Linking exogenous foliar application of glycine betaine and stomatal characteristics with salinity stress tolerance in cotton (Gossypium hirsutum L.) seedlings

BMC Plant Biol. 2021 Mar 20;21(1):146. doi: 10.1186/s12870-021-02892-z.


Background: Glycine betaine (GB) plays a crucial role in plants responding to abiotic stresses. Studying the physiological response of cotton seedlings to exogenous GB under salt stress provides a reference for the application of GB to improve the resistance of cotton seedlings under salt stress. The purpose of this research is to examine the impacts of foliar-applied GB on leaf stomatal structure and characteristics, gas exchange and chlorophyll fluorescence characteristics and plant growth indicators of Gossypium hirsutum L. under NaCl stress conditions.

Results: Under the salinity of 150 mM, the four concentrations of GB are 0, 2.5, 5, and 7.5 mM, and the control (CK) was GB-untreated non-saline. Salt stress negatively affected leaf stomata as well as gas exchange and chlorophyll fluorescence and decreased plant growth parameters of cotton seedlings. The treatment with 5 mM GB significantly increased the evolution of photosynthetic rate (Pn), transpiration rate (Tr), intracellular CO2 concentration (Ci) and stomatal conductance (gs) compared to the GB-untreated saline treatment. The Exogenous foliar-applied GB has sustainably decreased the carboxylation efficiency (Pn/Ci) and water use efficiency (WUE). The concentration of 5 mM GB leads to a significant improvement of leaf stomatal characteristics. The leaf gas exchange attributes correlated positively with stomatal density (SD), stomatal length (SL) and stomatal with (SW).

Conclusion: The overall results suggested that exogenous foliar supplementation with GB can effectively alleviate the damage of salt stress to cotton seedlings. The effect of applying 5 mM GB could be an optional choice for protecting cotton seedlings from NaCl stress through promoting the stomatal functions, photosynthetic activities and growth characteristics.

Keywords: Chlorophyll fluorescence; Cotton; Glycine betaine; Photosynthesis; salinity; Stomata.

MeSH terms

  • Betaine / pharmacology*
  • Chlorophyll / metabolism
  • Gossypium / drug effects*
  • Gossypium / metabolism
  • Gossypium / physiology
  • Photosynthesis
  • Plant Leaves / drug effects*
  • Plant Proteins / metabolism
  • Plant Stomata / drug effects*
  • Plant Stomata / physiology
  • Proline / metabolism
  • Salt Stress / drug effects
  • Salt Stress / physiology
  • Salt Tolerance / drug effects
  • Salt Tolerance / physiology
  • Seedlings / drug effects
  • Seedlings / physiology
  • Sugars / metabolism


  • Plant Proteins
  • Sugars
  • Chlorophyll
  • Betaine
  • Proline