ELISA QUANTITATION AND GC-MS IDENTIFICATION OF ABSCISIC-ACID IN STIGMA, OVARY AND PEDICEL OF POLLINATED POPLAR FLOWERS (POPULUS-NIGRA L)

A method of fractionation, quantitation and identification of abscisic acid (ABA) in poplar flowers is presented in the context of intra- an d interspecific pollination studies in Populus nigra x P. nigra and P. nigra x P. deltoides, respectively. Poplar flowers were dissected int o stigma, ovary and pedicel. Abscisic acid concentrations were measure d at receptivity and 5 days after pollination in each part of the flow er. Abscisic acid was fractionated by reverse-phase HPLC followed by a n enzyme-linked immunosorbent assay (ELISA) with anti-ABA polyclonal a ntibody and GC-MS identification of the immunoreactive ABA fractions. Samples were fractionated and ABA was identified by the presence of a cross-reactive metabolite of ABA in the extracts. The interspecific cr oss (P. nigra x P. deltoides) had a high concentration of ABA in the p edicel, where abscission occurred, whereas in the intraspecific cross, ABA concentration in the pedicel was low. The results are discussed w ith reference to the control ABA exerts on the abscission of poplar fl owers after interspecific incompatible pollinations.