Cellular and Molecular Mechanisms of Cold Plasma Action Under Pathogen-Associated Salinity Stress In-Vitro Study

Abstract

Background: Salinity is a major abiotic stress that severely limits the growth and productivity of sweet pepper (Capsicum annuum L.) by inducing osmotic imbalance, ionic toxicity, and oxidative stress. Developing sustainable and eco-friendly approaches to enhance plant tolerance under saline conditions is therefore essential.

Objectives: This study aimed to investigate the effectiveness of cold plasma (dielectric barrier discharge device, DBD) seed priming in improving germination, growth performance, biochemical responses, and stress-related gene expression in sweet pepper under pathogen-associated salinity stress.

Methodology: This experimental study was conducted in the Department of Biology, College of Science for Women, University of Baghdad, Baghdad, Iraq. Between December 2024 to September 2025. Seeds were treated with cold plasma for 60 and 180 seconds and cultured under different salinity levels (8, 10, and 12 dS/m). Germination parameters and seedling growth traits were evaluated, along with callus induction and growth. Biochemical analyses included proline content and antioxidant enzymes (CAT and SOD), while gene expression of CaDHN3 and CaSOS1 was quantified using qRT-PCR.

Results: Plasma treatment significantly improved germination percentage (from 75% to 91.67%) and enhanced seedling growth, particularly root development (25.33 roots at 8 dS/m). Salinity reduced growth and callus biomass; however, plasma mitigated these effects under moderate stress. Biochemical responses showed increased proline accumulation (41.06 μmol/g FW) and enhanced antioxidant enzyme activities, with CAT reaching 0.976 U/mL and SOD 145.28 U/mL. At the molecular level, CaDHN3 expression increased up to 22.47-fold in callus and 13.74-fold in leaves, while CaSOS1 reached 13.64-fold and 13.18-fold, respectively, indicating improved osmotic adjustment and ion homeostasis.

Conclusion: Cold plasma priming effectively enhances physiological, biochemical, and molecular defense mechanisms in sweet pepper under salinity stress. This approach improves germination, growth, antioxidant capacity, and stress-responsive gene expression, offering a promising and sustainable strategy for enhancing salinity tolerance and crop productivity.

Bangladesh Journal of Infectious Diseases, June 2026;13(1):113-125