Antagonistic effects of iron and/or magnesium deficiencies on enzyme activities in lettuce (Lactuca sativa L.) plants

Abstract

SummaryLactuca sativa L. is one of the most important sources of phytonutrients including vitamins, carotenoids, and antioxidants. However, lettuce growth and quality are strongly affected by soil fertility. In this study, the influence of iron (Fe) and/or magnesium (Mg) deficiencies on the growth, anti-oxidant properties, and ferric chelate reductase (FCR) and phosphoenolpyruvate carboxylase (PEPC) activities in lettuce plants was studied, after 15 d of treatment. Deficiencies in Fe and Mg decreased the accumulation of fresh weight and the concentration of chlorophyll. Intracellular Fe and Mg concentrations were affected by Fe- and/or Mg-deficiency, especially by the combined deficiency. This study also showed that Fe- and Mg-deficiencies had antagonistic effects on the activities of FCR and PEPC. The activity of catalase (CAT) was not significantly altered by Mg-deficiency, but a significant decline in CAT activity was recorded in Fe-deficient shoots. This decline increased with the concentration of Mg in the medium. Moreover, guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) activities were reduced by Fe-deficiency at normal levels of Mg, but were increased by Mg-deficiency at normal or low levels of Fe.