1006 OVERVIEW OF GENE AVAILABILITY, IDENTIFICATION AND REGULATION

Abstract

A growing number of horticulturally useful genes have been introduced into plants. Most are designed to impart resistance to pests, but others affect plant morphology, cold or drought tolerance, sucrose transport, starch synthesis, flower color or fruit ripening. Although most of the genes introduced were originally cloned from plants or plant viruses, some were cloned from bacteria or animals. Identification of gene function has generally involved characterization of the gene product prior to cloning the gene. Recent advances in genetic mapping, however, have opened new approaches to cloning genes prior to isolation of the gene product or to an understanding of the biology of the trait conferred. Most candidate genes for introduction need to be modified to achieve the intended purpose. Rational modification is now possible, to a considerable extent, based upon current knowledge of gene structure and regulation. Some guidlines for modification and examples thereof will be examined.