Physiological changes and anti-oxidative responses of Arabidopsis plants after acute and chronic γ-irradiation

Abstract

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.

Pretreatment with High-Dose Gamma Irradiation on Seeds Enhances the Tolerance of Sweet Osmanthus Seedlings to Salinity Stress

“…As reported by Ashraf [6], the extent to which the activities of enzymatic antioxidants and the level of non-enzymatic antioxidants were up-regulated under salinity stress is highly variable among plant species and even between two cultivars of the same species. The response and activation of antioxidant systems induced by irradiation exposure are dependent upon the γ-ray dose rate, the doses of gamma rays and the developmental stages [36,37]. The ASC-GSH cycle system were the main ROS-scavenging systems in the chloroplasts [11], the activities of APX and GR were found to be higher in the salt-tolerant cultivars of potato than those in the salt-sensitive cultivars [38].…”

Effects of Acute and Chronic Gamma Irradiation on the Cell Biology and Physiology of Rice Plants

“…Irradiation induces oxidative stress via excessive ROS production, which activates enzymatic and non-enzymatic antioxidant defense systems in plants to induce ROS scavenging [6,19]. Low IC50 values observed in high-dose irradiated plants (Figure 4) demonstrates that higher doses activate the antioxidant defense systems to a greater extent than lower doses in both acute and chronic irradiation treatments to mitigate the detrimental effects of ROS [8,20]. Generally, antioxidant enzyme activities showed a greater increase in acutely irradiated plants than in chronically irradiated plants, implying a more prompt response of enzymatic ROS scavenging to irradiation at a high dose rate ( Figure 5).…”

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

“…The acutely exposed plants demonstrated up-regulation of genes involved with DNA repair, oxidative stress response and signal transduction pathways, whilst the chronically exposed plants showed no alteration of expression profiles of genes associated with DNA repair or cell antioxidant response. Goh et al (2014) demonstrated a similar effect at 200 Gy, which induced changes in gene expression when spread over hours but when spread over 2 or 3 weeks had no effect on gene expression. There is also evidence that the stage of plant development affects both the expression of IR sensitive genes in unexposed plants and their general plant response to IR ( Biermans et al, 2015 ).…”

“…In rice varieties produced by IR mutagenesis Hwang et al (2015) report, for example, changed carbohydrate and protein degradation metabolism. Often such changes include those to anti-oxidant systems ( Goh et al, 2014 ; Ramabulana et al, 2015 ). Several studies have shown that γ-radiation has an effect on chlorophyll content.…”