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Radiation exposure of barley seeds can modify the early stages of plants' development
Abstract
The reactions of barley seeds (Nur and Grace varieties) in terms of the root and sprout lengths, germination
and root mass were studied after g-irradiation with doses in the range of 2e50 Gy. The dose range
in which plants' growth stimulation occurs (16e20 Gy) was identified. It was shown that increased size
of seedlings after irradiation with stimulating doses was due to the enhancing pace of development
rather than an earlier germination. The activity of the majority of the enzymes studied increased in the
range of doses that cause stimulation of seedlings development. The influences of the dose rate, the
quality of seeds, their moisture and time interval between irradiation and initiation of germination on
the manifestation of the effects of radiation were investigated. The experimental data on the effect of girradiation
on seedlings development were significantly better explained by mathematical models that
take into account the hormetic effect.
... Under specific and controlled conditions, it was shown that ionizing radiation (IR), such as gamma rays, can trigger positive growth effects on plants after the exposure of seeds to low doses of IR (Jan, Parween, Siddiqi, & Mahmooduzzafar., 2012). On crop species, positive effects of the pre-sowing seed radiation treatment include an increase in biomass, accelerated growth and development, stimulated immunity, and increased resistance to stresses of various nature (Geras'kin, Churyukin, & Volkova, 2017;Tang & Loke, 2015). High doses of IR are, however, extremely harmful or even lethal for living organisms. ...
... Some of the phenotypic consequences of pre-sowing seed irradiation fall into the eustress conception, including increased root and shoot sizes (Geras'kin et al., 2017;Jan et al., 2012), increased germination rate, and acceleration of the early plant ontogeny stages, which shortens the harvesting time and, ultimately, leads to an increase in the yield of cereals and other crops by 5%-20% (Jan et al., 2012). However, the molecular background of such changes and its correlation with phenotypic traits is only started to be unravelled. ...
... The microarray analysis was performed with seeds harvested in 2016, while the quantitative real-time PCR (qRT-PCR) and hydrogen peroxide assay were carried out using seeds harvested in 2017. The optimal conditions for gamma irradiation of barley seeds for induction of the stimulatory effect (10-20 Gy at 60 Gy/hr) have been previously established by our group (Geras'kin et al., 2017). Working on eustress effects, we revealed the necessity to make morphological assessments on the each new harvest of the same cultivar due to modifications of irradiation effect by weather conditions during the year of harvest, which apparently influence the state of barley endosperm. ...
At low intensity, certain stress conditions may have a positive effect on growth and development of plants (eustress). Growth stimulation of barley plants after gamma irradiation of seeds in low doses was observed as an increase in root and shoot lengths. Hydrogen peroxide concentrations in shoots of irradiated plants were significantly higher than in control, while the opposite effect was observed in the roots. To elucidate the molecular basis of growth stimulation after gamma irradiation of barley seeds, we performed the transcriptomic analysis of barley embryos at different stages of seed germination. The transcriptomic data were correlated with morphological parameters and the hydrogen peroxide levels in irradiated and control plants. These data indicate that the growth stimulation by low‐dose irradiation involves the transcriptional control of genes related to phytohormones, antioxidant system, late embryogenesis abundant proteins and cell wall components, with possible involvement of jasmonate and ABA signalling. Gamma irradiation of seeds at dose 100 Gy caused significant growth inhibition and promoted expression changes in transcripts related to cell cycle arrest, DNA damage repair and antioxidant system.
... В наших исследованиях (11,12) была проанализирована реакция разных сортов ячменя на γ-облучение семян в дозах 2-50 Гр и оценен диапазон, в котором наблюдается стимуляция развития растений на ранних этапах онтогенеза (10-20 Гр). Было показано (4,12), что активность ряда ферментов, вовлеченных в метаболизм и антиоксидантную защиту в клетках, увеличивается в диапазоне доз [16][17][18][19][20] Гр, стимулирующих развитие проростков. ...
... В наших исследованиях (11,12) была проанализирована реакция разных сортов ячменя на γ-облучение семян в дозах 2-50 Гр и оценен диапазон, в котором наблюдается стимуляция развития растений на ранних этапах онтогенеза (10-20 Гр). Было показано (4,12), что активность ряда ферментов, вовлеченных в метаболизм и антиоксидантную защиту в клетках, увеличивается в диапазоне доз [16][17][18][19][20] Гр, стимулирующих развитие проростков. В этой связи возникает вопрос: как полученное на ранних этапах онтогенеза преимущество реализуется в ходе дальнейшего развития растений и формирования урожая? ...
... Объектом исследования служил яровой ячмень (Hordeum vulgare L.) сорта Нур (1-я репродукция). Семена облучали на γ-установке ГУР (Россия) 120 ( 60 Co) в установленном ранее (11,12) диапазоне стимулирующих доз -16-20, а также дозами 8 и 50 Гр, мощность дозы 60 Гр/ч. Влажность семян (≈ 14 %) соответствовала ГОСТу 12041-82 (13). ...
... В наших исследованиях (11,12) была проанализирована реакция разных сортов ячменя на γ-облучение семян в дозах 2-50 Гр и оценен диапазон, в котором наблюдается стимуляция развития растений на ранних этапах онтогенеза (10-20 Гр). Было показано (4,12), что активность ряда ферментов, вовлеченных в метаболизм и антиоксидантную защиту в клетках, увеличивается в диапазоне доз [16][17][18][19][20] Гр, стимулирующих развитие проростков. ...
... В наших исследованиях (11,12) была проанализирована реакция разных сортов ячменя на γ-облучение семян в дозах 2-50 Гр и оценен диапазон, в котором наблюдается стимуляция развития растений на ранних этапах онтогенеза (10-20 Гр). Было показано (4,12), что активность ряда ферментов, вовлеченных в метаболизм и антиоксидантную защиту в клетках, увеличивается в диапазоне доз [16][17][18][19][20] Гр, стимулирующих развитие проростков. В этой связи возникает вопрос: как полученное на ранних этапах онтогенеза преимущество реализуется в ходе дальнейшего развития растений и формирования урожая? ...
... Объектом исследования служил яровой ячмень (Hordeum vulgare L.) сорта Нур (1-я репродукция). Семена облучали на γ-установке ГУР (Россия) 120 ( 60 Co) в установленном ранее (11,12) диапазоне стимулирующих доз -16-20, а также дозами 8 и 50 Гр, мощность дозы 60 Гр/ч. Влажность семян (≈ 14 %) соответствовала ГОСТу 12041-82 (13). ...
Identification of mechanisms of adaptive response to weak external exposure is one of the most complex and urgent problems of the modern biology. Such reactions include the effect of hormesis which is the stimulating effect of moderate doses of stressors (e.g. the low doses of various physical and chemical agents) repeatedly confirmed at all levels of the organization of living matter. The dynamics of the growth and development of barley (Hordeum vulgare L.) plants, grown from γ- irradiated barley seeds of Nur variety, which combines high productivity potential (up to 80 c/ha), resistance to drought, good forage and brewing qualities of grain, high resistance to lodging and serious diseases, was studied in a field trial. It was shown that irradiation of seeds significantly influenced the development of plants throughout the vegetative period. The duration of the initial stages of ontogenesis was shortened, and the phase of full ripeness came on 5-7 days earlier than in the control. The length of the stems, the weight of 1000 grains, the number of grains per ear, the number of productive stems, the weight of straw and ears increased. The dependence of economically valuable traits on the dose of γ-irradiation of seeds was statistically significantly better described by models that take into account the effect of hormesis. The manifestation of the effect of presowing γ-irradiation was different in the years with contrasting weather conditions. In the dry year of 2014, the increase in yield was determined by the increase in the number of productive stems, and under optimal conditions in 2015, this was due to the increase in the number of grains per ear. In 2016, an increase in the amount of precipitation by 2.5 times relative to the climatic norm leveled the stimulating effects. The results obtained in this study indicate that presowing ?γ irradiation of seeds notably affects the development of barley plants throughout the growing season, significantly changing the structure of the crop. In the plants from the seeds irradiated at stimulating doses, the manifestation of economically valuable traits was statistically significantly increased when vegetation seasons were contrasting in weather conditions. Realization of the effect of hormesis specifically depends on the conditions in which the plants developed. © 1997. The American Astronomical Society. All rights reserved.
... Barley as a model object of research is widely used in radiobiology [28][29][30][31]. This species has been selected by the International Commission on Radiological Protection as one of references in the "wild grasses" group to assess the impact of chronic ionizing radiation on terrestrial ecosystems [32]. ...
... The radioresistance of barley lines was assessed under laboratory conditions. Irradiation doses for mature and dormant seeds were chosen according to LD 50 of various barley cultivars [12,14,15], excluding the range of low doses (up to 20 Gy), at which hormesis can take place [28]. Irradiation of air-dried seeds was carried out on a γ-installation of the "Researcher" type with a 137 Cs source at a dose rate of 0.74 R/min and doses of 50, 100, or 200 Gy (Department of Radioecology, federal research center of the Institute of Biology of Komi Science Centre (IB KSC), the Ural Branch of the Russian Academy of Sciences (UB RAS) (Syktyvkar, Russia). ...
The genes NUD and WIN1 play a regulatory role in cuticle organization in barley. A knockout (KO) of each gene may alter plant mechanisms of adaptation to adverse environmental conditions. A putative pleiotropic effect of NUD or WIN1 gene mutations in barley can be assessed in a series of experiments in the presence or absence of a provoking factor. Ionizing radiation is widely used in research as a provoking factor for quantifying adaptive potential of living organisms. Our aim was to evaluate initial stages of growth and development of barley lines with a KO of NUD or WIN1 under radiation stress. Air-dried barley grains with different KOs and wild-type control (WT) were exposed to γ-radiation at 50, 100, or 200 Gy at a dose rate of 0.74 R/min. Approximately 30 physiological parameters were evaluated, combined into groups: (1) viability, (2) radiosensitivity, and (3) mutability of barley seed progeny. Seed germination, seedling survival, and shoot length were similar among all barley lines. Naked nud KO lines showed lower weights of seeds, roots, and seedlings and shorter root length as compared to win1 KO lines. The shoot-to-root length ratio of nud KO lines’ seedlings exceeded that of win1 KO and WT lines. In terms of the number of seedlings with leaves, all the KO lines were more sensitive to pre-sowing γ-irradiation. Meanwhile, the radioresistance of nud KO lines (50% growth reduction dose [RD50] = 318–356 Gy) and WT plants (RD50 = 414 Gy) judging by seedling weight was higher than that of win1 KO lines (RD50 = 201–300 Gy). Resistance of nud KO lines to radiation was also demonstrated by means of root length (RD50 = 202–254 Gy) and the shoot-to-root length ratio. WT seedlings had the fewest morphological anomalies. In nud KO lines, mainly alterations of root shape were found, whereas in win1 KO lines, changes in the color and shape of leaves were noted. Thus, seedlings of nud KO lines are characterized mainly by changes in the root system (root length, root number, and root anomalies). For win1 KO lines, other parameters are sensitive (shoot length and alterations of leaf shape and color). These data may indicate a pleiotropic effect of genes NUD and WIN1 in barley.
... In a series of experiments on the spring barley cultivar Nur, we demonstrated that irradiation of barley seeds in the dose range of 15-20 Gy induced growth stimulation in seedlings [10], transcriptional changes in embryos several hours after seed irradiation and forward developmental shift of irradiated plants [5], as well as metabolomic rearrangements, including nitrogen redistribution between shoots and roots [6]. These experiments were conducted using the first reproduction of the Nur cultivar after certified seeds, and findings of those studies require confirmation on a certified genetically homogenous seeds of different cultivars, considering high variability of the stimulating effect depending on the year of harvest and reproduction of a cultivar [5]. ...
... Seeds were irradiated using γ-facility "GUR-120" ( 60 Co) at the Russian Institute of Radiology and Agroecology (Obninsk, Russia). Seeds were placed in plastic envelops (approximately 1000 seeds per envelope) and irradiated at the dose of 20 Gy (dose rate 60 Gy/h [10]). The relative humidity of seeds was 16-18%, and the treatment was performed at room temperature (20-22 • C). ...
Gamma (γ)-irradiation of plants at low doses can provoke a broad range of growth-stimulating effects. In order to reveal universal target genes that are involved in molecular pathways of radiation hormesis establishment, we studied nine barley cultivars for their tolerance to γ-irradiation of seeds. Four morphological traits were assessed in barley seedlings after γ-irradiation of seeds at 20 Gy. Nine cultivars were sorted according to the sensitivity to irradiation as γ-stimulated, "no morphological effect", or γ-inhibited. Gene expression of 17 candidate genes was evaluated for the 7 most contrasting cultivars. Changes in expression of barley homologues of PM19L and CML31 were suggested as possible determinants of radiation hormesis effect. The possible role of jasmonate signaling in roots in radiation growth stimulations was revealed. Morphological analysis and gene expression study showed that the genetic background of a cultivar plays an important role in eustress responses to low-dose γ-irradiation of seeds.
... 7 Such favorable responses, depending on the conditions, include an increase in linear sizes of plant organs and biomass, stimulation of germination, and acceleration of development. 5,6,[8][9][10] Hormetic effects in plant species seem to depend on the induction of general adaptive response to moderate stress conditions, 11 which includes chaperons and proteasomes activation and general response of antioxidant, repair, and hormonal systems. 12,13 Seedlings play a pivotal role in the life cycle of plants, forming the bridge between the heterotrophic embryo and the established photoautotrophic plant, 14 and their successful development under unfavorable conditions is critical for the effective crop production. ...
... Several experiments on this cultivar showed the induction of growth stimulation in a certain dose range. 10,15 The analyses were performed using seeds harvested in 2017. g-Irradiation of dry barley seeds was conducted using doses 5, 10, 15, 20, and 100 Gy (dose rate 60 Gy/h) at the Russian Institute of Radiology and Agroecology on a g-facility GUR-120 ( 60 Co). ...
The favorable responses of crop species to low-dose γ irradiation can help to develop cultivars with increased productivity and improved stress tolerance. In the present study, we tried to reveal the candidate metabolites involved in growth stimulation of barley seedlings after applying low-dose γ-radiation ( ⁶⁰ Co) to seeds. Stimulating doses (5-20 Gy) provided a significant increase in shoot length and biomass, while relatively high dose of 100 Gy led to significant inhibition of growth. Gas chromatography–mass spectrometry metabolomic analysis uncovered several compounds that may take part in radiation hormesis establishment in irradiated plants. This includes molecules involved in nitrogen redistribution (arginine, glutamine, asparagine, and γ-aminobutyric acid) and stress-responsive metabolites, such as ascorbate, myo-inositol and its derivates, and free amino acids (l-serine, β-alanine, pipecolate, and GABA). These results contribute to the understanding of the molecular mechanisms of hormesis phenomenon.
... Typically, radiation hormesis in plants has a positive effect, resulting in increased germination, growth rate, height, weight, pigment content, flowering, fertility, accelerated development, and increased radiation resistance. The degree of hormesis depends on the genetic characteristics of the seeds or plant, moisture of the seeds, type of low-dose radiation, and duration of irradiation [224,225]. The adaptive response triggered by hormesis includes both short-term mechanisms, such as the use of existing proteins, and long-term mechanisms, such as the expression of genes encoding specific enzyme systems. ...
The purpose of this review is to critically evaluate the effects of different stress factors on higher plants, with particular attention given to the typical and unique dose-dependent responses that are essential for plant growth and development. Specifically, this review highlights the impact of stress on genome instability, including DNA damage and the molecular, physiological, and biochemical mechanisms that generate these effects. We provide an overview of the current understanding of predictable and unique dose-dependent trends in plant survival when exposed to low or high doses of stress. Understanding both the negative and positive impacts of stress responses, including genome instability, can provide insights into how plants react to different levels of stress, yielding more accurate predictions of their behavior in the natural environment. Applying the acquired knowledge can lead to improved crop productivity and potential development of more resilient plant varieties, ensuring a sustainable food source for the rapidly growing global population.
... Various growth promoting hormones reported to be elevated significantly in the gamma radiated treatment of plant material. It has be reported by Geras'kin et al., (2017) that gamma rays at low doses effectively enhanced the Glucose-6-phosphate dehydrogenase and pyruvate kinase level in barley treated seeds which automatically leads to the larger respiration and larger energy production water splitting activity represented by J-I fluorescence phase whereas OJ phase from OJIP induction curves represent the reduction of primary electron acceptors of PSII such as NADPH production indicator is IP phase. So, highest IP leads to the highest NADPH production. ...
... In Lathyrus chrysanthus Boiss, a low dose of γ-rays (50 Gy at 0.8 kGy/h) stimulated an increased germination percentage, seedling and root lengths, fresh weight, dry matter content, and total chlorophyll content of the seedlings [36]. Additionally, in barley, 16-20 Gy γ-rays enhanced the contents of glucose-6-phosphate dehydrogenase, pyruvate kinase, and guaiacol peroxidase activity, which induced the accelerating pace of the seedling's development [43]. With the optimization of the development parameters by 150 Gy γ-rays, the grain yield for Zea mays and Arachis hypogaea was markedly increased [69]. ...
To overcome various factors that limit crop production and to meet the growing demand for food by the increasing world population. Seed priming technology has been proposed, and it is considered to be a promising strategy for agricultural sciences and food technology. This technology helps to curtail the germination time, increase the seed vigor, improve the seedling establishment, and enhance the stress tolerance, all of which are conducive to improving the crop yield. Meanwhile, it can be used to reduce seed infection for better physiological or phytosanitary quality. Compared to conventional methods, such as the use of water or chemical-based agents, X-rays, gamma rays, electron beams, proton beams, and heavy ion beams have emerged as promising physics strategies for seed priming as they are time-saving, more effective, environmentally friendly, and there is a greater certainty for yield improvement. Ionizing radiation (IR) has certain biological advantages over other seed priming methods since it generates charged ions while penetrating through the target organisms, and it has enough energy to cause biological effects. However, before the wide utilization of ionizing priming methods in agriculture, extensive research is needed to explore their effects on seed priming and to focus on the underlying mechanism of them. Overall, this review aims to highlight the current understanding of ionizing priming methods and their applicability for promoting agroecological resilience and meeting the challenges of food crises nowadays.
... One of the methods of increasing yield in modern, sustainable agriculture is the enhancement of germination rate and the improvement of vigour of seedlings. There are various methods of the pre-treatment of seeds to stimulate germination and seedlings growth, including thermal treatment [1], seed priming [2], seed coating [3], nonthermal plasma treatment [4], laser irradiation [5], or gamma irradiation [6]. One of promising techniques is the exposure of seeds to an electromagnetic field (EMF) or magnetic field (MF). ...
In the experiment, the impact of magnetisation on cucumber seeds is examined with the use of Bitter magnets with a constant magnetic field. The magnetisation process is performed in three magnetic fields: low—200 mT, medium—1 T, and high—9 T for 15 and 60 min. After germination, the biometric parameters are determined. The results of this research show that cucumber after pre-treatment in a magnetic field of 1 T for 60 min has a similar germination capacity and root length as the control sample. However, cucumber seeds magnetised in a 1 T field for 60 min have a significantly higher dry weight than the control sample (5.50 ± 0.32 mg vs. 3.01 ± 0.18 mg). The magnetisation in 9 T for both 15 and 60 min shows that these samples have a significantly lower germination capacity (86.8 ± 4.4% and 81.4 ± 7.3% vs. 91.8 a ± 3.2%) and root length (1.78 ± 0.02 cm and 4.42 ± 0.83 cm vs. 8.21 ± 0.34 cm) compared to the control sample. The cucumber seeds pre-treated at 9 T have a significantly greater dry weight than the control sample. Additionally, our research shows that some magnetic field intensities and magnetisation durations inhibit root growth and limit germination. These results are also important as they indicate which values of magnetic fields should be avoided.
... The choice of this time range is based on the fact that the radiation-induced boost in cell division and seedling growth seems to be limited to a short time frame (about 6-7 days) after irradiation (Gudkov, 1991). The assessment of enzyme activities was carried out according to protocols detailed in Geras'kin et al. (2017). ...
... The choice of this time range is based on the fact that the radiation-induced boost in cell division and seedling growth seems to be limited to a short time frame (about 6-7 days) after irradiation (Gudkov, 1991). The assessment of enzyme activities was carried out according to protocols detailed in Geras'kin et al. (2017). ...
The main goals of this study were to evaluate the agronomic performance of wheat mutant lines; to detect the effect of genotype, location and different fertilizer levels on analysed traits; to assess seed and feed quality; and to select best performing mutant lines for dual-purpose growing. Ten wheat mutant lines were sown on two loca�tions in Macedonia, for evaluation of their agronomic performance. At both locations, grain yield, straw mass, harvest index, nitrogen use efficiency, nitrogen and protein content in seed and straw, neutral detergent fibre and acid detergent fibre in the straw were determined. In order to classify the genotypes based on all analysed traits, two-way cluster analysis was applied. According to their overall performance, at both locations and with the three different fertilization treatments, the mutant lines were classified in two main groups. The first cluster con�sisted of mutants 5/1-8, 2/2-21, 4/2-56 and 2/1-51, characterized by very high values for seed yield, straw yield and harvest index, and high to moderate values for all other traits. Only 4/2-56 had very low values for N and protein content in the seed. One mutant line, 6/2-2, did not belong to any of the groups and differed from all other genotypes based on its very low seed and straw yield and very high values for nitrogen and protein content in the straw and neutral detergent fibre. All other mutants belonged to the second group, with low to moderate yield and moderate to high values for the other traits. Mutant lines with the highest seed and straw yield, as well as the best quality of seed and straw under different management systems, were identified and after additional evalu�ation will be submitted for official variety registration.
... The choice of this time range is based on the fact that the radiation-induced boost in cell division and seedling growth seems to be limited to a short time frame (about 6-7 days) after irradiation (Gudkov, 1991). The assessment of enzyme activities was carried out according to protocols detailed in Geras'kin et al. (2017). ...
This book presents reviews on the application of the technology for crop improvement towards food and nutrition security, and research status on mutation breeding and associated biotechnologies in both seed crops and vegetatively propagated crops. It also presents perspectives on the significance of next-generation sequencing and bioinformatics in determining the molecular variants underlying mutations and on emerging biotechnologies such as gene editing. Reviews and articles are organized into five sections in the publication: (1) Contribution of Crop Mutant Varieties to Food Security; (2) Mutation Breeding in Crop Improvement and Climate-Change Adaptation; (3) Mutation Induction Techniques for Enhanced Genetic Variation; (4) Mutation Breeding in Vegetatively Propagated and Ornamental Crops; and (5) Induced Genetic Variation for Crop Improvement in the Genomic Era. The contents of this volume present excellent reference material for researchers, students and policy makers involved in the application of induced genetic variation in plants for the maintenance of biodiversity and the acceleration of crop adaptation to climate change to feed a growing global population in the coming years and decades.
... The choice of this time range is based on the fact that the radiation-induced boost in cell division and seedling growth seems to be limited to a short time frame (about 6-7 days) after irradiation (Gudkov, 1991). The assessment of enzyme activities was carried out according to protocols detailed in Geras'kin et al. (2017). ...
This book presents reviews on the application of the technology for crop improvement towards food and nutrition security, and research status on mutation breeding and associated biotechnologies in both seed crops and vegetatively propagated crops. It also presents perspectives on the significance of next-generation sequencing and bioinformatics in determining the molecular variants underlying mutations and on emerging biotechnologies such as gene editing. Reviews and articles are organized into five sections in the publication: (1) Contribution of Crop Mutant Varieties to Food Security; (2) Mutation Breeding in Crop Improvement and Climate-Change Adaptation; (3) Mutation Induction Techniques for Enhanced Genetic Variation; (4) Mutation Breeding in Vegetatively Propagated and Ornamental Crops; and (5) Induced Genetic Variation for Crop Improvement in the Genomic Era. The contents of this volume present excellent reference material for researchers, students and policy makers involved in the application of induced genetic variation in plants for the maintenance of biodiversity and the acceleration of crop adaptation to climate change to feed a growing global population in the coming years and decades.
... The development of "omic" technologies led to a breakthrough in the search for determinants of stress tolerance in plants [11]. Our group studied the hormesis effect after γ-irradiation of barley seeds on biochemical [12], transcriptomic [5], and metabolomic [2] levels. Several metabolites possibly related to the radiation stimulation effect have been established based on the transcriptional activity of genes in embryos of γ-irradiated barley seeds and on metabolic profiles of the roots and shoots of seedlings [2,5]. ...
Low-dose γ-irradiation can stimulate plant growth and development; however, the knowledge on the molecular mechanisms of such stimulation is yet fragmented. Irradiation of seeds leads to the mobilisation of endosperm resources and reallocation of available nitrogen to facilitate development. Based on the metabolomic analysis, several metabolites possibly involved in radiation stimulation were studied using the HPLC approach in barley cultivars after γ-irradiation of seeds. The comparison of changes in metabolite concentrations and changes in morphological traits after irradiation revealed seven metabolites that may be involved in the growth stimulation after γ-irradiation of barley seeds. Among them are free amino acids, such as γ-aminobutyric acid, β-alanine, arginine, lysine, glutamine, methionine, and a signalling compound methylglyoxal.
... Wang, Ma, Cao, Shan, & Jiao [23] en su estudio con la variedad de cebada de altura "Kunlun 15", irradiadas a diferentes dosis de rayos gamma (testigo, 50, 100, 150, 200, 250 y 300 Gy), indica que a medida que incrementa la dosis de irradiación disminuye la altura en plántula (testigo 14.3 cm; 300 Gy 7 cm), similares a los datos obtenidos en este estudio con la variedad INIAP Cañicapa (testigo 14.5 cm; 250 Gy 8.6 cm) [23]. Varias investigaciones mencionan que la variación en altura no solamente puede presentarse en una disminución del tamaño, sino también puede darse un incremento del crecimiento comparado con el testigo [20,21,24,25]. ...
La cebada es un cultivo de importancia económica, social y alimentaria en la Sierra ecuatoriana. Es el segundo cereal más cultivado en Ecuador y el cuarto a nivel mundial. La inducción de mutaciones es una técnica de mejoramiento que permite generar variabilidad genética; es por ello, que el INIAP está empleado esta técnica en el cultivo de cebada en busca de germoplasma con características deseables. El objetivo principal de esta investigación fue determinar la dosimetría y dosis letal media de irradiación para inducir mutaciones en variedades de cebada, usando para ello cinco dosis de rayos gamma (0, 100, 150, 200 y 250 Gy). Los parámetros evaluados fueron: germinación (en invernadero); emergencia, altura de plántula y vigor (en campo). Los resultados mostraron que las variedades respondieron de diferente forma en las distintas dosis empleadas, sin embargo, fue evidente que a medida que la dosis aumentaba, la emergencia, altura de plántula y vigor, se afectaban y mermaban. Se determinó que la dosis letal media se encuentra entre los 150 y 200 Gy. Sin embargo, la dosis que produjo ligeros cambios morfológicos en los materiales y que se la considera como la dosis optima es la de 150 Gy.
... Однако в работе S.A. Geras'kin и соавт. [16] кратковременное облучение семян ячменя разными мощностями доз и, следовательно, разной длительностью, приводило к разным эффектам роста корней, несмотря на одинаковую поглощенную дозу (10-20 Гр). ...
... Well-established quantitative data about developmental stages is fundamental to studies involving DNA level responses [25] and phenotypic responses [50] to gamma radiation [21]. Gamma irradiation affects the early developmental stage of barley [51] and the growth rate of offspring from wild carrots [52]. These studies suggest that growth patterns and of dosage effects can be compared if continuous phenotyping data for irradiated plants is available. ...
The effects of radiation dosages on plant species are quantitatively presented as the lethal dose or the dose required for growth reduction in mutation breeding. However, lethal dose and growth reduction fail to provide dynamic growth behavior information such as growth rate after irradiation. Irradiated seeds of Arabidopsis were grown in an environmentally controlled high-throughput phenotyping (HTP) platform to capture growth images that were analyzed with machine learning algorithms. Analysis of digital phenotyping data revealed unique growth patterns following treatments below LD50 value at 641 Gy. Plants treated with 100-Gy gamma irradiation showed almost identical growth pattern compared with wild type; the hormesis effect was observed >21 days after sowing. In 200 Gy-treated plants, a uniform growth pattern but smaller rosette areas than the wild type were seen (p < 0.05). The shift between vegetative and reproductive stages was not retarded by irradiation at 200 and 300 Gy although growth inhibition was detected under the same irradiation dose. Results were validated using 200 and 300 Gy doses with HTP in a separate study. To our knowledge, this is the first study to apply a HTP platform to measure and analyze the dosage effect of radiation in plants. The method enabled an in-depth analysis of growth patterns, which could not be detected previously due to a lack of time-series data. This information will improve our knowledge about the effects of radiation in model plant species and crops.
... These findings have revealed that the models counting hormesis explained the H. vulgare data significantly better than the dose-response one. Several authors reported the hormesis phenomenon for plants developing on the presence of metals (Baderna et al. 2015;Calabrese & Blain 2009;Hagner et al. 2018;Wang et al. 2010) or other substances (Geras'kin et al. 2017). Moreover, Martínez-Moreno et al. (2017) reported that the barley varieties contain genes for tolerance and resistance to abiotic and biotic stresses. ...
In this work three heavy metals: cadmium (as CdSO 4 ), cobalt (as CoCl 2 ) and zinc (as ZnSO 4 ), were used to determine and compare their toxicity towards two subspecies of barley ( Hordeum vulgare subsp. vulgare L. and Hordeum vulgare subsp. distichum L.), focusing on seeds germination, seedlings growth, and cytological parameters. The results indicate that the effect of these heavy metals depends on the metal kind, the metal concentrations and the plant subspecies. Generally, in the case of H. vulgare , the heavy metal salts understudy did not influence significantly seed germination and seedling growth parameters. However, these metal salts influence significantly these parameters for H. distichum . The cytological test showed significant decrease ( p < 0.05) in the mitotic index among the increase of the heavy metal concentrations when evaluated with the control for H. vulgare and H. distichum . Consequently, H. vulgare seemed to be more tolerant of the increase of the three heavy metals concentrations than H. distichum .
... Melki and Sallami (2008) showed that seed treatment with low doses of gamma rays significantly elongated the root system in chickpea plants. Geras'kin et al. (2017) exposed barley seeds to gamma radiation (2-50 Gy); maximum growth stimulation occurred at 2-16 Gy due to the higher enzyme activation at these levels. ...
Seed priming is a pre-sowing technique in which seeds are moderately hydrated to the point where pre-germination metabolic processes begin without actual germination. Seeds are then re-dried to near their actual weight for normal handling. Seeds can be soaked in tap water (hydropriming), aerated low water potential solutions of polyethylene glycol or salt solutions (KNO3, KH2PO4, KCl, NaCl, CaCl2 or MgSO4; osmopriming), plant growth regulators, polyamines (hormonal priming), plant growth promoting bacteria (biopriming), macro-micronutrients (nutripriming) or some plant-based natural extracts. Here, we review that (i) seed priming is a simple and effective approach for improving stand establishment, economic yields and tolerance to biotic and abiotic stresses in various crops by inducing a series of biochemical, physiological, molecular and subcellular changes in plants; (ii) seed priming tends to reduce the longevity of high vigour seeds and improve the longevity of low vigour seeds; (iii) physical methods of seed priming to enhance plant production have advantages over conventional methods based on the application of different chemical substances; (iv) of the various available physical methods, magneto-priming and ionising radiation including gamma rays (γ-rays), ultraviolet rays (UVA, UVC) and X-rays are the most promising pre-sowing seed treatments for improving crop productivity under stressful conditions; (v) seed priming techniques are effective for micronutrient delivery at planting in field crops. Seed priming as cost-effective approach is being practiced in different crops and countires to improve the yield, as complementary strategy to grain biofortification and genetically improved crop varieties to enhance their performance under stress condition including submergence and low phosphorus conditions. Longevity of seed after conventional priming types under ambient storage conditions, studies on heremtic packaging materials for extended storage period and of physical priming types are some of challenges for for wide-scale commercial adaption of seed priming.
In plants, radiation hormesis phenomenon occurs as enhanced growth, accelerated development, increased tolerance to stressors, or accumulation of compounds of interest in response to low-dose irradiation. This review summarizes the recent findings regarding radiation hormesis in plants in response to ionising or UV-radiation. While molecular mechanisms of UV-hormesis are clearer and involve sensing of UV-radiation by the specific photoreceptors, the precise molecular events underlying hormetic responses to ionising radiation are yet to be uncovered. Based on the available information, the scheme of possible pathways triggering radiation stimulation response in cells is discussed. It is argued that beneficial responses to low-dose ionising radiation may depend on the optimization of hydrogen peroxide (H2O2) levels and the interplay between the signalling pathways of reactive oxygen species (ROS) and phytohormones.
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) incessantly produced as by-products of metabolism play significant roles in seed physiology. ROS (hydroxyl, superoxide radical and hydrogen peroxide) and RNS (nitric oxide, nitric dioxide, nitrous acid and dinitrogen tetroxide) content changes in all phases of seed life cycle that influence seed germination, dormancy and longevity. Recent studies illustrate that ROS and RNS are performing oxidative and nitrosative signaling to induce seed germination within oxidative window level. Besides, ROS/RNS-mediated post-translational modifications (PTM) like carbonylation, S-nitrosylation and nitration are gaining interest in promoting seed germination. Understanding the signalling pathways, cross-talk with plant
hormones and their role in promoting seed germination and dormancy alleviation could pave way for hormone engineering that help in crop productivity, particularly under climatic changing conditions. In addition, role of antioxidants and glutathione thiols in protecting from oxidative damage indicate that these compounds can be used for seed viability/quality markers that aid in monitoring of crop establishment. In this review, sources of ROS and RNS, their cross-talk with plant hormones (prospects for hormone engineering), signalling functions pertaining to seed germination, dormancy and deterioration have been illustrated. In addition, seed quality markers under climatic changing conditions for effective monitoring of crop stand establishment and diagnostics development have been elucidated.
Purpose
The purpose of this study was to assess the long-term effects of gamma-radiation, including low-dose radiation, on growth parameters of onion (Allium cepa) seedling roots 6–10 days after irradiation.
Materials and methods
Onion seedlings were exposed to a ¹³⁷Cs gamma source at doses ranging from 0.1 to 10 grays (Gy). Responses of root and shoot length growth were studied 6 and 10 days after irradiation.
Results
Our results showed inhibition of the root and shoot length growth 6 days after exposure at all doses, including the low dose − 0.1 Gy. At a later point in time (day 10), root and shoot inhibition was only observed after irradiation at high doses (above 5 Gy), and that suggested the occurrence of cell repair after irradiation at low doses. The results indicated that the length of seedling roots was more sensitive to gamma-irradiation than the shoot length.
Conclusion
The results of the study suggested that short-term gamma-irradiation of onion seedlings (absorbed doses of 0.1−10 Gy) caused inhibition of plant growth 6 and 10 days after irradiation. The dose dependence of the onion root length was linear. The present study showed for the first time that short-term low-dose gamma-irradiation could induce long-term negative effects on plant growth.
Barley is the main forage crop in the Russian Federation. Barley grain is also used for food and brewery (Filippov, 2013). It is common knowledge that low doses of gamma irradiation can have a stimulating effect on the growth and development of plants, in particular barley. However, there is a lack of knowledge about the molecular pathways responsible for the formation of the stimulation effect after low-dose seed irradiation. The use of varieties with different radio sensitivity to low-dose gamma irradiation will allow studying specific molecular mechanisms to form a stimulating irradiation effect. Such knowledge could further help in the development of varieties with a large stable productivity over the years and with high resistance to biotic and abiotic stressors. In 2019 there was conducted a gamma irradiation of the original seeds of nine winter and spring barley varieties developed in the FSBSI “Agricultural Research Center “Donskoy” in order to assess intensity of the response on low-dose ionizing irradiation based on changes in the morphological parameters of irradiated and unirradiated plants. The original seeds of each barley variety were irradiated at the FSBSI “All-Russian Research Institute of Radiology and Agroecology” by the gamma device “GUR-120” with 60Со radiation sources at a dose of 20 Gy (dose rate of 60 Gy/hour). The statistical data processing was performed by the Microsoft Office Excel 2019. The morphological analysis of the length and weight of roots and sprouts made it possible to establish the presence or absence of the stimulating irradiation effect on the studied indicators of the varieties and to conduct their subsequent ranking according to the value of the radiobiological effect. There have been identified the winter and spring barley varieties with different sensitivity to a dose of 20 Gy. The stimulating irradiation effect was established in such varieties as “Foks 1”, “Ratnik”, “Yerema” and “Master”. The variety “Leon” had an inhibitory irradiation effect.
Reactive oxygen species (ROS) are considered to be detrimental to seed viability. However, recent studies have demonstrated that ROS have key roles in seed germination particularly in the release of seed dormancy and embryogenesis, as well as in protection from pathogens.
This review considers the functions of ROS in seed physiology. ROS are present in all cells and at all phases of the seed life cycle. ROS accumulation is important in breaking seed dormancy, and stimulating seed germination and protection from pathogens. However, excessive ROS accumulation can be detrimental. Therefore, knowledge of the mechanisms by which ROS influence seed physiology will provide insights that may not only allow the development of seed quality markers but also help us understand how dormancy can be broken in several recalcitrant species.
Reactive oxygen species have a dual role in seed physiology. Understanding the relative importance of beneficial and detrimental effects of ROS provides great scope for the improvement and maintenance of seed vigour and quality, factors that may ultimately increase crop yields.
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The effect of Al stress on peroxidase activity and peroxidase isozymes was studied in roots of two barley cultivars with contrasting sensitivity to Al. Al treatment induced a tremendous enhancement of guaiacol peroxidase activity especially in roots of Al-sensitive barley cv. Alfor. After 48 h of Al treatment activity of peroxidase in roots of cv. Alfor was up to 5.5 times higher than the control roots. In contrast, activity of peroxidase in the roots of Al-resistant cv. Bavaria was about one half than that in roots of Al-sensitive Alfor. SDS-PAGE analysis revealed that at least five peroxidase isozymes are activated by Al treatment. Using IEF we determined that three of Al-induced peroxidase isozymes are cationic with pI about 8.2, 8.4 and 8.6, while two other are anionic isoperoxidases with pI about 4.0 and 4.5. Al induced increase in the activity of root peroxidases correlated with the extent of Al induced root growth inhibition. The inhibition of root growth in Al-sensitive Alfor represented 44% but in Al-resistant Bavaria only 21% in comparison with control plants. Higher peroxidase activity, as well, as higher inhibition of root growth in Al-sensitive Alfor suggest that enhanced oxidative stress generated by Al treatment is significantly more stressful in Alfor than in the Al-resistant Bavaria.
Purposes:
To review research progress on the molecular mechanisms of low dose ionizing radiation (LDIR)-induced hormesis, adaptive responses, radioresistance, bystander effects, and genomic instability in order to provide clues for therapeutic approaches to enhance biopositive effects (defined as radiation-induced beneficial effects to the organism), and control bionegative effects (defined as radiation-induced harmful effects to the organism) and related human diseases.
Conclusions:
Experimental studies have indicated that Ataxia telangiectasia-mutated (ATM), extracellular signal-related kinase (ERK), mitogen-activated protein kinase (MAPK), phospho-c-Jun NH(2)-terminal kinase (JNK) and protein 53 (P53)-related signal transduction pathways may be involved in LDIR-induced hormesis; MAPK, P53 may be important for adaptive response; ATM, cyclooxygenase-2 (COX-2), ERK, JNK, reactive oxygen species (ROS), P53 for radioresistance; COX-2, ERK, MAPK, ROS, tumor necrosis factor receptor alpha (TNFα) for LDIR-induced bystander effect; whereas ATM, ERK, MAPK, P53, ROS, TNFα-related signal transduction pathways are involved in LDIR-induced genomic instability. These results suggest that different manifestations of LDIR-induced cellular responses may have different signal transduction pathways. On the other hand, LDIR-induced different responses may also share the same signal transduction pathways. For instance, P53 has been involved in LDIR-induced hormesis, adaptive response, radioresistance and genomic instability. Current data therefore suggest that caution should be taken when designing therapeutic approaches using LDIR to induce beneficial effects in humans.
There are some reports that low doses of γ-irradiation could induce antioxidant activities in plant material, including soybean.
Irradiation, required for the inactivation of some pathogens and induction of mutations, may have adverse effects on sensorial,
nutritional and antioxidant qualities. The effects of different γ-irradiation doses (100–200 Gy) on antioxidant properties
of soybean seeds was investigated. In this study, we report the results obtained by analysis of antioxidant enzyme activities,
reduced glutathione, malonyldialdehyde (MDA) and hydroxyl (HO−) radical quantities, soluble protein content, and total antioxidant activity in irradiated soybean seeds. Antioxidant enzyme
activities were affected due to high irradiation intensity. Significant changes of total antioxidant activity and MDA and
HO.quantities were observed only under the highest irradiation dose, with a 15.7% reduction in total antioxidant activity,
MDA quantity increase of 21.6%, and HO− radical quantity increase of 79.3% compared to the non-irradiated control. The total soluble protein content increased slightly.
To characterize the stimulatory effects of low-dose gamma radiation on early plant growth, we investigated alterations in
the photosynthesis and antioxidant capacity of red pepper (Capsicum annuum L.) seedlings produced from gamma-irradiated seeds. For two cultivars (Yeomyung and Joheung), three irradiation groups (2,
4, and 8 Gy, but not 16 Gy) showed enhanced development, although Fv/Fm, the maximum photochemical efficiency of Photosystem
II (PSII), did not differ significantly among any of the four groups. In contrast, values for 1/Fo — 1/Fm, i.e., a measure
of functional PSII content, decreased in the irradiated groups of ‘Yeomyung’ but increased in those of ‘Joheung’. Pigment
analyses and enzyme activity assays revealed that irradiation altered the compositions of photosynthetic pigments (chlorophylls
and carotenoids) as well as the activities of antioxidant enzymes (superoxide dismutase and glutathione reductase). However,
these shifts were not directly related to the increase in early growth, although they were cultivar-and developmental stage-dependent
In addition, the effects of irradiation on the enzymatic activities measured here were at opposition between the two cultivars.
The effects of irradiation with low doses (0, 10, 20 and 30Gy) of radioactive cobalt (60Co) γ rays on seed germination, shoot and epicotyl growth of hard wheat (Triticum durum Desf.) were investigated under laboratory and glasshouse conditions. Irradiated wheat seeds kept their germination speed
and capacity levels compared to the control. However, improvements of +18 and +32% were, respectively obtained in root number
and root length at the 20-Gy dose. Moreover, the 20-Gy-irradiation dose generated an increase of +33% in epicotyl length.
The 20-Gy-irradiation dose improved the root length by +32% and root number by +75% in plants grown on liquid medium. A lower
root length increase of +23% was obtained with the same treatment under glasshouse growing conditions. These results show
that the in depth development stimulation of hard wheat roots following gamma ray treatment may be used for drought control.
KeywordsRadio stimulation-Epicotyls-Seedling-Root length-Drought
We describe an add-on package for the language and environment R which allows simultaneous fitting of several non-linear regression models. The focus is on analysis of dose response curves, but the functionality is applicable to arbitrary non-linear regression models. Features of the package is illustrated in examples.
The aromatic amino acids phenylalanine, tyrosine and tryptophan in plants are not only essential components of protein synthesis, but also serve as precursors for a wide range of secondary metabolites that are important for plant growth as well as for human nutrition and health. The aromatic amino acids are synthesized via the shikimate pathway followed by the branched aromatic amino acid metabolic pathway, with chorismate serving as a major branch point intermediate metabolite. Yet, the regulation of their synthesis is still far from being understood. So far, only three enzymes in this pathway, namely, chorismate mutase of phenylalanine and tyrosine synthesis, tryptophan synthase of tryptophan biosynthesis and arogenate dehydratase of phenylalanine biosynthesis, proved experimentally to be allosterically regulated. The major biosynthesis route of phenylalanine in plants occurs via arogenate. Yet, recent studies suggest that an alternative route of phynylalanine biosynthesis via phenylpyruvate may also exist in plants, similarly to many microorganisms. Several transcription factors regulating the expression of genes encoding enzymes of both the shikimate pathway and aromatic amino acid metabolism have also been recently identified in Arabidopsis and other plant species.
Research on the basic interaction of radiation with biological systems has contributed to human society through various applications in medicine, agriculture, pharmaceuticals and in other technological developments. In the agricultural sciences and food technology sectors, recent research has elucidated the new potential application of radiation for microbial decontamination due to the inhibitory effect of radiation on microbial infestation. The last few decades have witnessed a large number of pertinent works regarding the utilization of radiation with special interest in γ-rays for evolution of superior varieties of agricultural crops of economic importance. In this review, general information will be presented about radiation, such as plant specificity, dose response, beneficial effects, and lethality. A comparison of different studies has clarified how the effects observed after exposure were deeply influenced by several factors, some related to plant characteristics (e.g.; species, cultivar, stage of development, tissue architecture, and genome organization) and some related to radiation features (e.g.; quality, dose, duration of exposure). There are many beneficial uses of radiation that offer few risks when properly employed. In this review, we report the main results from studies on the effect of γ-irradiations on plants, focusing on metabolic alterations, modifications of growth and development, and changes in biochemical pathways especially physiological behaviour.
This paper evaluated the frequency, magnitude and dose/concentration range of hormesis in four species: The aquatic plant Lemna minor, the micro-alga Pseudokirchneriella subcapitata and the two terrestrial plants Tripleurospermum inodorum and Stellaria media exposed to nine herbicides and one fungicide and binary mixtures thereof. In total 687 dose-response curves were included in the database. The study showed that both the frequency and the magnitude of the hormetic response depended on the endpoint being measured. Dry weight at harvest showed a higher frequency and a larger hormetic response compared to relative growth rates. Evaluating hormesis for relative growth rates for all species showed that 25% to 76% of the curves for each species had treatments above 105% of the control. Fitting the data with a dose-response model including a parameter for hormesis showed that the average growth increase ranged from 9+/-1% to 16+/-16% of the control growth rate, while if measured on a dry weight basis the response increase was 38+/-13% and 43+/-23% for the two terrestrial species. Hormesis was found in >70% of the curves with the herbicides glyphosate and metsulfuron-methyl, and in >50% of the curves for acifluorfen and terbuthylazine. The concentration ranges of the hormetic part of the dose-response curves corresponded well with literature values.
The physiological dormancy of sunflower (Helianthus annuus) embryos can be overcome during dry storage (after-ripening) or by applying exogenous ethylene or hydrogen cyanide (HCN) during imbibition. The aim of this work was to provide a comprehensive model, based on oxidative signaling by reactive oxygen species (ROS), for explaining the cellular mode of action of HCN in dormancy alleviation. Beneficial HCN effect on germination of dormant embryos is associated with a marked increase in hydrogen peroxide and superoxide anion generation in the embryonic axes. It is mimicked by the ROS-generating compounds methylviologen and menadione but suppressed by ROS scavengers. This increase results from an inhibition of catalase and superoxide dismutase activities and also involves activation of NADPH oxidase. However, it is not related to lipid reserve degradation or gluconeogenesis and not associated with marked changes in the cellular redox status controlled by the glutathione/glutathione disulfide couple. The expression of genes related to ROS production (NADPHox, POX, AO1, and AO2) and signaling (MAPK6, Ser/ThrPK, CaM, and PTP) is differentially affected by dormancy alleviation either during after-ripening or by HCN treatment, and the effect of cyanide on gene expression is likely to be mediated by ROS. It is also demonstrated that HCN and ROS both activate similarly ERF1, a component of the ethylene signaling pathway. We propose that ROS play a key role in the control of sunflower seed germination and are second messengers of cyanide in seed dormancy release.
Reactive Oxygen Species (ROS) are continuously produced during seed development, from embryogenesis to germination, but also during seed storage. ROS play a dual role in seed physiology behaving, on the one hand, as actors of cellular signaling pathways and, on the other hand, as toxic products that accumulate under stress conditions. ROS, provided that their amount is tightly regulated by the balance between production and scavenging, appear now as being beneficial for germination, and in particular to act as a positive signal for seed dormancy release. Such an effect might result from the interplay between ROS and hormone signaling pathways thus leading to changes in gene expression or in cellular redox status. We also propose that changes in ROS homeostasis would play a role in perception of environmental factors by seeds during their germination, and thus act as a signal controlling the completion of germination. However, uncontrolled accumulation of ROS is likely to occur during seed aging or seed desiccation thus leading to oxidative damage toward a wide range of biomolecules and ultimately to necroses and cell death. We present here the concept of the "oxidative window for germination", which restricts the occurrence of the cellular events associated with germination to a critical range of ROS level, enclosed by lower and higher limits. Above or below the "oxidative window for germination", weak or high amounts of ROS, respectively, would not permit progress toward germination.
Changes in CuZn-SOD activity and content in isolated wheat chloroplasts under the light, and the involvement of protease(s) and/or active oxygen species in this process were studied. Both SOD activity and content decayed with exposure time to photooxidative stress. Ascorbate, a H2O2 scavenger, prevented photooxidation-associated inactivation of SOD, while benzoate, a .OH scavenger, prevented SOD degradation. Wheat chloroplasts incubated in the dark did not hydrolyze exogenous or endogenous SOD, either H2O2-pretreated or not. Protease inhibitors did not prevent SOD degradation under photooxidative treatment, suggesting that plastid protease(s) did not participate in this process. Purified chloroplast CuZn-SOD was exposed to H2O2 and O2- or .OH-generating systems. O2- had no effect on either SOD activity or stability (estimated by native PAGE). H2O2 up to 700 microM inhibited SOD in a dose-dependent manner and induced charge/mass changes as seen by native PAGE. .OH also reduced SOD activity by inducing its fragmentation. High levels of active oxygen, as can be generated under strong stress conditions, could directly inactivate and degrade chloroplastic SOD.
The regulation of water uptake of germinating tobacco (Nicotiana tabacum) seeds was studied spatially and temporally by in vivo (1)H-nuclear magnetic resonance (NMR) microimaging and (1)H-magic angle spinning NMR spectroscopy. These nondestructive state-of-the-art methods showed that water distribution in the water uptake phases II and III is inhomogeneous. The micropylar seed end is the major entry point of water. The micropylar endosperm and the radicle show the highest hydration. Germination of tobacco follows a distinct pattern of events: rupture of the testa is followed by rupture of the endosperm. Abscisic acid (ABA) specifically inhibits endosperm rupture and phase III water uptake, but does not alter the spatial and temporal pattern of phase I and II water uptake. Testa rupture was associated with an increase in water uptake due to initial embryo elongation, which was not inhibited by ABA. Overexpression of beta-1,3-glucanase in the seed-covering layers of transgenic tobacco seeds did not alter the moisture sorption isotherms or the spatial pattern of water uptake during imbibition, but partially reverted the ABA inhibition of phase III water uptake and of endosperm rupture. In vivo (13)C-magic angle spinning NMR spectroscopy showed that seed oil mobilization is not inhibited by ABA. ABA therefore does not inhibit germination by preventing oil mobilization or by decreasing the water-holding capacity of the micropylar endosperm and the radicle. Our results support the proposal that different seed tissues and organs hydrate at different extents and that the micropylar endosperm region of tobacco acts as a water reservoir for the embryo.
A number of plant species were examined for the presence of pyruvate kinase (pyruvate-ATP phosphotransferase, EC 2.7.1.40), and of a phosphatase activity which hydrolyzes phosphoenolpyruvate. Of those examined, only cotton (Gossypium sp. L.) seeds were found to be sufficiently free of the phosphatase to permit a kinetic study of pyruvate kinase.During germination of cotton seeds, pyruvate kinase activity rises for the first 3 days, after which it falls back to its original level. This developmental pattern is characteristic of enzymes involved in the conversion of fat into carbohydrate in fatstoring seeds. The phosphatase also rose rapidly during germination, which precluded the use of extracts from seedlings in the study of pyruvate kinase. No evidence was found for the presence of more than one pyruvate kinase in cotton seedlings.In crude extracts from ungerminated seeds, the enzyme shows slight deviations from normal kinetics with respect to phosphoenolpyruvate, magnesium, and to a lesser extent, ADP. After partial purification of the enzyme by ion exchange chromatography, the enzyme shows normal kinetics. The enzyme is activated by AMP, and inhibited by both ATP and citrate, in both crude and partially purified preparations. It is suggested that cotton seed pyruvate kinase is a regulatory enzyme.
At harvest, sunflower (Helianthus annuus L.) seeds are dormant and unable to germinate at temperatures below 15 degrees C. Seed storage in the dry state, known as after-ripening, is associated with an alleviation of embryonic dormancy allowing subsequent germination at suboptimal temperatures. To identify the process by which dormancy is broken during after-ripening, we focused on the role of reactive oxygen species (ROS) in this phenomenon. After-ripening entailed a progressive accumulation of ROS, namely superoxide anions and hydrogen peroxide, in cells of embryonic axes. This accumulation, which was investigated at the cellular level by electron microscopy, occurred concomitantly with lipid peroxidation and oxidation (carbonylation) of specific embryo proteins. Incubation of dormant seeds for 3 h in the presence of hydrogen cyanide (a compound that breaks dormancy) or methylviologen (a ROS-generating compound) also released dormancy and caused the oxidation of a specific set of embryo proteins. From these observations, we propose a novel mechanism for seed dormancy alleviation. This mechanism involves ROS production and targeted changes in protein carbonylation patterns.
Integrity of human skin is endangered by exposure to UV irradiation and chemical stressors, which can provoke a toxic production of reactive oxygen species (ROS) and oxidative damage. Since oxidation of proteins and metabolites occurs virtually instantaneously, immediate cellular countermeasures are pivotal to mitigate the negative implications of acute oxidative stress. We investigated the short-term metabolic response in human skin fibroblasts and keratinocytes to H2O2 and UV exposure. In time-resolved metabolomics experiments, we observed that within seconds after stress induction, glucose catabolism is routed to the oxidative pentose phosphate pathway (PPP) and nucleotide synthesis independent of previously postulated blocks in glycolysis (i.e., of GAPDH or PKM2). Through ultra-short (13)C labeling experiments, we provide evidence for multiple cycling of carbon backbones in the oxidative PPP, potentially maximizing NADPH reduction. The identified metabolic rerouting in oxidative and non-oxidative PPP has important physiological roles in stabilization of the redox balance and ROS clearance.
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Dose-response studies are an important tool in weed science. The use of such studies has become especially prevalent following the widespread development of herbicide resistant weeds. In the past, analyses of dose-response studies have utilized various types of transformations and equations which can be validated with several statistical techniques. Most dose-response analysis methods 1) do not accurately describe data at the extremes of doses and 2) do not provide a proper statistical test for the difference(s) between two or more dose-response curves. Consequently, results of dose-response studies are analyzed and reported in a great variety of ways, and comparison of results among various researchers is not possible. The objective of this paper is to review the principles involved in dose-response research and explain the log-logistic analysis of herbicide dose-response relationships. In this paper the log-logistic model is illustrated using a nonlinear computer analysis of experimental data. The log-logistic model is an appropriate method for analyzing most dose-response studies. This model has been used widely and successfully in weed science for many years in Europe. The log-logistic model possesses several clear advantages over other analysis methods and the authors suggest that it should be widely adopted as a standard herbicide dose-response analysis method.
To identify the effects of acute and chronic γ-irradiation in Arabidopsis plants, physiological responses and antioxidant-related gene expression were investigated. Seedlings were exposed to 200 Gy of γ-irradiation in acute manner for 1 or 24 h (A1 and A24) or in chronic manner for 1, 2, or 3 weeks (C1 W, C2 W, and C3 W). Plant height, silique number, and silique length in A1 and A24 irradiated plants were significantly reduced when compared to non-irradiated plants. Silique number decreased in response to both acute and chronic irradiation, except with the C3 W treatment, and the number of trichomes dramatically increased in A1 and C1 W. Electron spin resonance signal intensities increased in A1 and in all chronically irradiated plants, but decreased in the A24-treated plant. To investigate the effects of acute and chronic γ-irradiation on antioxidant enzymes, we examined activity of four antioxidant enzymes: catalase (CAT), peroxidase (POD), ascorbate peroxidase, and superoxide dismutase. In general, POD and CAT activities decreased in response to acute and chronic γ-irradiation. Oligonucleotide microarrays were used to investigate transcriptional changes after irradiation. Several genes related to reactive oxygen species signaling were up-regulated after acute and chronic exposure, including genes encoding heat shock factors, zinc finger proteins, NADPH oxidase, WRKY DNA-binding proteins, and calcium binding proteins. Taken together, our data indicate that the responses and activation of antioxidant systems prompted by irradiation exposure are dependent upon the γ-ray dose rate.
Herbicide hormesis is commonly observed at sub-toxic doses of herbicides and other phytotoxins. The occurrence and magnitude of this phenomenon is influenced by plant growth stage and physiological status, environmental factors, the endpoint measured, and the timing between treatment and endpoint measurement. The mechanism in some cases of herbicide hormesis appears to be related to the target site of the herbicide, whereas, in other examples hormesis may be by overcompensation to moderate stress induced by the herbicides or a response to disturbed homeostasis. Theoretically, herbicide hormesis could be used in crop production, but this has been practical only in the case of the use of herbicides as sugarcane "ripeners" to enhance sucrose accumulation. The many factors that can influence the occurrence, the magnitude, and the dose range of hormetic increases in yield for most crops make it too unpredictable and risky as a production practice with the currently available knowledge. Herbicide hormesis can cause undesired effects in situations in which weeds are unintentionally exposed to hormetic doses (e.g., in adjacent fields, when shielded by crop vegetation). Some weeds that evolved herbicide resistance may have hormetic responses to recommended herbicide application rates. Little is known about such effects under field conditions. A more complete understanding of herbicide hormesis is needed to exploit its potential benefits and to minimize its potential harmful effects in crop production.
Abstract The aromatic compounds such as aromatic amino acids, vitamin K and ubiquinone are important prerequisites for the metabolism of an organism. All organisms can synthesize these aromatic metabolites through shikimate pathway, except for mammals which are dependent on their diet for these compounds. The pathway converts phosphoenolpyruvate and erythrose 4-phosphate to chorismate through seven enzymatically catalyzed steps and chorismate serves as a precursor for the synthesis of variety of aromatic compounds. These enzymes have shown to play a vital role for the viability of microorganisms and thus are suggested to present attractive molecular targets for the design of novel antimicrobial drugs. This review focuses on the seven enzymes of the shikimate pathway, highlighting their primary sequences, functions and three-dimensional structures. The understanding of their active site amino acid maps, functions and three-dimensional structures will provide a framework on which the rational design of antimicrobial drugs would be based. Comparing the full length amino acid sequences and the X-ray crystal structures of these enzymes from bacteria, fungi and plant sources would contribute in designing a specific drug and/or in developing broad-spectrum compounds with efficacy against a variety of pathogens.
The activities and isoenzyme pattern of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) have been studied
during germination of Chenopodium murale seeds. CAT and SOD activities were similar in dry seeds and during first 2 d of imbibition. CAT activity increased during
radicle protrusion and early seedling development. The maximum SOD activity was found at final stages of germination and early
seedling development. POD activity was not detected until the 6th day of germination, indicating POD involvement not until early seedling development. Gibberellic acid (GA3, 160 µM) delayed and synchronized C. murale germination.
Barley (Hordeum vulgare) seedlings were treated with spermidine prior to water deficit treatment to determine whether this polyamine is able to influence
the activity of catalase (EC 1.11.1.6) and guaiacol peroxidase (EC 1.11.1.7). The content of endogenous polyamines was determined
as well. This stress caused a visible increase of catalase activity and a much higher increase of guaiacol peroxidase activity.
Treatment with exogenous spermidine induced a significant decrease in the activity of the both enzymes, whereas the polyamine
level was enhanced, suggesting that polyamines are able to influence the activity of hydrogen peroxide scavenging enzymes
and to moderate in that way this signal molecule level.
Stimulation of plant growth by very low doses of ionizing radiation, radiation hormesis, has been frequently documented, but remains in question because it is difficult to reproduce. Interpretation of the literature is hampered by the infrequent use of appropriate controls and blind measurement protocols. We approached hormesis as a stochastic phenomenon using 28 repetitions of a small experiment in an attempt to achieve reproducible hormesis. Shoot length of wheat (Triticum aestivum) and barley (Hordeum vulgare) was measured, following a blind measurement protocol, 1–10 days after irradiation at 0.05–50 Gy. Both non-irradiated and shielded controls were included. We observed statistically significantly increased growth relative to the non-irradiated controls in six experiments, trends toward increases in 18 experiments, trends toward decreases in the three experiments, and significant decreases in two experiments. However, there was no clear relationship between these effects on growth and factors such as species, cultivar, seed lot or time or irradiation. Further, the shielded controls were never significantly different from the irradiated plants. This suggest involvement of factors other than radiation. Effects of the irradiated atmosphere did not seem to be involved. At present, we have no explanation of the increased growth, but clearly great care must be taken when attributing such responses to radiation.
A database has been developed that demonstrates experimental evidence of hormesis. It includes information from a broad range of biological models, including plants, and information on study design, dose–response features, and physical/chemical properties of the agents. An assessment of plant hormetic dose responses is presented based on greater than 3000 plant endpoints. Plant hormetic dose responses were observed for numerous endpoints including disease incidence, reproductive indices, mutagenic endpoints, various metabolic parameters, developmental processes, and a range of growth indicators. Quantitative features of these dose responses typically display a maximum stimulatory response less than two-fold greater than controls and a width of the stimulatory response usually less than 10-fold in dose range. The database establishes that hormetic dose responses commonly occur in plants, are broadly generalizable, and have quantitative features similar to hormetic dose responses found for animals.
In a previous publication, we showed that the treatment of pea seeds in the presence of hydrogen peroxide (H(2)O(2)) increased germination performance as well as seedling growth. To gain insight into the mechanisms responsible for this behaviour, we have analysed the effect of treating mature pea seeds in the presence of 20 mm H(2)O(2) on several oxidative features such as protein carbonylation, endogenous H(2)O(2) and lipid peroxidation levels. We report that H(2)O(2) treatment of the pea seeds increased their endogenous H(2)O(2) content and caused carbonylation of storage proteins and of several metabolic enzymes. Under the same conditions, we also monitored the expression of two MAPK genes known to be activated by H(2)O(2) in adult pea plants. The expression of one of them, PsMAPK2, largely increased upon pea seed imbibition in H(2)O(2) , whereas no change could be observed in expression of the other, PsMAPK3. The levels of several phytohormones such as 1-aminocyclopropane carboxylic acid, indole-3-acetic acid and zeatin appeared to correlate with the measured oxidative indicators and with the expression of PsMAPK2. Globally, our results suggest a key role of H(2)O(2) in the coordination of pea seed germination, acting as a priming factor that involves specific changes at the proteome, transcriptome and hormonal levels.
The relationships between changes in energy metabolism and the antioxidant defense system in the weed species Ipomoea triloba L. during seed germination and early seedling growth were investigated. The effects of some common allelochemicals on these parameters also were studied. Respiratory activity and the activities of alcohol dehydrogenase, superoxide dismutase, catalase, guaicol peroxidase, ascorbate peroxidase, glutathione reductase, and lipoxygenase were measured. Mitochondrial oxidative phosphorylation resumed shortly after the seed imbibition period, as indicated by considerable KCN-sensitive respiratory activity in embryos of I. triloba. The occurrence of superoxide dismutase, catalase, guaicol peroxidase, and lipoxygenase activities in the embryos, along with significant KCN-insensitive respiration, suggest that production of reactive oxygen species (ROS) is initiated as soon as mitochondrial respiration is resumed. All assayed antioxidant enzymes were present in the embryos except ascorbate peroxidase, which appeared only in primary roots. The activities of antioxidant enzymes increased after completion of germination, especially in primary roots. Superoxide dismutase, catalase, and guaicol peroxidase probably were the crucial enzymes involved in the neutralization of ROS, since they had higher levels of activity compared with other enzymes, such as ascorbate peroxidase and glutathione reductase. When seeds were grown in the presence of α-pinene, coumarin, quercetin, and ferulic acid, there was an additional increase in activities of antioxidant enzymes, as well as increases in lipoxygenase activity and KCN-insensitive respiration, suggesting a further increase in ROS generation. The antioxidant defense system of I. triloba was not effective in preventing lipid peroxidation caused by α-pinene. The data indicate that during seed germination and initial growth of I. triloba, a period when antioxidant enzyme activity increases to counteract the harmful ROS effects produced during mitochondrial metabolism resumption, the presence of allelochemicals, which cause further oxidative stress, may leave the seeds/seedlings more vulnerable to cellular dysfunction and cell death.
Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants which are highly reactive and toxic and cause damage to proteins, lipids, carbohydrates and DNA which ultimately results in oxidative stress. The ROS comprises both free radical (O(2)(-), superoxide radicals; OH, hydroxyl radical; HO(2), perhydroxy radical and RO, alkoxy radicals) and non-radical (molecular) forms (H(2)O(2), hydrogen peroxide and (1)O(2), singlet oxygen). In chloroplasts, photosystem I and II (PSI and PSII) are the major sites for the production of (1)O(2) and O(2)(-). In mitochondria, complex I, ubiquinone and complex III of electron transport chain (ETC) are the major sites for the generation of O(2)(-). The antioxidant defense machinery protects plants against oxidative stress damages. Plants possess very efficient enzymatic (superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; glutathione reductase, GR; monodehydroascorbate reductase, MDHAR; dehydroascorbate reductase, DHAR; glutathione peroxidase, GPX; guaicol peroxidase, GOPX and glutathione-S- transferase, GST) and non-enzymatic (ascorbic acid, ASH; glutathione, GSH; phenolic compounds, alkaloids, non-protein amino acids and α-tocopherols) antioxidant defense systems which work in concert to control the cascades of uncontrolled oxidation and protect plant cells from oxidative damage by scavenging of ROS. ROS also influence the expression of a number of genes and therefore control the many processes like growth, cell cycle, programmed cell death (PCD), abiotic stress responses, pathogen defense, systemic signaling and development. In this review, we describe the biochemistry of ROS and their production sites, and ROS scavenging antioxidant defense machinery.
The initial and rate-limiting enzyme of the oxidative pentose phosphate shunt, glucose-6-phosphate dehydrogenase (G6PD), is inhibited by NADPH and stimulated by NADP(+). Hence, under normal growth conditions, where NADPH levels exceed NADP(+) levels by as much as 100-fold, the activity of the pentose phosphate cycle is extremely low. However, during oxidant stress, pentose phosphate cycle activity can increase by as much as 200-fold over basal levels, to maintain the cytosolic reducing environment. G6PD-deficient (G6PD(-)) cell lines are sensitive to toxicity induced by chemical oxidants and ionizing radiation. Compared to wild-type CHO cells, enhanced sensitivity to ionizing radiation was observed for G6PD(-) cells exposed to single-dose or fractionated radiation. Fitting the single-dose radiation response data to the linear-quadratic model of radiation-induced cytotoxicity, we found that the G6PD(-) cells exhibited a significant enhancement in the alpha component of radiation-induced cell killing, while the values obtained for the beta component were similar in both the G6PD(-) and wild-type CHO cell lines. Here we report that the enhanced alpha component of radiation-induced cell killing is associated with a significant increase in the incidence of ionizing radiation-induced apoptosis in the G6PD(-) cells. These data suggest that G6PD and the oxidative pentose phosphate shunt protect cells from ionizing radiation-induced cell killing by limiting the incidence of radiation-induced apoptosis. The sensitivity to radiation-induced apoptosis was lost when the cDNA for wild-type G6PD was transfected into the G6PD(-) cell lines. Depleting GSH with l-BSO enhanced apoptosis of K1 cells while having no effect in the G6PD(-) cell line
The threshold dose-response model is widely viewed as the most dominant model in toxicology. The present study was designed to test the validity of the threshold model by assessing the responses of doses below the toxicological NOAEL (no observed adverse effect level) in relationship to the control response (i.e., unexposed group). Nearly 1,800 doses below the NOAEL, from 664 dose-response relationships derived from a previously published database that satisfied a priori entry criteria, were evaluated. While the threshold model predicts a 1:1 ratio of responses "greater than" to "less than" the control response (i.e., a random distribution), a 2.5:1 ratio (i.e., 1171:464) was observed, reflecting 31% more responses above the control value than expected (p < 0.0001). The mean response (calculated as % control response) of doses below the NOAEL was 115.0% +/- 1.5 standard error of the mean (SEM). These findings challenge the long-standing belief in the primacy of the threshold model in toxicology (and other areas of biology involving dose-response relationships) and provide strong support for the hormetic-like biphasic dose-response model characterized by a low-dose stimulation and a high-dose inhibition. These findings may affect numerous aspects of toxicological and biological/biomedical research related to dose-response relationships, including study design, risk assessment, as well as chemotherapeutic strategies.
During the past two decades, the phenomenon of hormesis has gained increased recognition. To promote research in hormesis, a sound statistical quantification of important parameters, such as the level and significance of the increase in response and the range of concentration where it occurs, is strongly needed. Here, we present an improved statistical model to describe hormetic dose-response curves and test for the presence of hormesis. Using the delta method and freely available software, any percentage effect dose or concentration can be derived with its associated standard errors. Likewise, the maximal response can be extracted and the growth stimulation calculated. The new model was tested on macrophyte data from multiple-species experiments and on laboratory data of Lemna minor. For the 51 curves tested, significant hormesis was detected in 18 curves, and for another 17 curves, the hormesis model described that data better than the logistic model did. The increase in response ranged from 5 to 109%. The growth stimulation occurred at an average dose somewhere between zero and concentrations corresponding to approximately 20 to 25% of the median effective concentration (EC50). Testing the same data with the hormesis model proposed by Brain and Cousens in 1989, we found no significant hormesis. Consequently, the new model is shown to be far more robust than previous models, both in terms of variation in data and in terms of describing hormetic effects ranging from small effects of a 10% increase in response up to effects of an almost 100% increase in response.
Fundamentals of General and Agricultural Radiobiology
- I N Gudkov
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In: Radiation Technologies in the Agriculture and Food industry
- G V Kozmin
- S A Geras 'kin
- N I Sanzharova
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Genetic Basis of Radioresistance and Evolution (in Russian)
- B I Sarapul'tzev
- S A Geras'kin
Sarapul'tzev, B.I., Geras'kin, S.A., 1993. Genetic Basis of Radioresistance and Evolution (in Russian). Energoatomizdat Publishers, Moscow.
Herbicides and plant hormesis
- R G Belz
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Practical Enzymology. Willey-VCH Verlag GmbH & KGaA
- H Bisswanger
Bisswanger, H., 2004. Practical Enzymology. Willey-VCH Verlag GmbH & KGaA,
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Effect of grain irradiation with gamma rays on growth, nitrogen content and yield of wheat plants
- S Saleh
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