Transformation in Cucumber (Cucumis sativus L.)

Abstract

Cucumber is an economically important crop. It is widely grown in the tropics, subtropics, and milder portion of the temperate zone of both hemispheres. Its total world tonnage production ranks sixth among the vegetable species (Reynolds 1986). Numerous diseases attack the cultivated species and cause tremendous annual losses. In many cases these diseases are the result of infection by viruses or microbes. Although various pest control measures have been attempted, none has yet proven entirely successful. A main objective of breeding programs is thus not only to increase yield and quality, but also to select cultivars resistant to diseases. One method of obtaining these traits is to hybridize many of the wild species with the cultivated species (Deakin et al. 1971). However, this approach is associated with many difficulties such as the number of backcrosses required to obtain the original cultivar containing the desirable traits. The recent advances in genetic engineering appear to offer a promising alternative for improvement of this economically important crop. The major advantage of genetic transformation is the potential to add a characteristic trait directly to an existing genotype, while avoiding the necessity for a further conventional breeding procedure to stabilize the new gene in a background suitable for sexual propagation. The transformation of the pre-existing genotype would also enable the retention of already proven cultivars and products.