Do reactive oxygen species (ROS) induced by NaCl contribute to ammonium accumulation in Spartina alterniflora?

Abstract

Growth, activity of antioxidant enzymes viz. glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX), and some metabolic processes related to ammonium metabolism were investigated in a salt-tolerant Spatina alterniflora. In comparison to 0 mM-NaCl treatment, growth of S. alterniflora plant increased significantly at 200 mM NaCl, but was highly inhibited at 500 mM NaCl. Ammonium concentration in the leaves and roots increased 2.1-3.4 times when plants were treated with 500 mM NaCl. Under 200 mM NaCl, antioxidant-enzyme activities increased, however, at 500 mM the antioxidant system was unable to compensate reactive oxygen species induced by NaCl. At this high level of salinity, ammonium production through nitrate reductase (NR) was inhibited, but no significant changes in the activities of glutamine synthetase (GS) or glutamate dehydrogenase (GDH) were found. We conclude that the accumulation of ammonium under high salt stress was not due to inhibition of the assimilatory activities of GS or GDH. Ammonia accumulation under high salinity may result from amino acid and protein catabolism activated by reactive oxygen species (ROS) and/or a lack of carbon skeletons to incorporate ammonium into organic molecules due to a decrease in photosynthetic activity in salt-stressed plants.

Transcriptomic and Physiological Analysis Reveals Genes Associated with Drought Stress Responses in Populus alba × Populus glandulosa

“…Drought stress can lead to oxidative damage in plants due to the accumulation of ROS, such as H 2 O 2 , superoxide, hydroxyl radical, and singlet oxygen. These ROS can cause the peroxidation of unsaturated fatty acids in phospholipids, resulting in damage to the cell membrane and macromolecules under both abiotic and biotic stress conditions [ 57 ]. The drought-treated clone 72-30 showed a nearly threefold increase in MDA content, which was associated with an increase in H 2 O 2 content and a decrease in SOD and POD activity ( Figure 2 ).…”

Drought and salinity: A comparison of their effects on the ammonium‐preferring species Spartina alterniflora

“…Thus, regulating the distribution of ions within cells may be a crucial feature of osmotic stress resistance. However, and in accordance with previous studies (Hessini et al ., 2008; 2009a), S. alterniflora seems better adapted to salinity than drought, which may reflect its halophytic characteristics (Fuchen and Fang, 2007; Hessini et al ., 2009b; Carol et al ., 2019). Although detrimental to most plants, moderate salinity levels (millimolar‐range) can be beneficial for some halophytic C 4 ‐type plants and non‐halophytic species, such as maize ( Zea mays ; Pilon‐Smits et al ., 2009, Maathuis, 2014, Colmenero‐Flores et al ., 2019).…”

“…Nitrogen as a mineral nutrient is one of the crucial environmental factors regulating plant development. Plants mainly take up N as nitrate and ammonium, with most species thriving in the presence of nitrate (Hessini et al ., 2009b; Marino and Moran, 2019), and only a few favoring ammonium (Ashraf et al ., 2018; Hessini et al ., 2019).…”

Exogenous proline affects nitrogen assimilation, mineral uptake, and antioxidant activity in tomato plants under NO3–/NH4+ proportions

“…There is also a lack of studies showing the interaction between NH 4 + and its assimilation products, such as the amino acid: proline. The interaction could be important for the activation of N assimilation in metabolic pathway, antioxidant system improvement and photosynthesis (Misra and Gupta, 2006;Hessini et al, 2009). Therefore, the hypothesis of the current study is that exogenous proline may interact with NO 3 -/NH 4 + to increase N assimilation and thus mineral uptake, photosynthesis, and plant growth.…”