Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/1999
Publication Date: N/A
Technical Abstract: Plant species/cultivars differ greatly in their resistance to nickel (Ni) toxicity, which might be used to identify or develop tolerant/accumulating genotypes for the remediation of high Ni soils. However, limited information is available about the mechanisms of Ni resistance in plant genotypes. Our previous studies showed that ryegrass is more sensitive to Ni toxicity and accumulates much more Ni in shoots than maize. And the resistance of maize to Ni toxicity was associated with a low xylem transport rate of Ni and enhanced accumulation of organic acids, malic acid in particular, in roots. In this study, the cellular and sub-cellular distribution of Ni with relation to Ni resistance in maize and ryegrass at different Ni levels were examined. The results indicated that higher proportion of Ni distributed in the youngest leaves of ryegrass than that in maize grown at relative high Ni levels. The Ni concentrations in root tips and root elongation zone were two-fold higher in ryegrass than that i maize, while Ni concentration in root hair zone of ryegrass was 10-fold lower than that of maize, Extremely higher Ni distributed in the shoot membrane fraction of ryegrass compared to maize. Whereas, about 11-fold higher Ni distributed in root cell soluble fraction of ryegrass than that of maize. The results implied that greater Ni resistance in maize than in ryegrass might be closely associated with Ni confinement in root hair zone and efficient detoxification in root cell membrane system. The relationship of cellular and sub-cellular distribution of Ni with relation to Ni resistance is discussed.