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Title: Genetic Linkage Mapping of the Soybean Aphid Resistance Gene in PI 243540

Author
item Mian, Rouf
item KANG, SUNG-TAEG - SUWON, KOREA
item Beil, Scott

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2008
Publication Date: 7/15/2008
Citation: Mian, R.M., Kang, S., Beil, S.E. 2008. Genetic Linkage Mapping of the Soybean Aphid Resistance Gene in PI 243540. Journal of Theoretical and Applied Genetics. 117:955-962.

Interpretive Summary: The soybean aphid (Aphis glycines Matsumura) is a pest of soybean [Glycine max (L.) Merr.] mainly in Asia and North America. A single dominant gene in PI 243540 controlled resistance to the soybean aphid. DNA markers linked to a gene of interest can be useful for marker assisted breeding. The polymerase chain reaction (PCR) based simple sequence repeat (SSR) DNA markers were used to map the aphid resistant gene from PI 243540 on the consensus soybean genetic map. A total of nine SSR markers from soybean linkage group F flanking the gene were identified as linked to the gene. The aphid resistance gene was positioned in the interval between SSR markers Satt334 and Sct_033 with a distance of 1.8 centimorgan (cM) from Satt334 and 2.7 cM from Sct_033. These two SSR markers will be very useful for marker assisted breeding with this gene. The aphid resistance gene from PI 243540 mapped to a different linkage group than the only named soybean aphid gene Rag1 gene from cultivar ‘Dowling’. Also, the responses of the two known biotypes of the soybean aphid to the gene from PI 243540 and Rag1 were different. Thus, the aphid resistance gene from PI 243540 was a new and independent gene and this gene was named Rag2. This new gene is a unique source of resistance to the Ohio biotype of the soybean aphid.

Technical Abstract: The soybean aphid (Aphis glycines Matsumura) is a pest of soybean [Glycine max (L.) Merr.] in many soybean growing countries of the world, mainly in Asia and North America. A single dominant gene in PI 243540 confers resistance to the soybean aphid. The objectives of this study were to identify simple sequence repeats (SSR) markers closely linked to the gene in PI 243540 and position the gene on the consensus soybean genetic map. One hundred eighty four F2 plants and their F2:3 families from a cross between susceptible cultivar ‘Wyandot’ and PI 243540 and the two parental lines were screened with the Ohio biotype of soybean aphid using greenhouse choice tests. A SSR marker from each 10 cM section of the consensus soybean map was selected for bulk segregant analysis (BSA) to identify the tentative genomic location of the gene. The BSA technique was useful to localize the gene to a genomic region in soybean linkage group (LG) F. The entire F2 population was then screened with polymorphic SSR markers from this genomic region and a linkage map with nine SSR markers flanking the gene was constructed. The aphid resistance gene was positioned in the interval between SSR markers Satt334 and Sct_033 with a distance of 1.8 centimorgan (cM) from Satt334 and 2.7 cM from Sct_033. These SSR markers will be useful for marker assisted selection of this gene. The aphid resistance gene from PI 243540 mapped to a different linkage group than the only named soybean aphid gene Rag1 gene from ‘Dowling’. Also, the responses of the two known biotypes of the soybean aphid to the gene from PI 243540 and Rag1 were different. Thus, the aphid resistance gene from PI 243540 was a new and independent gene and this gene was named Rag2.