Submitted to: Germplasm Release
Publication Type: Germplasm Release
Publication Acceptance Date: 5/19/2006
Publication Date: 10/2/2006
Citation: Mengistu, A., Kilen, T., Donald, P.A. 2006. Notice of release of d99-2065 soybean germplasm line resistant to phytophthora rot and soybean cyst nematode races 3 and 4.. Germplasm Release. Crop Sci 2006 46:2325-2326.
Technical Abstract: Soybean germplasm line D99-2065 was released in October 2003. The objective was to provide private and public soybean breeders with a parent to develop high yielding, multiple pest resistant cultivars. Phytophthora rot (PR) and soybean cyst nematode (SCN) continue to be serious yield-limiting diseases of soybean. D99-2065 is a product of a backcrossing program to transfer the Rps1-b gene into a 'Bedford' background. This line has value as a parent because of its resistance to PR and races 3 and 14 of the soybean cyst nematode. It also has value to the research community because it will expand the set of previous releases of PR-resistant lines which are near-isogenic to the cultivar Bedford. The reaction of 12 F3 plants was used to identify lines uniformly resistant to PR. F2:3 lines uniformly resistant to PR were selected as pollen parents between each of the five crossing cycles. Seedlings were inoculated in a greenhouse during the years 2000 through 2002 by the hypocotyl puncture method using race and 1 and 2 of the pathogen. After the fourth backcross to Bedford, an F3 line uniformly resistant to race 2 was increased for two generations, and 100 F5 plants were again inoculated with race 2 to verify the reaction of the F3. D99-2065 was evaluated in F8 generation for reaction to races 3 and 14 of the SCN at Jackson, TN. D99-2065 had a similar level of resistance to races 3 and 14 as the recurrent parent, Bedford. In a yield test on clay soil at Stoneville, MS unfavorable environmental conditions resulted in low yields in the first two years of testing, but D99-2065 still yielded higher with 1492 Kg/ha per hectare versus 1269 Kg/ha for Bedford. In 2002, D99-2065 yielded 3740 Kg/ha hectare compared with a yield of 3281 Kg/ha for Bedford. The 3-year means were 1850 Kg/ha for Bedford and 2538 Kg/ha for D99-2065. A breeding line very susceptible to phytophthora rot planted in the same field showed symptoms of the disease all 3 years, but D99-2065 showed none.