Transcriptomic and physiological analyses of Medicago sativa L. roots in response to lead stress

Abstract

Lead (Pb) is one of the nonessential and toxic metals that threaten the environment and human health. Medicago sativa L. is a legume with high salt tolerance and high biomass production. It is not only a globally important forage crop but is also an ideal plant for phytoremediation. However, the biological and molecular mechanisms that respond to heavy metals are still not well defined in M. sativa. In this study, de novo and strand-specific RNA-sequencing was performed to identify genes involved in the Pb stress response in M. sativa roots. A total of 415,350 unigenes were obtained from the assembled cDNA libraries, among which 5,416 were identified as significantly differentially expressed genes (DEGs) (false discovery rate < 0.005) between cDNA libraries from control and Pb-treated plants. Gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the DEGs showed they mainly clustered with terms associated with binding, transport, membranes, and the pathways related to signal and energy metabolism. Moreover, a number of candidate genes included antioxidant enzymes, metal transporters, and transcription factors involved in heavy metal response were upregulated under Pb stress. Quantitative real-time PCR(qRT-PCR) validation of the expression patterns of 10 randomly selected candidate DEGs were consistent with the transcriptome analysis results. Thus, this study offers new information towards the investigation of biological changes and molecular mechanisms related to Pb stress response in plants.

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

“…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.…”

Lead in Agricultural Soils and Cultivated Pastures Irrigated with River Water Contaminated by Mining Activity

“…Lead is a very toxic metal for plants with a toxicity threshold of less than one μM, almost as much as mercury (Hg) [Kopittke et al 2010]. Not only does it affect the growth of plants and productivity, but also the food chain, putting the health risk of humans and animals [Khan et al 2019, Sahi et al 2002, Xu et al 2017].…”

The Overexpression of a Transcription Factor Gene VbWRKY32 Enhances the Cold Tolerance in Verbena bonariensis

“…The antioxidant enzyme system, including POD, SOD, CAT, and APX, could scavenge excessive ROS and improve plant resistance under various types of abiotic stresses (Yu et al, 2014;Singh et al, 2017;Xu et al, 2017;Ma et al, 2018). Compared with the OE lines, the WT plants showed deeper intense histochemical staining by cold treatment.…”