Tomato has been targeted for regulating processes such as fruit ripening to improve the efficiency and quality of the final product. The "mature green" stage is an important stage in the ripening processes of the tomato fruit and it is in this stage that etylene is released in the plant, which then influences other metabolic pathways involved in the ripening process. It is known that ethylene plays a regulatory role in integrating the developmental effects on internal signals and external stimuli in the plants. Fruit ripening represents just one example in plant development where ethylene synthesis and perception have been shown to be essential for the full completion of the ripening process. In climateric fruit, ethylene promotes ripening by co-ordinately inducing the expression of a large number of genes that encode enzymes responsible for different aspects of the ripening process. We have isolated new mutants defective in showing triple response of ethylene. Few of these mutants also show delayed ripening of the fruits. We are now attempting to carry out a detailed characterization of these mutants using modern biochemical and molecular techniques.