How Two Types of Licorice Plants Withstand Salt Stress

Jim Crocker
12th April, 2024

How Two Types of Licorice Plants Withstand Salt Stress

Under salt stress, the more tolerant Glycyrrhiza inflata maintained stable biomass and low levels of cellular damage (MDA), whereas Glycyrrhiza uralensis experienced significantly reduced root and leaf dry weight (b, c) and a sharp increase in MDA content (d).

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

Key Findings

  • In China, G. inflata licorice tolerates salty soils better than G. uralensis
  • G. inflata manages salt by controlling sodium intake and boosting potassium and calcium uptake
  • The plant's salt tolerance is linked to specific gene activity, aiding nutrient regulation and stress defense
Licorice, a plant with a storied history in traditional Chinese medicine, faces a challenge: salinity. Saline soils, which contain high levels of salt, can be detrimental to plant growth and development, posing a problem for the cultivation of licorice, particularly for the species Glycyrrhiza uralensis, which is widely used in medicinal preparations. However, its relative, Glycyrrhiza inflata, has shown a higher tolerance to such harsh conditions. Understanding the underlying mechanisms that confer this tolerance to G. inflata could unlock new ways to cultivate licorice in less-than-ideal soil conditions, ensuring a steady supply for medicinal use. Researchers at Shihezi University have embarked on a study[1] to dissect the differences in salt tolerance between G. uralensis and G. inflata. By examining growth responses, ion accumulation, and gene expression, they aimed to pinpoint the factors that enable G. inflata to thrive in salty soils. This research builds on previous findings that silicon (Si) can mitigate the effects of salt stress in licorice[2], and that various physicochemical approaches can influence the growth and biochemistry of medicinal plants in saline environments[3]. It also aligns with the understanding that a plant's ability to manage sodium (Na+) is crucial for salt tolerance[4]. The study found that under salt stress, G. inflata maintained stable growth and continued to produce important compounds such as flavonoids, which have various health benefits. G. inflata's roots restricted sodium uptake while absorbing more potassium (K+) and calcium (Ca2+), essential nutrients that contribute to plant health. In contrast, G. uralensis experienced more difficulty under the same conditions. A deeper look into the plants' biology through transcriptome analysis, which examines the expression of genes, revealed that G. inflata's resilience is linked to several key pathways. These include carbon metabolism, which is fundamental for energy production; the development of the Casparian strip, a barrier that helps regulate the movement of water and nutrients; and the transport of K+ and Ca2+. The study also highlighted the importance of antioxidant compounds like carotenoids and flavonoids in protecting the plant from the damaging effects of salt stress. Interestingly, the study observed that despite higher sodium levels in G. inflata's roots, the plant kept the concentration of malondialdehyde (MDA)—a marker of stress-induced damage—low. This suggests that G. inflata has robust mechanisms to cope with the oxidative stress caused by salt. The plant's ability to maintain a balance of ions, particularly by accumulating more K+ and Ca2+, and synthesizing protective compounds, seems to be key to its salt tolerance. The research also pointed to the role of hormone signaling, particularly abscisic acid (ABA), and specific transcription factors in managing the plant's response to salinity. These findings open up potential strategies for cultivating G. uralensis in saline conditions by selecting for or engineering these traits. In conclusion, the Shihezi University study has provided valuable insights into the genetic and physiological mechanisms that underpin the salt tolerance of G. inflata. It has expanded on previous research by highlighting the importance of carbon metabolism, ion transport, and antioxidant defense in enabling licorice to grow in saline soils[2][3][4]. This knowledge is not only crucial for the licorice industry but also offers broader lessons for the cultivation of medicinal plants facing the challenge of salinity, a growing concern in many parts of the world.

GeneticsBiochemPlant Science

References

Main Study

1) Integrative physiology and transcriptome reveal salt-tolerance differences between two licorice species: Ion transport, Casparian strip formation and flavonoids biosynthesis.

Published 11th April, 2024

https://doi.org/10.1186/s12870-024-04911-1

Related Studies

2) Silicon improves ion homeostasis and growth of liquorice under salt stress by reducing plant Na+ uptake.

https://doi.org/10.1038/s41598-022-09061-8

3) The physicochemical approaches of altering growth and biochemical properties of medicinal plants in saline soils.

https://doi.org/10.1007/s00253-022-11838-w

4) Na+ transport in plants.

Journal: FEBS letters, Issue: Vol 581, Issue 12, May 2007


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