Nutrient–Specific Variation of C–N Metabolism in the Leaves and Roots of Bell Pepper (Capsicum annunm. L) in Response to Macronutrient Deficiency

Mineral nutrients as an essential element for agricultural crops are absorbed by the roots, transported in the xylem to the shoots, and assimilated into organic molecules or involved in a large number of metabolism. Visual symptoms such as growth retardation, reduced crop production and resistance against disease and pests are strongly connected with a result of metabolic disturbance by mineral deficiency. Of essential mineral nutrients, we looked into mineral–mineral interactions (expressed by synergism and antagonism) and subsequent metabolic changes in the leaves and roots of bell pepper during macronutrient deficiency. The deficiency of cationic nutrients (K, Ca and Mg) and S responded generally antagonistically each other in terms of uptake, and these blockages resulted in significant changes in metabolite levels which are able to be caused by restricted shoots–roots communication of phytosynthates. Each nutrient affected differently to the type and amount of metabolites and plant organs. Interesting finding was significant increase in amino acids in both organs by cations deficiency, and, of them, glutamine and asparagine were more than 10–fold accumulated, which could be considered as a potential indicator of cation deficiency. Furthermore, it was carefully assumed that a limited uptake of sulfur accompanied by cations deficiency could be direct cause of disturbance in primary metabolism rather than cations itself. In view of this, on the premise of further study to verify what happens between cations and sulfur in plants, our study might help to make clear the complicated mechanisms of metabolic networks in responses to individual and multiple nutrient stresses.