Biochemical adaptations of four submerged macrophytes under combined exposure to hypoxia and hydrogen sulphide

Abstract

A hydroponic experiment was performed to investigate the stress responses and biochemical adaptations of four submerged macrophytes, Potamogeton crispus, Myriophyllum spicatum, Egeria densa, and Potamogeton oxyphyllus, to the combined exposure of hypoxia and hydrogen sulfide (H2S, provided by NaHS). The investigated plants were subjected to a control, hypoxia, 0.1mM NaHS, 0.5 mM NaHS, 0.1 mM NaHS+hypoxia and 0.5 mM NaHS+hypoxia conditions. All experimental plants grew optimally under control, hypoxic and NaHS conditions in comparison to that grown in the combined exposure of hypoxia and hydrogen sulfide. For P. crispus and M. spicatum, significant decreases of total chlorophyll and increases in oxidative stress (measured by hydrogen peroxide, H2O2, and malondialdehyde, MDA) were observed with exposure to both sulfide concentrations. However, the decrease in catalase (CAT) and ascorbate peroxidase (APX) from exposure to 0.5 mM NaHS suggests that the function of the protective enzymes reached their limit under these conditions. In contrast, for E. densa and P. oxyphyllus, the higher activities of the three antioxidative enzymes and their anaerobic respiration abilities (ADH activity) resulted in higher tolerance and susceptibility under high sulfide concentrations.

Impact of moderate heat stress on the biochemical and physiological responses of the invasive waterweed Elodea canadensis (Michx. 1803)

“…Obviously, the plants exposed to mild or moderate HS exhibited an increase in activity of the enzymatic antioxidant systems. Similar results were observed in plants exposed to other moderate environmental stresses, such as water [36,37] and salt stress [20].…”

“…However, increased ROS accumulation was observed at a higher temperature (35°C) for E. nuttallii; as a result, it suppressed the competitive ability of the plant [40]. Similar results were observed after moderate salt stress [20] and exposure to low concentrations of urea [41] in E. densa.…”

“…However, less attention has been paid to heat-induced oxidative stress and antioxidant system activity in aquatic macrophytes. There are a few cases where the stressinduced oxidative reactions in aquatic macrophytes have been measured, and most of these studies have focused on the biochemical and physiological changes under different stressors such as hypoxia, salinity, heavy metals [17][18][19][20][21].…”

Invasive Macrophytes Control the Spatial and Temporal Patterns of Temperature and Dissolved Oxygen in a Shallow Lake: A Proposed Feedback Mechanism of Macrophyte Loss

“…While some submerged macrophytes may survive bottom-water anoxia by supplying oxygen to below-ground tissue ( Sand-Jensen et al, 1982 ; Lemoine et al, 2012 ), P. crispus cannot maintain oxygenated conditions within the sediments ( Aldridge and Ganf, 2003 ; Boros et al, 2011 ) and thus may be more susceptible to anoxia exposure. Although the effect of water column anoxia on P. crispus survival has not yet been investigated, P. crispus can tolerate hypoxic conditions but is unable to survive under a combination of hypoxia and 0.5 mM of sulfide ( Parveen et al, 2017 ). Under anoxic conditions, sulfide is likely to accumulate ( Borum et al, 2005 ).…”

Evaluation of Habitat Preferences of Invasive Macrophyte Egeria densa in Different Channel Slopes Using Hydrogen Peroxide as an Indicator

“…In natural water, macrophytes are subjected to environmental stresses, such as flow velocity, high solar radiation, excessive high or low temperature, etc. In cell organelles, then, reactive oxygen species (ROS) are generated based on the intensity of the stresses, photosynthesis and metabolic activities (Zaman and Asaeda, 2013;Asaeda and Rashid, 2017;Parveen et al, 2017a). A part of these ROS is scavenged relatively quickly by antioxidant activities, and the homogeneity of ROS in tissues is maintained by a balance between the ROS and the antioxidants.…”