Phaseolin Gene from Bean Is Expressed After Transfer to Sunflower Via Tumor-Inducing Plasmid Vectors

Abstract

Sequences coding for the bean seed protein phaseolin were inserted into transferred DNA regions of tumor-inducing plasmids. Constructions were devised in which the coding region of phaseolin was fused in the correct reading frame with the coding region of octopine synthase and placed under the transcriptional control of the octopine synthase promoter. Other plasmids were prepared to permit expression of the phaseolin-encoding sequences from the flanking phaseolin promoter region. The RNA transcribed in sunflower cells transformed with these constructions was characterized by hybridization procedures, SI nuclease mapping, and by translation in vitro of extracted RNA. These tests showed that the genomic intervening sequences were correctly excised. Immunoreactive phaseolin polypeptides were detected by enzyme-linked immunosorbent assay and by antibody hybridization to electrophoretically separated protein extracts of sunflower tissues isolated from crown gall tumors and of transformed sunflower cells grown in tissue culture. These results demonstrate the expression of a plant gene after transfer to a taxonomically distinct botanical family.