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Plant function and evolutionary biology
RESEARCH ARTICLE (Open Access)

Modulation of ion transporter genes of salt-stressed sorghum (Sorghum bicolor L. Moench) by foliar application of digitoxin

Hanan Shaaban https://orcid.org/0009-0002-4485-6479 A * , Alyaa S. Abdel Halim B , Hemmat I. Khattab A and Rabab A. Abdulhai C
+ Author Affiliations
- Author Affiliations

A Department of Botany, Faculty of Science, Ain Shams University, Abasia, Cairo, Egypt.

B Department of Biochemistry, Faculty of Science, Ain Shams University, Abasia, Cairo, Egypt.

C Department of Botany, Faculty of Women for Arts, Science and Education, Ain Shams University, Abasia, Cairo, Egypt.

* Correspondence to: hanan.shaban@sci.asu.edu.eg

Handling Editor: Fanrong Zeng

Functional Plant Biology 52, FP25031 https://doi.org/10.1071/FP25031
Submitted: 6 February 2025  Accepted: 1 August 2025  Published: 4 September 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Salinity poses a major threat to cereal crops such as sorghum. The foliar application of digitoxin at concentrations of 50, 100, and 200 ppm was tested for its potential to alleviate salt stress in sorghum (Sorghum bicolor) exposed to 200 mM NaCl. Various growth parameters were analyzed, such as relative water content, malondialdehyde (MDA), osmoregulatory compunds (soluble carbohydrates and proline), ionic markers (Na+ and K+ levels in shoots and roots), and the expression of specific ion transporter genes including NHX, SOS1, AKT1, PPV, and PHA1 during the seedling stage. Digitoxin treatment significantly enhanced biochemical and ionic characteristics in salt-stressed plants by enhancing the membrane stability index and reducing MDA levels while boosting soluble carbohydrates, free amino acids, and proline. Real-time PCR showed that digitoxin application triggered the upregulation of genes promoting Na+ and K+ balance and reducing ion toxicity. This study underscores the potential role of digitoxin in improving salt tolerance through its influence on the regulation of ion transporter gene expression specific for K+ and Na+ ion transport and homeostasis. The effect of digitoxin on the ion transporters seems to be dose-dependent. The mechanism of digitoxin’s effect on ion transporter gene expression of salt-stressed plants is discussed.

Keywords: abiotic stress, digitoxin, foliar application, ion homeostasis, ion transporter genes, salinity, secondary metabolites, sorghum.

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