Abstract
Effects of colchicine used for chromosome doubling of haploid plants were examined as a possible cause for the genetic variation among anther-derived doubled haploid lines of an inbred tobacco (Nicotiana tabacum L.). Colchicine induced doubled haploid lines (C-DH) and spontaneous doubled haploid lines (S-DH) were developed and their agronomic traits were compared with those of the selfed lines of the parental plant used for the anther culture. S-DH exhibited as great quantitative variability within the family as C-DH did. In each case, the direction of the changes was towards low productivity ; reduction of plant height and leaf size. Some doubled haploid lines were revealed to have nornicotine, another type of the alkaloids, whereas all of the selfed lines of the source plant for anther culture had normal nicotine as the major alkaloid. This change in the alkaloid type was found in the plantlets before the colchicine treatment was applied. In addition, colchicine treatment of seed-derived diploid seedlings did not produce the nornicotine-type plantlets. These findings indicate that the colchicine treatment contributed little to the genetic variation of doubled haploid lines.
