Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 4/11/2008
Publication Date: 6/1/2008
Citation: Paul, C., Hartman, G.L. 2008. Evaluation of sources of soybean rust resistance using detached leaves [abstract]. Phytopathology. 98:S123.
Technical Abstract: Soybean rust (SBR), caused by the fungus Phakopsora pachyrhizi, is a potentially devastating disease that can cause significant yield losses. Resistance in soybean germplasm, both qualitative and quantitative, may be effective in providing partial control of SBR. Thirty soybean accessions that contained a known major gene for resistance and/or were reported to have field resistance to SBR were evaluated for resistance to P. pachyrhizi. Detached leaves of the 30 accessions were inoculated with six U.S. domestic P. pachyrhizi isolates. Of the 30 accessions, two accessions had a hypersensitive reaction, eight had reddish brown (RB) lesions, and the remainder had tan lesions. There were significant differences by accession in the number of sporulating uredinia and the number of stained uredinia in fixed tissue. The number of sporulating uredinia and stained uredinia in RB lesions ranged from 0 to 7.7 with a mean of 0.67 per cm(^2) and from 0 to 13.3 with the mean of 1.2 per cm(^2), respectively. The number of sporulating uredinia and stained uredinia in tan lesions ranged from 2.3 to 56.3 with a mean of 26.2 per cm(^2) and from 7.5 to 143 with the mean of 47.24 per cm(^2), respectively. None of the resistance sources carrying the Rpp2 and Rpp4 genes were resistant to the six isolates. In conclusion, both qualitative and quantitative resistance was observed among these 30 soybean accessions to the six U.S. domestic P. pachyrhizi isolates.