Optimization of a digoxigenin-based immunoassay system for gene detection in Arabidopsis thaliana

Digoxigenin is derived from a plant steroid hormone digoxin found in the plants Digitalis sp. Digoxigenin has been used successfully in labeling nucleic acids. In this experiment we optimized minimum probe requirement for a nonradioactive digoxigenin-based gene detection system in the model plant Arabidopsis thaliana. We showed that 1 microL of labeled probe was sufficient to hybridize onto 1-10 microg of target plasmid DNA. We also examined the sensitivity of labeled probe and showed that 2 microL of labeled probe was not able to hybridize with 1 microg of target DNA, although 2 microL of labeled probe was able to detect target DNA ranging from 2 to 10 microg. To test the efficacy of our optimization protocol, we used 1 microL of labeled plasmid DNA pU16893 harboring an Arabidopsis housekeeping gene elongation factor-1 and showed that the elongation factor-1 gene could be detected in Arabidopsis genome under various environmental conditions. This paper describes a nonradioactive in situ hybridization technique to detect nucleic acids in plants.