Co-Authors:
Bates, G.W., Department of Biological Science B-165, Florida State University, Tallahassee, 32306-3015, FL, United States
Zelcer, A., Department of Plant Genetics and Breeding, A.R.O. The Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel
Abstract:
The hypersensitive response of tobacco to inoculation with tobacco mosaic virus (TMV) is controlled by a single dominant gene, the N gene. As a first step in localizing and transferring the N gene, we have prepared a line of tobacco plants in which the kanamycin-resistance (Kmr) gene is closely linked to the N gene. Nicotiana tabacum plants heterozygous for the N gene were transformed to Kmr by Agrobacterium carrying pMON200. Eighty-nine independent transformed clones were regenerated and were backcrossed with nontransformed, TMV-sensitive plants. Progeny from these crosses were screened first for Kmr; then the Kmr progeny were inoculated with TMV and scored for the hypersensitive response. Of the initial 89 clones, 68 appeared to have integrated a single functional Kmr gene. Initial tests for TMV resistance indicated possible linkage between Kmr and the N gene in 11 plants. With further testing, linkage has been established for two of these plant lines. In one of these lines, the two genes were 30-40 map units apart, and evidence of somatic instability in the linkage was obtained. However, in the second line, linkage between Kmr and the N gene was tight, and recombination between the genes in this case was only 5%. Southern hybridization revealed that this plant contained only a single copy of the Kmr gene. Linkage between Kmr and the N gene in this plant line has been verified in each of two additional backcross generations. © 1992 Springer-Verlag.