EXPRESSION OF A SOYBEAN (GLYCINE-MAX [L] MERR) SEED STORAGE PROTEIN GENE IN TRANSGENIC ARABIDOPSIS-THALIANA AND ITS RESPONSE TO NUTRITIONALSTRESS AND TO ABSCISIC-ACID MUTATIONS

Among the three subunits of beta-conglycinin, the 7S seed storage prot ein of soybean (Glycine max [L.] Merr.), expression of the beta subuni t gene is unique. Accumulation of the beta subunit is enhanced in sulf ate-deficient soybean plants, and its mRNA levels increase when abscis ic acid (ABA) is added to the in vitro cotyledon culture medium. Trans genic Arabidopsis thaliana lines carrying a gene encoding the beta sub unit was constructed and grown under sulfate deficiency. Accumulation of both beta subunit mRNA and protein were enhanced in developing A. t haliana seeds. Accumulation of one of the A. thaliana seed storage pro tein mRNAs was also enhanced by sulfate deficiency, although the respo nse was weaker than that observed for the soybean beta subunit mRNA. W hen the aba1-1 or abi3-1 mutations were crossed into the transgenic A. thaliana line, accumulation of the beta subunit was significantly red uced, whereas accumulation of the A. thaliana seed storage protein was not greatly affected. These results indicate that soybean and A. thal iana share a common mechanism for response to sulfate deficiency and t o ABA, although the sensitivity is different between the species. The transgenic A. thaliana carrying the beta subunit gene of beta-conglyci nin will be a goad system to analyze these responses.