To clarify the physiological factors associated with the development of tomato leaf marginal necrosis associated with potassium deficiency, tomato leaf blades prior to development of the symptoms were collected, and profiles of water-soluble metabolites were analyzed using gas chromatography-mass spectrometry. Multivariate analysis was conducted to screen for a component that was related to potassium deficiency-induced leaf necrosis among the 60 metabolites detected in tomato leaves. Polyamines, sugars, and branched amino acids were ranked highly. Putrescine was most strongly and negatively correlated with potassium concentration and exhibited an exponential response, regardless of the site or plant body. In addition to putrescine, glucose, xylose and L-isoleucine are known to play important roles in stress response and ion balance control, and it is thought that changes in metabolite profiles are linked to tomato leaf marginal necrosis associated with a decrease in endogenous potassium concentration. These findings will be useful for cultivation management to mitigate this physiological disorder of tomato. (C) 2020, The Society for Biotechnology, Japan. All rights reserved.