Plant tolerance to nitrogen deficit and excess: Ion compartmentation in root cells

Abstract

The paper deals with plasmalemma H⁺-ATPase and redox system activity and K⁺ and Ca²⁺ uptake, concentration and compartmentation (free space, metabolic and reserve pools) in root cells of winter wheat (Triticum aestivum L.) plants grown for 21 days using water culture (Hogland-Anion’s (H-A) mixture) and with different nitrogen contents (from complete exclusion of nitrogen to 1,5–2 times). Nitrogen deficit (1/4 times) caused an increase in activity of H⁺-ATPase and redox potential. However, the change in these parameters depends on the level of nitrogen deficit. Under full nitrogen exclusion redox activity as well as K⁺ and Ca²⁺ uptake were inhibited, but K⁺ content of root tissue was increased. An increase in H⁺ excretion and Ca²⁺ and K⁺ uptake by roots was observed with nitrogen excess. This was accompanied by a decrease in ferricyanide reductase activity and by an increase in K⁺ and Ca²⁺ content within free space, metabolic and reserve pools. Under complete nitrogen exclusion, K⁺ content in three investigated compartments increased also compared with control plants, while Ca²⁺ content on the contrary decreased in free space and metabolic pools.