Fig. 2.

Assays of Fe³⁺ chelate-reductase activity in vector control and the transformants. (A) Transformants (lines 7, 8, and 11) and vector control (V) were grown on standard culture solution for 3 weeks and then transferred to Fe-deficient culture solution for 5 days before the assay. pHs of assay buffers were 5.5 or 8.0. (B) Fe³⁺ chelate-reductase activity per root fresh weight in roots surface of transformants (lines 7 and 11) and vector control (V). Rice plants were grown for 3 weeks in normal nutrient solution and then transferred to Fe-deficient culture; roots were harvested 0, 3, and 7 days after the transfer (+2 and +5 indicate the number of days after Fe resupply; n = 9). (C) Total Fe³⁺ chelate-reductase activity in whole roots surface of transformants (lines 7 and 11) and vector control (V) (n = 9). (D) Degree of chlorosis of the fully expanded youngest leaf by using a SPAD-502 chlorophyll meter. The values followed by different letters are statistically different according to a Student-Newman-Keuls test (P < 0.05).