Document Type : Research Paper
Authors
1 Ferdowsi University Mashhad
2 Department of Horticultural Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
3 Dep. Ornamental Plants, Research Centre for Plant Sciences, Ferdowsi University Mashhad, Mashhad, Iran
Abstract
Background and objectives: Maintaining medicinal plants' quality and effective compounds is a fundamental challenge. Salvia L. has antioxidant, anti-inflammatory, and antimicrobial properties and is a rich source of biological compounds that destroy free radicals. Salvia virgate Jacq. has several biological activities and is used to treat wounds and various skin diseases and prevent blood cancer. Cadmium is one of the most toxic heavy metals due to its long biological half-life, significant mobility in soil, and capacity to be absorbed by plants. Cadmium's negative effects on plant growth, and physiological and biochemical activities reduce plant quality and performance. Sodium nitroprusside is involved in biological processes and responds to various stresses by releasing nitric oxide (NO).
Methodology: To investigate the effect of different levels of sodium nitroprusside on improving the response of salvia virgata to cadmium stress under in vitro conditions, an experiment was conducted in the Research Institute of Plant Sciences of the Ferdowsi University of Mashhad with a factorial design based on a completely randomized design with four replications. The studied factors included different levels of cadmium (0 (control), 25, 50, and 100 µM) and sodium nitroprusside (0 (control), 15, and 30 µM). Murashig and Skoog culture media were used for seed cultivation. In this experiment, different amounts of cadmium nitrate were added to the culture medium before adjusting the pH. Sodium nitroprusside was added to the medium after autoclaving and a sub-laminar filter due to its sensitivity to high temperatures. At first, the seeds were sterilized with 70% alcohol and 2% sodium hypochlorite; then, they were planted in a culture medium. After three months of growth, the seedlings were removed from the culture medium. Growth traits include the fresh and dry weight of the aerial part, root, and whole seedling, and physiological and biochemical traits including photosynthetic pigments (measurement of chlorophyll a, chlorophyll b, carotenoid, total chlorophyll, and total photosynthetic pigment), flavonoid, total phenol, carbohydrate, proline, protein, and antioxidant activity were measured. The data obtained from this research were analyzed by Minitab software. The mean comparisons were done by the Bonferroni test at the five percent probability level.
Results: According to the results of the analysis of variance of the data, the interaction effect of cadmium and nitroprusside on seedling fresh weight, chlorophyll a, chlorophyll b, carotenoid, total photosynthetic pigments, total phenol, carbohydrate and proline at the probability level of one percent and seedling dry weight, total chlorophyll, flavonoid, and protein were significant at the five percent probability level. The interaction effect of treatments on antioxidant activity was not significant, but their simple effects were significant. The results of the mean comparison of the data indicated that cadmium stress decreased the fresh and dry weight of seedlings, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, and total photosynthetic pigments in S. virgata, and the application of sodium nitroprusside led to the improvement of these traits; so that the application of 30 μM sodium nitroprusside under cadmium stress with a 50 μM concentration showed the highest fresh and dry weight of seedlings and the proline content, and the application of 15 μM sodium nitroprusside under cadmium stress with a 25 μM concentration showed the highest amount of photosynthetic pigments. Also, this research indicated that cadmium stress increased antioxidant activity, total flavonoid, total phenol, soluble carbohydrate, proline, and protein in the S. virgata plant. However, sodium nitroprusside application improved these negative effects of cadmium stress. So, the application of 30 μM sodium nitroprusside led to an increase in total flavonoid, total phenol, soluble carbohydrate, and protein under cadmium stress conditions at 25 μM concentration.
Conclusion: The results showed that cadmium stress reduces plant growth and physiological and biochemical functions, but sodium nitroprusside application could improve cadmium's negative effects. These findings show that sodium nitroprusside can be used as an effective instrument in cadmium stress management in medicinal plants and help to improve the growth and quality of these plants. This research, in addition to enhancing our knowledge about the mechanisms of plants' response to cadmium stress, helps to analyze the effect of sodium nitroprusside in exposure to environmental life pollutants.
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