EFFECTS OF ZINC ON CELL, NUCLEAR AND NUCLEOLAR SIZE, AND ON RNA AND PROTEIN CONTENT IN THE ROOT MERISTEM OF A...

The effects of a 4 d exposure to Zn on some cellular characteristics in the root meristem were investigated in seedlings of a Zn-tolerant cultivar of Festuca rubra L. (Merlin) and in a non-tolerant cultivar (S59). In S59, 0.1 and 0.2 μg Zn cm^-3 resulted in a 7% and 17% reduction, respectively, in the mean area of mitotic cells compared with controls grown in the absence of Zn. Moreover, mean nuclear volume (13% and 28%) and total nucleolar volume (43% and 65 %) of G2 cells and RNA content (9 % and 44 %) and protein content (6 % and 17 %) of mitotic cells were also reduced by Zn. In Merlin, however, the mitotic cell area was 4 % and 19 % larger at 0.1 and 0.2 μg Zn cm^-3 compared with the controls. Treatment with Zn also increased nuclear volume (13% and 47%) and total nucleolar volume (42 % and 86%), of G2 cells and RNA content (40 % and 32 %) and protein content (8 % and 33 %) of mitotic cells. The concentration of protein in mitotic cells was also increased by Zn treatment in Merlin. The data are discussed in relation to the previously established effects of Zn on the duration of the cell cycle in these cultivars.