Figure 7.

Assay of POD activity in N-deficient rapeseed roots. POD activity assays in N-deficient rapeseed roots were determined by a colorimetric enzyme assay (A) and staining in gel (B). For the colorimetric enzyme assay, POD activities were determined by monitoring A₄₇₀ using the guaiacol method. Data represent means ± sd (n = 4). Asterisks indicate significant differences between N treatments at the same sampling day (Student’s t test, *, P < 0.05). For POD activity staining in gel, extracted proteins were equally loaded and separated on a native PAGE gel at 4°C and then incubated with staining substrates (0.03% [v/v] H₂O₂ and 1 mm diaminobenzidine). Four biological replicates for each treatment also were used for in gel assays. FW, Fresh weight.