Gibberellic Acid Protection against EMS and MMS Induced Damage to Chromosomes in <i>Pisum sativum</i> L

Abstract

Chromosomal aberrations produced by physical and chemical mutagens are the main causes of damage in mutation studies However, recent experiments have amply revealed that a great many factors modify the chromosomal damage by affecting the biological changes induced by physical and chemical mutagens (Curtis et al., 1958, Nilan et al., 1961and Konzak et al., 1965. Hormones, e.g., indole acetic acid, along with other chemicals have been found to modify the mutagenic damage only to the extent that they influence the growth pattern in plants (Guttman and Brown 1959, Gaur and Notani 1963and Arartjan 1967.The present experiments relate to cytological changes observed in ethyl methane sulphonate (EMS) and methyl methane sulphonate (MMS) treated peas during M,, M2 and M3 generations. Further, studies were also conducted to study the modify ing effect of post-mutagenic treatments with gibberellic acid. Materials and methodsPea seeds (Pisum sativum L., 2n=14) of variety Bonnvile were used for the present studies. Two chemical mutagens namely ethyl methane sulphonate (EMS) and methyl methane sulphonate (MMS) were employed, while gibberellic acid (GA) was the only hormone tested as a post treatment during these studies. In the first instance, preliminary studies were conducted to determine the suitable dose of each of the mutagens. These preliminary studies revealed that the suitable dose for EMS was 0.25% and 0.025% for MMS (volume by volume). The mutagenic solu tions were prepared in phosphate buffer adjusted to a pH of 7.0. Only one con centration of GA of 1000 ppm was used as this was found to be the most suitable concentration (Narsinghani and Kumar 1971). The following treatments were used:-1. EMS 0.25% 4. MMS 0.025%+GA (1000 ppm) 2. EMS 0.25%+GA (1000 ppm) 5. GA (Control) 1000ppm 3. MMS 0.025% 6. Control-distilled water. The seeds were first presoaked for two hours in distilled water and then im mersed in solutions of mutagens for ten hours. At the end of the treatment the seeds were washed with distilled water and sown in the field. Plants in the M1 generation were tagged individually and chromosomal aberrations recorded. The

Modification of mutagenic efficiency of sodium azide.

“…Several studies have shown that gibberelic acid treatment decreases the severity of mutagen induced damage (Singh et al 1979, Minocha and Saini 1971, Narsinghani and Kumar 1976 thereby enhancing survival and hence efficiency of mutagens. Studies conducted by Pearson et al 1975, Singh andOlejniczak 1979) have shown that chemical muta gens disturb the initiation of metabolism thereby effecting the kinetics of ATP Table 3.…”