Transformation of a dwarf Arabidopsis mutant illustrates gibberellin hormone physiology and the function of a Green Revolution gene
The introduction of dwarfing traits into crops was a major factor in increased grain yields during the "Green Revolution." In most cases those traits were the consequence of altered synthesis or response to the gibberellin (GA) plant hormones. Our current understanding of GA synthesis and physiology has been facilitated by the characterization of mutants. To introduce concepts about GA hormone physiology and plant transformation in an undergraduate laboratory course we have used ga5, a semi dwarf Arabidopsis mutant with reduced activity of GA 20 oxidase. In this laboratory exercise, Arabidopsis ga5 mutant plants are transformed by the floral dip method using Agrobacterium tumefaciens carrying plasmid constructs conferring kanamycin resistance and containing the GA5 gene. Within 4 weeks, seeds of transformed plants can be easily screened by antibiotic resistance on plates. After transfer to soil the dwarf mutant plants transformed with a wild type version of the gene show normal size. In addition to offering a visual understanding of the effect of GA on stem elongation, students learn additional techniques in this experiment, including PCR and agarose gel electrophoresis. This experiment is cost effective and can be completed within a 4 month term.
Biochemistry and molecular biology education a bimonthly publication of the International Union of Biochemistry and Molecular Biology