Cytokinins in the hemiparasiteMelampyrum arvense L. before and after attachment to the host

Concentration of cytokinins (CKs) of zeatin-type (Z) and isopentyladenine-type (iP) were determined using an enzyme-linked immunosorbent assay (ELISA) technique in xylem sap and bulk leaf extract of the hemiparasiteMelampyrum arvense before and after attachment to the host (Capsella bursa pastoris). In all the samples Z-type were dominant, though the iP-type was also frequent. The results also demonstrate that in comparison with the unattached hemiparasite after attachment to the host the concentration of Z-type in xylem sap increased about 92 and 182 times in the light and dark phase, respectively, and that of the iP-type about 34 times in the two phases. The concentration of Z-type and iP-type in leaves expressed per dm³ of cell water was at the level of 10^-7 M and 10^-8 M, respectively in the unattached hemiparasite. After attachment, the concentration of CKs increased to 10^-5 M and 10^-6 M for Z-type and iP-type, respectively. In xylem sap the concentration of Z-type was at the level of 10^-9 M and 10^-7 M and in the unattached and attached hemiparasite, respectively. The concentrations of iP-type were 10^-10 M and 10^-8 M for the unattached and attached hemiparasite, respectively. The diurnal oscillation of CK concentration was evident in the unattached hemiparasite, but after attachment their level was nearly constant and independent of the diurnal cycle.