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.
Citations
This study was carried out to evaluate effect of proton beam irradiation on M1 seed germination and seedling growth. For dosage effect, mature and healthy Supersami2 seeds were irradiated with 0, 204, 395, 502, and 700Gy. The traits for germination were not affected by dosage effect of proton beam irradiation. Germination rate evaluated at 7 days after imbibition ranged from 93.3% to 98.7%; germination vigor ranged from 59.3% to 68.7% where in the dose of 700Gy showed the lowest value of 59.3%. The average days of germination ranged from 1.36 to 1.48. The seedling growth was affected by the dosage. Withered rate (withered plants after germination) was increased as the dose increased. The withered rate of 53.9% was detected in 395Gy and no plant survived in 700Gy. In the ~400Gy treatment, the sensitivity of the traits of germination among Dianxi4, Jeogjinju, MS11(Maligaya Special 11), and Superjami2 was not different while the withered rate was different: 9.7% in MS11, 32.1% in Dianxi4, 53.9% in Superjami2, and 59.7% in Jeogjinju. Based on the germination rate and withered rate, it can be suggested that 350Gy to 450Gy is a starting point for applying proton beam irradiation to rice seed for mutation breeding.
Citations
First
Prev
