Elevated atmospheric CO2 concentration ameliorates effects of NaCl salinity on photosynthesis and leaf structure of Aster tripolium L.

Abstract

This study investigated the interaction of NaCl-salinity and elevated atmospheric CO2 concentration on gas exchange, leaf pigment composition, and leaf ultrastructure of the potential cash crop halophyte Aster tripolium. The plants were irrigated with five different salinity levels (0, 25, 50, 75, 100% seawater salinity) under ambient and elevated (520 ppm) CO2. Under saline conditions (ambient CO2) stomatal and mesophyll resistance increased, leading to a significant decrease in photosynthesis and water use efficiency (WUE) and to an increase in oxidative stress. The latter was indicated by dilations of the thylakoid membranes and an increase in superoxide dismutase (SOD) activity. Oxidative stress could be counteracted by thicker epidermal cell walls of the leaves, a thicker cuticle, a reduced chlorophyll content, an increase in the chlorophyll a/b ratio and a transient decline of the photosynthetic efficiency. Elevated CO2 led to a significant increase in photosynthesis and WUE. The improved water and energy supply was used to increase the investment in mechanisms reducing water loss and oxidative stress (thicker cell walls and cuticles, a higher chlorophyll and carotenoid content, higher SOD activity), resulting in more intact thylakoids. As these mechanisms can improve survival under salinity, A. tripolium seems to be a promising cash crop halophyte which can help in desalinizing and reclaiming degraded land.

Elevated atmospheric CO2 concentration enhances salinity tolerance in Aster tripolium L.

“…The low net assimilation rate on saline media has two likely consequences for the plant: First, the supply of energy-rich organic substances is shortened. Second, there will be an increase in oxidative stress (Lovelock and Ball 2002), indications of which have already been provided for A. tripolium (see ''Introduction'';Geissler et al 2009b).…”

Changes in Whole-Plant Metabolism During Grain-Filling Stage in Sorghum Bicolor L. (Moench) Grown Under Elevated Co2 and Drought

“…For instance, postanthesis drought can cause up to a 30% decrease in grain yield (Borrell et al, 2000). However, elevated [CO 2 ] commonly ameliorates the effects of environmental stresses Leakey et al, 2006;Geissler et al, 2009;Sicher and Barnaby, 2012;Naudts et al, 2013;Arenque et al, 2014;Zinta et al, 2014), reducing the impact on photosynthesis, biomass production, and loss in productivity.…”

Effects of elevated CO2 on growth, photosynthesis, elemental composition, antioxidant level, and phytochelatin concentration in Lolium mutiforum and Lolium perenne under Cd stress

“…Even at relatively low concentrations it can exert strong toxic effects on crops [13]. Cd induces severe oxidative stress by producing excessive ROS [14], causing severe damage to membrane systems, cell organelles and DNA [15,16]. MDA is a major product of membrane lipid peroxidation, and its level is an indicator of the extent of oxidative damage [14].…”