A 235-bp region from a nutritionally regulated soybean seed-specific gene promoter can confer its sulfur and nitrogen response to a constitutive promoter in aerial tissues of Arabidopsis thaliana

Abstract

The seed-specific promoter of the β subunit gene of β-conglycinin, a major seed storage protein of soybean, is upregulated in response to both sulfur and nitrogen nutrition. This response was studied in non-seed tissues of transgenic Arabidopsis thaliana by fusing the β subunit promoter (Pβ) downstream of an enhancer from the cauliflower mosaic virus 35S RNA promoter (P35S) and using the β-glucuronidase (GUS) reporter gene. The chimeric promoter was upregulated by sulfur deficiency (ΔS), indicating that the Pβ is able to direct the ΔS response in non-seed tissues. Deletion analysis of the Pβ revealed that, in seeds, the −307–−73 bp region is sufficient for the ΔS response. Insertion of the 235 bp region into the P35S conferred the ΔS response on this constitutive promoter in both seed and non-seed tissues. The extent of upregulation by ΔS was more evident when three of the 235 bp fragments were tandemly inserted into the P35S. The findings presented here suggest that a common mechanism exists for sulfur-regulated expression of the Pβ in both seed and non-seed tissues and that this 235 bp region of the Pβ is sufficient for regulation by both sulfur and nitrogen nutrition.