GRAFT-TRANSMISSIBLE INFLUENCE ON FATTY-ACID COMPOSITION OF SOYBEAN SEED

Studies involving reciprocal matings in soybean [Glycine max (L.) Merr.] show that the genotype of the maternal plant usually governs phenotypic expression of fatty acid traits in the seed, and that the maternal influence is not inherited through cytoplasmic genes. The objective of this research was to determine whether the maternal influence on fatty acid composition of soybean seed is graft-transmissible. Autografts and reciprocal heterografts were made prior to flowering in two field environments (early and late plantings) using two genotypes (N78-2245 and ''Essex''), which were similar in phenological development but differed in fatty acid composition. By comparing heterografted scions with autografted scions for a given rootstock genotype, the rootstock genotype significantly influenced the seed fatty acid composition of heterografted scions. The magnitude of the influence was greater when heterografted scions were defoliated throughout seed development. It was concluded that the genotype of the maternal plant may control phenotypic expression of fatty acid percentages in the seed via translocated factors. These factors presumably originated in leaf tissue instead of the roots.