EXPRESSION OF SOYBEAN SEED STORAGE PROTEIN GENES IN TRANSGENIC PLANTSAND THEIR RESPONSE TO SULFUR NUTRITIONAL CONDITIONS

beta-Conglycinin, the 7S seed storage protein of soybean (Glycine max [L.] Merr.), is comprised mainly of three subunits, designated alpha', alpha and beta. Among these subunits, expression of the beta subunit is unique because its accumulation is enhanced under sulfate deficienc y in vivo and repressed by exogenously applied L-methionine in cotyled on cultures of soybean. Transgenic Arabidopsis thaliana (L.) Heynh. st rains carrying either intact gene encoding the beta subunit, or beta-g lucuronidase fusion were constructed and the effects of sulfur nutriti onal conditions were analyzed. Expression of the transgene was enhance d under sulfate deficiency and repressed when the siliques of transgen ic A. thaliana plants were cultured in the presence of L-methionine. T he results indicate that response to sulfur nutritional conditions are conserved in transgenic A. thaliana. By using an A. thaliana mutant, designated mto1-1, that overaccumulates free methionine, activity of t he beta subunit gene promoter was shown to be repressed in the seeds. These transgenic and mutant A. thaliana plants will be useful in analy zing the plants' response to nutritional conditions.