Polyamine accumulation is a response of plants to various environmental stresses. Polyamine accumulation was assessed in relation to ammonium accumulation and ethylene evolution in tomato (Lycopersicon esculentum Mill.) under nutritional stress. Nutritional stresses were imparted on plants grown in quartz sand culture under greenhouse conditions with NH4-based modified Hoagland's solution or with NO3-based solutions without P, K, Ca, or Mg. The plants receiving NH4 nutrition were grown with or without 10-5 M (aminooxy)acetic acid (AOA) or 10-5 M silver thiosulfate (STS). Plants on nutrient deficient solution were grown with or without the AOA. When plants appeared with toxic or deficient symptoms, the new fully expanded leaves were collected and extracted by 5% perchloric acid for polyamine analyzes by HPLC. Plants receiving NH4-based nutrition had high putrescine and low spermidine concentrations. High spermidine and low putrescine concentrations occurred in plants receiving complete NO3-based nutrition. For plants receiving NH4-based nutrition, application of AOA suppressed accumulation of putrescine but had no effect on spermidine, and STS had no effect on polyamine accumulation. For plants receiving NO3-based nutrition without P, K, Ca, or Mg, the application of AOA restricted accumulation of putrescine and spermidine. High putrescine concentration was accompanied by high ammonium accumulation, high ethylene evolution, and stressinduced symptoms, indicating an association between polyamine accumulation and other stress-related phenomena.
Polyamine Concentration and Ethylene Evolution in Tomato Plants under Nutritional Stress