Role of salicylic acid in regulating ethylene and physiological characteristics for alleviating salinity stress on germination, growth and yield of sweet pepper

Abstract

Background During a preliminary study, effects of 0, 20, 40, and 60 mM NaCl salinity were assessed on germination rate in relation to electrolyte leakage (EL) in sweet pepper. Results explored significant rises in ethylene evolution from seeds having more EL. It was, therefore, hypothesized that excessive ethylene biosynthesis in plants due to salinity stress might be a root cause of low crop productivity. As salicylic acid is one of the potent ethylene inhibitors, thus SA was used to combat effects of ethylene produced under salinity stress of 60 mM NaCl on different physiological and morphological characteristics of sweet pepper. Methodology The effect of 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mM SA was evaluated on seed germination, growth and yield of sweet pepper cv. Yolo wonder at salinity stress on 60 mM NaCl. Seeds were primed with SA concentrations and incubated till 312 h in an incubator to study germination. Same SA concentrations were sprayed on foliage of plants grown in saline soil (60 mM NaCl). Results Seeds primed by 0.2 to 0.3 mM SA improved germination rate by 33% due to suppression of ethylene from 3.19 (control) to 2.23–2.70 mg plate−1. Electrolyte leakage reduced to 20.8–21.3% in seeds treated by 0.2–0.3 mM SA compared to 39.9% in untreated seeds. Results also explored that seed priming by 0.3 mM improved TSS, SOD and chlorophyll contents from 13.7 to 15.0 mg g−1 FW, 4.64 to 5.38 activity h−1 100 mg−1 and 89 to 102 ug g−1 compared to untreated seeds, respectively. Results also explore that SA up to 0.2 mM SA applied on plant foliage improved LAI (5–13%), photosynthesis (4–27%), WUE (11–57%), dry weight (5–20%), SOD activity (4–20%) and finally fruit yield (4–20%) compared to untreated plants by ameliorating effect of 60 mM NaCl. Foliar application of SA also caused significant increase in nutrient use efficiency due to significant variations in POD and SOD activities. Conclusion Salicylic acid suppressed ethylene evolution from germinating seeds up to 30% under stress of 60 mM NaCl due to elevated levels of TSS and SOD activity. Foliar application of SA upgraded SOD by lowering POD activity to improve NUE particularly K use efficiency at salinity stress of 60 mM NaCl. Application of 0.2 and 0.3 mM SA emerged as the most effective concentrations of SA for mitigating 60 mM NaCl stress on different physiological and morphological characteristics of sweet pepper.

Ethylene: A Master Regulator of Salinity Stress Tolerance in Plants

“…In Faba beans (Vicia faba), seed germination in salinity-tolerant Y134 is not inhibited during salinity stress as compared to the salinity-sensitive Y078 probably because of the downregulation of genes related to ABA and ethylene signaling pathways and upregulation of late embryogenesis abundant (LEA) genes [106]. Seeds of Capsicum annuum primed with SA showed higher a germination rate due to suppression of the ethylene level as well as elevation of total soluble sugar contents and SOD activity [107].…”

MES7 Modulates Seed Germination Via Regulating Salicylic Acid Content in Arabidopsis

“…4b). In addition to affecting germination under normal condition, SA also increases the resistance to various abiotic stresses, minimizes ROS-mediated oxidative damages, and enhances seed germination followed by an exposure to stress (Borsani et al 2001;Ahmed et al 2020). SA increases reactive oxygen species (ROS)-mediated oxidative damage and induces H 2 O 2 production, which adversely affects germination (Rao et al 1997;Harfouche et al 2008).…”

Uncover the salt tolerance potential of accessions based on photosynthetic attributes and interaction plot in tomato (Solanum lycopersicum)

“…Salinization is considered the most serious abiotic stress to crop productivity globally (Ghassemi et al., 1995). It induces negative impact on water use efficiency, nutritional balance, plant growth and development, photosynthetic pigments and production quality resulting in low crop production up to 80% or sometimes crop failure (Ahmed et al., 2020; Alcaraz‐Meléndez et al., 2015). At the global level, salinity has devastating impacts on irrigated land as well as dryland agriculture estimating about 230 million ha (19.5%) and 45 million ha (2.1%), respectively (FAO, 2017).…”

“…Furthermore, salt stress widely spreads in different parts of the world and could reveal devastating effects on all arable lands until 2050 (Arias et al., 2018; Wang et al., 2003). Though, saline conditions repress the plant growth and development due to osmotic stress, and additionally, ion toxicity also restricts the agricultural crop productivity (Ahmed et al., 2020; Alcaraz‐Meléndez et al., 2015; Munns, 2002; Wang et al., 2003). Naturally, plants adapt internal mechanism to cope with environmental stresses; while, under salinity stress plant occupy various defensive mechanisms against different stresses such as hormonal alterations, antioxidants production, ion formation both physical and chemical and compartmentalization and biosynthesis of sugars, betain and glycine (Arias et al., 2018).…”

“…However, primitive land races and related wild species of tomato are considered the likely potential source of salt tolerance (Bolarin et al., 1991; Tal & Shannon, 1983). The presence of phytohormone or plant growth regulator such as salicylic acid (SA) could trigger the regulation of ion uptake and antioxidant enzymes, which potentially mitigate the salinity impacts on growth and development of plants and establish defensive block in plants (Ahmed et al., 2020). Besides, grafting could be effective to facilitate plant tolerance against biotic and abiotic stresses (Keatinge et al., 2014) and, particularly, enhance resistance towards drought (Penella et al., 2017), salinity (Koleska et al., 2018) and temperature constraints (Venema et al., 2008; Xiaohui et al., 2019).…”