One of the most interesting signaling molecules that regulates a wide array of adaptive stress responses in plants are the micro RNAs (miRNAs) that are a unique class of non-coding RNAs constituting ...novel mechanisms of post-transcriptional gene regulation. Recent studies revealed the role of miRNAs in several biotic and abiotic stresses by regulating various phytohormone signaling pathways as well as by targeting a number of transcription factors (TFs) and defense related genes. Phytohormones are signal molecules modulating the plant growth and developmental processes by regulating gene expression. Studies concerning miRNAs in abiotic stress response also show their vital roles in abiotic stress signaling. Current research indicates that miRNAs may act as possible candidates to create abiotic stress tolerant crop plants by genetic engineering. Yet, the detailed mechanism governing the dynamic expression networks of miRNAs in response to stress tolerance remains unclear. In this review, we provide recent updates on miRNA-mediated regulation of phytohormones combating various stress and its role in adaptive stress response in crop plants.
Arsenic (As), a naturally occurring metallic element, is a dreadful health hazard to millions of people across the globe. Arsenic is present in low amount in the environment and originates from ...anthropogenic impact and geogenic sources. The presence of As in groundwater used for irrigation is a worldwide problem as it affects crop productivity, accumulates to different tissues and contaminates food chain. The consumption of As contaminated water or food products leads to several diseases and even death. Recently, studies have been carried out to explore the biochemical and molecular mechanisms which contribute to As toxicity, accumulation, detoxification and tolerance acquisition in plants. This information has led to the development of the biotechnological tools for developing plants with modulated As tolerance and detoxification to safeguard cellular and genetic integrity as well as to minimize food chain contamination. This review aims to provide current updates about the biochemical and molecular networks involved in As uptake by plants and the recent developments in the area of functional genomics in terms of developing As tolerant and low As accumulating plants.
•Arsenic affects plant growth and human health due to food chain contamination.•Omics can be an important tool to identify arsenic associated molecular networks.•Biotechnological interventions can modulate arsenic response in plants.•This review updates gene mining and approaches to develop altered arsenic response.
Rice is the most consumed food crop and essential determinant in global food security program. Currently, arsenic (As) accumulation in rice is a critical concern in terms of both crop productivity ...and grain quality; therefore, it is an urgent need to reduce As accumulation. Here, we selected a glutaredoxin (OsGrx_C7) gene that plays an essential role in AsIII tolerance in rice. To explore the mechanism, we raised OsGrx_C7 overexpression (OE) rice lines, which showed improved plant AsIII tolerance and lowered its accumulation in grains. Arsenic accumulation in husk, unpolished, and polished rice reduced by ca. 65%, 67%, and 85%, respectively, in OE lines, compared to wild-type (WT) plants. To know the rationale, expression of AsIII transporters (aquaporins) in root and shoot tissues were examined, and revealed that OsGrx_C7 regulates the expression of these genes, which ultimately reduces root to shoot AsIII translocation. Additionally, OsGrx_C7 improves root growth by regulating the expression of oxidative stress-induced root expansion related genes, promote root growth and plant health. Overall, current study suggested that AsIII induced OsGrx_C7 markedly enhanced tolerance to AsIII with reduced accumulation in grains by regulating root expansion and controlling root to shoot As transport by altered expression of AsIII aquaporins.
•Studied a novel role of rice glutaredoxin (OsGrx_C7) in facilitating root adaptation to AsIII toxicity.•Rice glutaredoxin regulate the expression of AsIII transporters (Aquaporins).•OsGrx_C7 control root to shoot arsenic translocation and reduces arsenic accumulation in grains.
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•Dehydrin can combat multiple types of abiotic stress in plants.•Dehydrin acts as a chaperone, chelator and cryo-protectant.•Dehydrin additionally participates in transcriptional ...regulation in cells.•Epigenetic modification is associated with DHN expression and the abiotic stress response.
Dehydrins are a multifunctional and diverse class of proteins that are crucial in combating abiotic stresses imposed on the plant kingdom. Plants use dehydrin to stabilize biomolecules and membranes; therefore, dehydrins are key during dehydration stress. For almost 30 years, dehydrins have been known to be chaperones that enable ion-binding functions, act as a cryo-protectants and aid in free radical scavenging. Other functions of dehydrin have been explored more recently, and the results suggest that dehydrin might have roles beyond its chaperone functions. First, dehydrin has recently been found to regulate stress-responsive genes, and evolution has enabled dehydrins to participate in the cell’s transcription regulatory machinery during the stress response. Second, dehydrins have been reported to play an indirect role in histone modification. In this epigenetic process, H3K4me3 modification is positively associated with the expression of dehydrin and other drought-responsive genes. This review describes the details of studies on dehydrin from its discovery until 2021, thus providing a progressive, complex, interlinked and comprehensive understanding of the dehydrin gene family. In addition, biotechnologies and integrative approaches that have aided in exploring the varying dynamics of dehydrin spatially and temporally are discussed.
Arsenic (As) contamination in rice leads to yield decline and causes carcinogenic risk to human health. Although the role of nitric oxide (NO) in reducing As toxicity is known, NO-mediated genetic ...modulation in the plant during arsenic toxicity has not yet been established. We analyzed the key components of NO metabolism and the correlations between NO interaction and arsenic stress using rice as a relevant model plant. Illumina sequencing was used to investigate the NO-mediated genome-wide temporal transcriptomic modulation in rice root upon AsIII exposure during 12 days (d) of the growth period. Sodium nitroprusside (SNP) was used as NO donor. SNP supplementation resulted in marked decrease in ROS, cell death and As accumulation during AsIII stress. NO was found to modulate metal transporters particularly NIP, NRAMP, ABC and iron transporters, stress related genes such as CytP450, GSTs, GRXs, TFs, amino acid, hormone(s), signaling and secondary metabolism genes involved in As detoxification. We detected NO-mediated change in jasmonic acid (JA) content during AsIII stress. The study infers that NO reduces AsIII toxicity through modulating regulatory networks involved in As detoxification and JA biosynthesis.
The basic helix-loop-helix (
bHLH
) is the second-largest TF family in plants that play important roles in plant growth, development, and stress responses. In this study, a total of 100 bHLHs were ...identified using Hidden Markov Model profiles in the
Nicotiana tabacum
genome
,
clustered into 15 major groups (I–XV) based on their conserved domains and phylogenetic relationships. Group VIII genes were found to be the most abundant, with 27
NtbHLH
members. The expansion of NtbHLHs in the genome was due to segmental and tandem duplication. The purifying selection was found to have an important role in the evolution of NtHLHs. Subsequent qRT-PCR validation of five selected genes from transcriptome data revealed that
NtbHLH3.1, NtbHLH3.2, NtbHLH24, NtbHLH50
, and
NtbHLH59.2
have higher expressions at 12 and 24 h in comparison to 0 h (control) of chilling stress. The validated results demonstrated that
NtbHLH3.2
and
NtbHLH24
genes have 3 and fivefold higher expression at 12 h and 2 and threefold higher expression at 24 h than control plant, shows high sensitivity towards chilling stress. Moreover, the co-expression of positively correlated genes of
NtbHLH3.
2 and
NtbHLH24
confirmed their functional significance in chilling stress response. Therefore, suggesting the importance of
NtbHLH3.2
and
NtbHLH24
genes in exerting control over the chilling stress responses in tobacco.
Key message
OsGSTU5 interacts and glutathionylates the VirE2 protein of
Agrobacterium
and its (
OsGSTU5
) overexpression and downregulation showed a low and high AMT efficiency in rice, respectively.
...During
Agrobacterium
-mediated transformation (AMT), T-DNA along with several virulence proteins such as VirD2, VirE2, VirE3, VirD5, and VirF enter the plant cytoplasm. VirE2 serves as a single-stranded DNA binding (SSB) protein that assists the cytoplasmic trafficking of T-DNA inside the host cell. Though the regulatory roles of VirE2 have been established, the cellular reaction of their host, especially in monocots, has not been characterized in detail. This study identified a cellular interactor of VirE2 from the cDNA library of rice. The identified plant protein encoded by the gene cloned from rice was designated OsGSTU5, it interacted specifically with VirE2 in the host cytoplasm.
OsGSTU5
was upregulated during
Agrobacterium
infection and involved in the post-translational glutathionylation of VirE2 (gVirE2). Interestingly, the in silico analysis showed that the ‘gVirE2 + ssDNA’ complex was structurally less stable than the ‘VirE2 + ssDNA’ complex. The gel shift assay also confirmed the attenuated SSB property of gVirE2 over VirE2. Moreover, knock-down and overexpression of
OsGSTU5
in rice showed increased and decreased T-DNA expression, respectively after
Agrobacterium
infection. The present finding establishes the role of OsGSTU5 as an important target for modulation of AMT efficiency in rice.
Abiotic stresses adversely affect cellular homeostasis, impairing overall growth and development of plants. These initial stress signals activate downstream signalling processes, which, subsequently, ...activate stress-responsive mechanisms to re-establish homeostasis. Dehydrins (DHNs) play an important role in combating dehydration stress. Rice (Oryza sativa L.), which is a paddy crop, is susceptible to drought stress. As drought survival in rice might be viewed as a trait with strong evolutionary selection pressure, we observed DHNs in the light of domestication during the course of evolution. Overall, 65 DHNs were identified by a genome-wide survey of 11 rice species, and 3 DHNs were found to be highly conserved. The correlation of a conserved pattern of DHNs with domestication and diversification of wild to cultivated rice was validated by synonymous substitution rates, indicating that Oryza rufipogon and Oryza sativa ssp. japonica follow an adaptive evolutionary pattern; whereas Oryza nivara and Oryza sativa ssp. indica demonstrate a conserved evolutionary pattern. A comprehensive analysis of tissue-specific expression of DHN genes in japonica and their expression profiles in normal and PEG (poly ethylene glycol)-induced dehydration stress exhibited a spatiotemporal expression pattern. Their interaction network reflects the cross-talk between gene expression and the physiological processes mediating adaptation to dehydration stress. The results obtained strongly indicated the importance of DHNs, as they are conserved during the course of domestication.
Nickel (Ni) is an essential element for plant growth and is a constituent of several metalloenzymes, such as urease, Ni-Fe hydrogenase, Ni-superoxide dismutase. However, in high concentrations, Ni is ...toxic and hazardous to plants, humans and animals. High levels of Ni inhibit plant germination, reduce chlorophyll content, and cause osmotic imbalance and oxidative stress. Sustainable plant-bacterial native associations are formed under Ni-stress, such as Ni hyperaccumulator plants and rhizobacteria showed tolerance to high levels of Ni. Both partners (plants and bacteria) are capable to reduce the Ni toxicity and developed different mechanisms and strategies which they manifest in plant-bacterial associations. In addition to physical barriers, such as plants cell walls, thick cuticles and trichomes, which reduce the elevated levels of Ni entrance, plants are mitigating the Ni toxicity using their own antioxidant defense mechanisms including enzymes and other antioxidants. Bacteria in its turn effectively protect plants from Ni stress and can be used in phytoremediation. PGPR (plant growth promotion rhizobacteria) possess various mechanisms of biological protection of plants at both whole population and single cell levels. In this review, we highlighted the current understanding of the bacterial induced protective mechanisms in plant-bacterial associations under Ni stress.
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