Chiasma Formation in Induced Autotetraploids of Pea (Pisum sativum L.)-An efficient method of scoring

Abstract

Autotetraploids of four diverse cultivars, namely, T 163, 68 C, 5064-S and PI 280064 and their selfed progeny (C₂ and C₃) were examined for nature and frequency of chiasma formation. The proposed revised method of chiasma scoring, considering the varied appearance of chromosome configurations, was found to be 41 per cent more efficient than the conventional method. Further, it also helped in partitioning chiasma frequency in to proximal and distal. Chiasma formation and its distribution varied with the genotype. Autotetraploid of the cultivar 5064-S recorded maximum proximal and total chiasmata per cell. Both proximal and total chiasmata showed significant increase with the advance of generation; distal chiasma did not contribute in enhancing the frequency of total chiasmata suggesting different control mechanisms for proximal and distal chiasmata formation and distribution.