Role of Polyamines in SO2-Polluted Pea Plants

Abstract

The effect of SO₂ fumigation on free and bound putrescine and spermidine has been investigated in pea plants grown in nitrate-based and ammonium-containing nutrient solutions. Both amines increase significantly more in response to SO₂ fumigation when 50% of the nitrate nitrogen is substituted by ammonium. Amine levels are also increased in the unfumigated, ammonium-supplied plants relative to the exclusively nitrate-supplied ones. Since both SO₂ pollution and ammonium nutrition increase the H⁺ ion concentration of the cells and cause a shift in the cation/anion ratio, it is concluded that with both treatments amines are synthesized to bind these H⁺ ions and to compensate the relative cation deficit. The importance of this mode of metabolic buffering is discussed and its effectiveness calculated.