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PURPOSE: Radiation mutagenesis, which typically involves gamma rays, is important for generating new rice germplasm resources. Determining the appropriate radiation dose range is critical for the success of radiation mutagenesis. Clarifying the sensitivity and tolerance of genotypically diverse rice varieties to gamma irradiation as well as the radiation-induced changes to reactive oxygen species (ROS) generation and antioxidant enzyme activities is crucial for increasing the utility of radiation mutagenesis in rice breeding programs. MATERIALS AND METHODS: The seeds of the following four rice varieties with different genotypes were used as test materials: indica Zhe 1613, glutinous indica Zhe 1708, japonica Zhejing 100, and glutinous japonica Zhenuo 65. Additionally,60Co was used as the source of gamma rays. The rice seeds were irradiated with 14 doses (0, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, and 750 Gy). Non-irradiated seeds were used as the control. The seedling survival rate for each variety was recorded at 3, 7, 14, and 28 days after sowing. Moreover, the median lethal dose (LD50) and critical dose (LD40) were calculated according to the seedling survival rates at 28 days after sowing. The seedling superoxide anion (O2•-), hydrogen peroxide (H2O2), and malondialdehyde (MDA) contents and the superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) activities were analyzed at 7 days after sowing. RESULTS: As the radiation dose increased, the seedling survival rate decreased. The seedling survival rate also decreased significantly as the number of days after sowing increased. Among the rice genotypes, the rank-order of the radiation tolerance was as follows: indica Zhe 1613 > glutinous indica Zhe 1708 > japonica Zhejing 100 > glutinous japonica Zhenuo 65. The LD50 values were 426.7 Gy for Zhe 1613, 329.2 Gy for Zhe 1708, 318.3 Gy for Zhejing 100, and 316.6 Gy for Zhenuo 65. Increases in the radiation dose resulted in significant increases in the seedling O2•- and H2O2 contents, but only up to a certain point. Further increases in the radiation dose caused the seedling O2•- and H2O2 contents to decrease. The H2O2 content for each variety peaked when the radiation dose was very close to the LD50. We propose that the radiation dose associated with the highest H2O2 content (±50 Gy) should be used as the recommended dose for the gamma irradiation of rice. The radiation dose that resulted in peak seedling O2•- contents in the analyzed rice varieties was very close to the LD40. In all rice varieties, the MDA content increased as the radiation dose increased. The SOD, CAT, POD, and APX activities increased as the radiation dose increased within a certain range (less than 600 Gy for Zhe 1613 and 400 Gy for the other varieties), but there were slight differences among the rice varieties. CONCLUSIONS: Genotypically diverse rice varieties vary regarding their sensitivity to gamma irradiation. Our findings suggest that ROS generation and antioxidant enzyme activities are important factors associated with the radiation mutagenesis of rice. The close relationship between the activities of key antioxidant enzymes, such as SOD, POD, APX, and CAT, and the LD50 and LD40 may be exploited to enhance radiation mutagenesis through the use of plant growth regulators.

Asunto(s)

Antioxidantes , Oryza , Oryza/genética , Especies Reactivas de Oxígeno , Peróxido de Hidrógeno , Catalasa , Superóxido Dismutasa/genética , Plantones/efectos de la radiación

RESUMEN

Objective:To evaluate the clinical efficacy, tolerability and safety of adjunctive perampanel in focal epilepsy patients≥12 years old.Methods:One hundred and nineteen focal epilepsy patients≥12 years old accepted adjunctive perampanel in Department of Neurology, First Affiliated Hospital of Guangxi Medical University from July 2020 to December 2022 were chosen. At 1-3 months, 4-6 months, 7-9 months and 10-12 months after adjunctive perampanel, seizure frequency changes every 28 d, medication retention rate and adverse reactions were recorded to evaluate the clinical efficacy (a reduction in seizure frequency≥50% from baseline was defined as overall valid treatment), tolerability and safety of adjunctive perampanel. According to efficacy results after adjunctive perampanel of 4-6 months (short-term) and 10-12 months (long-term), these patients were divided into valid group and invalid group; and the influencing factors for short-term and long-term efficacy were analyzed.Results:At 1-3, 4-6, 7-9, 10-12 months after adjunctive perampanel, reduction in seizure frequency every 28 d was 66.7% (24.3%, 97.2%), 77.5% (48.6%, 100%), 94.6% (50%, 100%), 100% (70.9%, 100%), enjoying overall valid rate of 60.2% (59/98), 75.0% (7/76), 78.9% (45/57), 86.5% (32/37). The retention rate at 3, 6, 9 and 12 months after adjunctive perampanel was 85.2% (98/115), 67.9% (76/112), 54.3% (57/105), 41.1% (37/90). Adverse reactions were reported in 33 patents (27.7%), mainly with dizziness and secondly with mental symptoms. After short-term and long-term adjunctive perampanel, no significant difference was noted in gender, initial age of adjunctive perampanel, course of disease, etiology, EEG results, imaging results, number and type of combined anti-seizure drugs, or maximum dose of pirampanel between the valid group and invalid group ( P>0.05). Conclusion:Perampanel has good efficacy, tolerability and safety in adolescents and adults≥12 years old with focal epilepsy; no clear influencing factors for pirampanel valid treatment is found so far.