Nitrogen availability prevents oxidative effects of salinity on wheat growth and photosynthesis by up-regulating the antioxidants and osmolytes metabolism, and secondary metabolite accumulation

Abstract

BackgroundSalinity is one of the damaging abiotic stress factor. Proper management techniques have been proposed to considerably lower the intensity of salinity on crop growth and productivity. Therefore experiments were conducted to assess the role of improved nitrogen (N) supplementation on the growth and salinity stress tolerance in wheat by analyzing the antioxidants, osmolytes and secondary metabolites.ResultsSalinity (100 mM NaCl) stress imparted deleterious effects on the chlorophyll and carotenoid synthesis as well as the photosynthetic efficiency. N supplementation resulted in increased photosynthetic rate, stomatal conductance and internal CO2 concentration with effects being much obvious in seedlings treated with higher N dose. Under non-saline conditions at both N levels, protease and lipoxygenase activity reduced significantly reflecting in reduced oxidative damage. Such effects were accompanied by reduced generation of toxic radicals like hydrogen peroxide and superoxide, and lipid peroxidation in N supplemented seedlings. Antioxidant defence system was up-regulated under saline and non-saline growth conditions due to N supplementation leading to protection of major cellular processes like photosynthesis, membrane structure and function, and mineral assimilation. Increased osmolyte and secondary metabolite accumulation, and redox components in N supplemented plants regulated the ROS metabolism and NaCl tolerance by further strengthening the antioxidant mechanisms.ConclusionsFindings of present study suggest that N availability regulated the salinity tolerance by reducing Na uptake and strengthening the key tolerance mechanisms.

Nitrogen Enhances Salt Tolerance by Modulating the Antioxidant Defense System and Osmoregulation Substance Content in Gossypium hirsutum

“…Moreover, the higher reduction in the SS cultivar indicated a more severe adverse effect of salinity on the SS cultivar, which is consistent with previous reports [41,42]. Recent studies in tomato [17], wheat [21], Hordeum vulgare [43], Carrizo citrange [44], Spartina alterniflora [45], Sorghum bicolor [46], and Brassica [34] showed that higher nitrogen supplementation can regulate the salinity tolerance and improve plant growth. In the experiments reported here, application of 2.5 mmol·L −1 nitrogen increased the SL, NL per plant, and total biomass in both ST and SS genotypes under salt stress (Figure 2).…”

“…Moreover, in support of the outcomes of the present study, several other scholars reported that co-application of nitrogen significantly boosted the level of antioxidant enzymes in soybean [56], Catharanthus roseus [57], and blueberry [58]. Nitrogen serves as a first line of defense against internal and environmental oxidative stressors [17,21,59,60]. Moreover, the positive effect of nitrogen may be related to nitrogen being an effective component of antioxidant enzymes and antioxidants [17,27].…”

“…This has partly been attributed to higher activities of their antioxidant enzyme system and/or a higher content of non-enzymatic antioxidants [8,54,55]. Since nitrogen can improve the antioxidant capacity and salt tolerance [21], this study examined the contents of H 2 O 2 , SOD, CAT, POD, and free amino acids. The results showed that the generation rate of H 2 O 2 was increased by salinity compared with control, especially in the SS genotype.…”

“…The over-accumulation of ROS not only damages cellular and biological activities [18][19][20], but also degrades chlorophyll pigments and obstructs the synthesis of proteins, amino acids, lipids, deoxyribonucleic acid, as well as enzymatic and non-enzymatic activities of plants [17]. To avoid ROS-induced oxidative damage, plant-assured endogenous tolerance approaches, such as the antioxidant defense system as well as the accumulation of organic solutes and secondary metabolites [21]. Superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) are considered active oxygen-scavenging enzymes.…”

Serratia marcescens BM1 Enhances Cadmium Stress Tolerance and Phytoremediation Potential of Soybean Through Modulation of Osmolytes, Leaf Gas Exchange, Antioxidant Machinery, and Stress-Responsive Genes Expression

“…Cadmium retards vital physio-biochemical activities in plants, which include photosynthesis, biosynthesis of chlorophyll and accessory pigments, and the uptake and assimilation of essential mineral nutrients by triggering the overproduction of reactive oxygen species (ROS), including singlet oxygen ( 1 O 2 ), hydrogen peroxide (H 2 O 2 ), superoxide radical (O 2 • − ), and the hydroxyl radical (OH•) [5,6]. ROS accumulation causes high toxicity in plant cells [7][8][9][10][11][12][13][14][15][16]. Cadmium evokes peroxidation of membrane lipids and modulates the expression of genes of antioxidant defense systems in plants [17].…”