These results indicate that the effect of BR on Fe nutrition is
independent of Fe species in the growth medium. We therefore
focused on the effect of BR on rice plants with FeEDTA
in the medium throughout our study.
The involvement of BR in the mediation of Fe deficiencyinduced
changes in physiological processes was further
evaluated using a BR-deficient mutant d2-1. Similar to WT
plants, Fe deficiency also decreased leaf chlorophyll in the
d2-1 mutant, and exogenous application of EBR enhanced
Fe-deficiency-induced leaf chlorosis in young leaves of d2-
1 seedlings (Fig. 2). However, the d2-1 mutant had a higher
chlorophyll concentration than the WT plant, and the magnitude
of decrease in chlorophyll concentration by EBR was
much greater in WT plants than in d2-1 mutants under Fedeficient
conditions (Fig. 2), indicating that the WT is more
sensitive to EBR than d2-1 mutant plants under Fe-deficient
conditions. In contrast, application of EBR had no apparent
effect on foliar chlorophyll concentration in Fe-sufficient d2-1
mutant seedlings (Fig. 2).