ZINC-INDUCED VACUOLATION IN ROOT MERISTEMATIC CELLS OF CEREALS

In the absence of Zn, vacuolar volume fractions of root meristematic cells of Secale cereale L. cv. K2, Triticum aestivum L. cv. Chinese Spring and Oryza sativa L. cv. IR34 were 5.64 × 10-2, 2.17 × 10-2 and 1.63 × 10-2 μm3 vacuole μm-3 tissue, respectively. A 4-d exposure to a subtoxic concentration of zine (0.2 μg Zn cm-3) induced a 2.93-fold and a 6.78-fold increase in the total vacuolar volume fraction in Oryza and Triticum, respectively, whereas no significant increase was observed for Secale. It is proposed that this Zn-induced vacuolation represents a compartmentalization mechanism. The initial total vacuolar volume fraction in Secale was greater than that for Oryza and Triticum and this may enable compartmentalization of the metal soon after the onset of treatment so reducing its cytotoxic effects. These findings are similar to those observed in contrasting cultivars of Festuca rubra L. © 1992 Annals of Botany Company.