Morphological and chromosomal abnormalities in gamma radiation-induced mutagenized faba bean genotypes

Adverse outcome pathways (AOPs) for radiation-induced reproductive effects in environmental species: state of science and identification of a consensus AOP network

BACKGROUND

Reproductive effects of ionizing radiation in organisms have been observed under laboratory and field conditions. Such assessments often rely on associations between exposure and effects, and thus lacking a detailed mechanistic understanding of causality between effects occurring at different levels of biological organization. The Adverse Outcome Pathway (AOP), a conceptual knowledge framework to capture, organize, evaluate and visualize the scientific knowledge of relevant toxicological effects, has the potential to evaluate the causal relationships between molecular, cellular, individual, and population effects. This paper presents the first development of a set of consensus AOPs for reproductive effects of ionizing radiation in wildlife. This work was performed by a group of experts formed during a workshop organized jointly by the Multidisciplinary European Low Dose Initiative (MELODI) and the European Radioecology Alliance (ALLIANCE) associations to present the AOP approach and tools. The work presents a series of taxon-specific case studies that were used to identify relevant empirical evidence, identify common AOP components and propose a set of consensus AOPs that could be organized into an AOP network with broader taxonomic applicability.

CONCLUSION

Expert consultation led to the identification of key biological events and description of causal linkages between ionizing radiation, reproductive impairment and reduction in population fitness. The study characterized the knowledge domain of taxon-specific AOPs, identified knowledge gaps pertinent to reproductive-relevant AOP development and reflected on how AOPs could assist applications in radiation (radioecological) research, environmental health assessment, and radiological protection. Future advancement and consolidation of the AOPs is planned to include structured weight of evidence considerations, formalized review and critical assessment of the empirical evidence prior to formal submission and review by the OECD sponsored AOP development program.

Radiosensitivity of seedling traits to varying gamma doses, optimum dose determination and variation in determined doses due to different time of sowings after irradiation and methods of irradiation in faba bean genotypes

PURPOSE

Three experiments were conducted to assess the effect of different doses of gamma radiation on various seedling traits; determine the optimum doses of gamma radiation for different faba bean genotypes; find out the variation in optimum doses with respect to the different times of sowings after irradiation and methods of irradiation.

MATERIALS AND METHODS

Five faba bean genotypes viz., L-2013-060, L-2013-092, Anandnagar Local, Gazipur Local and Bangla Gangachar were used in these experiments. In Experiment I, seeds of five experimental genotypes were exposed to different doses (100 Gy 200 Gy, 300 Gy, 400 Gy, 500 Gy, 600 Gy, 700 Gy and 800 Gy) of gamma radiation and were sown immediately after irradiation. In Experiment II, seeds of Bangla Gangachar and L-2013-060 were exposed to varying doses (100-800 Gy) of gamma radiation and were sown at seven sowings starting from 0 h to 24 h at 4-h intervals after irradiation. In Experiment III, L-2013-092 genotypes was exposed to different doses (100 -800 Gy) of gamma radiation with two different methods of irradiation.

RESULTS

In Experiment I, the lethal dose 50 (LD₅₀) values have arrived at 140 Gy, 669 Gy, 575 Gy, 386 Gy and 158 Gy for L-2013-060, L-2013-092, Anandnagar Local, Gazipur Local and Bangla Gangachar, respectively. The growth reduction 50 (GR₅₀) doses for different seedling traits ranged from 130 Gy to 320 Gy for L-2013-060, 250 Gy to 480 Gy for L-2013-092, 130 Gy to 370 Gy for Anandnagar Local, 200 Gy to 350 Gy for Gazipur Local and 250 Gy to 400 Gy for Bangla Gangachar. In Experiment II, the values for LD₅₀ of the genotypes Bangla Gangachar and L-2013-060 were significantly singular for different time intervals of sowing. The values of GR₅₀ for most of the seedling traits were found to increase with the delay in sowing after irradiation from 4 to 24 h when compared with the immediately sown seed lots. In Experiment III, LD₅₀ for L-2013-092 was 337 Gy with Method 1 and 669 Gy with Method 2. In Method 1, most of the growth parameters attained GR₅₀ doses lower than Method 2. The first method was found to increase the radiosensitivity of L-2013-092.

CONCLUSION

Every experimental genotype used in these three experiments showed dose-dependent retardation of different seedling traits. These optimized doses may be employed to establish mutant populations for exploiting the novel traits of faba bean. The time of sowing after irradiation and method of irradiation was found to be essential for confirming optimum doses.

Occurrence of cytogenetic effects under the action of epimutagen in winter wheat

Research on studying the features of 0.01%, 0.05%, 0.10% and 0.50% epimutagen Triton-X-305 impact at the cellular level, which means the way of identifying the viability of pollen in plants of the first generation, and cytological analysis of chromosomal aberrations in the cells of the primary meristem of germinal roots during germination of bread winter wheat seeds have been conducted. Research in this direction allows us to significantly improve the monitoring of same type of substances in the environment and to forecast the nature of their action at the DNA-level. Genotypes Podolyanka and Spivanka created by Ukrainian selection and varieties of French selection Altigo, Courtot, Lyrik, Flamenko have been studied. These genotypes were selected in order to characterize possible genotype-mutagenic interactions for a compound of complex hereditary pattern for a range of concentrations with maximum contrast taking into account the possible high site-specific effect. The main purpose of this research was to identify the specificity of impact of the agent Triton X-305 at the cellular level and identify parameters fully showing the effect of this substance on the subsequent induction of biodiversity and the enhancement of hereditary variability at the cellular level. Such indicators as pollen sterility effected by various concentrations, the total frequency of chromosomal rearrangements, the spectrum of chromosomal rearrangements, including fragments and double fragments, single and double bridges, micronuclei and lagging chromosomes have been investigated. The ratio of fragments to bridges as an indicator of the active factor nature, the number of cells with two or more rearrangements as an indicator of genetic toxicity of this substance has been established. As a result, a significantly weaker effect of the epimutagen on the overall frequency of chromosomal rearrangement has been shown unlike other factors of a mutagenic nature, at the same time changing the ratio of the obtained aberrations in favour of micronuclei and lagging chromosomes. In addition, other parameters are determined as more meaningful for identifying a specific agent of impact, and the differences in concentrations are less contrasting. There is also a less significantly decreasing fertility, however, this parameter is highly dependent on the source material. In the future, we intend to assess the variability, primarily of a hereditary nature, by the way of a visual analysis of the obtained material in subsequent generations, as well as through biochemical analysis, yield qualities analysis and morphometry of the obtained material.

Effects of the Cobalt-60 gamma radiation on Pichia pastoris glyceraldehyde-3-phosphate dehydrogenase

PURPOSE

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a key enzyme of the glycolytic pathway, can play a physiological regulatory role and vital other roles in metabolism. This study investigated the effects of gamma radiation generated by Cobalt-60 source on GAPDH activity and protein levels in Pichia pastoris as an eukaryotic organism model.

MATERIALS AND METHODS

After purification of the GAPDH from P. pastoris, in vitro effects of irradiation to the dose of 2 Gy, using Cobalt-60 at the dose rate of 0.25 Gy/min, on activity and kinetic parameters were investigated. In vivo effects of gamma exposition (dose of 5 Gy) on P. pastoris GAPDH and on reactive oxygen species (ROS) markers were also explored.

RESULTS AND CONCLUSIONS

The in vitro irradiation of the purified GAPDH reduces the specific activity and the maximum velocity (V_max) without alteration of substrates binding (K_m). No changes occurred in the specific activity and in kinetic parameters when P. pastoris cells were exposed to Cobalt-60 source. However, this in vivo irradiation of cells produced a significant increase of the GAPDH protein level. The changes of GAPDH activity and the increase of the enzyme population as a target for gamma radiation exposure will play a role in cells adaptation under stress conditions. On the other hand, the increase of malondialdehyde and carbonyl contents and the enhancement of catalase and superoxide dismutase in irradiated cells have been noticed. The antioxidant system can play an important role in the protection of P. pastoris GAPDH against the gamma induced-ROS damage. This is the first report of the P. pastoris GAPDH as a physiological target of gamma exposition.

AFLP-Based Analysis of Variation and Population Structure in Mutagenesis Induced Faba Bean

Genetic diversity enrichment is urgently necessary to develop climate-resilient faba bean cultivars. The present study aimed to measure the enrichment of genetic diversity and changes in the population structure of faba bean, following induced mutagenesis. 120 samples, including 116 M2 mutant plants, generated by exposing the ILB4347 accession to four mutagen treatments (25 and 50 Gray gamma radiation and 0.01%, and 0.05% diethyl sulfate) and four reference genotypes were characterized using 11 amplified fragment length polymorphism (AFLP) primer combinations. The AFLP markers generated 1687 polymorphic alleles, including 756 alleles (45%) that were detected infrequently (f ≤ 0.1). The total allele count of the mutant plants ranged from 117 to 545. We observed a wide range of banding patterns and counts among the mutant plants, showing the high genetic diversity induced by mutation. Mutations also changed the population structure, by altering 31.78% of the total membership coefficient (Q). Although mutations changed the population structure, Nei’s genetic distance showed that the mutant population remained closely related to its control parent. This is the first report examining genetic diversity and population changes in faba bean mutant populations and, thus, could facilitate the application of induced mutagenesis during faba bean breeding.

Characterization of 60CO γ-ray induced pod trait of blackgram-A promising yield mutants

Purpose: Blackgram (Vigna mungo (L.) Hepper) possesses natural flower dropping character with self-pollination, which was highly challenging to create variability through hybridization. Gamma irradiation is a powerful tool to induce genetic alteration and improvement in crops with beneficial mutants. Hence, the present investigation focused on finding out the mutant characters related to the improvement of the agronomic characters and yield-related traits by using gamma irradiation. Pod mutant isolated with fruitful agronomic trait at M₂ (Mutagenic) generation was identified and isolated by gamma irradiation is a central focus in the present study, which enhances the yield of the blackgram.Materials and methods: Viable and uniform size of blackgram Vamban-4 seeds were irradiated at a different dose of ⁶⁰CO (Cobalt) γ-rays viz., 200, 400, 600, 800, 1000, and 1200 Gray (Gy). The further generations were screened and raised to M₃ and M₄ plants to select the stable mutants with yield traits.Results: In the M₂ generation, the following viable and pod mutants were identified, such as tall, dwarf, multipod, small pod, bold pod, striata pod. Morphological traits, such as plant height (PH), number of branches per plant (NBP), number of leaves per plant (NLP), number of cluster per plant (NCP), number of pods per plant (NPP), number of seeds per pod (NSP), pod length (PL), a hundred seed weight (HSW), seed yield per plant (SYP), were measured. Among the mutants, the increased morphogenetic traits were recorded in tall mutants (600 Gy), and the enhancement of yield characteristics noticed in multipod (800 Gy) and bold pod mutants (600 Gy). Compared to other doses, 600 Gy shows enhanced quantitative traits for blackgram improvement.Conclusion: The ⁶⁰CO γ-rays induced genetic variation in the yield and its related traits and obtained pod mutants, which are useful to enhance the commercial value of Vigna species and crop improvement.

Novel inflorescence architecture in gamma radiation-induced faba bean mutant populations

Purpose: Inflorescence architecture is an important trait in the seed production of grain legumes. As several genes are responsible for this trait, any mutation, on these genes, may cause change in the inflorescence architecture. This study was conducted to evaluate inflorescence architecture in faba bean exposed to gamma radiation and to characterize the inflorescence architecture mutants phenotypically.Materials and methods: Faba bean M₂ seeds (4898) generated from M₁ generation of cultivars Hassawi 2 and ILB4347 were used in this study. M₁ seeds were produced by irradiation treatments at two doses of gamma radiations (25 and 50 Gy). Faba bean M₂ seeds were planted under field conditions. A total of 4032 mutant plants out of 4898 M₂ seeds were evaluated for their inflorescence architecture.Results: A total of 20 determinate mutants were found and classified into four different types. Determinate type 1 was characterized by the formation of single terminal inflorescence on shoot apical meristem (SAM), type 2 by the formation of multiple inflorescences on SEM and generated upper branches that act as indeterminate type. Type 3 was characterized by the formation of a panicle-like inflorescence. While type 4 was characterized by the formation of primary and secondary panicle-like inflorescence. All of the determinate mutant types had shorter plant height and earlier maturity than control indeterminate type but had lower biological yield and seed yield. Among the determinate mutant types, determinate type 1 was only mutant that had a higher harvest index than the control indeterminate type. This promising mutant can be used to further breeding program to increase biological yield and seed yield.Conclusions: This study indicated potential of gamma radiation in inducing novel inflorescence architecture in faba bean. The mutants developed are valuable resources to study genes related to inflorescence architecture through forward genetics approach.

Utility of TRAP markers to determine indel mutation frequencies induced by gamma-ray irradiation of faba bean (Vicia faba L.) seeds

Purpose: The aims were to determine the optimal gamma ray dose for faba bean (Vicia faba) and to identify genetic variation and indel mutation frequency among mutants using target region amplification polymorphism (TRAP) markers. Materials and methods: Seeds from 10 elite lines were irradiated with gamma rays (50-700 Gy), and germination, survival rate, and representative morphological traits were measured. The extent of DNA damage was investigated using comet assays, and TRAP markers were used to evaluate genetic variation, genetic diversity, and mutation frequencies. Results: Germination percentages significantly decreased at doses >100 Gy. Survival percentages and morphological traits decreased with elevation in dose. The comet assays revealed that high irradiation doses decreased head DNA levels. Phylogenetic and principal component analysis of 555 individual faba bean plants resolved eight major groups. Genetic variation between controls and mutants was limited to within groups. Mutation frequencies were associated with gamma dose in each mutant line. Conclusions: The optimal gamma dose was 100-150 Gy on the basis of survival percentage and morphological response analysis. The TRAP markers distinguished mutant lines and showed association between mutation frequency and gamma doses. This study will be useful for faba bean mutation breeding and may be applicable to other crops.