Physiological and Proteomic Analysis in Chloroplasts of Solanum lycopersicum L. under Silicon Efficiency and Salinity Stress

Abstract

Tomato plants often grow in saline environments in Mediterranean countries where salt accumulation in the soil is a major abiotic stress that limits its productivity. However, silicon (Si) supplementation has been reported to improve tolerance against several forms of abiotic stress. The primary aim of our study was to investigate, using comparative physiological and proteomic approaches, salinity stress in chloroplasts of tomato under silicon supplementation. Tomato seedlings (Solanum lycopersicum L.) were grown in nutrient media in the presence or absence of NaCl and supplemented with silicon for 5 days. Salinity stress caused oxidative damage, followed by a decrease in silicon concentrations in the leaves of the tomato plants. However, supplementation with silicon had an overall protective effect against this stress. The major physiological parameters measured in our studies including total chlorophyll and carotenoid content were largely decreased under salinity stress, but were recovered in the presence of silicon. Insufficient levels of net-photosynthesis, transpiration and stomatal conductance were also largely improved by silicon supplementation. Proteomics analysis of chloroplasts analyzed by 2D-BN-PAGE (second-dimensional blue native polyacrylamide-gel electrophoresis) revealed a high sensitivity of multiprotein complex proteins (MCPs) such as photosystems I (PSI) and II (PSII) to the presence of saline. A significant reduction in cytochrome b6/f and the ATP-synthase complex was also alleviated by silicon during salinity stress, while the complex forms of light harvesting complex trimers and monomers (LHCs) were rapidly up-regulated. Our results suggest that silicon plays an important role in moderating damage to chloroplasts and their metabolism in saline environments. We therefore hypothesize that tomato plants have a greater capacity for tolerating saline stress through the improvement of photosynthetic metabolism and chloroplast proteome expression after silicon supplementation.

Na2CO3-Responsive Photosynthetic and ROS Scavenging Mechanisms in Chloroplasts of Alkaligrass Revealed by Phosphoproteomics

“…Current high-throughput proteomic approaches are powerful to untangle the complicated mechanisms of chloroplast development, metabolism and stress response [7-10]. More than 522 NaCl-responsive chloroplast proteins were found in different plant species, such as tomato ( Solanum lycopersicum ) [11], wheat ( Triticum aestivum ) [12], and other plant species [13-18]. The presence of these proteins indicate that the light harvesting, photosynthetic electron transfer, carbon assimilation, ROS homeostasis, energy metabolism, signaling, and membrane trafficking were modulated in chloroplasts in response to NaCl stress.…”

Silicon-induced Salinity Tolerance Improves Photosynthesis, Leaf Water Status, Membrane Stability, and Growth in Pepper (Capsicum annuum L.)

“…As a result of this imbalance, levels of reactive oxygen species increase, while plant growth and yield decline (Liang et al, 2015). It has been widely reported that the application of Si to plants may increase salt tolerance among many important agricultural crops, such as wheat (Ahmad, 2014;Gurmani et al, 2013a), rice (Gong et al, 2006;Gurmani et al, 2013b;Kim et al, 2014), maize (Kochanov a et al, 2014;Xie et al, 2015), barley (Liang et al, 2005), sorghum (Kafi et al, 2011;Yin et al, 2013), tomato (Liang et al, 2015;Muneer et al, 2014), and soybean (Lee et al, 2010). In this study, we investigate the effect of Si (grown under two salinity regimes) on two pepper cultivars, one salt-tolerant and the other saltsensitive.…”

INOCULATION WITH Rhizobial consortium FOR IMPROVING THE GROWTH, YIELD AND QUALITY OF MAIZE UNDER SALT-STRESSED CONDITIONS

“…Deficiency of these minerals especially N, may cause inhibition in the formation of chlorophyll molecules under increased salinity stress (Huang et al, 2004). Moreover, high concentration of salts in the leaves might have caused overproduction of reactive oxygen species (ROS) and forced the chloroplast to destroy all protein component of chloroplast (Muneer et al, 2014). However, rhizobial inoculation resulted in improved chlorophyll contents a, b, and carotenoids compared to respective un-inoculated controls.…”