Boosting Sweetness in Stevia Using Gamma Radiation

Greg Howard
14th June, 2024

Boosting Sweetness in Stevia Using Gamma Radiation

Image Source: Natural Science News, 2024

Key Findings

  • The study by CSIR-IHBT in India used gamma rays to induce mutations in Stevia rebaudiana seeds to enhance sweetening compounds
  • Doses above 40 kR were lethal to the seedlings, while 20-23 kR was optimal for beneficial mutations without excessive damage
  • Mild doses of 5 and 10 kR increased the overall glycosidic content, making these doses promising for future stevia mutation programs
The perennial herb Stevia rebaudiana Bertoni, native to South America, is renowned for its intense sweetness and potential health benefits. The key compounds responsible for its sweetness are stevioside and rebaudioside-A, which are significantly sweeter than traditional sugar and have been the focus of research for over a century[2][3]. Recent research conducted by the Council of Scientific and Industrial Research - Institute of Himalayan Bioresource Technology (CSIR-IHBT) aimed to enhance these sweetening compounds through induced mutagenesis using gamma-rays[1]. In the study, healthy seeds of the 'Madhuguna' variety of Stevia rebaudiana Bertoni were irradiated with ten different doses of gamma rays ranging from 5 to 100 kR. Gamma-rays are a form of ionizing radiation that can induce mutations in the DNA of organisms. The seeds were exposed to these doses in a controlled environment at CCS Haryana Agricultural University in India. The results of the study showed significant variations in the growth parameters of the seedlings. It was observed that doses above 40 kR resulted in absolute mortality, meaning the seedlings could not survive such high levels of radiation. The optimal dose for inducing beneficial mutations without causing excessive damage was found to be between 20-23 kR based on probit analysis, a statistical method used to analyze binary response variables. High-performance liquid chromatography (HPLC) was used to profile the glycosidic content of 296 mutants. This technique allows for the separation, identification, and quantification of components in a mixture. The study found that higher doses of radiation generally decreased the total steviol glycoside content. However, doses of 5 kR and 10 kR were effective in increasing the overall glycosidic content, making these doses promising for future stevia mutation programs. In addition to glycosidic profiling, the study also examined the nuclear DNA content of the mutants using flow cytometry, a technique that measures the physical and chemical characteristics of cells. It was found that the total nuclear DNA content decreased with increasing radiation doses. The average genome size at doses of 5, 10, 15, 20, and 30 kR were slightly reduced compared to the control, indicating that gamma radiation can induce changes at the genomic level. This research builds on previous studies that have highlighted the potential of Stevia rebaudiana as a low-calorie sweetener with additional health benefits such as antioxidant, antimicrobial, and antifungal properties[3]. The ability to enhance the glycosidic content through mild doses of gamma radiation could make stevia an even more attractive alternative to traditional sweeteners, especially for those who need to restrict carbohydrate intake in their diets. In conclusion, the study conducted by CSIR-IHBT demonstrates that mild doses of gamma rays (5 and 10 kR) can effectively improve the mean steviol glycoside content in Stevia rebaudiana Bertoni. This finding could be instrumental in future stevia mutation programs aimed at enhancing the sweetening properties of stevia while maintaining its health benefits.

GeneticsBiochemPlant Science

References

Main Study

1) Assessment of radiosensitivity and enhancing key steviol glycosides in Stevia rebaudiana Bertoni through gamma radiation.

Published 13th June, 2024

https://doi.org/10.1080/09553002.2024.2362647

Related Studies

2) Steviol glycoside biosynthesis.

Journal: Phytochemistry, Issue: Vol 68, Issue 14, Jul 2007

3) Stevia rebaudiana Bertoni, source of a high-potency natural sweetener: A comprehensive review on the biochemical, nutritional and functional aspects.

https://doi.org/10.1016/j.foodchem.2011.11.140


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