The Climacteric in Ripening Tomato Fruit

Abstract

Phosphofructokinase is identified as the regulator reaction activated at the onset of the climacteric rise in respiration of the ripening tomato fruit (Lycopersicon esculentum Mill). The concentration of ATP in the fruit increases to a maximum value after the climacteric peak of respiration is past. Orthophosphate is proposed as the most probable activator of phosphofructokinase in the ripening fruit.Fifteen hours after infiltrating tomato fruit with orthophosphate, the rate of respiration increased and remained high until the end of the experiment, 45 hours after infiltration. In experiments where tomato plants were grown at various nutrient levels of P, the rate of respiration when fruit harvested at the mature-green stage reached the respiratory climacteric was correlated with the concentration of orthophosphate in the fruit at the end of the experiment. These results are consistent with the hypothesis that stimulation of phosphofructokinase through increasing concentration of orthophosphate in the cytoplasm of the fruit contributes to the climacteric rise in respiration.

Similarities between the Actions of Ethylene and Cyanide in Initiating the Climacteric and Ripening of Avocados

“…The most pronounced changes, however, are shown by FDP, whose level rises 10-fold during the rise in respiration. Similar increases in FDP have been reported previously for climacteric bananas (6,40) and tomatoes (15 The rates of CO2 production quoted in Table I are those observed at the end of the experimental period. Anoxia causes an increase in lactic acid (Table I) and its rate of production varies with the fruit from 390 to 670 nmoles/g fresh weight-hr.…”

“…It has been observed in recent years that during the climacteric, glycolytic intermediates show a pattern similar to that found in plant and animal tissues and yeast when glycolysis is enhanced, and which reflects the activation of two regulatory enzymes, namely PFK2 and PK (5,6,15,28). On these observations it has been suggested that glycolysis is accelerated in the course of the climacteric rise in respiration (6,15,40).…”

“…On these observations it has been suggested that glycolysis is accelerated in the course of the climacteric rise in respiration (6,15,40). However, activation of glycolysis per se cannot be the cause of ripening or even of the climacteric, because anaerobiosis, while enhancing glycolysis in avocados (see below) and apples (11), prevents ripening, and uncouplers of oxidative phosphorylation, which enhance respiration and presumably glycolysis in banana slices, neither accelerate ripening nor inhibit it when ripening is induced by ethylene or occurs naturally (31,42).…”

“…Ethylene is considered to be the agent that triggers the climacteric and fruit ripening (34). It is questionable whether protein synthesis constitutes a requisite for the climacteric rise, because the stimulation of glycolysis in preclimacteric fruits by anoxia (11), the acceleration of respiration in preclimacteric slices by uncouplers of oxidative phosphorylation (33), the demonstration of full respiratory capacity of isolated mitochondria from preclimacteric tissue (29), and the development of the climacteric under conditions which may be thought to preclude synthesis of protein (18,31,42) these observations it has been suggested that glycolysis is accelerated in the course of the climacteric rise in respiration (6,15,40). However, activation of glycolysis per se cannot be the cause of ripening or even of the climacteric, because anaerobiosis, while enhancing glycolysis in avocados (see below) and apples (11), prevents ripening, and uncouplers of oxidative phosphorylation, which enhance respiration and presumably glycolysis in banana slices, neither accelerate ripening nor inhibit it when ripening is induced by ethylene or occurs naturally (31,42).…”

Pepper β-Galactosidase 1 (PBG1) Plays a Significant Role in Fruit Ripening in Bell Pepper (Capsicum annuum)

“…Tomato is a climacteric fruit that produces ethylene, known as a plant hormone, during fruit ripening. 54,55) Ethylene is the dominant trigger for ripening in climacteric fruit, and introduces fruit ripening-related enzymes, such as endopolygalacturonase. 56) On the other hand, bell pepper is a non-climacteric fruit that produces no or only a little ethylene during fruit ripening.…”