ISHS Acta Horticulturae 463: VIII International Symposium on Plant Bioregulation in Fruit Production
HORMONAL CONTROL OF FRUIT RIPENING IN CLIMACTERIC FRUITS |
| Authors: | M. Vendrell, X. Palomer |
| Keywords: | Climatic fruits, ripening, hormonal control |
| Abstract:
Fruit ripening is a coordinated series of biochemical changes that renders the fruit attractive to eat. This process is under genetic regulation, but plant hormones play an essential control. Ethylene has a key role throughout ripening. The molecular biology of ethylene production and perception is increasingly unfolding. Ethylene is synthesized from S-adenosylmethionine via 1-aminocyclopropane-1-carboxylic acid (ACC), catalized by ACC synthase and ACC oxidase. Both enzymes are limiting in preclimacteric fruits, but are greatly induced during ripening. They have been purified and characterized from various fruit tissues and their cDNAs cloned. They are encoded by multigene families. Studies of these enzymes have demonstrated that induction of the ACC oxidase gene precedes that of climacteric ACC synthase. While ACC oxidase gene expression is a system 2 ethylene-independent process, the climacteric ACC synthase genes are activated by system 2 ethylene. Ethylene is not the only hormone present in fruits. A balance between opposing promotory and inhibitory hormonal factors control the ripening process. Although their mode of action is not well known, abscisic acid, auxins and giberellins may play an important role. They may affect the sensitivity of fruit to ethylene. Cytokinins, polyamines and jasmonic acid should be considered also. Besides genetics and hormones, other factors contribute to the overall phenomena of ripening. | |
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