Reporter Gene Expression Patterns Regulated by an Ara h 2 Promoter Differ in Homologous Versus Heterologous Systems1

Abstract

Abstract Peanut (Arachis hypogaea L.) is a globally important crop whose seeds are widely used in food products. Peanut seeds contain proteins that serve a nutrient reservoir function and that also are major allergens. As part of an investigation to determine the effect of reducing/eliminating the peanut allergen Ara h 2 from seeds, gene sequence including upstream regulatory regions was characterized. The ability of regions upstream of the translation initiation site to regulate seed-specific expression of reporter genes was tested in peanut and Arabidopsis. Two independent transgenic peanut lines biolistically transformed with 1kb of DNA upstream of the Ara h 2.02 (B-genome) coding sequence controlling a Green Fluorescent Protein – β-glucuronidase (Gfp-Gus) fusion were obtained. All T1, T2 and T3 generations of transgenic plants showed the expression of GFP and GUS restricted to seeds and near background levels in vegetative tissues. However, constitutive GUS expression was observed in Arabidopsis transgenic lines, a heterologous system. It is possible that trans-acting factors regulating seed specificity in peanut are too divergent in Arabidopsis to enable the seed specific response. Thus, the promoter described in this paper may have potential use for expression of transgenes in peanut where seed-specificity is desired, but expression patterns should be tested in heterologous systems prior to off-the-shelf adoption.