Wednesday, November 7, 2007
258-6

Development of Soybean Germplams Genetically Diverse for SCN Resistance.

S.R. Cianzio, Iowa State University, Ames, IA 50011, P.R. Arelli, USDA-ARS-MSA, 605 Airways Blvd, Jackson, TN 38301, B.W. Diers, University of Illinois, Urbana, IL 61801, and H.T. Knap, Clemson University, Clemson, SC 29634.

Soybean cyst nematode (SCN) Heterodera glycines Ichinohe is the most serious pest of cultivated soybean [Glycine max (L.) Merr.]. Genetic resistance has been the most effective and environmentally friendly means of controlling this pest. Nematode populations, however, are genetically variable and have adapted to reproduce on resistant cultivars. New and genetically diverse sources of resistance might provide durable resistance. PI 22897 (Columbia) is an introduction from China with resistance to both SCN Races 3 and 14 (corresponding to HG Types 0 and 1.3.5.7, respectively) , green- seeded and a Maturity Group III soybean line. It is genetically diverse from mostly used sources of resistance; Peking, PI 437654 and PI 88788. Soybean PI 88788 is also a Maturity Group III introduction from China, with resistance to both SCN Races 3 and 14 but differs from Columbia by having a black-seed coat. It is the primary source of SCN resistance in the cultivars grown in the North. Both PIs were crossed to develop five germplasm lines for resistance to both SCN Races 3 and 14; one in Maturity Group II (AR4SCN) and four in Maturity Group III (AR5SCN, AR6SCN, AR7SCN and AR8SCN). These sister lines were developed using a combination of pedigree and mass selection methods. Selection for SCN resistance involved both greenhouse bioassays and molecular markers. These lines have tawny pubescence, brown pods, seeds with imperfect brown hila, yellow seed coat (a desirable character) and dull seed coat luster. Flower color is white except for AR4SCN which has purple flowers. These lines are released on the basis of their statistically significant differences in seed yield and maturity.