Ammonia stress on the carbon metabolism of Ceratophyllum demersum

Abstract

In the present study, carefully controlled pH ranges (7 and 9) were used to distinguish between the effects of un-ionized NH3 and the NH4 (+) ion. The objective was to find the effect of different total ammonia nitrogen concentrations and pH values on the carbon metabolism of Ceratophyllum demersum. The authors investigated the effects of ammonia on the nonstructural carbohydrate content in shoots of C. demersum. Ammonia treatment decreased the contents of nonstructural carbohydrate, soluble sugar, sucrose, fructose, and starch in leaves. Meanwhile, increasing the pH value exacerbated the decline of the C. demersum nonstructural carbohydrate content. In addition, the activity of invertase was increased during the experiment. These results suggest that ammonia severely inhibits plant growth by disturbing nonstructural carbohydrate content. It has been suggested that ammonia has toxic effects on C. demersum and that the higher the pH in water, the more obvious the physiological responses that C. demersum exhibits. The results of the present study can provide some reference for studying the living conditions of submersed macrophytes under the stress of NH3.

Higher Tolerance of Canopy-Forming Potamogeton crispus Than Rosette-Forming Vallisneria natans to High Nitrogen Concentration as Evidenced From Experiments in 10 Ponds With Contrasting Nitrogen Levels

“…In addition to excessive loading of phosphorus (P) (Scheffer, 1998; Carpenter, 2003), high nitrogen (N) loading has also been suggested to contribute importantly to the recession of macrophytes (Moss, 2001; Jeppesen et al, 2007; Moss et al, 2013). High N may cause physiological damage to the submersed macrophytes by generating oxidative stress (Wang et al, 2010; Zhang et al, 2011), disturbing the metabolism of carbon and nitrogen (Cao et al, 2009b; Gao et al, 2015; Yuan et al, 2015) and inhibiting photosynthesis (Wang et al, 2008; Su et al, 2012). High N may also affect the plants indirectly by promoting the growth of phytoplankton (Sayer et al, 2010a,b) or periphyton (Olsen et al, 2015; Zhao et al, 2016) and hence their shading effects.…”

Does the responses of Vallisneria natans (Lour.) Hara to high nitrogen loading differ between the summer high-growth season and the low-growth season?

“…Most scientists agree that phytoplankton shading promoted by increasing inputs of phosphorus is an underlying cause of the decreasing abundance, but the role of nitrogen has received increasing attention in recent years (Moss, 2001;Jeppesen et al, 2007;Moss et al, 2013). In previous studies, two main mechanisms have been identified to explain the effects of nitrogen on submersed macrophytes: 1) it promotes the growth and hence shading of phytoplankton (Sayer et al, 2010a(Sayer et al, , 2010b or periphyton (Olsen et al, 2015;Zhao et al, 2016) that uses nitrogen as its nutrient source; 2) it causes physiological stress on the submersed macrophytes and limits the metabolism of carbohydrates (Cao et al, 2009a;Yuan et al, 2015;Gao et al, 2015), inducing oxidative stress (Wang et al, 2010;Zhang et al, 2011) and inhibiting photosynthesis (Wang et al, 2008;Su et al, 2012). Experimental studies have revealed that ammonium (NH 4 )-related physiological stress may be aggravated by low light conditions .…”

Effect of ammonia stress on nitrogen metabolism of Ceratophyllum demersum

“…Of course, many factors affect glutamine synthetase enzyme activity, such as organism situation, carbohydrates, amino acids, and light exposure . It has been shown that increased ammonium N reduced the chlorophyll content of C. demersum , resulting in reduced photosynthesis activity and reduced carbohydrate production , thus indirectly influencing glutamine synthetase enzyme activity.…”

“…The main reason may be that when a plant passively absorbs a large amount of N, ammonium N accumulation in the tissue leads to changes in the concentration of free amino acid in N metabolism. This results in substantial ammonia accumulation, physiological toxicity, and a response to this ammonia stress through a high consumption of nonstructural carbohydrates .…”