Transcriptome profiling of Fagopyrum tataricum leaves in response to lead stress

Abstract

Background: Lead (Pb) pollution is a widespread environmental problem that is harmful to living organisms. Tartary buckwheat (Fagopyrum tataricum), a member of the family Polygonaceae, exhibits short growth cycles and abundant biomass production, could be an ideal plant for phytoremediation due to its high Pb tolerance. Here, we aimed to explore the molecular basis underlying the responses of this plant to Pb stress. Results: In our study, ultrastructural localization assays revealed that Pb ions primarily accumulate in leaf vacuoles. RNA deep sequencing (RNA-Seq) of tartary buckwheat leaves was performed on two Pb-treated samples, named Pb1 (2000 mg/kg Pb (NO 3) 2) and Pb2 (10,000 mg/kg Pb (NO 3) 2), and a control (CK). A total of 88,977 assembled unigenes with 125,203,555 bases were obtained. In total, 2400 up-regulated and 3413 down-regulated differentially expressed genes (DEGs) were identified between CK and Pb1, and 2948 up-regulated DEGs and 3834 downregulated DEGs were generated between CK and Pb2, respectively. Gene Ontology (GO) and pathway enrichment analyses showed that these DEGs were primarily associated with 'cell wall', 'binding', 'transport', and 'lipid and energy' metabolism. The results of quantitative real-time PCR (qRT-PCR) analyses of 15 randomly selected candidate DEGs and 6 regulated genes were consistent with the results of the transcriptome analysis. Heterologous expression assays in the yeast strain Δycf1 indicated that overexpressing CCCH-type zinc finger protein 14 (ZFP14) enhanced sensitivity to Pb 2+ , while 5 other genes, namely, metal transporter protein C2 (MTPC2), phytochelatin synthetase-like family protein (PCSL), vacuolar cation/proton exchanger 1a (VCE1a), natural resistance-associated macrophage protein 3 (Nramp3), and phytochelatin synthetase (PCS), enhanced the Pb tolerance of the mutant strain. Conclusion: Combining our findings with those of previous studies, we generated a schematic model that shows the metabolic processes of tartary buckwheat under Pb stress. This study provides important data for further genomic analyses of the biological and molecular mechanisms of Pb tolerance and accumulation in tartary buckwheat.

Metal and Metalloid Toxicity in Plants: An Overview on Molecular Aspects

“…As expected, many of the differentially expressed genes (DEGs) are involved in the antioxidative machinery [ 152 , 154 , 167 , 168 ], transport, [ 151 , 156 , 163 ], and cell wall biosynthesis [ 157 ]; therefore, the expression (constitutive or metal stress induced) of such genes is vital for the plant, mostly in the roots during the first stages of metal stress. The localization of some transporter-like genes within the cell structure (plasma membrane or vacuoles) provides knowledge of which mechanisms are preferred by plants at the molecular level [ 163 , 164 ].…”

“…Another aspect of this type of analysis is the translocation or accumulation of toxic elements within the different complex cell structures that make up plant roots. Furthermore, the use of technologies such as microarrays, RNAseq, and wide genome analysis has increased the amount of transcriptomic and genomic information available for plants under metal stress [ 135 , 151 , 152 , 153 , 154 , 155 , 156 , 157 , 158 , 159 ]. When analyzing the different plant transcriptomes under conditions of metal/metalloid stress, conserved trends have been observed.…”

“…Five genes were evaluated in a yeast model, among them Metal Transporter Protein C2 (MTPC2), phytochelatin synthetase-like family protein (PCSL), a vacuolar cation/proton exchanger 1a (VCE1a), NRAMP3, and phytochelatin synthetase (PCS). All of them helped to increase the Pb tolerance in the yeast model [ 156 ] ( Table 2 ).…”

Comparative and Systematic Omics Revealed Low Cd Accumulation of Potato StMTP9 in Yeast: Suggesting a New Mechanism for Heavy Metal Detoxification

“…The recombinant plasmid and empty vector (control) were transformed into yeast strain cells. The transformed yeast is cultured in a glucose (SD-U) liquid nutrient medium lacking uracil [ 65 , 66 ]. When the OD 600 (600 nm optical density) is 0.7–0.8, serial dilution (OD 600 = 10 0 , 10 −1 , 10 −2 , 10 −3 and 10 −4 ).…”

Metal Tolerance Protein Encoding Gene Family in Fagopyrum tartaricum: Genome-Wide Identification, Characterization and Expression under Multiple Metal Stresses

“…Due to its vital nutritional and medicinal values, it has been processed into a variety of foods, including tea, noodles, and shakima, which are popular all over the world [ 29 ]. However, it was reported that Tartary buckwheat had the ability to uptake toxic metals (Pb, Cd, and Hg) from the growth medium and accumulate them in the edible parts [ 30 , 31 , 32 , 33 ], and our previous research also found excessively high levels of some heavy metals in Tartary buckwheat tea [ 34 ]. These results suggest that heavy metal stress is one of the non-negligible factors restricting Tartary buckwheat production and food safety.…”