CARBON-14 STUDIES OF INTERMEDIARY METABOLISM IN POTASSIUM-DEFICIENT TOMATO PLANTS

Abstract

The effect of potassium deficiency on the metabolism of tomato leaves was studied by the use of14CO2. After normal and potassium-deficient plants had been exposed to14CO2in the light for 5 minutes, the latter showed smaller amounts of label in starch, uridine–diphosphate–glucose, glucose, fructose, glyceric acid, phosphoenol-pyruvate, pyruvic acid, alanine, and aspartic acid. Relatively more was present in 3-phosphoglycerate, serine, glycine, and glutamine. When exposure for 5 minutes to14CO2in the light was followed by 2 hours of darkness, the potassium-deficient plants had less14C in glucose, fructose, alanine, and aspartic acid, but relatively more in sucrose, glycine, and glutamine.Exposure to14CO2in the dark for 2 hours resulted in less label entering aspartic acid, but relatively more in glycine in potassium-deficient plants.The results are consistent with decreased pyruvic kinase activity in potassium-deficient plants, and there is evidence of a similar effect on glyceric acid production, invertase activity, and UDPG synthesis.