Properties of plate meristem of growing epigeal cotyledons in an experimental system

Plate meristem activity in epigeal cotyledons of plants, which are largely used in research, was comparatively studied. Formation of growing clusters of daughter cells is a common feature of cotyledon meristems. Species-specific differences connected with the number of cells entering division, the homogeneity of the palisade cell population, tissue specification of proliferation, the end number of daughter cells in clusters and the possibility to use clusters for simultaneous determination of the cell growth and division activity are shown. Exogenous cytokinin enlarges the number of cells entering proliferative divisions in the division competent tissues of the respective cotyledon and stimulates the growth of isolated cotyledons cultured in darkness. The analysis of morphological peculiarities substantiates the properties of the meristems of studied species in an experimental system and the possible light microscopy approach for using them in obtaining data on the number of divisions and accompanying cell growth. The first palisade layer of zucchini cotyledon was chosen as the most suitable experimental system reflecting the cellular behaviour during the growth of a plant organ and permitting easy and exact quantification of the cell divisions and growth simultaneously.