Vesicular-arbuscular mycorrhizas of wild-type soybean and non-nodulating mutants with Glomus mosseae contain symbiosis-specific polypeptides (mycorrhizins), immunologically cross-reactive with nodulins.

Wild-type soybean (Glycine max L. Merr. cv. Bragg) plants and two soybean mutants derived from cv. Bragg (nod 49 and nod 139) unable to form nodules with Bradyrhizobium japonicum were compared with regard to their reaction to the vesicular-arbuscular mycorrhizal fungus Glomus mosseae. The roots from wild-type and mutant plants entered equally well into vesicular-arbuscular mycorrhiza symbiosis. Polyadenylated RNA was isolated from nodule-free mycorrhizal and non-mycorrhizal roots of wild-type and mutant plants and translated in vitro. The translation products were subjected to immunoprecipitation using antisera reacting with soluble or membrane-bound nodulins. The antisera did not immunoprecipitate any of the translation products from non-mycorrhizal roots. However, they reacted with specific translation products from mycorrhizal roots of both wild-type and mutant plants: two polypeptides (MWs 135-140 and 18 kDa) were immunoprecipitated with the antiserum against soluble nodulins and three (MWs 21-28 kDa) with the antiserum against membrane-bound nodulins. These results indicate that symbiosis-specific polypeptides, possibly identical with nodulins, are induced in the mycorrhiza and therefore can be termed "mycorrhizins".