•Plant growth response to NMs exhibits a trend of low-promoting and high-inhibiting.•NMs increase the overall nutritional quality of food plants.•The rhizosphere processes of NMs are summarized and ...discussed.•Perspectives are presented for the potentials of NMs in sustainable agriculture.
With the rising global population growth and limitation of traditional agricultural technology, global crop production could not provide enough nutrients to assure adequate intake for all people. Nano-fertilizers and nano-pesticides have 20–30% higher efficacy than conventional products, which offer an effective solution to the above-mentioned problem. Rhizosphere is where plant roots, soil, and soil biota interact, and is the portal of nutrients transporting from soil into plants. The rhizosphere processes could modify the bioavailability of all nutrients and nanomaterials (NMs) before entering the food plants. However, to date, the overall rhizosphere processes regulating the behaviors and bioavailability of NMs to enhance the nutritional quality are still uncertain. In this review, a meta-analysis is conducted to quantitatively assess NMs-mediated changes in nutritional quality from food plants. Furthermore, the current knowledge and related mechanisms of the behavior and bioavailability of NMs driven by rhizosphere processes, e.g., root secretions, microbial and earthworm activities, are summarized. A series of rhizosphere processes can influence how NMs enter plants and change the biological responses, including signal transduction and nutrient absorption and transport. Moreover, future perspectives are presented to maximize the potentials of NMs applications for the enhancement of food crop production and global food security.
In the present study, the level of thiols and activity of related enzymes were investigated in coontail (
Ceratophyllum demersum L.) plants to analyze their role in combating the stress caused upon ...exposure to cadmium (Cd; 0–10
μM) for a duration up to 7
d. Plants showed the maximum accumulation of 1293
μg
Cd
g
−1
dw after 7
d at 10
μM. Significant increases in the level of total non-protein thiols (NP-SH) including phytochelatins (PCs) as well as upstream metabolites of the PC biosynthetic pathway, cysteine and glutathione (GSH) were observed. In addition, significant increases in the activities of cysteine synthase (CS), glutathione-
S-transferase (GST), glutathione reductase (GR), as well as
in vitro activation of phytochelatin synthase (PCS), were noticed in response to Cd. In conclusion, under Cd stress, plants adapted to a new metabolic equilibrium of thiols through coordinated synthesis and consumption to combat Cd toxicity and to accumulate it.
Simulated pot experiments were conducted on four rice (Oryza sativa L.) genotypes (Triguna, IR-36, PNR-519, and IET-4786) to examine the effects of AsV on amino acids and mineral nutrient status in ...grain along with antioxidant response to arsenic exposure. Rice genotypes responded differentially to AsV exposure in terms of amino acids and antioxidant profiles. Total amino acid content in grains of all rice genotypes was positively correlated with arsenic accumulation. While, most of the essential amino acids increased in all cultivars except IR-36, glutamic acid and glycine increased in IET-4786 and PNR-519. The level of nonprotein thiols (NPTs) and the activities of superoxide dismutase (SOD; EC 1.15.1.1), glutathione reductase (GR; EC 1.6.4.2) and ascorbate peroxidase (APX; EC 1.11.1.11) increased in all rice cultivars except IET-4786. A significant genotypic variation was also observed in specific arsenic uptake (SAU; mg kg−1dw), which was in the order of Triguna (134) > IR-36 (71) > PNR-519 (53) > IET-4786 (29). Further, application of AsV at lower doses (4 and 8 mg L−1 As) enhanced the accumulation of selenium (Se) and other nutrients (Fe, P, Zn, and S), however, higher dose (12 mg L−1 As) limits the nutrient uptake in rice. In conclusion, low As accumulating genotype, IET-4786, which also had significantly induced level of essential amino acids, seems suitable for cultivation in moderately As contaminated soil and would be safe for human consumption.
Camelina sativa (L.) Crantz is an oilseed crop with favorable potentials for biodiesel production, such as the high plant yield, high oil content in the seed, high net energy ratio, and low oil ...production cost. This review paper deals with the present state and perspectives of biodiesel production from camelina oil. First, important issues of camelina seed pretreatment and biodiesel production are reviewed. Emphasis is given to different biodiesel technologies that have been used so far worldwide, the economic assessment of the camelina oil biodiesel (COB) production, the camelina‐based biorefineries for the integrated biodiesel production, the COB life cycle analysis, and impact human health and ecosystem. Finally, the perspectives of COB production from the techno‐economic and especially genetic engineering points of view are discussed.
Camelina sativa (L.) Crantz is an oilseed crop with favorable potentials for biodiesel production, such as the high plant yield, high oil content in the seed, high net energy ratio, and low oil production cost. This review paper deals with the present state and perspectives of biodiesel production from camelina oil. First, important issues of camelina seed pretreatment and biodiesel production are reviewed. Emphasis is given to different biodiesel technologies that have been used so far worldwide, the economic assessment of the camelina oil biodiesel (COB) production, the camelina‐based biorefineries for the integrated biodiesel production, the COB life cycle analysis, and impact human health and ecosystem. Finally, the perspectives of COB production from the techno‐economic and especially genetic engineering points of view are discussed.
Selenium (Se) is an essential element for many animals including humans, prokaryotes and a few green algae. For plants, Se essentiality is yet to be demonstrated. Nevertheless, it is well recognized ...that Se is a beneficial element for plants. For all organisms, while, a narrow range of Se is beneficial, at elevated levels it becomes toxic. This is due to accumulation of various toxic inorganic and organic Se forms during Se metabolism as well as nonspecific replacement by Se of chemically similar sulfur (S) analogs. Interestingly, Se can act both as an antioxidant and a pro-oxidant. Hence, Se chemistry and metabolism play crucial roles in determining its effects at specific concentration in an organism. A lot of knowledge has been gained regarding Se metabolites, however, the functions of many of these metabolites are yet to be resolved. Other Se containing metabolites and proteins might yet be awaiting their identification. Future research in this direction would pave the way towards identification of Se as an essential element for plants too. This review discusses the various aspects of Se uptake and metabolism with a major focus on functions of Se-containing metabolites in plants.
Nitric oxide (NO) is a gaseous signaling molecule and has a profound impact on plant growth and development. It is reported to serve as pro oxidant as well as antioxidant in plant system. In the ...present study, we evaluated the protective role of NO against arsenate (As(V)) toxicity in rice plants. As(V) exposure has hampered the plant growth, reduced the chlorophyll content, and enhanced the oxidative stress, while the exogenous NO supplementation has reverted these symptoms. NO supplementation has reduced the arsenic (As) accumulation in root as well as shoot. NO supplementation to As(V) exposed plants has reduced the gene expression level of OsLsi1 and OsLsi2. As(V) stress significantly impacted thiol metabolism, it reduced GSH content and GSH/GSSG ratio, and enhanced the level of PCs. NO supplementation maintained the GSH/GSSG ratio and reduced the level of PCs. NO supplementation reverted As(V) induced iron deficiency in shoot and had significant impact of gene expression level of various iron transporters (OsYSL2, OsFRDL1, OsIRT1, and OsIRO2). Conclusively, exogenous application of NO could be advantageous against As(V) toxicity and could confer the tolerance to As(V) stress in rice.
Glutaredoxins (Grxs) are a family of small multifunctional proteins involved in various cellular functions, including redox regulation and protection under oxidative stress. Despite the high number ...of Grx genes in plant genomes (48 Grxs in rice), the biological functions and physiological roles of most of them remain unknown. Here, the functional characterization of the two arsenic-responsive rice Grx family proteins, OsGrx_C7 and OsGrx_C2.1 are reported. Over-expression of OsGrx_C7 and OsGrx_C2.1 in transgenic Arabidopsis thaliana conferred arsenic (As) tolerance as reflected by germination, root growth assay, and whole plant growth. Also, the transgenic expression of OsGrxs displayed significantly reduced As accumulation in A. thaliana seeds and shoot tissues compared to WT plants during both AsIII and AsV stress. Thus, OsGrx_C7 and OsGrx_C2.1 seem to be an important determinant of As-stress response in plants. OsGrx_C7 and OsGrx_C2.1 transgenic showed to maintain intracellular GSH pool and involved in lowering AsIII accumulation either by extrusion or reducing uptake by altering the transcript of A. thaliana AtNIPs. Overall, OsGrx_C7 and OsGrx_C2.1 may represent a Grx family protein involved in As stress response and may allow a better understanding of the As induced stress pathways and the design of strategies for the improvement of stress tolerance as well as decreased As content in crops.
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