Maternal Effects ofmto1Mutation, That Causes Overaccumulation of Soluble Methionine, on the Expression of a SoybeanβConglycinin Gene Promoter-GUS Fusion in TransgenicArabidopsis thaliana

摘要

β-Conglycinin, the 7S seed storage protein of soybean (Glycine maxL. Merr.), is comprised mainly of three subunits, designatedα,α′andβ. Expression of the gene encoding theβsubunit is unique because its expression has been shown to be down-regulated by exogenously applied L-methionine in immature soybean cotyledon cultures in vitro.Arabidopsis thalianastrain carrying amto1-1mutation overaccumulates soluble methionine. By using this mutant, we analyzed the effects of methionine on expression of theβsubunit gene in vivo. Reciprocal crosses were made between themto1-1mutant and a transgenicA. thalianastrain, designated SNTβ3, which carries aβ-glucuronidase (GUS) reporter gene under the control of the promoter region of theβsubunit gene. Analysis of GUS activity in F1seeds indicated that the GUS activity was dramatically repressed when themto1-1mutant plants were used as female parents. We constructed a strain which carries both the transgene andmto1-1mutation in the homozygous state. Analyses of the GUS activity in seeds of this double homozygous strain indicated that the GUS activity was repressed to 2.5of control by introduction of themto1-1mutation. These results indicate that theβsubunit gene promoter activity in seeds is down-regulated by maternal genotype and suggest that soluble methionine, or its mobile metabolite, is translocated from mother plants to repressβsubunit gene express