Differences in the Responses to Iron Deficiency Stress between Bean and Maize

The responses to iron deficiency stress in bean and maize were compared. The susceptibility to iron deficiency stress was smaller in bean than in maize;i.e., the tolerance to iron deficiency was greater in bean than in maize. The roots of the bean plants exposed to iron deficiency stress, developed iron reducing capacity and medium-pH lowering capacity,but not the roots of maize. The iron reducing capacity and medium-pH lowering capacity of the bean roots were inhibited by a shadowing, detopping, and the addition of 2,4-dinitrophenol. Iron absorption in the bean plants was stimulated by the pretreatment without iron in the growth medium, but not in the maize plants. The finding suggest that the high tolerance of bean plants to iron deficiency stress is caused by the development of iron reducing capacity and medium-pH lowering capacity of the bean roots.