Evidence that a 25 kilodalton protein associated with sugar beet root plasmalemmas may be involved in the enhanced uptake of iron by iron stressed plants

Abstract

Electrophoresis of a root plasmalemma fraction from three sugar beet cultivars with different iron uptake capacities revealed a 25 kilodalton (kd) protein which is produced in enhanced amounts in response to Fe deficiency in a manner corresponding to the Fe uptake capacities of the three cultivars. An assay was developed to measure the plasmalemma‐bound ferric iron reductase. Using this assay, we were able to detect differences in specific activity of the reductase among the three cultivars but not increases in activity in response to iron stress. The results suggest that a 25 kD plasma lemma‐bound protein could be involved in the dramatically enhanced uptake of Fe which occurs when Fe is resupplied to Fe deficient sugar beets.

Key words:

• Sugar beet
• Iron deficiency
• Plasmalemma
• Fe³⁺ reductase
• Electrophoresis