The present study was conducted to evaluate the biological responses of soybean irradiated by gamma-rays. Four elite Korean soybean cultivars, Kwangankong, Shinpaldal-2, Shinhwakong, and Ilmikong, were irradiated with 100–400 Gy of gamma-rays. All cultivars showed significant reductions in morphological parameters. Seedling emergence rates of Kwangankong, Shinpaldal-2, Shinhwakong, and Ilmikong decreased by 46%, 31%, 44%, and 43% at 400 Gy, respectively. Plant height and fresh weight decreased with increasing dose. The median reduction dose (RD50) for plant height ranged from 184 to 278 Gy with an average of 212 Gy. The optimal dose of gamma irradiation for inducing mutation in the four elite soybean cultivars was in the range 200–300 Gy. Contents of malonaldehyde (MDA) in the gamma-ray irradiated plants were higher than those in the controls. With the exception of Kwangankong, activities of ascorbate peroxidase (APX) in other cultivars decreased at 100 Gy and started to increase significantly at 200 Gy and Shinhwakong cultivar had highest APX value observed at 300 Gy. No significant changes in peroxidase (POD) activity were observed in the Kwangankong, Shinpaldal-2, and Shinhwakong, while, POD activity increased with increasing dose in Ilmikong. In addition, gamma-ray treatments elicited a marked reduction in chlorophyll
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Boysenberry, a
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The present study evaluated the biochemical effects of proton beam irradiation in soybean. Seeds of two Korean elite cultivars (Kwangan and Pungsannamul) were irradiated by a 57-MeV proton beam in the range of 50–400 Gy. We measured the contents of malondialdehyde (MDA), antioxidant enzymes, and chlorophyll. MDA contents in proton beam-irradiated plants were higher than those in control plants. The activity of antioxidant enzymes differed between the two cultivars. In Kwangan, ascorbate peroxidase (APX) activity increased by 29% relative to the control at 55 Gy and decreased by 58% at 308 Gy. Superoxide dismutase (SOD) and peroxidase (POD) activities decreased by 47 and 25% relative to the control at 55 Gy and recovered to 87 and 56% of that at 55 Gy with 172 Gy and 117 Gy, respectively. In Pungsannamul, APX and SOD decreased by 32 and 35% relative to the control at 62 Gy, with the highest value observed at 243 Gy. In terms of the chlorophyll content, the two varieties responded similarly to proton beam irradiation, whereas in Kwangan, no significant reduction was observed above 100 Gy when compared with the control. Proton beam irradiation affected chlorophyll b more than chlorophyll a. These results show that the activity of antioxidant enzymes decreased in response to irradiation with approximately 50 Gy proton beams, then increased gradually with increasing doses, followed by a moderate decrease at higher doses. According to correlation with MDA contents and antioxidant enzyme activities, defense system of Pungsannamul was less activated by proton-beam irradiation than that of Kwangan.
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