Studies on Effect of Mutagens on Quantitative Characters in M2 and M3 Generation of Horsegram [Macrotyloma uniflorum (Lam.) Verdc]

Background: Induction of mutation plays an important role in the breeding programme among modern methods of plant breeding. Genetic variability is prerequisite for crop improvement and through induced mutation it was found to be very effective for creating variability in the quantitative and qualitative characters. Hence, the present study was aimed to induce genetic variability within short time. In the present investigation positive as well as negative impact on quantitative traits were recorded. Methods: The experiment material comprised of seeds of horsegram [Macrotyloma uniflorum (Lam.) Verdc] variety Paiyur 2 which was subjected to ethyl methane sulphonate (02, 0.3, 0.4 and 0.5%), gamma radiation (100, 200, 300 and 400 Gy) and combination treatments. The mutations affecting gross morphological changes in growth and yield characters such as plant habit, flowering, pod morphology, maturity and seed yield were scored as quantitative characters. The micro mutations at population level can be easily detected in the form of increased variations for quantitative traits in the segregation of mutagen treated populations. Micro mutations can alter morpho-physiological characters hence they are of a particular interest to the plant breeders. ANOVA test was performed to determine the significant differences and duncan’s multiple range test (p=0.05) to compare the differences among treatment means. Result: Among the twenty-five treatments studied both the mutagens, gamma radiations and Ethyl Methane Sulphonate proved to be very effective to induce variability in quantitative traits in M2 and M3 generations. The results of Duncan’s multiple range test analysis revealed that the treatment of mutagens in combinations induced more positive effects as compared to that of using alone. The combined treatments were found positive for improvement of primary branches per plant, no. of pods per plant, pod length, no. of seeds/pod and seed yield per plant in M2 and M3 generations whereas the treatment of gamma irradiation imparted its significant role for improvement of plant height, days required for 50% flowering, days to maturity and 1000 seed weight in both M2 and M3 generations whereas the treatment with Ethyl Methane Sulphonate is useful for improving no. of pods per plant and no. of seeds/pod in M2 generation alone.

Impact of Ethyl Methane Sulphonate Mutagenesis in Artemisia vulgaris L. under NaCl Stress

The present investigation aimed to obtain salt-tolerant Artemisia vulgaris L. to develop a constant form through in vitro mutagenesis with ethyl methane sulphonate (EMS) as the chemical mutagen. NaCl tolerance was evaluated by the ability of the callus to maintain its growth under different concentrations, ranges from (0 mM to 500 mM). However, NaCl salinity concentration at (500 mM) did not show any development of callus, slight shrinking, and brown discoloration taking place over a week. Thus, all the biochemical and antioxidant assays were limited to (0–400 mM) NaCl. On the other hand, selected calluses were treated with 0.5% EMS for 30, 60, and 90 min and further subcultured on basal media fortified with different concentrations of 0–400 mM NaCl separately. Thus, the callus was treated for 60 min and was found to induce the mutation on the callus. The maximum salt-tolerant callus from 400 mM NaCl was regenerated in MS medium fortified with suitable hormones. Biochemical parameters such as chlorophyll, carotenoids, starch, amino acids, and phenol contents decreased under NaCl stress, whereas sugar and proline increased. Peroxidase (POD) and superoxide dismutase (SOD) activities peaked at 200 mM NaCl, whereas catalase (CAT) was maximum at 100 mM NaCl. Enhanced tolerance of 0.5% the EMS-treated callus, attributed to the increased biochemical and antioxidant activity over the control and NaCl stress. As a result, the mutants were more tolerant of salinity than the control plants.

EFFECT OF PHYSICAL AND CHEMICAL MUTAGENESIS IN LITTLE MILLET (PANICUM SUMATRENSE ROTH EX ROEMER AND SCHULTZ) ON SEED GERMINATION, SEEDLING SURVIVAL THROUGH INDUCED MUTATION

Little millet (Panicum sumatrense Roth ex Roemer & Schultz) belongs to Poaeceae family and it is Indian in origin. Milletsare mostly rain fed crops and used as food and fodder. Mutations can be induced in a variety of ways, such as by exposure to electromagnetic or ionizing radiation or chemical mutagens. The seed of little millet variety of Co (samai) 4 seeds were treated with different dose/concentration of physical mutagens (5,10,15,20,25,30,35,40,45 and 50KR) and chemical mutagens like EMS (Ethyl Methane Sulphonate) (5,10,15,20,25,30,35,40,45 and 50 mM). After that the treated seeds are sown in Petri dish under the laboratory conditions. It was found that the M1 generation is effected in seed germination, seedling survival and morphology mutation.

Induced polygenic variability in sesame by combining hybridization and recurrent mutagenesis in F3M3 generation

The investigation was made to estimate the combined effects of hybridization and ethyl methane sulphonate (EMS) induced mutagenesis on the variability of seed yield and its attributes in F3M3 generation. A total of 15 populations were grown in randomized block design (RBD) with three replications. F3M3 results indicated an increase in variability for plant height, number of capsules per plant and seed yield per plant, whereas non significant variability was observed for number of primary branches per plant in mutant populations than respective controls. Increased mean value and increase in variability in the present investigation denoted the occurrence of more favorable mutations and breaking up of undesirable linkages with enhancing recombination. Correlation study in F3M3 generation indicated remarkable changes among seed yield per plant and its component traits and these changes might have come through independent polygenic mutations and enhanced recombination of polygenes affecting different traits. The outcome of this study will facilitate in understanding the effectiveness of combined effects of hybridization and EMS induced mutagenesis for sesame improvement.

Mutagen treatment affects the regeneration efficiency of the shoot-tip explant in Celosia cristate L. (Cockscomb)

The shoot-tip explant harvested from ethyl methane sulphonate (EMS) and gamma ray (GR) mutagenized seedling was cultured over MS medium fortified with NAA and BAP for five generations to amplify the mutated sector. Mutagens reduced the regeneration efficiency of the explant and affected its plant growth regulator-dependence for multiple shoot induction. While the 12d-old shoot-tip from GR-treated seedling induced shoots with 0.5µM NAA+6.6µM BAP; that from EMS-treated seedling induced shoots with 8.8µM BAP. The present study establishes that the mutagens affect the regeneration process in the explant.