Division of Genetics, Indian Agricultural Research Institute, New Delhi-12
Online published on 25 January, 2012.
The internuclear distribution of univalents was analysed in several partially asynaptic plants obtained from irradiated and inbred populations of Delphinium. It was observed that in all the three inbred plants the distribution pattern deviated significantly from a normal or poisson type of distribution. One of these plants was found to show preponderance of two extreme classes of cells— one showing complete bivalent formation, the other showing all the chromosomes as univalents. This indicates that the control of chromosome pairing and chiasma formation in a cell is based to some extent on qualitative rather than purely quantitative type of genetic determination. In contrast to the inbred plants, several of the plants from the irradiated population showed a distribution of univalents which corresponds with the poisson type. On the basis of all the observations it has been concluded that the genetic control of chromosome pairing and chiasma formation involves major genes and some modifiers.
