Effects of Hydrogen Peroxide and Benzene Treatments on Morphological Traits of Sesame (Sesamum indicum L.)

A study was carried out on the effects of hydrogen peroxide and benzene treatments on morphological traits of sesame (Sesamum indicum L.) in Keffi. NCRIBEN-02M variety of sesame was exposed to varying concentration (100, 75, 50, 25 and 0%), of benzene, hydrogen peroxide, and the mixture of the two chemical mutagens. The M2 generation of the genotypes were assessed for plant height, number of leaves, leaves area. Benzene treatment, at all levels, have the highest plant height. The increase in number of leaves and leaf area are significant at p≤0.05 and 95% confidence. The optimum concentrations of the mutagens used for mutation in sesame, were effective at 100 and 75% of all the treatments. The most effective mutagen for inducing mutation in sesame under Keffi environment is benzene, followed by Hydrogen Peroxide. Benzene and hydrogen peroxide have proven themselves as chemical mutagens, in mutation breeding. They have unlocked several agronomic traits in sesame. Further, study on these mutagens will enhance the genetic variability in the growing of sesame for higher performance

Induced variability for yield and its attributing traits in cluster bean [Cyamopsis tetragonoloba (L. ) Taub] through gamma irradiation

Gamma ray is an effective mutagen which creates useful variability for crop like cluster bean where the natural variation is very meagre and creation of variability by conventional methods is cumbersome. In the present study, cluster bean cv. Pusa Navbahar was treated with different level of gamma rays from 50 Gy to 600 Gy with 50Gy interval and obtained M2 population was subjected to variability estimation for yield and its attributing traits in augmented block design. The variance between the control and the mutants was found to be significant for plant height, number of pods per cluster, number of pods per plant, pod length, pod width, pulp to seed ratio. For these traits, PCV ranged from 14.28 per cent (pod width) to 31.99 per cent (pulp to seed ratio) whereas, GCV ranged from 10.10 per cent (pod width) to 24.16 per cent (pulp to seed ratio). The heritability in broad sense ranged from 50 per cent (pod width) to 79.99 per cent (Plant height). Genetic advance expressed as percentage over mean ranged from 2.06 per cent (pod width) to 222.44 per cent (plant height). The traits like plant height, pod length, pod width, pulp to seed ratio showed sufficient variability due to induced mutation. All these traits showed medium to high heritability and high genetic advance hence selection for these traits will be effective.

An Argon-Ion-Induced Pale Green Mutant of Arabidopsis Exhibiting Rapid Disassembly of Mesophyll Chloroplast Grana

Argon-ion beam is an effective mutagen capable of inducing a variety of mutation types. In this study, an argon ion-induced pale green mutant of Arabidopsis thaliana was isolated and characterized. The mutant, designated Ar50-33-pg1, exhibited moderate defects of growth and greening and exhibited rapid chlorosis in photosynthetic tissues. Fluorescence microscopy confirmed that mesophyll chloroplasts underwent substantial shrinkage during the chlorotic process. Genetic and whole-genome resequencing analyses revealed that Ar50-33-pg1 contained a large 940 kb deletion in chromosome V that encompassed more than 100 annotated genes, including 41 protein-coding genes such as TYRAAt1/TyrA1, EGY1, and MBD12. One of the deleted genes, EGY1, for a thylakoid membrane-localized metalloprotease, was the major contributory gene responsible for the pale mutant phenotype. Both an egy1 mutant and F1 progeny of an Ar50-33-pg1 × egy1 cross-exhibited chlorotic phenotypes similar to those of Ar50-33-pg1. Furthermore, ultrastructural analysis of mesophyll cells revealed that Ar50-33-pg1 and egy1 initially developed wild type-like chloroplasts, but these were rapidly disassembled, resulting in thylakoid disorganization and fragmentation, as well as plastoglobule accumulation, as terminal phenotypes. Together, these data support the utility of heavy-ion mutagenesis for plant genetic analysis and highlight the importance of EGY1 in the structural maintenance of grana in mesophyll chloroplasts.

Ems and gamma radiation induced mutation in grasspea (Lathyrus sativus L.)

Present investigation has been undertaken to study the induction of mutation by individual and combination treatments of EMS and gamma rays in three diverged genotypes of grasspea viz. Nirmal, Biol-212 and Berhampur Local. Combination treatments caused the more biological damage (lethality, injury and sterility) followed by gamma rays and EMS alone. The LD50 dose of gamma rays for Nirmal, Biol-212 and Berhampur Local corresponded to 590 Gy, 630 Gy and 539 Gy respectively. Above 0.5% EMS for Nirmal and Biol-212 and above 1% EMS in case of Berhampur Local was found to be lethal. Average total mutation frequency of three varieties together was highest (6.32 %) in gamma radiation followed by both EMS and combination treatment (5.8%). The most efficient dose/concentration of gamma rays and EMS were found to be 400 Gy and 0.5% EMS respectively. Mutagenic efficiency increases and effectiveness decreases with increasing concentration of EMS but the consequence was showed almost inverse relationship in case of gamma rays. Overall, irrespective of genotypes, gamma rays and EMS respectively were found to be most efficient and effective mutagen.

Efficient recovery of ENU-induced mutations from the zebrafish germline.

We studied the efficiency with which two chemical mutagens, ethyl methanesulfonate (EMS) and N-ethyl-N-nitrosourea (ENU) can induce mutations at different stages of spermatogenesis in zebrafish (Brachydanio rerio). Both EMS and ENU induced mutations at high rates in post-meiotic germ cells, as indicated by the incidence of F1 progeny mosaic for the albino mutation. For pre-meiotic germ cells, however, only ENU was found to be an effective mutagen, as indicated by the frequencies of non-mosaic mutant progeny at four different pigmentation loci. Several mutagenic regimens that varied in either the number of treatments or the concentration of ENU were studied to achieve an optimal ratio between the mutagenicity and toxicity. For the two most mutagenic regimens: 4 x 1 hr in 3 mM ENU and 6 x 1 hr in 3 mM ENU, the minimum estimate of frequencies of independent mutations per locus per gamete was 0.9-1.3 X 10(-3). We demonstrate that embryonic lethal mutations induced with ENU were transmitted to offspring and that they could be recovered in an F2 screen. An average frequency of specific-locus mutations of 1.1 X 10(-3) corresponded to approximately 1.7 embryonic lethal mutations per single mutagenized genome. The high rates of mutations achievable with ENU allow for rapid identification of large numbers of genes involved in a variety of aspects of zebrafish development.

INDUCTION OF TWO MUTANTS IN BIRDSFOOT TREFOIL (Lotus corniculatus) BY X-RAYS AND CHEMICAL MUTAGENS

The mutagenic effects of X-rays, ethyl methanesulfonate (EMS), 8-ethoxycaffeine (EOC), N-hydroxyurea (HU) and 2-aminopurine (2AP) on seed treatment of birdsfoot trefoil (Lotus corniculatus L. ’Mirabel’) were assessed over four generations. Mutants were recovered in the M2, M3 and M4 generations from selfed lines, from crosses derived from selfed lines and from open pollination lines. Mutant plants exhibiting vestigial floret character were recovered from X-ray, EMS, EOC and HU treatments. Mutant chlorotica plants were obtained from EMS treatment only. No mutants were recovered from 2AP treatment, EMS, the most effective mutagen, produced nine vestigial floret and 12 chlorotica mutants. Mutants were obtained from only one exposure of X-rays (12 krad). There was evidence for preferential elimination of gametes. The chlorotica and vestigial floret mutants were inherited as tetrasomic recessives. Mutation frequencies of 0.4–3.1% in a tetrasomic background are indicative of the effectiveness of EMS in birdsfoot trefoil.