II.3. Effect of phosphate treatments on chromosome pairing in desynaptic barley.
George Fedak. Research Branch, Canada Department of Agriculture, Ottawa, Ontario, Canada.
It has been well established that the chiasma frequency at meiosis can be altered markedly by different environments. The various environments have even a more marked effect on the chiasma frequency of desynaptic mutants. Among the various chemical treatments applied to the desynaptic mutant in Husky barley was a high rate of phosphate fertilizer. In a field-grown trial the equivalent of 100 lb. P/acre was applied as a treatment to a plot of 10 ds plants and Ds checks while a similar plot was left unfertilized to serve as a control. PMC were collected at the proper stage and 20 metaphase cells were scored from each plant. Shown in Table 1 are mean configurations per cell based on 20 cells scored per plant on each of 10 plants in each treatment. The high P treatment caused a significant decrease in the mean frequency of univalents while increasing the frequency of ring bivalents as a result of an increased frequency of chiasmata per cell. The frequency of rod bivalents was not appreciably affected by the P treatment. These results are not sufficiently extensive to permit speculation on the mechanism of action of the ds gene nor further on the mechanism of chromosome pairing. This data indicates however that it is possible to alter chiasma frequency and possible recombination without affecting plant morphology or physiology as is the case with ionizing radiations or chemical mutagens.
Table 1. Effect of P treatment on mean chromosome configuration.
BGN 2 toc
BGN Main Index