Transgenic breeding: Perspectives and prospects
Transgenic technology serves to introduce gene sequences for expression of a desired trait. Production of transgenic plants is reported in many crops, but commercialization is limited to a few selected crops, such as cotton (Gossypium hirsutum L.), corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and canola (Brassica napus L. and B. rapa L.). This paper presents the sequential processes of transgenic event design, event selection, and 'cleaning up' genetic background for forward breeding programs. Expression of the foreign gene cannot be viewed in isolation and is more complex than has been assumed because of the interaction of transgene with native genes. Variations among clones and within the progeny are observed, and hence all the clones are taken into account for evaluation. Plant breeding must be involved to move transgenes from transformable but agronomically unacceptable genotypes into elite breeding lines with two backcrosses. Production of transgenic plants in large numbers is difficult and laborious and requires large investments. It is worthwhile investing in parallel efforts to incorporate the transgene into improved plant material to satisfy commercial interests.