Heavy metal stress tolerance in Enterobacter sp. PR14 is mediated by plasmid

115-121Last two decades have witnessed the significant exploitation of many plant growth-promoting rhizobacteria (PGPR) as bioinoculants and biocontrol agents (BCAs). However, PGPR with potential of producing multiple biocontrol traits along with heavy metal stress tolerance and ACC deaminase activity are expected to control phytopathogens and increase tolerance of crop to heavy metal stress, thus helping in bioremediation of heavy metal ions and reducing ethylene level in the root zone. The present work reports the production of multiple biocontrol traits like ammonia (NH3), hydrogen cyanide (HCN), siderophore (79%), ACC deaminase (0.8 µM/mg/h), chitinase (9.7 U/mL) and tolerance to heavy metal ions (3200 μg/mL) and trace minerals in Enterobacter sp. PR14 isolated from the model organic farm of Sam Higginbottom University of Agriculture, Technology and Sciences (SHUATS), Allahabad, India. Elimination of plasmid in the organism resulted in the loss of tolerance of heavy metal ions and trace elements, indicating the role of the plasmid in heavy metal tolerance

EVALUATION OF CALCIUM OXIDE NANOPARTICLES TO ENHANCE HEAVY METAL STRESS TOLERANCE IN PLANTS

Heavy metal contamination is a severe environmental problem affecting global food production and safety. Heavy metal stress due to its toxicity, bioaccumulation, and non-biodegradability, it become quite serious in nature. The available strategies for preventing heavy metal contamination are not frequently used because of their inefficient and time- or money-consuming properties. Recent developments in nanotechnology have been made based on ameliorative strategies which have a potential alternative to physic-chemical methods. Under heavy metal stress, the application of calcium oxide nanoparticles (CaO-NPs) significantly boosts plant biomass, anti-oxidative enzyme activities (such as catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD), and glutathione reductase (GR)), and the level of non-enzymatic antioxidants (ascorbate and glutathione). Additionally, CaO-NPs enhance the gene expression linked to anti-oxidative enzymes. It can be suggested that CaO-NPs could be used as a potential chemical to reduce heavy metal uptake and toxicity in the plants grown under heavy metal contaminated soil. This review provides an overview of plant-CaO-NPs research in increasing heavy metal stress tolerance in plants. View Article DOI: 10.47856/ijaast.2022.v10i01.00

Heavy metal stress tolerance in Enterobacter sp. PR14 is mediated by plasmid

Last two decades have witnessed the significant exploitation of many plant growth-promoting rhizobacteria (PGPR) as bioinoculants and biocontrol agents (BCAs). However, PGPR with potential of producing multiple biocontrol traits along with heavy metal stress tolerance and ACC deaminase activity are expected to control phytopathogens and increase tolerance of crop to heavy metal stress, thus helping in bioremediation of heavy metal ions and reducing ethylene level in the root zone. The present work reports the production of multiple biocontrol traits like ammonia (NH3), hydrogen cyanide (HCN), siderophore (79%), ACC deaminase (0.8 µM/mg/h), chitinase (9.7 U/mL) and tolerance to heavy metal ions (3200 μg/mL) and trace minerals in Enterobacter sp. PR14 isolated from the model organic farm of Sam Higginbottom University of Agriculture, Technology and Sciences (SHUATS), Allahabad, India. Elimination of plasmid in the organism resulted in the loss of tolerance of heavy metal ions and trace elements, indicating the role of the plasmid in heavy metal tolerance

Overexpression of RsMYB1 Enhances Anthocyanin Accumulation and Heavy Metal Stress Tolerance in Transgenic Petunia

The RsMYB1 transcription factor (TF) controls the regulation of anthocyanin in radishes (Raphanus sativus), and its overexpression in tobacco and petunias strongly enhances anthocyanin production. However, there are no data on the involvement of RsMYB1 in the mechanisms underlying abiotic stress tolerance, despite strong sequence similarity with other MYBs that confer such tolerance. In this study, we used the anthocyanin-enriched transgenic petunia lines PM6 and PM2, which overexpress RsMYB1. The tolerance of these lines to heavy metal stress was investigated by examining several physiological and biochemical factors, and the transcript levels of genes related to metal detoxification and antioxidant activity were quantified. Under normal conditions (control conditions), transgenic petunia plants (T2-PM6 and T2-PM2) expressing RsMYB1, as well as wild-type (WT) plants, were able to thrive by producing well-developed broad leaves and regular roots. In contrast, a reduction in plant growth was observed when these plants were exposed to heavy metals (CuSO4, ZnSO4, MnSO4, or K2Cr2O7). However, T2-PM6 and T2-PM2 were found to be more stress tolerant than the WT plants, as indicated by superior results in all analyzed parameters. In addition, RsMYB1 overexpression enhanced the expression of genes related to metal detoxification [glutathione S-transferase (GST) and phytochelatin synthase (PCS)] and antioxidant activity [superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX)]. These results suggest that enhanced expression levels of the above genes can improve metal detoxification activities and antioxidant activity, which are the main components of defense mechanism included in abiotic stress tolerance of petunia. Our findings demonstrate that RsMYB1 has potential as a dual-function gene that can have an impact on the improvement of anthocyanin production and heavy metal stress tolerance in horticultural crops

A LEA Gene Regulates Cadmium Tolerance by Mediating Physiological Responses

In this study, the function of a LEA gene (TaLEA1) from Tamrix androssowii in response to heavy metal stress was characterized. Time-course expression analyses showed that NaCl, ZnCl2, CuSO4, and CdCl2 considerably increased the expression levels of the TaLEA1 gene, thereby suggesting that this gene plays a role in the responses to these test stressors. To analyze the heavy metal stress-tolerance mechanism regulated by TaLEA1, TaLEA1-overexpressing transgenic poplar plants (Populus davidiana Dode × P. bollena Lauche) were generated. Significant differences were not observed between the proline content of the transgenic and wild-type (WT) plants before and after CdCl2 stress. However, in comparison with the WT plants, the TaLEA1-transformed poplar plants had significantly higher superoxide dismutase (SOD) and peroxidase (POD) activities, and lower malondialdehyde (MDA) levels under CdCl2 stress. Further, the transgenic plants showed better growth than the WT plants did, indicating that TaLEA1 provides tolerance to cadmium stress. These results suggest that TaLEA1 confers tolerance to cadmium stress by enhancing reactive oxygen species (ROS)-scavenging ability and decreasing lipid peroxidation. Subcellular-localization analysis showed that the TaLEA1 protein was distributed in the cytoplasm and nucleus

Comprehensive In-Silico Study Of PLAT Domain Containing Protein 1 Upregulated From Salinity Stress In Oryza Sativa

Salinity stress is one of the most detrimental causes of productivity loss and death among plants including crops. Worldwide, rice is the most common staple food and also, most commonly under stressed crop.  Plant protein with single PLAT (Polycystin-1, Lipoxygenase, Alpha-toxin and Triacylglycerol lipase) domain and PLAT plant stress protein family are found in most angiosperms. The exact mechanism of PLAT plant protein isn’t assuredly understood yet available reports suggest, overexpressed PLAT1 protein enhances abiotic stress, especially temperature and salt tolerance along with heavy metal stress tolerance in plants. In Arabidopsis and tobacco plant, PLAT1 appeared to be a positive mediator for growth under non-stressed condition, ABA signalling and ER stress tolerance. PLAT1 is also present in Oryza sativa both in indica and japonica group. Most of the proteins were predicted, hence lacking proper PDB structure. So, this study intended to find the possible structural resemblance between PLAT1 both in Oryza and Arabidopsis. Possibly to understand the nature of mechanism by building homology models by using SWISSMODEL and comparing sequences by MSA. Thus, encouraging further scientific use and proteomic study in order to improve salinity stress tolerance and crop yielding

Assessing Tolerance to Heavy-Metal Stress in Arabidopsis thaliana Seedlings

The deposited book chapter is a post-print version and has been submitted to peer review.The deposited book chapter version contains attached the supplementary materials within the pdf.This publication hasn't any creative commons license associated.The deposited book chapter is part of the book series: "Environmental Responses in Plants: Methods and Protocols" (pp.197-208) published by Springer.Heavy-metal soil contamination is one of the major abiotic stress factors that, by negatively affecting plant growth and development, severely limit agricultural productivity worldwide. Plants have evolved various tolerance and detoxification strategies in order to cope with heavy-metal toxicity while ensuring adequate supply of essential micronutrients at the whole-plant as well as cellular levels. Genetic studies in the model plant Arabidopsis thaliana have been instrumental in elucidating such mechanisms. The root assay constitutes a very powerful and simple method to assess heavy-metal stress tolerance in Arabidopsis seedlings. It allows the simultaneous determination of all the standard growth parameters affected by heavy-metal stress (primary root elongation, lateral root development, shoot biomass, and chlorophyll content) in a single experiment. Additionally, this protocol emphasizes the tips and tricks that become particularly useful when quantifying subtle alterations in tolerance to a given heavy-metal stress, when simultaneously pursuing a large number of plant lines, or when testing sensitivity to a wide range of heavy metals for a single line.Fundação para a Ciência e a Tecnologia grants: (EXPL/AGR-PRO/1013/2013, SFRH/BPD/44640/2008); GREEN-it "Bioresources for Sustainability": (UID/Multi/04551/2013).info:eu-repo/semantics/publishedVersio

POSSIBILITIES OF PURIFICATION OF HEAVY METALS CONTAMINATION IN SOILS

Methods of neutralisation of different types of soils contaminated with heavy metals are studied. Certain strains of microorganisms have been selected, local microflora has been studied and identified at the genus level in laboratory conditions. Considering the conducted works, development of modified forms of humic acids, stimulation of local microorganisms and creation of geochemical barriers using local natural raw materials is recomended. Obtained results makes possible to develop comprehensive and rational model by means of inovative technologies for effective purification of soils contaminated with heavy metals.Methods of neutralisation of different types of soils contaminated with heavy metals are studied. Certain strains of microorganisms have been selected, local microflora has been studied and identified at the genus level in laboratory conditions. Considering the conducted works, development of modified forms of humic acids, stimulation of local microorganisms and creation of geochemical barriers using local natural raw materials is recomended. Obtained results makes possible to develop comprehensive and rational model by means of inovative technologies for effective purification of soils contaminated with heavy metals

Application of microbial synthesized phytohormones in the management of environmental impacts on soils

With the world's population growing at an exponential rate, pollution of the ecosystem by heavy metals from anthropogenic activities poses a major threat to agricultural and food security worldwide. Phytohormones are biochemical signal molecules that alter plant responses to different biotic and abiotic stresses. Exogenous use of microbially produced phytohormone in heavy metal remediation and stress tolerance induction, has gained popularity due to its environmental friendliness and sustainability. Microbially produced phytohormones have huge biotechnological potentials and have been exploited in phytoremediation assisted removal of heavy metals, and inducing stress tolerance to plants. This paper exhaustively discusses the remedial roles of microbial phytohormones in heavy metal removal and enhancing plant tolerance to stress. However, the exact mechanism of action and the genetic interplay during the process need to be further studied to better understand the specific key pathways involved in the process