Aluminum tolerance in Arabidopsis thaliana as affected by endogenous salicylic acid

Abstract

Endogenous salicylic acid (SA) functions in plant response to an aluminum stress were assessed. We used different Arabidopsis thaliana genotypes including snc1 with a constitutively high content of SA, sid2 and nahG (transgenic lines) both with a low content of SA, SA insensitive mutant npr1-1, and snc1/nahG (i.e., the nahG expression in the snc1 background) with a similar SA content as in wild type (WT) plants. Results show that the snc1 plants displayed obvious growth retardation of roots and shoots under the Al 3+ stress, whereas the sid2, nahG, and npr1-1 plants exhibited alleviated symptoms in comparison with the WT plants. The Al 3+ content increased in all the tested genotypes with the increasing AlCl 3 concentration applied, but no significant variations were detected among the tested genotypes. The snc1 had much higher superoxide dismutase and peroxidase activities, and a lower catalase activity and the ratio of reduced to oxidized glutathione accompanied by higher accumulations of H 2 O 2 and malondialdehyde compared with the WT plants. These changes were largely reversed by the introduction of nahG; the sid2, nahG, and npr1-1 plants were less affected than WT plants in all the above-mentioned parameters. The Al 3+ stress significantly enhanced malate exudation in all the tested genotypes, but no significant correlation was observed between the SA-involved response to the Al 3+ stress and the malate exudation. Based on these data, it was concluded that the SA-related functions in Arabidopsis response to the Al 3+ stress were associated with the control of oxidative stress, but not of malate exudation.

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

“…After induction of plant defense, SA activated a change of NPR1 from oligomeric to monomeric form, and then it was translocated to the nucleus and activates downstream target gene expression. Arabidopsis snc1, sid2, nahG, npr1-1 , and snc1/nahG mutants that exhibited SA functions in response to Al stress were associated with the control of oxidative stress, but not of malate exudation (Guo et al, 2014 ). Kunihiro et al ( 2011 ) documented that Al-induced AtrbohD expression and cell death were involved in NPR1-dependent SA signaling by using npr1 mutant cells and NPR1 overexpressing cells.…”

“…Pathogen infection induces SA biosynthesis at infection sites, which regulates the expression of several defense genes, including pathogenesis-related ( PR ) genes and non-expresser of pathogenesis-related ( NPR ) genes, leading to systemic acquired resistance (SAR) (Mou et al, 2003 ; Durrant and Dong, 2004 ). 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 ).…”

Jasmonic Acid Enhances Al-Induced Root Growth Inhibition

“…Phytohormones such as auxin, ethylene, cytokinin, salycilic acid, and abscisic acid, etc. have been reported to regulate the Al-induced root growth inhibition (Kollmeier et al, 2000;Shen et al, 2004;Sun et al, 2010;Yang et al, 2014;Guo et al, 2014). In maize, the blockage of the auxin signal from the DTZ to the elongation zone has been revealed as the major reason for Al-induced inhibition of root elongation (Kollmeier et al, 2000), while in Arabidopsis (Arabidopsis thaliana), Trp aminotransferase 1 (TAA1)-mediated local auxin biosynthesis in the root apex transition zone (TZ) leads to the Al-induced root growth inhibition, and this process is controlled by ethylene signaling .…”

Concerted Plant Growth and Defense Through Targeted Phytohormone Crosstalk Modification

“…We therefore addressed whether ROS levels could be linked to altered reproductive phenotypes observed in s35 plants. A histochemical assay for H2O2 staining showed a high basal accumulation of H2O2 in leaf tissue snc1 and s35 (Figure 5I), a known phenotype associated with immunity activation (37)(38)(39)(40). In inflorescence tissue, however, snc1 plants accumulated less H2O2 than wildtype plants, and ckx3,5 and s35 had markedly pronounced staining in young flower buds near meristematic tissue (Figure 5J).…”