MANY chemicals employed successfully for inducing mutations at the molecular
level in bacteria and viruses have not been similarly effective in higher plants.
Typical examples are 5-bromo-uracil, 2-aminopurine, nitrous acid and
hydroxylamine (HA). Szybalski (1964) has also reported that several mutagens
active in microbial systems are ineffective in increasing mutation rates in in
vitro cultures of human cell lines. Difficulties in manipulating accurately the
various treatment conditions which influence the penetration, reactivity and
cyto-toxicity of these chemicals as well as the complications introduced by
intra-somatic selection may be responsible for such negative results in multicellular organisms. Alkylating agents, particularly di-ethyl sulphate and ethylmethane-sulfonate (EMS) have, on the other hand, yielded in many plants
mutation frequencies exceeding those obtained with radiations. At the
molecular level, EMS (CH3S0 20C2H 5 ) and HA (NH 20H) are known to
react preferentially with guanine and cytosine respectively (Freese, 1963).
Also, both have been reported to induce chromosome breakage at the same
regions in Vicia faba (Natarajan and Upadhyaya, 1964).
Article DOI: NA
Print ISSN: 0019-5200
Online ISSN: 0975-6906
V. L. CHOPRA and M. S. SWAMINATHAN info_circle