[Cytokinin content and immunolocalization in wheat primary root cells]

Immunohystochemical localization of cytokinins in cells of different root zones of wheat plants showed intensive immunostaining of zeatin in the apical root zone and its subsequent decline with the increase in the distance from the root tip. More intensive labeling of metaxylem and parenchyma cells of the root central cylinder was observed on the sections of the zone where root hairs appeared. Above this zone the decline in immunostaining of the cells of the central cylinder was paralleled by the signs if finalization of differentiation of the xylem vessels shown by lignin deposition. The data of immunohystochemical staining were confirmed by the results of enzyme immunoassay of different cytokinin forms. Likely sources of zeatin accumulation are considered. Possibility of additional (alongside with that in apical root zone) synthesis of cytokinins in the vascular tissues of root and the role of cytokinins in stimulation oflignification are discussed.