Dataset Information

Cell Wall Polysaccharide-Mediated Cadmium Tolerance Between Two Arabidopsis thaliana Ecotypes.

ABSTRACT: Cadmium (Cd) is a toxic metal element and the mechanism(s) underlying Cd tolerance in plants are still unclear. Increasingly more studies have been conducted on Cd binding to plant cell walls (CW) but most of them have focused on Cd fixation by CW pectin, and few studies have examined Cd binding to cellulose and hemicellulose. Here we found that Cd binding to CW pectin, cellulose, and hemicellulose was significantly higher in Tor-1, a Cd tolerant A. thaliana ecotype, than in Ph2-23, a sensitive ecotype, as were the concentrations of pectin, cellulose, and hemicellulose. Transcriptome analysis revealed that the genes regulating CW pectin, cellulose, and hemicellulose polysaccharide concentrations in Tor-1 differed significantly from those in Ph2-23. The expressions of most genes such as pectin methyl esterase inhibitors (PMEIs), pectin lyases, xyloglucan endotransglucosylase/hydrolase, expansins (EXPAs), and cellulose hydrolase were higher in Ph2-23, while the expressions of cellulose synthase-like glycosyltransferase 3 (CSLG3) and pectin ethyl esterase 4 (PAE4) were higher in Tor-1. The candidate genes identified here seem to regulate CW Cd fixation by polysaccharides. In conclusion, an increase in pectin demethylation activity, the higher concentration of cellulose and hemicellulose, regulated by related genes, in Tor-1 than in Ph2-23 are likely involved in enhanced Cd CW retention and reduce Cd toxicity.

SUBMITTER: Xiao Y

PROVIDER: S-EPMC7239314 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Cell Wall Polysaccharide-Mediated Cadmium Tolerance Between Two <i>Arabidopsis thaliana</i> Ecotypes.

Xiao Yan Y Wu Xiuwen X Liu Dong D Yao Junyue J Liang Guihong G Song Haixing H Ismail Abdelbagi M AM Luo Jin-Song JS Zhang Zhenhua Z

Frontiers in plant science 20200513

Cadmium (Cd) is a toxic metal element and the mechanism(s) underlying Cd tolerance in plants are still unclear. Increasingly more studies have been conducted on Cd binding to plant cell walls (CW) but most of them have focused on Cd fixation by CW pectin, and few studies have examined Cd binding to cellulose and hemicellulose. Here we found that Cd binding to CW pectin, cellulose, and hemicellulose was significantly higher in Tor-1, a Cd tolerant <i>A. thaliana</i> ecotype, than in Ph2-23, a sen ...[more]

PMID: 32477379

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Project description:Cadmium (Cd) in soil inhibits plant growth and development and even harms human health through food chain transmission. Switchgrass (Panicum virgatum L.), a perennial C4 biofuel crop, is considered an ideal plant for phytoremediation due to its high efficiency in removing Cd and other heavy metals from contaminated soil. The key to understanding the mechanisms of switchgrass Cd tolerance is to identify the genes involved in Cd transport. Heavy-metal ATPases (HMAs) play pivotal roles in heavy metal transport, including Cd, in Arabidopsis thaliana and Oryza sativa, but little is known about the functions of their orthologs in switchgrass. Therefore, we identified 22 HMAs in switchgrass, which were distributed on 12 chromosomes and divided into 4 groups using a phylogenetic analysis. Then, we focused on PvHMA2.1, which is one of the orthologs of the rice Cd transporter OsHMA2. We found that PvHMA2.1 was widely expressed in roots, internodes, leaves, spikelets, and inflorescences, and was significantly induced in the shoots of switchgrass under Cd treatment. Moreover, PvHMA2.1 was found to have seven transmembrane domains and localized at the cell plasma membrane, indicating that it is a potential transporter. The ectopic expression of PvHMA2.1 alleviated the reduction in primary root length and the loss of fresh weight of Arabidopsis seedlings under Cd treatment, suggesting that PvHMA2.1 enhanced Cd tolerance in Arabidopsis. The higher levels of relative water content and chlorophyll content of the transgenic lines under Cd treatment reflected that PvHMA2.1 maintained water retention capacity and alleviated photosynthesis inhibition under Cd stress in Arabidopsis. The roots of the PvHMA2.1 ectopically expressed lines accumulated less Cd compared to the WT, while no significant differences were found in the Cd contents of the shoots between the transgenic lines and the WT under Cd treatment, suggesting that PvHMA2.1 reduced Cd absorption from the environment through the roots in Arabidopsis. Taken together, our results showed that PvHMA2.1 enhanced Cd tolerance in Arabidopsis, providing a promising target that could be engineered in switchgrass to repair Cd-contaminated soil.

Project description:Background and aimsExcess selenium (Se) is toxic to plants, but relatively little is known about the regulatory mechanism of plant Se tolerance. This study explored the role of the TPS22 gene in Se tolerance in Arabidopsis thaliana.MethodsArabidopsis wild type and XVE mutant seeds were grown on half-strength MS media containing Na2SeO3 for screening of the Se-tolerant mutant tps22. The XVE T-DNA-tagged genomic sequence in tps22 was identified by TAIL-PCR. The TPS22 gene was transformed into the mutant tps22 and wild type plants using the flower infiltration method. Wild type, tps22 mutant and transgenic seedlings were cultivated on vertical plates for phenotype analysis, physiological index measurement and gene expression analysis.Key resultsWe identified an Arabidopsis Se-tolerant mutant tps22 from the XVE pool lines, and cloned the gene which encodes the terpenoid synthase (TPS22). TPS22 was downregulated by Se stress, and loss-of-function of TPS22 resulted in decreased Se accumulation and enhanced Se tolerance; by contrast, overexpression of TPS22 showed similar traits to the wild type under Se stress. Further analysis revealed that TPS22 mediated Se tolerance through reduction of Se uptake and activation of metabolism detoxification, which decreased transcription of high-affinity transporters PHT1;1, PHT1;8 and PHT1;9 and significantly increased transcription of selenocysteine methyltransferase (SMT), respectively. Moreover, loss-of-function of TPS22 resulted in reduced cytokinin level and repression of cytokinin signalling components AHK3 and AHK4, and upregulation of ARR3, ARR15 and ARR16. Exogenous cytokinin increased transcription of PHT1;1, PHT2;1 and SMT and decreased Se tolerance of the tps22 mutant. In addition, enhanced Se resistance of the tps22 mutant was associated with glutathione (GSH).ConclusionsSe stress downregulated TPS22, which reduced endogenous cytokinin level, and then affected the key factors of Se uptake and metabolism detoxification. This cascade of events resulted in reduced Se accumulation and enhanced Se tolerance.

Dataset Information

Cell Wall Polysaccharide-Mediated Cadmium Tolerance Between Two Arabidopsis thaliana Ecotypes.

Publications

Cell Wall Polysaccharide-Mediated Cadmium Tolerance Between Two <i>Arabidopsis thaliana</i> Ecotypes.

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