Changes in the level of protein and activity of Cu/Zn-superoxide dismutasein zinc deficient rice plant, Oryza sativa L.

In order to clarify the physiological role of Zn in rice plants through the identification and characterization of proteins affected by Zn deficiency, changes in the peptide profile in Zn-sufficient and Zn-deficient rice meri stems were examined by two-dimensional pI-SDS PAGE. The level of some pepti des fluctuated under Zn deficiency. One of the peptides for which the spot intensity decreased in the profile derived from Zn-deficient rice meristems was identified as Cu/Zn superoxide dismutase (Cu/Zn-SOD) by amino-terminal sequencing. Decrease in the Cu/Zn-SOD activity and of the Cu/Zn-SOD protei n content was observed based on a nitro blue tetrazolium reduction assay an d immunoblotting analysis, respectively. These results indicate that Zn def iciency in rice causes a reduction of the activity of Cu/Zn-SOD through the decrease of the protein content and/or inactivation of the enzyme in the m eristem.