II.25 Increasing the efficiency of EMS treatment.
N. P. Sarma. Indian Agricultural Research Institute. New Delhi, India.
Walles (1967) has suggested that the uptake of chemical mutagen in hydrated seeds follows a simple diffusion law as long as the concentration of mutagen in the solution is greater than that in the cell. Recently several attempts have been made to enhance the efficiency of mutagen through a change in the metabolic state of the treated material (Savin, et al., 1968; Mikaelsen, et al., 1968). When the problem is of diffusion of chemical either due to its inability to penetrate water resistant corky layer of bran as in rice or the presence of hull in other cases, suggestions have been made to use a carrier agent for the chemical or a physical force such as pressure to ensure rapid diffusion (Bhatia 1967; Nerkar, et al., 1970).
In our studies which involve large number of pulse treatments with EMS (Ethyl methane Sulphonate) we tried both a carrier agent, DMSO (Dimethyl Sulfoxide) as well as a physical technique - treatment of EMS under vacuum and the results of these experiments are reported in this note.
Seeds of Var. NP 104,a six-rowed hulled barley, were presoaked for a period of 16.00 hrs. in distilled water and then treated with EMS of a 1% conc. prepared as aqueous solution, for half an hour duration. In another set, the treatments were repeated with EMS prepared in 5% solution of DMSO. In a third set treatments with EMS (aqueous) were given under vacuum. Data collected on seedling injury, pollen fertility and mutation frequency are presented in Table 1.
Judged from the effect of EMS on M1 parameters as well as from the M2 mutation frequency the treatments with EMS using DMSO as the carrier did not show any enhancement over the treatments with EMS in aqueous solution. On the other hand treatments with EMS given under vacuum did increase the frequency of chlorophyll mutations considerably. There have been several conflicting reports about the ability of DMSO as carrier agent of chemical mutagens through biological membranes. DMSO seems to enhance the mutagenicity of EMS by a factor or two in Arabidopsis thaliana (Bhatia, 1967) but had no effect on EMS induced mutation rate in rice and wheat (Siddq et al., 1968; Rana and Mathur, 1969). The results of the present study also confirm the findings of the latter in barley in treatments of EMS for short duration.
References:
Bhatia, C. R., (1967). Mutation Res., 4:375-76.
Mikaelsen, K. and Nararatna, S. K. Symposium on the use of Induced mutations in Rice breeding IAEA Vienna 1968: 127 p.
Nerkar, Y. S., Siddiq., E. A. and Puri, R. P. (1970). Curr. Sci., 39:274-75.
Rana, R. S. and Mathur, H. C. (1969). Mutation Res., 8:666-67.
Savin, V. N., Swaminathan, M. S. and Sharma, B. (1968). Mutation Res., 6:101-7.
Siddiq, E. A., Puri, R. P. and Singh V. P. (1968). Curr. Sci., 37:686-88.
Walles, S. (1967). Hereditas, 58:95-102.
