Simultaneous detection of plant growth regulators jasmonic acid and methyl jasmonate in plant samples by a monoclonal antibody-based ELISA

Methyl jasmonate (MeJA) and its free-acid form, jasmonic acid (JA), collectively referred to as jasmonates (JAs) are natural plant growth regulators presenting widely in higher plants. Simultaneous detection of JA and MeJA in plant samples is of significance and is a great challenging issue. In this study, coupling with two extraction methods, a sensitive monoclonal antibody (mAb) based enzyme-linked immunosorbent assay (ELISA) for simultaneous detection of JA and MeJA in plant samples was developed. JA-bovine serum albumin (BSA) conjugate was used as an immunogen for the production of mAb. As the produced mAb displayed higher recognition ability to MeJA than to JA, the ELISA was established using MeJA as standard. Under the optimal experimental conditions, the IC50 and LOD of the ELISA for MeJA were 2.02 ng mL-1 and 0.20 ng mL-1, respectively. In the first extraction method, MeJA in plant samples was evaporated and only JA was extracted. In the second extraction method, both JA and MeJA were extracted. After methylation, the JA in the extracts were converted to MeJA, and the whole MeJA in the extracts was measured by the ELISA. Plant samples including the leaves of Salvia splenden, the flowers of Salvia Splenden and the fruit of grapes were collected. JA and MeJA in theses samples were respectively detected by the proposed ELISA. It was found that the concentrations of JA in three plant samples were about 3~5 times higher than that of MeJA. The ELISA was also confirmed by HPLC. There was a good correlation between ELISA and HPLC.