Proteomic and ecophysiological responses of soybean (Glycine max L.) root nodules to Pb and hg stress

Abstract

BackgroundLead (Pb) and mercury (Hg) are persistent hazardous metals in industrially polluted soils which can be toxic in low quantities. Metal toxicity can cause changes at cellular and molecular level which should be studied for better understanding of tolerance mechanism in plants. Soybean (Glycine max L.) is an important oilseed crop of the world including India. Indian soils growing soybean are often contaminated by Pb and Hg. The aim of this study was to explore how soybean root nodule responds to Pb and Hg through proteomic and ecophysiological alterations in order to enhance tolerance to metal stress.ResultsSoybean plants were exposed to Pb (30 ppm PbCl2) and Hg (0.5 ppm HgCl2) to study histological, histochemical, biochemical and molecular response of N2-fixing symbiotic nodules. Both Pb and Hg treatment increased the level of oxidative stress in leaves and nodules. Chlorosis in leaves and morphological/anatomical changes in nodules were observed. Activities of ascorbate peroxidase, glutathione reductase and catalase were also modulated. Significant changes were observed in abundance of 76 proteins by Pb and Hg. Pb and Hg influenced abundance of 33 proteins (17 up and 16 down) and 43 proteins (33 up and 10 down), respectively. MS/MS ion search identified 55 proteins which were functionally associated with numerous cellular functions. Six crucial proteins namely catalase (CAT), allene oxide synthase (AOS), glutathione S-transferase (GST), calcineurin B like (CBL), calmodulin like (CML) and rapid alkalinisation factor (RAF) were selected for transcript abundance estimation. The qRT-PCR based real time expression exhibited a positive correlation with proteomics expression except for GST and RAF.ConclusionSoybean root nodule responds to metal stress by increased abundance of defence, development and repair related proteins. An efficient proteomic modulation might lead to metal-induced stress tolerance in N2-fixing nodules. Although concentrations of Pb and Hg used in the study cannot be considered equimolar, yet Hg seems to induce more changes in nodule proteomic profile, and higher damage to both bacteroides and root anatomy.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1499-7) contains supplementary material, which is available to authorized users.

Polyamine Action under Metal/Metalloid Stress: Regulation of Biosynthesis, Metabolism, and Molecular Interactions

“…From last two decades, numerous innovative methods such as protein detection using mass spectrometry, microarray technique, and the yeast two-hybrid system have been developed and used for large scale analysis of proteins, which involved in stress signaling and stress tolerance. Though several groups around the world have used the transcriptomics approach to investigate and to underpin expression level and patterns of different genes relating to PAs induced stress amelioration [115,116]; nonetheless, such analysis of mRNA levels has some limitations [117], such as the poor correlation between the expression patterns of mRNAs and their corresponding proteins [118]. Moreover, although the correlation between the expressions of mRNA and corresponding proteins has been identified [119] protein expression is also influenced or regulated at both translational and post-translational levels.…”

“…Moreover, targeting these proteins can be useful in improving metal stress in non-tolerant plant species. Similarly, Baig et al [118] used proteomics approach and showed that Pb stress tolerance in soybean was associated with a high accumulation of thermospermine synthase ACAULIS5-like protein, this is encoded by ACAULIS5 ( ACL5 ) gene and converts Spd to thermospermidine [124].…”

24-Epibrassinolide Improves Root Anatomy and Antioxidant Enzymes in Soybean Plants Subjected to Zinc Stress

“…Soybean (Glycine max L.) is the most widely cultivated legume around the world due to its high protein and oil content (Singh et al 2008;Nisa et al 2016;Baig et al 2018). Its world production reached 338 million tons in the 2017/2018 harvest, with the United States, Brazil and Argentina being the main producers (FAO 2018).…”

Some aspects of metal ion transport and <em>in silico</em> gene expression analysis of potassium/sodium ion transporters, channels and exchangers in root nodules

“…In Arabidopsis these transporters are localized in different membrane compartments: SOS1/ AtNHX7 on the plasma membrane, AtNHX5/6 on endosomes, and AtNHX1-4 on the tonoplast (Chanroi et al, 2012). The mutations in the gene NHX7/SOS1 cause oversensitivity to salt due to disrupted efflux of sodium (Sze et al, 2004;Pardo et al, 2006, Bassil andBlumwald, 2014;Sandhu et al, 2018). Upregulation of NHX7/SOS1 was shown to be associated with salt tolerance in Medicago species (Liu et al, 2015;Sandhu et al, 2017).…”