[Preparation of a monoclonal antibody against methyl jasmonate and quantification of jasmonic acid in florets of wheat and Italian ryegrass].

A monoclonal antibody (McAb) against methyl jasmonate (MeJA) was prepared and characterized. The McAb, J2-4B, was derived from an immunogen in which the C1-COOH of jasmonic acid (JA) was conjugated to the -NH2 of keyhole limpet hemocyanin (KLH). The McAb showed a higher recognition ability to methyl esters of JA than to its free acids. The integrity of a pentenyl in JA molecule was necessary for the recognition of McAb. Hydrogenation at C-9 and C-10 (dihydrojasmonic acid, 2H-JA) or eliminating the methyl group at C-12 (JAS-25) significantly abolished the binding force of JA molecule with the McAb. Some structural or functional analogues or precursor of JA, such as cucurbic acid, theobroxide, coronatine, and linolenic acid, could not be recognized by the McAb. The McAb has been used to set up a competitive enzyme-linked immunosorbent assay (ELISA) with a linearity range from 2.06 to 500 pmol of MeJA. Using this method, the fluctuations of JA content in florets during anthesis of wheat and Italian ryegrass were analyzed. Results showed that JA level increased obviously as the florets approaching to opening, arrived at a "peak" value at full opening and decreased sharply afterwards.