Induction of hairy roots on cultivated soybean genotypes and their use to propagate the soybean cyst nematode.

Abstract

Ten soybean (Glycine max ) genotypes were evaluated for hairy root induction by four strains of Agrobacterium rhizogenes . Influence of inoculation site was assessed by infecting hypocotyls and cotyledons on germinated seedlings. The presence of extracts of cultured roots was used to score transformed roots. A cucumopine strain, K599, induced hairy roots on 37% of the cotyledons infected on the 10 genotypes tested. Transformed root development after infection of cotyledons with the mannopine strain 8196 occurred at a frequency of 3% on four genotypes. Agropine strains 1855 and A4 induced hairy roots on 1% of cotyledons of different genotypes. Opine-containing hairy roots were established permanently in tissue culture and exhibited typical hairy root morphologies and growth parameters. Infection of soybean cultivar Williams 82 hairy root cultures with second-stage juveniles or cysts of the soybean cyst nematode, Heterodera glycines race 3, led to the appearance of mature cysts about 3 wk later. The nematode was propagated by excising an infected root and transferring it to a fresh root culture.