Polyamine levels in pollinated and auxin‐induced fruit of tomato (Lycopersicon esculentum) during development

Abstract

The changes taking place during fruit development in the concentration of the 3 polyamine fractions, i.e. free, perchloric acid‐soluble conjugates and perchloric acid‐insoluble bound polyamines, were analyzed in tomato fruits (Lycopersicon esculentum Mill, cv. F121) induced to set by either pollination or auxin application. Before the onset of cell division, total polyamines were 50% higher in auxin‐treated fruits than in pollinated ones, most of the polyamines being found as perchloric acid‐soluble conjugates in both fruit set treatments. At the onset the level of polyamines in both fruit types was 100 times higher than during cell expansion or ripening. The highest polyamine found during cell division was perchloric acid‐soluble conjugated spermidine in both fruit set treatments. After cell division, polyamine concentration was similar in both fruit set treatments. The concentration of polyamines in the jelly was similar in pollinated and auxin‐induced fruits during cell expansion but not during ripening. At the onset of ripening there was an increase of one order of magnitude in the concentration of perchloric acid‐insoluble bound putrescine in the jelly of pollinated fruits. Polyamines were more than 5‐fold higher in unpollinated ovaries than in fruits induced to set by either pollination or auxins. It is suggested that pollinated and parthenocarpic fruits differ in their polyamine metabolism during the initial stages of development, but not after cell division. It is also suggested that polyamines undergo rapid turnover during cell division. Perchloric acid‐insoluble bound putrescine might play a role in seed formation in tomatoes.