Metal tolerance mechanisms in plants and microbe-mediated bioremediation

Narayanan, Mathiyazhagan; Ma, Ying

doi:10.1016/j.envres.2023.115413

Cited by 36 publications

(8 citation statements)

References 69 publications

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“…Our results are consistent with the findings of Lou et al [19], who showed that Cd and Pb contaminations cause significant toxicity to ryegrass and impair plant growth. As HMs are not biologically important, they could impose harmful effects on plants by causing chlorosis, photosynthetic inhibition, water imbalance, and lower nutrient assimilation that leads to growth reduction [22,47]. Our research elaborated that HMs stress affected ryegrass plants' morphological, physiological, and biochemical parameters and eventually reduced plant growth.…”

Section: Discussionmentioning

confidence: 65%

Farmyard Manure Enhances Phytoremediation and Mitigates Pb, Cd, and Drought Stress in Ryegrass

Nasir,

Khan,

Asif

et al. 2023

Sustainability

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Here, a pot experiment was designed to evaluate the phytoremediation potential of ryegrass (Lolium perennne L.) for Pb- and Cd-polluted soils under various drought levels in the presence of farmyard manure (FYM). Three levels of Pb (0, 300, and 600 mg kg−1), Cd (0, 100, and 200 mg kg−1), and drought (field capacity 100, 50, and 30%) as well as two levels of FYM (0 and 1%) were used in this experiment. Results from this study showed a significant decrease (up to 84%) in the overall growth and physiology of ryegrass. A substantial increase in antioxidants (SOD, CAT, and POD) was observed under HMs and drought stress. By the application of FYM, antioxidant activities were significantly reduced. The ryegrass accumulated higher amounts of Pb (up to 150 mg kg−1 in shoots and 193 mg kg−1 in roots) and Cd (up to 71 mg kg−1 in shoots and 92 mg kg−1 in roots) in plant tissues; however, an FYM addition significantly reduced the accumulation of both metals. Furthermore, the results of this research indicated that ryegrass has a promising ability to phytoremediate Pb and Cd, and the addition of FYM may be helpful in enhancing metal stabilization and plant growth despite water constraints.

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Section: Discussionmentioning

confidence: 65%

Farmyard Manure Enhances Phytoremediation and Mitigates Pb, Cd, and Drought Stress in Ryegrass

Nasir,

Khan,

Asif

et al. 2023

Sustainability

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“…Furthermore, plants grown on contaminated soils may accumulate heavy metals in aerial parts such as leaf tissues and seeds and can result in severe health consequences for foraging animals and humans if these metals enter the food supply (Peralta-Videa et al, 2009). The presence of a Hg tolerance adaptation in symbiotic a-proteobacteria strains which can be used to fix nitrogen for host plants, improve nitrogen in soils at the entire plant community/population scale, while also contributing to heavy metal detoxification, may be an advantage to future efforts in removing toxins from plants (Narayanan and Ma, 2023), and also in bioremediation using legume-rhizobia interactions (Fagorzi et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

Local adaptation to mercury contamination by nitrogen-fixing rhizobia is driven by horizontal gene transfer, copy number, and enhanced gene expression

Bhat,

Sharma,

Lucas

et al. 2023

Preprint

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Mercury (Hg) is highly toxic and has the potential to cause severe health problems for foraging animals and humans when transported into edible plant parts. Soil rhizobia that form symbiosis with legumes may possess mechanisms to prevent heavy metal translocation from roots to shoots in plants by exporting metals from nodules or compartmentalizing metal ions inside nodules. Using long-read sequencing, we assembled the genomes ofSinorhizobium medicaeandRhizobium leguminosarumfrom the Almadén mercury mine in Spain with high variation in Hg-tolerance to identify structural and transcriptomic differences between low and high Hg-tolerant strains. While independent mercury reductase A (merA) genes are prevalent in α-proteobacteria, Mer operons are rare and often vary in their gene organization. Our analyses identified multiple structurally conserved merA homologs in the genomes ofS. medicae, including a dihydrolipoamide 2-oxoglutarate dehydrogenase (D2OD), but only the strains that possessed a Mer operon exhibited hypertolerance to Hg. Using RNAseq reads mapped to the unique genome assemblies, we found the Hg-tolerant strains which possessed a Mer operon, that nearly all genes within the operon were significantly up-regulated in response to Hg stress in free-living conditions and in nodules. In both free-living and nodule environments, we found the Hg-tolerant strains with a Mer operon exhibited the fewest number of DEGs in the genome, indicating a rapid and efficient detoxification of Hg2+from the cells that reduced general stress responses to the Hg-treatment. Expression changes inS. medicaewhile inside of nodules showed that both rhizobia strain and host-plant tolerance affected the number of DEGs. Aside from Mer operon genes,nifgenes which are involved in nitrogenase activity inS. medicaeshowed significant up-regulation in the most Hg-tolerant strain while inside the most Hg-accumulating host-plant, indicating a genotype-by-genotype interaction that influences nitrogen-fixation under stress conditions. Transfer of the Mer operon to non-tolerant strains resulted in an immediate increase in Hg tolerance, indicating that the operon is solely necessary to confer hypertolerance to Hg, despite paralogous merA genes present elsewhere in the genome. This study demonstrated that the Mer operon can be exchanged via horizontal gene transfer into non-tolerant rhizobia strains naturally and experimentally.

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“…The inoculation of beneficial microbes mitigates heavy metal stress in plants. Microbes, such as bacteria, fungi, viruses, and nematodes, are used to minimize heavy metal stress ( Ge et al., 2023 ; Narayanan and Ma, 2023 ; Rahman et al., 2023 ). Microbes have been acknowledged as an eco-friendly and alternative way to increase plant productivity and alleviate stress.…”

Section: Role Of Microbes In the Alleviation Of Heavy Metal Stressesmentioning

confidence: 99%

Recent progress on the microbial mitigation of heavy metal stress in soybean: overview and implications

et al. 2023

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Plants are adapted to defend themselves through programming, reprogramming, and stress tolerance against numerous environmental stresses, including heavy metal toxicity. Heavy metal stress is a kind of abiotic stress that continuously reduces various crops’ productivity, including soybeans. Beneficial microbes play an essential role in improving plant productivity as well as mitigating abiotic stress. The simultaneous effect of abiotic stress from heavy metals on soybeans is rarely explored. Moreover, reducing metal contamination in soybean seeds through a sustainable approach is extremely needed. The present article describes the initiation of heavy metal tolerance mediated by plant inoculation with endophytes and plant growth-promoting rhizobacteria, the identification of plant transduction pathways via sensing annotation, and contemporary changes from molecular to genomics. The results suggest that the inoculation of beneficial microbes plays a significant role in rescuing soybeans under heavy metal stress. They create a dynamic, complex interaction with plants via a cascade called plant–microbial interaction. It enhances stress metal tolerance via the production of phytohormones, gene expression, and secondary metabolites. Overall, microbial inoculation is essential in mediating plant protection responses to heavy metal stress produced by a fluctuating climate.

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Metal tolerance mechanisms in plants and microbe-mediated bioremediation

Cited by 36 publications

References 69 publications

Farmyard Manure Enhances Phytoremediation and Mitigates Pb, Cd, and Drought Stress in Ryegrass

Farmyard Manure Enhances Phytoremediation and Mitigates Pb, Cd, and Drought Stress in Ryegrass

Local adaptation to mercury contamination by nitrogen-fixing rhizobia is driven by horizontal gene transfer, copy number, and enhanced gene expression

Recent progress on the microbial mitigation of heavy metal stress in soybean: overview and implications

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