RE Evenson

Department of Economics, Yale University, New Haven, Connecticut, USA

Biotechnology changes the technology of plant breeding and alters the role of genetic resources. Conventional breeding methods allow breeders to make within-species crosses, i.e. to combine and recombine landraces and combinations of landraces within the major crop species. The first generation of biotechnology consisted of techniques allowing 'interspecific' crosses or combinations of genetic materials from closely related species. For example, in rice breeding, 'embryo resource' techniques were used to combine genetic resources from Oryza nivara, one of the 20-plus 'wild' or uncultivated species of rice, with Oryza sativa, the chief cultivated rice species to incorporate host plant resistance to the grassy stunt virus disease in rice. These 'wide crossing' techniques have been increasingly used over the past three or four decades.

More recent developments in biotechnology enable marker-aided plant breeding and 'transgenic' breeding. (Transgenic plants are defined as having genetic resources from an alien species incorporated into them.) There are several techniques for achieving transgenic plants now available to plant breeders. These have been available for most crops for more than a decade. Transgenic breeding is also increasing in importance.

How have these biotechnology developments affected the use of, and hence the value of, genetic resources as traditionally defined, i.e. landrace and related genetic resources in germplasm or gene bank collections?

In this chapter, a review of two evaluation studies of rice research programmes is provided to shed light on this question in the case of rice research. The first study reviewed is on evaluation of achievements of the Rice Biotechnology Program (funded by the Rockefeller Foundation) (Evenson 1996). The second is a research prioritization study for rice research in Asia (Evenson et al. 1996). Both studies indicated that the biotechnology techniques developed to date are best suited for qualitative 'trait breeding'. This is because these techniques are suited to genetic transfer of very limited DNA or singlegene materials. As a consequence, both wide-crossing and transgenic breeding will have very similar objectives to those of conventional trait breeding.

These studies indicate that there is likely to be a considerable broadening of source genetic materials as the new techniques are increasingly employed. They do not indicate, however, that there will be a major shift away from genetic source materials that have been useful with conventional breeding methods.

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