ISSN:
1573-5028
Keywords:
β-conglycinin
;
embryogenesis
;
Glycine max
;
legumin box
;
regulatory elements
;
seed storage proteins
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract β-conglycinin is one of the major seed storage proteins in soybean. It is composed of three subunits, namely α, α′ and β. The expression of β-conglycinin is highly regulated, being restricted to the embryo during the mid-maturation phase of embryogeny. Two series of constructs were made with the α′ subunit promoter and the GUS reporter gene to investigate the cis-acting elements involved in the regulated expression of this promoter. The activity of each construct was tested in transgenic tobacco plants. In the first series of constructs, we checked if the ‘legumin box’, a sequence found in most legume seed storage protein genes as well as in other seed-specific genes, is involved in the regulated expression of the α′ subunit of the β-conglycinin gene in tobacco. To this end, both copies of the α′ subunit promoter legumin boxes were mutagenized in vitro. The transcriptional activity of the single mutants and the double mutant were compared with that of the wild-type promoter. Our results show that the legumin boxes act together to increase transcription of the β-conglycinin α′ subunit gene by about a factor of ten. This is the first demonstration of a function for the legumin box in transcriptional regulation. In the second series of experiments, we wished to determine if the 3′ part of the promoter (the CCAAT and TATAA region) contains important regulatory elements. We found that this small fragment (−82 to +13 bp) can confer by itself a low level of seed-specific gene expression. Chimaeric promoters constructed from parts of the α′ subunit promoter and of the constitutive CaMV 35S promoter were also analysed. These constructs also revealed the importance of the CCAAT and TATAA region of the α′ subunit promoter in seed-specific gene expression.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00040526
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