Abstract
In this study, the anti-stress capabilities of the foliar application of chitosan, dissolved in four different organic acids (acetic acid, ascorbic acid, citric acid and malic acid) have been investigated on tomato (Solanum lycopersicum L.) plants under salinity stress (100 mM NaCl). Morphological traits, photosynthetic pigments, osmolytes, secondary metabolites, oxidative stress, minerals, antioxidant enzymes activity, isozymes and protein patterns were tested for potential tolerance of tomato plants growing under salinity stress. Salinity stress was caused a reduction in growth parameters, photosynthetic pigments, soluble sugars, soluble proteins and potassium (K+) content. However, the contents of proline, ascorbic acid, total phenol, malondialdehyde (MDA), hydrogen peroxide (H2O2), sodium (Na+) and antioxidant enzyme activity were increased in tomato plants grown under saline conditions. Chitosan treatments in any of the non-stressed plants showed improvements in morphological traits, photosynthetic pigments, osmolytes, total phenol and antioxidant enzymes activity. Besides, the harmful impacts of salinity on tomato plants have also been reduced by lowering MDA, H2O2 and Na+ levels. Chitosan treatments in either non-stressed or stressed plants showed different responses in number and density of peroxidase (POD), polyphenol oxidase (PPO) and superoxide dismutase (SOD) isozymes. NaCl stress led to the diminishing of protein bands with different molecular weights, while they were produced again in response to chitosan foliar application. These responses were varied according to the type of solvent acid. It could be suggested that foliar application of chitosan, especially that dissolved in ascorbic or citric acid, could be commercially used for the stimulation of tomato plants grown under salinity stress.
Highlights
This article is an open access articleSalinity considers one of the major abiotic stressors causing severe damage to crops throughout the world
Data in the current study have shown that treatment of tomato plants grown under salinity stress conditions treated with chitosan solutions significantly improved plant salt tolerance by increasing photosynthetic pigments
Our results have shown that stressed tomato plants treated with chitosan either dissolved in ascorbic acid or citric acid appeared a maximum banding of POD isozyme compared to other treatments
Summary
This article is an open access articleSalinity considers one of the major abiotic stressors causing severe damage to crops throughout the world. All the important physiological and metabolic pathways of plants are affected by salinity [2], distributed under the terms and conditions of the Creative Commons. Various biological processes in plants are affected as a result of an imbalance in the nutrient content, as well as ionic and osmotic stress, and/or these factors combined as a result of salt stress [4,5]. Obvious oxidative stress markers resulting from high salinity stress are the formation of reactive oxygen species (ROS) such as superoxide ions, hydrogen peroxide, hydroxyl radicals and hydrogen peroxide (H2 O2 ), which are proven to be highly detrimental to plants [7]. In plants grown under salt stress, substantial elevations of ROS scavenging enzymes such as polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) have been documented [8,9]. Biochemical markers have provided great interest in recent years as the data more accurately reflect genetic variability since they are direct gene products
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