Abstract
Zinc is essential for plant growth. However, it at excess level causes toxic effects in many plant cells. In the present study, we examined effects of Zn on cell growth, Zn accumulation and Zn-binding complex formation in tomato cells using either suspension-cultured cells or those in plant seedlings. We found that Zn at 1 mM caused a 20-30% growth inhibition in tomato suspension-cells with a concomitant formation of phytochelatin (PC) peptides, while it does cause neither growth inhibition nor PC formation in cells at lower concentrations (< 0.1 mM). By contrast, Zn at 1mM applied to roots had no apparent effects on growth of root and shoot in tomato plants. Under this condition, neither PC formation nor remarkable Zn accumulation were observed, unlike in suspension-cells. We conclude that PC has a role in Zn accumulation and detoxification in tomato cells, but its biosynthesis is controlled by many factors in plants.
