Metabolic, Ultra-Structural and Growth Responses of Nuttall’s Waterweed Elodea Nuttallii (Planch) St. John When Subjected to Water Flow

Abstract

Importance of water movements on distribution and abundance of aquatic plants is well studied, but there is a dearth of information on its impacts on physiology, anatomy and biochemistry of these plants. Therefore, present study was carried out to investigate the growth, metabolism and ultra-structural changes in aquatic macrophyte Elodea nuttallii upon exposure to water flow (10 cm∙s-1) for 30 days, compared to exposure to stagnant water as the control. Three replicates of five plants each were used for each treatment. At the end of the exposure period, shoot length of the plants were measured, and metabolic and ultra-structural changes were analyzed using capillary electrophoresis–mass spectrometry (CE-MS) and electron microscopy respectively. Shoot length appeared to be similar in both treatments but a flow oriented stream lined growth was exhibited in plants exposed to water flow. In the control group, only 12% of internodes were longer than 6 mm while in plants exposed to water flow more than 35 % of internodes were longer than 6 mm. Fructose-6-phosphate, glucose-1-phosphate, glucose-6-phosphate, phosphoenolpyruvate, ribose-5-phosphate and cinnamate contents were significantly higher in flow treated plants when compared to controls. Content of all other metabolites were similar in both treatment groups. These findings offer insights to understand the interactions between water flow regimes and the functions of aquatic plants and such information would help aquatic ecosystem management.