Immunchemie und Immunpathologie

The Development and Application of ELISA for 3-Indole-Butyric Acid

Abstract

Eline P Meulenberg

Indole-3-butyric acid (IBA) is a plant growth hormone used to improve the formation of roots during the culture of cuttings in the greenhouse. According to new EC regulations, IBA levels should approach zero at the time the plantlets are entering the market (30 days). In order to be able to measure IBA in soil samples, polyclonal antibodies and corresponding ELISA was developed. Both chicken (IgY) and rabbit (IgG) were raised and used to evaluate direct and indirect ELISAs. It appeared that rabbit antibody in the indirect ELISA showed the best performance. Due to matrix effects, the standard curve was made in blank soil extract in a range of 0-500 μg/mL. The detection limit at 3SD from zero standard varied from 0.35-3.1 μg/mL. The antibody was highly specific for IBA and showed a mean recovery of 74.5% after two consecutive extraction steps of spiked blank samples. This ELISA was used to monitor IBA in cutting soils extracts from 0-30 days after application (Day 0-1-3-8-30). It appeared that at day 8 IBA was already undetectable. The results were confirmed with HPLC. It may be concluded that the ELISA for IBA developed was suitable to analyze IBA in soil samples and that plantlets in cutting soil treated with IBA are allowed to market according to EC regulations.