Table I.

Activities of the cytosolic marker enzymes c-mdh and c-hpi in apoplastic fluid and xylem sap (in nmol mL⁻¹ s⁻¹) and whole extracts of leaves and petioles (in μmol g⁻¹ FW s⁻¹) of iron-sufficient (300 μmol Chl m⁻²) and iron-deficient (50 μmol Chl m⁻²) sugar beet

Material	Iron-Sufficient		Iron-Deficient
	c-mdh	c-hpi	c-mdh	c-hpi
Leaf homogenate	0.472 ± 0.200	84 ± 10	0.626 ± 0.321	57 ± 3
Apoplastic fluid	0.013 ± 0.004 (3%)	2.5 ± 1.8 (3%)	0.014 ± 0.010 (2%)	1.7 ± 0.5 (3%)
Petiole homogenate	0.071 ± 0.009	10.8 ± 5.7	0.174 ± 0.030	24.6 ± 9.0
Xylem sap	<0.001 (0%)	0.07 ± 0.01 (0.6%)	0.001 ± 0.001 (0.6%)	0.24 ± 0.01 (1%)

Values in brackets represent the percentages with respect to the maximum activities in total homogenates. Data are the mean ± se of five replications.