POSTHARVEST PHYSIOLOGY OF CLIMACTERIC FRUITS - RECENT DEVELOPMENTS INTHE BIOSYNTHESIS AND ACTION OF ETHYLENE

The plant hormone ethylene plays an important role in the ripening pro cess of climacteric fruits and the postharvest life of many horticultu ral products. Its biosynthetic pathway is now well known at the bioche mical, cellular and molecular level. The development of competence to ripen and to respond to exogenous ethylene is of major importance in t he determination of the harvest date and, as a consequence, in the pos tharvest quality of fruits. Ethylene biosynthesis and action can be mo dulated by environmental factors in order to maintain the quality of f ruits as long as possible in the distribution circuits. The mode of ac tion of some of these factors will be reviewed in relation to a number of postharvest technologies including cold storage and controlled or modified atmosphere storage. Recent developments in molecular biology have led to the isolation and characterization of genes involved in et hylene synthesis. Their application in the control of fruit ripening t hrough genetic engineering is in full development.