Salicylic Acid Alleviates Aluminum Toxicity in Tomato Seedlings (Lycopersicum esculentum Mill.) through Activation of Antioxidant Defense System and Proline Biosynthesis

Abstract

The aim of this work was to evaluate the alleviating efficacy of salicylic acid (100, 250 and 500 μM) against the toxic effects of aluminum (Al) on two tomato cultivars (GOWRI and SIRI) differing in their sensitivity to Al stress. Al treatment (500 µM) caused 40% -80% drop in plant growth, relative water content (RWC) and cell viability and a reduction of 1 -2.5 fold and 0.5 -2 fold in glutathione and proline content respectively, when compared to their control plants grown in Al free medium. Al treatment also resulted in 2 -5 fold raise in malondialdehyde (MDA) levels, 2 -3 fold higher Al uptake and 55% -80% more electrolyte leakage and caused severe DNA damage. Al stress enhanced (1 -2 fold) the activities of superoxide dismutase (SOD) and peroxidase (POD), but decreased catalase (CAT) activity over their respective controls. Exogenously-applied Salicylic acid (SA) significantly (p < 0.05) and dose-dependently alleviated Al-induced toxicity in tomato seedlings as marked by much improved plant growth, retention of higher RWC, cell viability, glutathione and proline content. SA also caused 0.6 -1.5 fold reduction in Al uptake, 50% -80% less electrolyte leakage, 40% -80% drop in lipid peroxidation and considerable protection against DNA damage. Also, supplementation of SA could considerably reverse the Al-induced changes in the activities of SOD, POD and CAT. Together, our findings demonstrate that, SA is an efficient growth regulator with diversified roles that contribute to its potential alleviating effect against Al induced toxicity and SIRI is a relatively Al-resistant cultivar compared to GOWRI. * Corresponding author. V. Surapu et al.778

Sulfur-Mediated-Alleviation of Aluminum-Toxicity in Citrus grandis Seedlings

“…Al-toxicity can stimulate ROS production, thus causing peroxidation of proteins and membrane lipids in plant cells [ 10 , 11 , 12 , 13 ]. Both MDA (an indicator for lipid peroxidation) and electrolyte leakage (an indicator for cell membrane integrity) are often used to estimate the ROS-mediated damage to cell membranes and to evaluate plant Al-tolerance [ 12 ]. To explore the role of S in mediating Al-induced oxidative stress, we measured H 2 O 2 production, MDA, and total soluble protein levels and electrolyte leakage in roots and leaves ( Figure 4 B–E,G–J).…”

“…Al-toxicity can cause the accumulation of reactive oxygen species (ROS), thus leading to peroxidation of proteins and membrane lipids in plant cells. Lipid peroxidation may cause loss of plasma membrane integrity and electrolyte leakage [ 9 , 10 , 11 , 12 , 13 ]. Increasing evidence shows that antioxidant enzyme activities play a key role in plant Al-tolerance [ 14 , 15 , 16 ].…”

Salicylic Acid Alleviates Aluminum Toxicity in Soybean Roots through Modulation of Reactive Oxygen Species Metabolism

“…SA suppressed the Al-induced enhancement in SOD, GPX, and APX activities but alleviated the Al-induced reduction in CAT activity in rice (Pandey et al, 2013 ). In tomato, SA significantly reversed the Al-induced changes in the activities of SOD, POD, and CAT (Surapu et al, 2014 ). These discrepancies may be caused by the different research methods, the time course of measurements and plant species.…”

“…It has been shown that Arabidopsis NPR1 plays a role in SA-mediated antioxidant defense under Al stress (Guo et al, 2014 ; Zhang et al, 2014 ). The protective effects of exogenous SA on Al-toxicity by preventing Al-induced oxidative stress have been extensively described in various plant species, such as, tomato (Surapu et al, 2014 ), Coffea arabica (Mu-oz-Sanchez et al, 2013 ), Cassia tora (Yang et al, 2003 ), cauliflower (Sinha et al, 2015 ), barley (Song et al, 2011 ), wheat (Uysal et al, 2009 ), Matricaria chamomilla (Kováčik et al, 2012 ), and rice (Pandey et al, 2013 ). It was found that SA suppressed the Al-induced enhancement of superoxide dismutase (SOD), glutathione peroxidase (GPX) and ascorbate peroxidase (APX) activities and increased catalase (CAT) activity in rice plants exposed to Al stress (Pandey et al, 2013 ).…”

Importance of Mineral Nutrition for Mitigating Aluminum Toxicity in Plants on Acidic Soils: Current Status and Opportunities

“…SA alleviated Al toxicity by positive modulation of the citrate efflux in Cassia tora roots [ 194 ]. In addition, Al toxicity was alleviated in tomato [ 195 ], and soybean [ 191 ] by SA (<20 µM) through activation of the antioxidant system.…”