Induced Structural Changes and Meiotic Abberrations in <i>Sorghum</i>

Abstract

Cytological observations were made in M1 plants treated with radiations (X- and gamma rays), chemical mutagens (EMS, MMS, DES and NEU) and their combination treatments to study the effects on types of chromosome associations, the frequency and type of other nuclear and nucleolar anomalies in three cultivated varieties (Co. 11, Co. 12 and Co. 18) of Eu-Sorghum. Reciprocal translocations having ring or rod configuration occurred in higher frequency than the other types of structural changes. A positive correlation between the percentage of M1 plants crarying chromosomes with interchanges and the dose of mutagens was observed. The treatments with radiations induced not only a greater frequency of interchanges per cell but also a higher percentage of PMCs with quadrivalents than treatments with chemical mutagens. The effect on disturbances in meiosis as judged by the chromosome association was measured by the mean number of univalents, bivalents and multivalents per cell. The combined treatments did not lead to any additive effect in inducing chromosome breakages. Meiotic anomalies other than translocations comprised mostly laggards, bridges tripolar spindles, micronuclei and multi-nucleoli. The percentage of PMCs with meiotic disturbances was on the increase with increase in dose of the mutagens. Radiation treatments induced the maximum frequency of PMCs carrying meiotic anomalies as compared to treatments with chemical mutagens.