Metabolic and biochemical changes caused by gamma irradiation in plants

Cytogenetic impact of gamma radiation and its effects on growth, yield and drought tolerance of maize (Zea mays L.)

Maize is the third most important grain crop worldwide after wheat and rice; it is a vital global crop, serving as a key source of food, animal feed, and industrial products, making it essential for food security and economic stability in many countries. Drought stress adversely affects water uptake and can stunt growth, reducing the overall productivity of maize. So, this study was carried out to investigate the cytogenetic effects of gamma radiation and drought stress on maize SC131 genotype, focusing on chromosomal aberrations in seedling root meristems induced by varying doses of gamma irradiation (50, 100, 150, 200, and 250 Gray) and drought stress imposed by 10% polyethylene glycol (PEG). The present study also aims to evaluate the impact of these treatments on growth parameters under a controlled pot experiment. Additionally, molecular polymorphism induced by both gamma irradiation and drought stress was analyzed using Real-Time quantitative PCR techniques for DREB2, ERF, and EF transcription factors. Also, under a field condition experiment, maize plants were subjected to the same gamma irradiation doses and drought stress by reducing the number of irrigations, with subsequent evaluations of yield attributes to assess the overall impact of treatments on plant performance. The study also investigates the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) banding patterns of proteins in grains yielded under the influence of gamma radiation and drought treatments. Findings of the current investigation indicate that the low dose of gamma radiation (50 Gray) not only induces cytogenetic changes but also enhances drought tolerance and improves yield characteristics, suggesting that targeted gamma irradiation could serve as a viable strategy to bolster maize resilience in challenging environmental conditions.

Development and validation of a minimal SNP genotyping panel for the differentiation of Cannabis sativa cultivars

BACKGROUND

Due to its previously illicit nature, Cannabis sativa had not fully reaped the benefits of recent innovations in genomics and plant sciences. However, Canada's legalization of C. sativa and products derived from its flower in 2018 triggered significant new demand for robust genotyping tools to assist breeders in meeting consumer demands. Early molecular marker-based research on C. sativa focused on screening for plant sex and chemotype, and more recent research has sought to use molecular markers to target traits of agronomic interest, to study populations and to differentiate between C. sativa cultivars.

RESULTS

In this study, we have conducted whole genome sequencing of 32 cultivars, mined the sequencing data for SNPs, developed a reduced SNP genotyping panel to discriminate between sequenced cultivars, then validated the 20-SNP panel using DNA from the sequenced cultivars and tested the assays on commercially available dried flower. The assay conversion rate was higher in DNA extracted from fresh plant material than in DNA extracted from dried flower samples. However, called genotypes were internally consistent, highlighting discrepancies between genotypes detected using sequencing data and observed using genotyping assays. The primary contributions of this work are to clearly document the process used to develop minimal SNP genotyping panels, the feasibility of using such panels to differentiate between C. sativa cultivars, and outline improvements and goals for future iterations of PCR-based, minimal SNP panels to enable efficient development genotyping tools to identify and screen C. sativa cultivars.

CONCLUSIONS

Our key recommendations are to increase sampling density to account for intra-cultivar variability; leverage higher read length paired-end short-read technology; conduct in-depth pre- and post-processing of reads, mapping, and variant calling data; integrate trait-associated loci to develop multi-purpose panels; and use iterative approaches for in vitro validation to ensure that only the most discriminant and performant SNPs are retained.

Effects of Gamma Irradiation on Changes in Chemical Composition and Antioxidant Activity of Euphorbia maculata Callus

In this study, we investigated the effects of gamma irradiation on the antioxidant activity and metabolite profiles of Euphorbia maculata calli (PC3012). Gamma irradiation at various doses (0, 0.05, 0.5, and 10 kGy) significantly enhanced the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS+) radical scavenging activities of the callus extracts of PC3012 in a dose-dependent manner. High-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography-quadrupole time-of-flight/mass spectrometry (UPLC-Q-TOF/MS) analyses revealed that irradiation increased the lysophospholipid content, although no new antioxidant compounds were formed. Furthermore, a PLS-DA analysis revealed evident metabolic differences between non-irradiated and irradiated samples, which were further verified by statistical validation. These findings suggest that gamma irradiation induces specific biochemical modifications that enhance the bioactive properties of PC3012 calli. This technology exhibits potential for utilization in the natural product and food sectors, particularly in the development of functional foods and nutraceuticals with improved health benefits.

Effect of low-dose ionizing radiation on spatiotemporal parameters of functional responses induced by electrical signals in tobacco plants

Plants growing under an increased radiation background may be exposed to additional stressors. Plant acclimatization is formed with the participation of stress signals that cause systemic responses-a change in the activity of physiological processes. In this work, we studied the mechanisms of the effect of ionizing radiation (IR) on the systemic functional responses induced by electrical signals. Chronic β-irradiation (31.3 μGy/h) have a positive effect on the morphometric parameters and photosynthetic activity of tobacco plants (Nicotiana tabacum L.) at rest. An additional stressor causes an electrical signal, which, when propagated, causes a temporary change in chlorophyll fluorescence parameters, reflecting a decrease in photosynthesis activity. Irradiation did not significantly affect the electrical signals. At the same time, more pronounced photosynthesis responses are observed in irradiated plants: both the amplitude and the leaf area covered by the reaction increase. The formation of such responses is associated with changes in pH and stomatal conductance, the role of which was analyzed under IR. Using tobacco plants expressing the fluorescent pH-sensitive protein Pt-GFP, it was shown that IR enhances signal-induced cytoplasmic acidification. It was noted that irradiation also disrupts the correlation between the amplitudes of the electrical signal, pH shifts, changes in chlorophyll fluorescence parameters. Also stronger inhibition of stomatal conductance by the signal was shown in irradiated plants. It was concluded that the effect of IR on the systemic response induced by the electrical signal is mainly due to its effect on the stage of signal transformation into the response.

Influence of Increased Radiation Background on Antioxidative Responses of Helianthus tuberosus L

As a result of the accident at the Chornobyl Nuclear Power Plant, significant territories were exposed to ionizing radiation. Some isotopes, such as ¹³⁷Cs, are capable of making a significant impact on living organisms in the long-term perspective. The generation of reactive oxygen species is one mechanism by which ionizing radiation affects living organisms, initiating mechanisms of antioxidant protection. In this article, the effect of increased ionizing radiation on the content of non-enzymatic antioxidants and the activity of antioxidant defense enzymes of Helianthus tuberosum L. was studied. This plant is widely distributed in Europe and characterized by high adaptability to abiotic factors. We found that the activity of antioxidant defense enzymes, such as catalase and peroxidase, weakly correlated with radiation exposure. The activity of ascorbate peroxidase, on the contrary, is strongly positively correlated with radiation exposure. The samples growing on the territory with constant low exposure to ionizing radiation were also characterized by an increased concentration of ascorbic acid and water-soluble phenolic compounds compared to the controls. This study may be useful for understanding the mechanisms underlying the adaptive reactions of plants under prolonged exposure to ionizing radiation.

Response of Satureja hortensis L. to gamma radiation and its impact on secondary metabolite content and biochemical characteristics

PURPOSE

The current study investigated the effects of gamma irradiation on biochemical parameters and secondary metabolite accumulation in Summer Savory under field conditions.

MATERIALS AND METHODS

The dry seeds of Summer Savory (with a moisture content of 12%) were exposed to gamma radiation at the doses of 20, 40, 60, 80, and 100 Gy. Non-irradiated seeds (0 Gy) were used as control.

RESULTS

Our findings showed that gamma radiation at low doses (20-40 Gy) had no effect on biochemical parameters and secondary metabolites accumulation in S. hortensis. These parameters are steadily and significantly increased by raising gamma irradiation doses from 40 to 100 Gy. The highest amount of chlorophyll a and b, carotenoids, anthocyanin, and total phenolic and flavonoid content were observed in 80 and 100 Gy treatments. Plants exposed to 80 and 100 Gy treatments accumulated the maximum amounts of rosmarinic acid and caffeic acid, respectively. Furthermore, the analysis of S. hortensis essential oil revealed that gamma radiation significantly alters its components. Carvacrol, α-Pinene, and α-Thujene levels raised dramatically compared to control with an increase in gamma irradiation dose from 20 to 100 Gy, while Thymol and α-Terpinene levels lowered.

CONCLUSIONS

Our results showed that treatment of Summer Savory seeds with gamma radiation at 80 and 100 Gy doses could significantly be raised biochemical parameters and secondary metabolites accumulation under field conditions. The current study showed that gamma irradiation could be used as a pre-sowing elicitor to improve the quantity and quality of phytochemicals in Summer Savory.

Influence of gamma radiation and phenylalanine on secondary metabolites in callus cultures of milk thistle (Silybum marianum L.)

BACKGROUND

A useful technique for growing large amounts of plant material is in vitro propagation of important medicinal plants. The present investigation deals with the enhancement of secondary metabolite production via elicitation using gamma (γ)-radiation and phenylalanine (Phe) precursor feeding in callus cultures of Silybum marianum L.

RESULTS

Seeds were exposed to two doses of γ-radiation (25 and 50 Gy) and the calli derived from stem explants  obtained from seedlings of these radiated seeds were treated with different concentrations of Phe. The biosynthesis of phenols and flavonoids was evaluated. It was found that callus cultures derived from explants of the seeds exposed to 25 Gy γ-radiation and treated with 4 mg/l Phe accumulated the maximum phenolic content (34.27±0.02 mg/g d.wt.), while the highest flavonoid content (9.56±0.12 mg/g d.wt.) was found in callus cultures derived from explants of seeds radiated with 25 Gy γ-radiation and subjected to 1 mg/l Phe. Similarly, HPLC quantification revealed that the production of flavonoids was highly accumulated (1343.06 μg/mg d.wt.) in callus cultures from explants of seeds  exposed to 25 Gy γ-radiation and grown at 1 mg/l Phe compared to the other treatments. In addition, a total of 11 important flavonoids have been determined in all callus cultures, except for acacetin-7-O-rutinoside, which was not found in the callus culture of the control.

CONCLUSIONS

These findings suggest that γ-radiation combined with Phe can improve the metabolism of S. marianum L. and could be used to produce such valuable metabolites on a commercial scale.

Combining NMR and MS to Describe Pyrrole-2-Carbaldehydes in Wheat Bran of Radiation

Nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) are indispensable analytical tools to provide chemical fingerprints in metabolomics studies. The present study evaluated radiation breeding wheat lines for chemical changes by non-targeted NMR-based metabolomics analysis of bran extracts. Multivariate analysis following spectral binning suggested pyrrole-2-carbaldehydes as chemical markers of four mutant lines with distinct NMR fingerprints in a δ_H range of 9.28-9.40 ppm. Further NMR and MS data analysis, along with chromatographic fractionation and synthetic preparation, aimed at structure identification of marker metabolites and identified five pyrrole-2-carbaldehydes. Quantum-mechanical driven ¹H iterative full spin analysis (QM-HiFSA) on synthetic pyrrole-2-carbaldehydes provided a precise description of complex peak patterns. Biological evaluation of pyrrole-2-carbaldehydes was performed with nine synthetic products, and six compounds showed hepatoprotective effects via modulation of reactive oxygen species production. Given that three out of five identified in wheat bran of radiation were described for hepatoprotective activity, the value of radiation mutation to greatly enhance pyrrole-2-carbaldehyde production was supported.

Radiation environment in exploration-class space missions and plants' responses relevant for cultivation in Bioregenerative Life Support Systems

For deep space exploration, radiation effects on astronauts, and on items fundamental for life support systems, must be kept under a pre-agreed threshold to avoid detrimental outcomes. Therefore, it is fundamental to achieve a deep knowledge on the radiation spatial and temporal variability in the different mission scenarios as well as on the responses of different organisms to space-relevant radiation. In this paper, we first consider the radiation issue for space exploration from a physics point of view by giving an overview of the topics related to the spatial and temporal variability of space radiation, as well as on measurement and simulation of irradiation, then we focus on biological issues converging the attention on plants as one of the fundamental components of Bioregenerative Life Support Systems (BLSS). In fact, plants in BLSS act as regenerators of resources (i.e. oxygen production, carbon dioxide removal, water and wastes recycling) and producers of fresh food. In particular, we summarize some basic statements on plant radio-resistance deriving from recent literature and concentrate on endpoints critical for the development of Space agriculture. We finally indicate some perspective, suggesting the direction future research should follow to standardize methods and protocols for irradiation experiments moving towards studies to validate with space-relevant radiation the current knowledge. Indeed, the latter derives instead from experiments conducted with different radiation types and doses and often with not space-oriented scopes.

Comparative Analysis of the Effect of Carbon- and Titanium-Ions Irradiation on Morpho-Anatomical and Biochemical Traits of Dolichos melanophthalmus DC. Seedlings Aimed to Space Exploration

The realization of manned missions for space exploration requires the development of Bioregenerative Life Support Systems (BLSSs) to make human colonies self-sufficient in terms of resources. Indeed, in these systems, plants contribute to resource regeneration and food production. However, the cultivation of plants in space is influenced by ionizing radiation which can have positive, null, or negative effects on plant growth depending on intrinsic and environmental/cultivation factors. The aim of this study was to analyze the effect of high-LET (Linear Energy Transfer) ionizing radiation on seed germination and seedling development in eye bean. Dry seeds of Dolichos melanophthalmus DC. (eye bean) were irradiated with two doses (1 and 10 Gy) of C- and Ti-ions. Seedlings from irradiated seeds were compared with non-irradiated controls in terms of morpho-anatomical and biochemical traits. Results showed that the responses of eye bean plants to radiation are dose-specific and dependent on the type of ion. The information obtained from this study will be useful for evaluating the radio-resistance of eye bean seedlings, for their possible cultivation and utilization as food supplement in space environments.

The effects of base station as an electromagnetic radiation source on flower and cone yield and germination percentage in Pinus brutia Ten

Electromagnetic radiation is a substantial pollution factor that most of the living things found almost everywhere are constantly exposed to with current technology. The number of studies conducted on the effects of this exposed radiation on the living things constantly is limited; and almost all of the studies conducted are aimed at measuring the effects of short-term exposure. In addition to this, most of the studies conducted on plants focus on herbaceous plant species. In this study, the effects of distance to base station on flower and cone yield and germination percentage were investigated in Pinus brutia individuals, one of the critical forest tree species. The study results revealed that being close to the base station significantly reduced the number of flowers and cones in P. brutia individuals, and that the values obtained in individuals at a distance of 800 m from the base station were 11 times more than the number of flowers and 7 times more than the number of cones compared to the individuals at a distance of 100 m. In the seeds subject to the study, there is a three-times difference in terms of the germination percentage among the individuals located at the furthest and closest distance to the base station. These results show that P. brutia individuals are considerably affected by the base station.

Compatibility of X-ray computed tomography with plant gene expression, rhizosphere bacterial communities and enzyme activities

Non-invasive X-ray computed tomography (XRCT) is increasingly used in rhizosphere research to visualize development of soil-root interfaces in situ. However, exposing living systems to X-rays can potentially impact their processes and metabolites. In order to evaluate these effects, we assessed the responses of rhizosphere processes 1 and 24 h after a low X-ray exposure (0.81 Gy). Changes in root gene expression patterns occurred 1 h after exposure with down-regulation of cell wall-, lipid metabolism-, and cell stress-related genes, but no differences remained after 24 h. At either time point, XRCT did not affect either root antioxidative enzyme activities or the composition of the rhizosphere bacterial microbiome and microbial growth parameters. The potential activities of leucine aminopeptidase and phosphomonoesterase were lower at 1 h, but did not differ from the control 24 h after exposure. A time delay of 24 h after a low X-ray exposure (0.81 Gy) was sufficient to reverse any effects on the observed rhizosphere systems. Our data suggest that before implementing novel experimental designs involving XRCT, a study on its impact on the investigated processes should be conducted.

Effect of ionizing radiation on physiological and molecular processes in plants

The study of effects of ionizing radiation (IR) on plants is important in relation to several problems: (I) the existence of zones where background radiation - either natural or technogenic - is increased; (II) the problems of space biology; (III) the use of IR in agricultural selection; (IV) general biological problems related to the fundamental patterns and specifics of the effects of IR on various living organisms. By now, researchers have accumulated and systematized a large body of data on the effects of IR on the growth and reproduction of plants, as well as on the changes induced by IR at the genetic level. At the same time, there is a large gap in understanding the mechanisms of IR influence on the biochemical and physiological processes - despite the fact that these processes form the basis determining the manifestation of IR effects at the level of the whole organism. On the one hand, the activity of physiological processes determines the growth of plants; on the other, it is determined by changes at the genetic level. Thus, it is the study of IR effects at the physiological and biochemical levels that can give the most detailed and complex picture of IR action in plants. The review focuses on the effects of radiation on the essential physiological processes, including photosynthesis, respiration, long-distance transport, the functioning of the hormonal system, and various biosynthetic processes. On the basis of a large body of experimental data, we analyze dose and time dependences of the IR-induced effects - which are qualitatively similar - on various physiological and biochemical processes. We also consider the sequence of stages in the development of those effects and discuss their mechanisms, as well as the cause-effect relationships between them. The primary IR-induced physicochemical reactions include the formation of various forms of reactive oxygen species (ROS) and are the cause of the observed changes in the functional activity of plants. The review emphasizes the role of hydrogen peroxide, a long-lived ROS, not only as a damaging agent, but also as a mediator - a universal intracellular messenger, which provides for the mechanism of long-distance signaling. A supposition is made that IR affects physiological processes mainly by violating the regulation of their activity. The violation seems to become possible due to the fact that there exists a crosstalk between different signaling systems of plants, such as ROS, calcium, hormonal and electrical systems. As a result of both acute and chronic irradiation, an increase in the level of ROS can influence the activity of a wide range of physiological processes - by regulating them both at the genetic and physiological levels. To understand the ways, by which IR affects plant growth and development, one needs detailed knowledge about the mechanisms of the processes that occur at the (i) genetic and (ii) physiological levels, as well as their interplay and (iii) knowledge about regulation of these processes at different levels.

Ionizing Radiation, Higher Plants, and Radioprotection: From Acute High Doses to Chronic Low Doses

Understanding the effects of ionizing radiation (IR) on plants is important for environmental protection, for agriculture and horticulture, and for space science but plants have significant biological differences to the animals from which much relevant knowledge is derived. The effects of IR on plants are understood best at acute high doses because there have been; (a) controlled experiments in the field using point sources, (b) field studies in the immediate aftermath of nuclear accidents, and (c) controlled laboratory experiments. A compilation of studies of the effects of IR on plants reveals that although there are numerous field studies of the effects of chronic low doses on plants, there are few controlled experiments that used chronic low doses. Using the Bradford-Hill criteria widely used in epidemiological studies we suggest that a new phase of chronic low-level radiation research on plants is desirable if its effects are to be properly elucidated. We emphasize the plant biological contexts that should direct such research. We review previously reported effects from the molecular to community level and, using a plant stress biology context, discuss a variety of acute high- and chronic low-dose data against Derived Consideration Reference Levels (DCRLs) used for environmental protection. We suggest that chronic low-level IR can sometimes have effects at the molecular and cytogenetic level at DCRL dose rates (and perhaps below) but that there are unlikely to be environmentally significant effects at higher levels of biological organization. We conclude that, although current data meets only some of the Bradford-Hill criteria, current DCRLs for plants are very likely to be appropriate at biological scales relevant to environmental protection (and for which they were intended) but that research designed with an appropriate biological context and with more of the Bradford-Hill criteria in mind would strengthen this assertion. We note that the effects of IR have been investigated on only a small proportion of plant species and that research with a wider range of species might improve not only the understanding of the biological effects of radiation but also that of the response of plants to environmental stress.

Secondary metabolite perturbations in Phaseolus vulgaris leaves due to gamma radiation

Oxidative stress is a condition in which the balance between the production and elimination of reactive oxygen species (ROS) is disturbed. However, plants have developed a very sophisticated mechanism to mitigate the effect of ROS by constantly adjusting the concentration thereof to acceptable levels. Electromagnetic radiation is one of the factors which results in oxidative stress. In the current study, ionizing gamma radiation generated from a Cobalt-60 source was used to induce oxidative stress in Phaseolus vulgaris seedlings. Plants were irradiated with several radiation doses, with 2 kGy found to be the optimal, non-lethal dose. Metabolite distribution patterns from irradiated and non-irradiated plants were analyzed using UHPLC-qTOF-MS and multivariate data models such as principal component analysis (PCA) and orthogonal projection to latent structures discriminate analysis (OPLS-DA). Metabolites such as hydroxycinnamic phenolic acids, flavonoids, terpenes, and a novel chalcone were found to be perturbed in P. vulgaris seedlings treated with the aforementioned conditions. The results suggest that there is a compensatory link between constitutive protectants and inducible responses to injury as well as defense against oxidative stress induced by ionizing radiation. The current study is also the first to illustrate the power of a metabolomics approach to decipher the effect of gamma radiation on crop plants.

Gamma radiation and magnetic field mediated delay in effect of accelerated ageing of soybean

Soybean seeds were exposed to gamma radiation (0.5, 1, 3 and 5 kGy), static magnetic field (50, 100 and 200 mT) and a combination of gamma radiation and magnetic energy (0.5 kGy + 200 mT and 5 kGy + 50 mT) and stored at room temperature for six months. These seeds were later subjected to accelerated ageing treatment at 42 °C temperature and 95-100 % relative humidity and were compared for various physical and biochemical characteristics between the untreated and the energized treatments. Energy treatment protected the quality of stored seeds in terms of its protein and oil content . Accelerated aging conditions, however, affected the oil and protein quantity and quality of seed negatively. Antioxidant enzymes exhibited a decline in their activity during aging while the LOX activity, which reflects the rate of lipid peroxidation, in general, increased during the aging. Gamma irradiated (3 and 5 kGy) and magnetic field treated seeds (100 and 200 mT) maintained a higher catalase and ascorbate peroxidase activity which may help in efficient scavenging of deleterious free radical produced during the aging. Aging caused peroxidative changes to lipids, which could be contributed to the loss of oil quality. Among the electromagnetic energy treatments, a dose of 1-5 kGy of gamma and 100 mT, 200 mT magnetic field effectively slowed the rate of biochemical degradation and loss of cellular integrity in seeds stored under conditions of accelerated aging and thus, protected the deterioration of seed quality. Energy combination treatments did not yield any additional protection advantage.