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

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 635
Author(s):  
Paola I. Angulo-Bejarano ◽  
Jonathan Puente-Rivera ◽  
Rocío Cruz-Ortega

Worldwide, the effects of metal and metalloid toxicity are increasing, mainly due to anthropogenic causes. Soil contamination ranks among the most important factors, since it affects crop yield, and the metals/metalloids can enter the food chain and undergo biomagnification, having concomitant effects on human health and alterations to the environment. Plants have developed complex mechanisms to overcome these biotic and abiotic stresses during evolution. Metals and metalloids exert several effects on plants generated by elements such as Zn, Cu, Al, Pb, Cd, and As, among others. The main strategies involve hyperaccumulation, tolerance, exclusion, and chelation with organic molecules. Recent studies in the omics era have increased knowledge on the plant genome and transcriptome plasticity to defend against these stimuli. The aim of the present review is to summarize relevant findings on the mechanisms by which plants take up, accumulate, transport, tolerate, and respond to this metal/metalloid stress. We also address some of the potential applications of biotechnology to improve plant tolerance or increase accumulation.

2021 ◽  
Vol 10 (1) ◽  
pp. 456-475
Author(s):  
Efat Zohra ◽  
Muhammad Ikram ◽  
Ahmad A. Omar ◽  
Mujahid Hussain ◽  
Seema Hassan Satti ◽  
...  

Abstract In the present era, due to the increasing incidence of environmental stresses worldwide, the developmental growth and production of agriculture crops may be restrained. Selenium nanoparticles (SeNPs) have precedence over other nanoparticles because of the significant role of selenium in activating the defense system of plants. In addition to beneficial microorganisms, the use of biogenic SeNPs is known as an environmentally friendly and ecologically biocompatible approach to enhance crop production by alleviating biotic and abiotic stresses. This review provides the latest development in the green synthesis of SeNPs by using the results of plant secondary metabolites in the biogenesis of nanoparticles of different shapes and sizes with unique morphologies. Unfortunately, green synthesized SeNPs failed to achieve significant attention in the agriculture sector. However, research studies were performed to explore the application potential of plant-based SeNPs in alleviating drought, salinity, heavy metal, heat stresses, and bacterial and fungal diseases in plants. This review also explains the mechanistic actions that the biogenic SeNPs acquire to alleviate biotic and abiotic stresses in plants. In this review article, the future research that needs to use plant-mediated SeNPs under the conditions of abiotic and biotic stresses are also highlighted.


2022 ◽  
Vol 23 (2) ◽  
pp. 702
Author(s):  
Shuya Tan ◽  
Jie Cao ◽  
Xinli Xia ◽  
Zhonghai Li

Priming is an adaptive strategy that improves plant defenses against biotic and abiotic stresses. Stimuli from chemicals, abiotic cues, and pathogens can trigger the establishment of priming state. Priming with 5-aminolevulinic acid (ALA), a potential plant growth regulator, can enhance plant tolerance to the subsequent abiotic stresses, including salinity, drought, heat, cold, and UV-B. However, the molecular mechanisms underlying the remarkable effects of ALA priming on plant physiology remain to be elucidated. Here, we summarize recent progress made in the stress tolerance conferred by ALA priming in plants and provide the underlying molecular and physiology mechanisms of this phenomenon. Priming with ALA results in changes at the physiological, transcriptional, metabolic, and epigenetic levels, and enhances photosynthesis and antioxidant capacity, as well as nitrogen assimilation, which in turn increases the resistance of abiotic stresses. However, the signaling pathway of ALA, including receptors as well as key components, is currently unknown, which hinders the deeper understanding of the defense priming caused by ALA. In the future, there is an urgent need to reveal the molecular mechanisms by which ALA regulates plant development and enhances plant defense with the help of forward genetics, multi-omics technologies, as well as genome editing technology.


2020 ◽  
Author(s):  
Chong Yang ◽  
Juanjuan Li ◽  
Faisal Islam ◽  
Luyang Hu ◽  
Jiansu Wang ◽  
...  

Abstract Background: WRKY transcription factors play important roles in various physiological processes and stress responses in flowering plants. However, the information about WRKY genes in Helianthus annuus L. (common sunflower) is limited. Results: Ninety WRKY (HaWRKY) genes were identified and renamed according to their locations on chromosomes. Further phylogenetic analyses classified them into four main groups including a species-specific WKKY group and HaWRKY genes within same group or subgroup generally showed similar exon-intron structures and motif compositions. The tandem and segmental duplication possibly contributed to the diversity and expansion of HaWRKY gene families. Synteny analyses of sunflower WRKY genes provided deep insight to the evolution of HaWRKY genes. Transcriptomic and qRT-PCR analyses of HaWRKY genes displayed distinct expression patterns in different plant tissues, as well as under various abiotic and biotic stresses. Conclusions: Ninety WRKY (HaWRKY) genes were identified from H. annuus L. and classified into four groups. Structures of HaWRKY proteins and their evolutionary characteristics were also investigated. The characterization of HaWRKY genes and their expression profiles under biotic and abiotic stresses in this study provide a foundation for further functional analyses of these genes. Therefore, these functional genes related to increasing the plant tolerance or improving the crop quality, could be applied for the crop improvement..


2019 ◽  
Vol 11 (2) ◽  
pp. 167-174
Author(s):  
Francisca I. OKUNGBOWA ◽  
Hakeem O. SHITTU ◽  
Henry O. OBIAZIKWOR

An endophyte is a microorganism, usually bacterium or fungus, which lives within the internal tissue of a host plant, causing no apparent harm. Some characteristics of an endophyte include ability to promote plant growth and to confer plant tolerance to biotic and abiotic stresses. Endophytic bacteria spread across many phyla including the Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria. Endophytic bacteria are recruited by hosts and they get attached to the surface and eventually find their way into the internal tissues where they spread to the intercellular spaces of host plants. These bacteria have been isolated and characterized from different plants. Currently, culture-independent methods such as sequencing of the 16S rRNA gene or metalogenomics are used for identification and characterization of endophytes. The mechanisms by which the endophyte-induced plant protection is brought about can be through direct and/or indirect methods. The direct strategy antagonizes phytopathogens by the production of chemical substances while the indirect mechanisms improve resistance of hosts to pathogens. Global gene expression studies on some common endophytic bacteria implicated these direct and indirect strategies of bacterial-induced protection. More research should be geared towards how the economic importance of endophytic bacteria could be utilized to enhance global food security.


Agronomy ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 529 ◽  
Author(s):  
Agnese Bellabarba ◽  
Camilla Fagorzi ◽  
George C. diCenzo ◽  
Francesco Pini ◽  
Carlo Viti ◽  
...  

Rhizosphere and plant-associated microorganisms have been intensely studied for their beneficial effects on plant growth and health. These mainly include nitrogen-fixing bacteria (NFB) and plant-growth promoting rhizobacteria (PGPR). This beneficial fraction is involved in major functions such as plant nutrition and plant resistance to biotic and abiotic stresses, which include water deficiency and heavy-metal contamination. Consequently, crop yield emerges as the net result of the interactions between the plant genome and its associated microbiome. Here, we provide a review covering recent studies on PGP rhizobia as effective inoculants for agricultural practices in harsh soil, and we propose models for inoculant combinations and genomic manipulation strategies to improve crop yield.


Plants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 37
Author(s):  
Mohammad Saidur Rhaman ◽  
Shahin Imran ◽  
Farjana Rauf ◽  
Mousumi Khatun ◽  
Carol C. Baskin ◽  
...  

Plants are often exposed to abiotic stresses such as drought, salinity, heat, cold, and heavy metals that induce complex responses, which result in reduced growth as well as crop yield. Phytohormones are well known for their regulatory role in plant growth and development, and they serve as important chemical messengers, allowing plants to function during exposure to various stresses. Seed priming is a physiological technique involving seed hydration and drying to improve metabolic processes prior to germination, thereby increasing the percentage and rate of germination and improving seedling growth and crop yield under normal and various biotic and abiotic stresses. Seed priming allows plants to obtain an enhanced capacity for rapidly and effectively combating different stresses. Thus, seed priming with phytohormones has emerged as an important tool for mitigating the effects of abiotic stress. Therefore, this review discusses the potential role of priming with phytohormones to mitigate the harmful effects of abiotic stresses, possible mechanisms for how mitigation is accomplished, and roles of priming on the enhancement of crop production.


Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1403
Author(s):  
Jie Lin ◽  
Daofeng Liu ◽  
Xia Wang ◽  
Sajjad Ahmed ◽  
Mingyang Li ◽  
...  

The NAC (NAM, ATAFs, CUC) family of transcription factors (TFs) play a pivotal role in regulating all processes of the growth and development of plants, as well as responses to biotic and abiotic stresses. Yet, the functions of NACs from non-model plant species remains largely uncharacterized. Here, we characterized the stress-responsive effects of a NAC gene isolated from wintersweet, an ornamental woody plant that blooms in winter when temperatures are low. CpNAC68 is clustered in the NAM subfamily. Subcellular localization and transcriptional activity assays demonstrated a nuclear protein that has transcription activator activities. qRT-PCR analyses revealed that CpNAC68 was ubiquitously expressed in old flowers and leaves. Additionally, the expression of CpNAC68 is induced by disparate abiotic stresses and hormone treatments, including drought, heat, cold, salinity, GA, JA, and SA. Ectopic overexpression of CpNAC68 in Arabidopsis thaliana enhanced the tolerance of transgenic plants to cold, heat, salinity, and osmotic stress, yet had no effect on growth and development. The survival rate and chlorophyll amounts following stress treatments were significantly higher than wild type Arabidopsis, and were accompanied by lower electrolyte leakage and malondialdehyde (MDA) amounts. In conclusion, our study demonstrates that CpNAC68 can be used as a tool to enhance plant tolerance to multiple stresses, suggesting a role in abiotic stress tolerance in wintersweet.


Author(s):  
Priyanka Singh ◽  
Yamshi Arif ◽  
Andrzej Bajguz ◽  
Shamsul Hayat

Flavonoids are a special category of hydroxylated phenolic compounds having an aromatic ring structure. Quercetin is a special subclass of flavonoid. It is a bioactive natural compound built upon the flavon structure nC6(ring A)-C3(ring C)-C6(ring B). Quercetin facilitates several plant physiological processes, such as seed germination, pollen growth, antioxidant machinery, and photosynthesis, as well as induces proper plant growth and development. Quercetin is a powerful antioxidant, so it potently provides plant tolerance against several biotic and abiotic stresses. This review highlights quercetin’s role in increasing several physiological and biochemical processes in under stress and non-stress environments. Additionally, this review briefly assesses quercetin’s role in mitigating biotic and abiotic stresses (e.g., salt, heavy metal, and UV stress). The biosynthesis of flavonoids, their signaling pathways, and quercetin’s role in plant signaling are also discussed.


2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Fangwei Yu ◽  
Shenyun Wang ◽  
Wei Zhang ◽  
Hong Wang ◽  
Li Yu ◽  
...  

Abstract The members of myeloblastosis transcription factor (MYB TF) family are involved in the regulation of biotic and abiotic stresses in plants. However, the role of MYB TF in phosphorus remobilization remains largely unexplored. In the present study, we show that an R2R3 type MYB transcription factor, MYB103, is involved in phosphorus (P) remobilization. MYB103 was remarkably induced by P deficiency in cabbage (Brassica oleracea var. capitata L.). As cabbage lacks the proper mutant for elucidating the mechanism of MYB103 in P deficiency, another member of the crucifer family, Arabidopsis thaliana was chosen for further study. The transcript of its homologue AtMYB103 was also elevated in response to P deficiency in A. thaliana, while disruption of AtMYB103 (myb103) exhibited increased sensitivity to P deficiency, accompanied with decreased tissue biomass and soluble P concentration. Furthermore, AtMYB103 was involved in the P reutilization from cell wall, as less P was released from the cell wall in myb103 than in wildtype, coinciding with the reduction of ethylene production. Taken together, our results uncover an important role of MYB103 in the P remobilization, presumably through ethylene signaling.


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