval mapping detected three significant QTL on chromosomes 1, 13, and 18, which accounted for 4 to 16 % of the phenotypic variance. This study also reported six more putative QTL with intermediate significance between chromosome- and genome-wide logarithm of odd (LOD) thresholds, each accounting for only 2 to 3% of the variance. Six of the nine loci were novel. All QTL were located adjacent to known defense-related or disease resistance QTL. Since three QTL on chromosomes 3, 13 and 18 colocalized with known Rps genes PI 398841 was expected to have some Rps genes. However, it was susceptible to 48 isolates of P. sojae tested in this study. PI 398841 is a potential genetic source in improving soybean cultivars for partial resistance to P. sojae.

Last Modified: 12/28/2014
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