Effect of iron deficiency on the localization of phosphoenolpyruvate carboxylase in common bean nodules

Abstract

Phosphoenolpyruvate carboxylase (PEPC) plays an important role in nodules, when there is an increase in the demand for energy. This enzyme provides carbon skeletons to sustain amino acid synthesis and malate to support energy required to fix nitrogen. Since PEPC is important for nodules, and there is lack of information about the effect of some nutrient deficiency in the expression and localization of this enzyme in legume nodules, this work focused on the localization of PEPC in nodules under iron deficiency of two common bean cultivars: Flamingo tolerant and Coco blanc sensitive to iron (Fe) deficiency. The results of immunolocalization using polyclonal antibody showed that this enzyme was detected in all regions of nodule sections; but the signal intensity was increased in Fe-deficient nodules as compared to Fe-sufficient ones in the tolerant cultivar, whereas the intensity was less pronounced in nodules of Fe-deficient plants than in those of Fe-sufficient plants for the sensitive cultivar Coco blanc. This work showed that the symbiotic tolerance of Flamingo to iron deficiency was linked to the increase of PEPC enzymes expression. However, the activity of these enzymes supported the energy required in bacteroids to maintain the nitrogenase activity.

Keywords: Common bean, immunolocalization, iron deficiency, nodules, phosphoenol pyruvate carboxylase