Underwater Photosynthesis of Submerged Plants – Recent Advances and Methods

Abstract

We describe the general background and the recent advances in research on underwater photosynthesis of leaf segments, whole communities, and plant dominated aquatic ecosystems and present contemporary methods tailor made to quantify photosynthesis and carbon fixation under water. The majority of studies of aquatic photosynthesis have been carried out with detached leaves or thalli and this selectiveness influences the perception of the regulation of aquatic photosynthesis. We thus recommend assessing the influence of inorganic carbon and temperature on natural aquatic communities of variable density in addition to studying detached leaves in the scenarios of rising CO2 and temperature. Moreover, a growing number of researchers are interested in tolerance of terrestrial plants during flooding as torrential rains sometimes result in overland floods that inundate terrestrial plants. We propose to undertake studies to elucidate the importance of leaf acclimation of terrestrial plants to facilitate gas exchange and light utilization under water as these acclimations influence underwater photosynthesis as well as internal aeration of plant tissues during submergence.

A Shoot-Specific Hypoxic Response of Arabidopsis Sheds Light on the Role of the Phosphate-Responsive Transcription Factor PHOSPHATE STARVATION RESPONSE1

“…S2). Furthermore, submergence, where CO 2 in the surrounding water is still available in limited amounts (Pedersen et al, 2013), caused a similar but lower response (Fig. 1C).…”

“…As photoreceptors usually detect changes in light quality and quantity, it is unlikely that they could play a major role during oxygen or phosphate deficiency responses because of the similar light conditions used. However, under submergence, the quality and quantity of light could be modified (Sand-Jensen and KrauseJensen, 1997;Voesenek et al, 2006;Pedersen et al, 2013).…”

Gene Regulation and Survival under Hypoxia Requires Starch Availability and Metabolism

“…While during the day photosynthesis provides Glc for metabolic activities, transitory starch is required to sustain glycolysis at night (Streb and Zeeman, 2012). In the wild, plants are often submerged in muddy water, severely restricting photosynthesis (Pedersen et al, 2013), thus making starch produced before submergence of importance for maintaining glycolysis active. Differently from rice, little is known about the ability of Arabidopsis to utilize starch under conditions of limited oxygen availability.…”

The study of plant adaptation to oxygen deficiency in Saint Petersburg University

“…In wetland monocots hydrophobic wax cuticle on the leaf surface enlarges the gas-water interface and allows fast O 2 and CO 2 diffusion, which is important not only for respiration, but also for underwater photosynthesis (Pedersen, Colmer, and Sand-Jensen, 2013). During partial and complete submergence, internal aeration of wetland species relies on underwater photosynthesis during the day and entry of oxygen from the floodwater during the night (Winkel, Colmer, Ismail, and Pedersen, 2013).…”