Chemical mutagenesis: role in breeding and biofortification of lentil (Lens culinaris Medik) mutant lines.

BACKGROUND: Induced mutagenesis is a quick and effective breeding strategy to enhance genetic variability, an important prerequisite for the genetic improvement of existing lentil cultivars. Lentil is an important cool season food legume with low productivity due to the low yielding potential of existing lentil cultivars. The present study aimed at increasing the yielding potential, resulted in the isolation of six high-yielding mutant lines with dense micronutrients. METHODS AND RESULTS: Two lentil varieties were treated with different doses of ethyl methanesulphonate, hydrazine hydrate, and sodium azide, followed by phenotypic selection for consecutive three generations. In the M2 generation, six high-yielding mutant lines with stable phenotypes were isolated. The results revealed a substantial increase in mean values for quantitative and physiological traits coupled with a manifold increase in the genotypic coefficient of variation (GCV), heritability (h2), and genetic advance (GA). Correlation analysis revealed that plant yield was significantly and positively influenced (P < 0.001) by fertile branches per plant, pods per plant, and seed weight. Principal component analysis revealed two principal components contributed 63.5 and 62.5% of the total variation in the varieties Pant L-639 and Pant L-406, respectively. CONCLUSION: The isolated high-yielding mutant lines with dense micronutrients that serve as rich genetic resources could be subjected to further breeding trials. After attaining yield stability, these might be registered and released as new improved lentil varieties.

Coenzyme Q10 protects isolated human blood cells from TiO2 nanoparticles induced oxidative/antioxidative imbalance, hemolysis, cytotoxicity, DNA damage and mitochondrial impairment.

TiO2 NPs have been investigated for their toxic potential and studies have reported their toxicity is due to generation of oxidative stress. In the present study, we investigated the toxicity of TiO2 NPs and explored the potential of well-known antioxidant coenzyme Q10 (CoQ10) in counteracting the NP-induced toxicity in isolated human blood cells. When the isolated blood cells were treated with varying concentrations of TiO2 NPs (25-100 µg/ml), only 50 µg/ml dose induced statistically significant hemolysis in erythrocytes and cytotoxicity in lymphocytes (p < 0.05). None of the concentrations induced any significant increase in platelet aggregation. To investigate the protective effect of CoQ10, we incubated the isolated blood cells with 50 µg/ml of TiO2 NPs in the presence and absence of 25 µM of CoQ10 for 3 h. Hemolysis, oxidative stress, LDH leakage and ATPase enzyme activity were studied in erythrocytes; cytotoxic and DNA damaging potential of NPs were determined in lymphocytes, along with mitochondrial membrane potential (MMP) and ADP/ATP ratio. Hemolysis, generation of oxidative stress, LDH leakage and reduced ATPase activity were observed in the erythrocytes treated with NPs alone (50 µg/ml), the results were statistically significant at p < 0.05. Oxidative stress was evident by increased levels of malonaldehyde, indicating lipid peroxidation and generation of reactive oxygen species including hydrogen peroxide, together with statistically significant decrease in the activities of catalase and superoxide dismutase and reduced glutathione levels. In the lymphocytes treated with NPs alone (50 µg/ml), cytotoxicity in MTT assay and DNA damage in comet assay were observed; in addition, mitochondrial membrane potential collapsed and ADP/ATP ratio increased indicating mitochondrial function impairment. However, in the presence of CoQ10, hemolysis, oxidative stress and LDH leakage in the erythrocytes and lymphocyte cytotoxicity and DNA damage were drastically reduced, enzyme activities, MMP and ADP/ATP ratio were restored towards normal levels. TiO2 NPs induce cytotoxicity, damage DNA in lymphocytes, and induce oxidative/anti-oxidative imbalance in erythrocytes. Antioxidant CoQ10 protects erythrocytes and lymphocytes from toxicity induced by TiO2 NPs.

Antioxidant thymoquinone and eugenol alleviate TiO2 nanoparticle-induced toxicity in human blood cells in vitro.

Titanium dioxide (TiO2) nanoparticles (NPs) are used extensively in a variety of commercial, industrial, and medical products, due to which human exposure is inevitable. This study aimed to explore the potential of eugenol and thymoquinone (TQ), two well-known antioxidants, in counteracting the NP-induced toxicity in human blood cells in vitro. Fresh lymphocytes and erythrocytes were isolated from volunteer human blood donors and incubated with 50 µg/mL of TiO2 NPs in the presence and absence of 50 µM of TQ and 20 µg/mL of eugenol for 3 h. Results showed that NP-treatment-induced hemolysis, oxidative stress, lactate dehydrogenase (LDH) leakage, and reduced ATPase activity in the erythrocytes. In the lymphocytes treated with NPs alone (50 µg/mL), cytotoxicity in MTT assay and DNA damage in comet assay were observed; in addition, mitochondrial membrane potential collapsed and ADP/ATP ratio increased indicating mitochondrial function impairment. However, in the presence of antioxidants, all these NP-induced changes were mitigated significantly. The results were more significant when both antioxidants eugenol and TQ were given together. Thus, it seems that antioxidants eugenol and TQ can be used as a protective agent against TiO2 NP-induced toxicity.

Titanium dioxide nanoparticle genotoxicity: A review of recent in vivo and in vitro studies.

Titanium dioxide nanoparticles (TiO2 NPs, size <100 nm) find applications in a wide range of products including food and cosmetics. Studies have found that exposure to TiO2 NPs can cause inflammation, cytotoxicity, genotoxicity and cell apoptosis. In this article, we have reviewed the recent literature on the potential of TiO2 NPs to cause genotoxicity and summarized the results of two standard genotoxicity assays, the comet and micronucleus (MN) assays. Analysis of these peer-reviewed publications shows that the comet assay is the most common genotoxicity test, followed by MN, Ames, and chromosome aberration tests. These assays have reported positive as well as negative results, although there is inconsistency in some results that need to be confirmed further by well-designed experiments. We also discuss the possible mechanisms of TiO2 NP genotoxicity and point out areas that warrant further research.

Comparative Mutagenic Effectiveness and Efficiency of Gamma Rays and Sodium Azide in Inducing Chlorophyll and Morphological Mutants of Cowpea.

Mutagenic effectiveness and efficiency are the most important factors determining the success of mutation breeding, a coherent tool for quickly enhancing genetic diversity in crops. However, conclusive evidence of using an effective and efficient dose of gamma (γ) rays and sodium azide (SA) for genetic improvement is scant. The present study assesses genetic diversity in M2 mutants of cowpea and evaluates mutagenic effectiveness and efficiency of the single and combination doses of γ rays and SA. In M0 generation, 7200 M1 seeds obtained by SA treatment (0.01-0.1%) and γ irradiation (100-1000 Gy) at a dose rate of 11.58 Gy/min were sown to raise M1 generation. A total of 57,620 M2 seeds were generated from the M1 generation of two varieties-Gomati VU-89 and Pusa-578, from which 47,650 seeds germinated. Moreover, plants (38,749) that survived were screened for chlorophyll and morphological mutations. Among the mutagens, SA followed by γ rays + SA and γ rays was most effective in inducing higher frequency and a broader spectrum of chlorophyll mutants. A wide range of morphological mutants affecting every growth stage was recorded with the highest frequency in 400 Gy γ rays + 0.04% SA treatment. These morphological mutants with desirable agronomic traits represent a valuable genetic resource for future breeding programs. This study revealed the potency of γ rays and SA in increasing genetic diversity and demonstrated the successful conduct of induced mutagenesis in the cowpea.

Gamma Rays and Sodium Azide Induced Genetic Variability in High-Yielding and Biofortified Mutant Lines in Cowpea [Vigna unguiculata (L.) Walp.].

With the twin pressures of high population growth and extreme weather events, developing countries are the worst hit in meeting the food demands of their people, with millions unable to access adequate and nutritionally balanced food. Crop production must be increased by 70% to keep up with the food demands of a rapidly growing population, which is expected to rise to 9.6 billion by 2050. Legumes are ideal food crops to increase agricultural productivity and achieve sustainable development goals. Cowpea, a warm-season grain legume, is often categorized as a neglected crop with immense scope for genetic improvement through proper breeding strategies. A multi-year field experiment of induced mutagenesis was conducted to increase seed yield and genetic variability in the agro-economic traits of two cowpea varieties treated with different doses of gamma (γ) rays and sodium azide (SA). The study was also aimed to optimize different doses of γ rays and SA employed individually and in combinations. Quantitative trait analysis revealed a maximum increase in seed yield from M2 to M3 generation. Among the 10 quantitative traits studied, seeds per pod and seed weight positively correlated with a major direct impact on yield. An extensive phenotypic selection cycle from M2-M4 generations resulted in isolating new high-yielding and nutrient-dense mutant lines. Such high-yielding biofortified mutant lines with enhanced genetic variability could serve as a donor of elite genes and represent a valuable genetic resource for improving low-yielding warm-season grain legumes.

Eugenol attenuates TiO2 nanoparticles-induced oxidative damage, biochemical toxicity and DNA damage in Wistar rats: an in vivo study.

Titanium dioxide nanoparticles (TiO2 NPs) are widely used in food, edible dyes, and other commercial products. Human exposure to TiO2 NPs has raised concerns regarding their toxic potential. Various studies have evaluated the TiO2 NPs-induced toxicity, oxidative damage to the cellular components, and genotoxicity. In the present study, we examined whether co-treatment with the dietary antioxidant eugenol can attenuate or protect against TiO2 NPs-induced toxicity. We exposed the adult male Wistar rats to TiO2 NPs (150 mg/kg body weight) by intraperitoneal injection (i.p.) either alone or as co-treatment with eugenol (1-10 mg/kg body weight) once a day for 14 days. The untreated rats were supplied saline and served as control. Titanium (Ti) accumulation in various tissues was analyzed by inductively coupled plasma mass spectrometry. Serum levels of liver and kidney biomarkers and oxidative stress markers in the liver, kidney, and spleen were determined. A significant increase in hydrogen peroxide level confirmed that oxidative stress occurred in these tissues. TiO2 NPs induced oxidation of lipids, and decreased glutathione level and antioxidant enzyme activity in the kidney, liver, and spleen of treated rats. TiO2 NPs also increased the serum levels of alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, albumin, and total cholesterol and decreased the blood urea nitrogen, uric acid, and total bilirubin in serum, which indicates oxidative damage to the liver and kidney. In eugenol and TiO2 NPs co-treated rats, all these changes were mitigated. Single-cell gel electrophoresis (comet assay) of lymphocytes showed longer comet tail length in TiO2 NPs-treated groups, indicating DNA damage while tail length was reduced in eugenol and TiO2 NPs co-treated groups. Thus, it seems that eugenol can be used as a chemoprotective agent against TiO2 NPs-induced toxicity.

Phenotypic diversity in mutagenized population of urdbean (Vigna mungo (L.) Hepper).

The present study was conducted to assess the extent of induced genetic variability and to determine the inheritance pattern of various yield contributing phenotypic traits in M2 and M3 generations of urdbean following mutagenesis with single and combination treatments of gamma rays and ethyl methanesulphonate (EMS). The mean number of seeds per pod and 100-seed weight increased in all the mutagenic treatments in both the varieties with few exceptions in M2 generation. Mean pod length although increased considerably, however it did not differ significantly in most of the mutagenic treatments. In M3 generation, 0.2% EMS and 300 Gy γ rays+0.2% EMS treatments induced maximum increase in mean pod length, seeds per pod and 100-seed weight in both the varieties. Genetic parameters showed manifold increase in most of the mutagenic treatments and varied from trait to trait. Increased genetic variability for economically important traits in the selected mutant lines has successfully contributed in diversifying the accessible genetic base which could be exploited for subsequent improvement of urdbean through phenotypic selection.