Testing the Cruciferin Deficient Mutant, ssp-1, of Arabidopsis thaliana, as a Vehicle for Overexpression of Foreign Proteins

ssp-1 is a seed storage protein mutant which is deficient in one of the major seed storage proteins in Arabidopsis thaliana, the 12S cruciferins. To determine if this mutant can drive a higher level expression of a transgene than that found in wild type, the mutant was transformed with the phytohemagglutinin (PHA) gene and single copy PHA homozygotes were identified. These PHA transformants were crossed to wild type so that each PHA gene would be in the same copy number and chromosomal context in a wild type background. Immunoblotting was employed to compare the PHA levels of the single copy transformants in both genetic backgrounds. PHA levels ranged from 4.52% to 7.7% of the total protein in transformants. Two of the transformants showed 30.33% and 44.18% more PHA than that of their backcross. Therefore, a mutant such as ssp-1 may provide a means for overexpression of foreign proteins.MAS