Stimulating Stevia Plant Growth and Sweet Compound Production in the Lab

Jenn Hoskins
27th June, 2024

Stimulating Stevia Plant Growth and Sweet Compound Production in the Lab

Treatment with gibberellic acid promoted highly vigorous (d) and vigorous (e) growth in Stevia rebaudiana shoots, while stress-inducing elicitors such as PEG (a) and NaCl (b, c) resulted in stunted growth compared to the untreated control (f).

Image adapted from: Ghazal et al. / CC BY (Source)

Key Findings

  • Researchers at The University of Agriculture Peshawar found that using 2 mg/L and 4 mg/L gibberellic acid (GA3) resulted in the highest shooting response in stevia plants
  • Adding 100 mM sodium chloride (NaCl) to the media significantly increased the total phenolics, flavonoids, and polyphenolics content in stevia shoots
  • The highest antioxidant activity (81.8%) was observed in shoots treated with 50 mM NaCl, indicating enhanced health-promoting properties
Stevia rebaudiana, a plant in the Asteraceae family, is renowned for its biologically active compounds, particularly diterpene glycosides like stevioside, rebaudioside, and dulcoside. These compounds are notable for their antidiabetic properties and potential as zero-calorie sugar alternatives. A recent study conducted by researchers at The University of Agriculture Peshawar explored an elicitation strategy to enhance the production of these compounds in stevia shoot cultures[1]. The study utilized 5% polyethylene glycol (PEG), sodium chloride (NaCl; 50 and 100 mM), and gibberellic acid (GA3; 2.0 and 4.0 mg/L) to investigate their effects on various biochemical parameters. These included shoot morphogenesis, the production of phenolics, flavonoids, total soluble sugars, proline, stevioside, and antioxidant activity. The researchers found that media supplemented with 2 mg/L and 4 mg/L GA3 exhibited the highest shooting response (87% and 80%, respectively). When combined with 6-benzylaminopurine (BAP), a lower concentration of GA3 (2 mg/L) resulted in the maximum mean shoot length of 11.1 cm. This aligns with earlier findings that demonstrated the effectiveness of gibberellic acid in promoting biomass accumulation and secondary metabolite production in adventitious root cultures of stevia[2]. Interestingly, the addition of 100 mM NaCl to the media led to the highest observed total phenolics content (TPC; 4.11 mg/g-DW), total flavonoids content (TFC; 1.26 mg/g-DW), and polyphenolics concentration (5.39 mg/g-DW) in the shoots. This enhancement in phenolic and flavonoid content is consistent with previous studies where biotic elicitors like Cuscuta reflexa extract were used to improve the synthesis of these compounds in stevia cultures[3]. Moreover, the study revealed that the maximum antioxidant activity (81.8%) was observed in shoots raised in media treated with 50 mM NaCl. This finding is significant because antioxidant activity is often correlated with the presence of phenolic and flavonoid compounds, which are known for their health-promoting properties. The application of 2 mg/L GA3 resulted in the highest accumulation of proline (0.99 μg/mL), compared to controls (0.37 μg/mL). Proline is an amino acid that plays a crucial role in plant stress responses, indicating that GA3 may help stevia plants better cope with environmental stressors. The study also found that the maximum stevioside content (71 µL/mL) was observed in cultures supplemented with 100 mM NaCl and 5% PEG, followed closely by the 4 mg/L GA3 treatment (70 µL/mL). This is a notable increase compared to the control (60 µL/mL). The positive correlation between GA3 and stevioside content suggests that these two compounds are derived from a shared biochemical pathway, further emphasizing the role of GA3 in enhancing steviol glycoside production. These findings build upon earlier research that established efficient methods for regenerating stevia and producing its main steviol glycosides using various plant growth regulators (PGRs) and agar concentrations[4]. The current study extends this knowledge by demonstrating that elicitation with PEG, NaCl, and GA3 can significantly enhance the accumulation of these valuable compounds. In summary, the study conducted by The University of Agriculture Peshawar provides compelling evidence that elicitation is an effective strategy to boost the production of steviosides and other beneficial metabolites in stevia. This research lays the groundwork for future industrial-scale production using bioreactors, potentially leading to more efficient and cost-effective methods for producing these valuable compounds.

MedicineBiochemPlant Science

References

Main Study

1) Elicitors directed in vitro growth and production of stevioside and other secondary metabolites in Stevia rebaudiana (Bertoni) Bertoni.

Published 26th June, 2024

https://doi.org/10.1038/s41598-024-65483-6

Related Studies

2) Effect of Gibberellic Acid on Production of Biomass, Polyphenolics and Steviol Glycosides in Adventitious Root Cultures of Stevia rebaudiana (Bert.).

https://doi.org/10.3390/plants9040420

3) Elicitation of Submerged Adventitious Root Cultures of Stevia rebaudiana with Cuscuta reflexa for Production of Biomass and Secondary Metabolites.

https://doi.org/10.3390/molecules27010014

4) Efficient regeneration for enhanced steviol glycosides production in Stevia rebaudiana (Bertoni).

https://doi.org/10.1016/j.crvi.2013.10.002


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