Reactive oxygen species

Genome editing (GE) has revolutionized the biological sciences by creating a novel approach for manipulating the genomes of living organisms. Many tools have been developed in recent years to enable the editing of complex genomes. Therefore, a reliable and rapid approach for increasing yield and tolerance to various environmental stresses is necessary to sustain agricultural crop production for global food security. This critical review elaborates the GE tools used for crop improvement. These tools include mega-nucleases (MNs), such as zinc-finger nucleases (ZFNs), and transcriptional activator-like effector nucleases (TALENs), and clustered regularly interspaced short palindromic repeats (CRISPR). Specifically, this review addresses the latest advancements in the role of CRISPR/Cas9 for genome manipulation for major crop improvement, including yield and quality development of biotic stress- and abiotic stress-tolerant crops. Implementation of this technique will lead to the production of non-transgene crops with preferred characteristics that can result in enhanced yield capacity under various environmental stresses. The CRISPR/Cas9 technique can be combined with current and potential breeding methods (e.g., speed breeding and omics-assisted breeding) to enhance agricultural productivity to ensure food security. We have also discussed the challenges and limitations of CRISPR/Cas9. This information will be useful to plant breeders and researchers in the thorough investigation of the use of CRISPR/Cas9 to boost crops by targeting the gene of interest.

A Critical Review: Recent Advancements in the Use of CRISPR/Cas9 Technology to Enhance Crops and Alleviate Global Food Crises

Herein, the inoculation with strain wp-6 promoted the growth of wheat seedlings by improving the energy production and conversion of wheat seedlings and alleviating salt stress.
 Soil salinization decreases crop productivity due to high toxicity of sodium ions to plants. Plant growth-promoting rhizobacteria (PGPR) have been demonstrated to alleviate salinity stress. However, the mechanism of PGPR in improving plant salt tolerance remains unclear. In this study, physiological analysis, proteomics, and metabolomics were applied to investigate the changes in wheat seedlings under salt stress (150 mM NaCl), both with and without plant root inoculation with wp-6 (Bacillus sp.). Under salt stress, root inoculation with strain wp-6 increased plant biomass (57%) and root length (25%). The Na+ content was reduced, while the K+ content and K+/Na+ ratio were increased. The content of malondialdehyde was decreased by 31.94% after inoculation of wp-6 under salt stress, while the content of proline, soluble sugar, and soluble protein were increased by 7.48%, 12.34%, and 4.12%, respectively. The peroxidase, catalase, and superoxide dismutase activities were increased after inoculation of wp-6 under salt stress. Galactose metabolism, phenylalanine metabolism, caffeine metabolism, ubiquinone and other terpenoid-quinone biosynthesis, and glutathione metabolism might play an important role in promoting the growth of salt-stressed wheat seedlings after the inoculation with wp-6. Interaction analysis of differentially expressed proteins and metabolites found that energy production and transformation-related proteins and six metabolites (d-arginine, palmitoleic acid, chlorophyllide b, rutin, pheophorbide a, and vanillylamine) were mainly involved in the growth of wheat seedlings after the inoculation with wp-6 under salt stress. Furthermore, correlation analysis found that inoculation with wp-6 promotes the growth of salt-stressed wheat seedlings mainly through regulating amino acid metabolism and porphyrin and chlorophyll metabolism. This study provides an eco-friendly method to increase agricultural productivity and paves a way to sustainable agriculture.

Physiological, proteomic, and metabolomic analysis provide insights into Bacillus sp.-mediated salt tolerance in wheat

Global warming in this century increases incidences of various abiotic stresses restricting plant growth and productivity and posing a severe threat to global food production and security. The plant produces different osmolytes and hormones to combat the harmful effects of these abiotic stresses. Melatonin (MT) is a plant hormone that possesses excellent properties to improve plant performance under different abiotic stresses. It is associated with improved physiological and molecular processes linked with seed germination, growth and development, photosynthesis, carbon fixation, and plant defence against other abiotic stresses. In parallel, MT also increased the accumulation of multiple osmolytes, sugars and endogenous hormones (auxin, gibberellic acid, and cytokinins) to mediate resistance to stress. Stress condition in plants often produces reactive oxygen species. MT has excellent antioxidant properties and substantially scavenges reactive oxygen species by increasing the activity of enzymatic and non-enzymatic antioxidants under stress conditions. Moreover, the upregulation of stress-responsive and antioxidant enzyme genes makes it an excellent stress-inducing molecule. However, MT produced in plants is not sufficient to induce stress tolerance. Therefore, the development of transgenic plants with improved MT biosynthesis could be a promising approach to enhancing stress tolerance. This review, therefore, focuses on the possible role of MT in the induction of various abiotic stresses in plants. We further discussed MT biosynthesis and the critical role of MT as a potential antioxidant for improving abiotic stress tolerance. In addition, we also addressed MT biosynthesis and shed light on future research directions. Therefore, this review would help readers learn more about MT in a changing environment and provide new suggestions on how this knowledge could be used to develop stress tolerance.

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Melatonin-Induced Protection Against Plant Abiotic Stress: Mechanisms and Prospects

Climate change poses a serious threat to global agricultural activity and food production. Plant genome editing technologies have been widely used to develop crop varieties with superior qualities or can tolerate adverse environmental conditions. Unlike conventional breeding techniques (e.g., selective breeding and mutation breeding), modern genome editing tools offer more targeted and specific alterations of the plant genome and could significantly speed up the progress of developing crops with desired traits, such as higher yield and/or stronger resilience to the changing environment. In this review, we discuss the current development and future applications of genome editing technologies in mitigating the impacts of biotic and abiotic stresses on agriculture. We focus specifically on the CRISPR/Cas system, which has been the center of attention in the last few years as a revolutionary genome-editing tool in various species. We also conducted a bibliographic analysis on CRISPR-related papers published from 2012 to 2021 (10 years) to identify trends and potential in the CRISPR/Cas-related plant research. In addition, this review article outlines the current shortcomings and challenges of employing genome editing technologies in agriculture with notes on future prospective. We believe combining conventional and more innovative technologies in agriculture would be the key to optimizing crop improvement beyond the limitations of traditional agricultural practices.

https://www.mdpi.com/2223-7747/11/19/2625/pdf?version=1665467179

Genome Editing for Sustainable Crop Improvement and Mitigation of Biotic and Abiotic Stresses

Xanthine dehydrogenase (XDH) is an important enzyme in purine metabolism. It is involved in regulation of the normal growth and non-biological stress-induced ageing processes in plants. The present study investigated XDH’s role in regulating rice leaf senescence. We measured physical characteristics, chlorophyll content and fluorescence parameters, active oxygen metabolism, and purine metabolism in wild-type Kitaake rice (Oryza sativa L.), an OsXDH over-expression transgenic line (OE9), and an OsXDH RNA interference line (Ri3) during different growth stages. The expression patterns of the OsXDH gene confirmed that XDH was involved in the regulation of normal and abiotic stress-induced ageing processes in rice. There was no significant difference between the phenotypes of transgenic lines and wild type at the seedling stage, but differences were observed at the full heading and maturation stages. The OE9 plants were taller, with higher chlorophyll content, and their photosystems had stronger light energy absorption, transmission, dissipation, and distribution capacity, which ultimately improved the seed setting rate and 1000-seed weight. The opposite effect was found in the Ri3 plants. The OE9 line had a strong ability to remove reactive oxygen species, with increased accumulation of allantoin and alantoate. Experimental spraying of allantoin on leaves showed that it could alleviate chlorophyll degradation and decrease the content of H2O2 and malonaldehyde (MDA) in rice leaves after the full heading stage. The urate oxidase gene (UO) expression levels in the interference line were significantly lower than those in the over-expression line and wild-type lines. The allantoinase (ALN) and allantoate amidinohydrolase (AAH) genes had significantly higher expression in the Ri3 plants than the in OE9 or wild-type plants, with OE9 plants showing the lowest levels. The senescence-related genes ACD1, WRKY23, WRKY53, SGR, XERO1, and GH27 in Ri3 plants had the highest expression levels, followed by those in the wild-type plants, with OE9 plants showing the lowest levels. These results suggest that enhanced activity of XDH can regulate the synthesis of urea-related substances, improve plant antioxidant capacity, effectively delay the ageing process in rice leaves, and increase rice yield.

/pdf/enhancing-xanthine-dehydrogenase-activity-is-an-effective-emejmxinsz.pdf

Enhancing xanthine dehydrogenase activity is an effective way to delay leaf senescence and increase rice yield

Aluminium toxicity is adversely affecting the rice growth and production in acidic soils of developing countries. Rice is popular and stable crop which meets food requirements of about 50% world population. A set of 122 rice backcross recombinant inbreed lines (BRILs) derived from a cross between Japonica (cv.02428) and Indica (Changhui/891) was grown in nutrient solution. High density linkage map generated by using 3075 highly stable SNP markers. Relative root length (RRL) was used as standard criteria for aluminium tolerance. A total of 23 QTLs were detected in the current study for six traits across all experimental conditions. Regarding RRL, three QTLs qCRL-6, qSRL-6, and qRRL-6 were found stable and common QTLs across all environments. Out of these three QTLs, qRRL-6 with higher heritability estimates (H2 = 96.59%) was novel QTL with a positive additive effect. In addition, shoot length (SL), shoot fresh weight (SFW), root fresh weight (RFW), shoot dry weight (SDW) and root dry weight (RDW) were used and identified QTLs, qSSL-11, qRRFW-1, and qRRDW-1 and qRRDW-8 which were newly reported QTLs. Three pleiotropic QTLs qRRFW-1, qRSDW-1, and qRRDW-1 were also reported and these QTLs would facilitate to improve Al tolerance by MAS selection and QTLs pyramiding.

Identification of genomic regions at seedling related traits in response to aluminium toxicity using a new high-density genetic map in rice ( Oryza sativa L.)

Effects of humidity-cold combined stress at the seedling stage in direct-seeded indica rice

Heavy metals bioaccumulation and bio amplification in the environment are serious constraints for plants and all living organisms. Heavy metals have a serious impact on crop production, and, additionally, their intake in foodstuffs has devastating impacts on human health and causes severe diseases, including Alzheimer’s, cancer, and Parkinson’s disease. Heavy metals reduce seed germination, root and shoot growth, biomass accumulation, and yield, and cause chlorosis and necrosis and inhibit various physiological processes like photosynthesis, transpiration and cause oxidative damage in plants. The heavy metals interact with vital organs such as DNA and protein, and lead to the production of reactive species (ROS). The production of ROS brings severe metabolic, morphological as well as physiological abnormalities in plants which include the degradation of proteins and lipid peroxidation. In such circumstances, plants have adopted a range of defense mechanisms to overcome the toxic effects of metals. One of the key defense mechanisms of plants’ response to heavy metals is the use of chelating molecules through the production of Phyto-chelations, at both intra- and intercellular levels, which then act to remove ions of HMs from sensitive sites of the cell and, secondly, metallothioneins which protect plants by scavenging ROS. Many compounds, such as proline, which are not enzymatically synthesized, are able to boost the capacity of metals detoxification of intracellular enzymes. Plants’ symbiotic relationships with arbuscular mycorrhizal is another way to counter HMs as it has the capability to immobilize HMs and minimize their uptake via plant roots through the process of binding of ions of HMs. The use of miRNA, organic acids, amino acid and salicylic acid and transgenic species can effectively enhance plants’ defense response against HMs’ stress.

Ziming Wu

Papers

A Critical Review: Recent Advancements in the Use of CRISPR/Cas9 Technology to Enhance Crops and Alleviate Global Food Crises

Enhancing xanthine dehydrogenase activity is an effective way to delay leaf senescence and increase rice yield

Identification of genomic regions at seedling related traits in response to aluminium toxicity using a new high-density genetic map in rice ( Oryza sativa L.)

Effects of humidity-cold combined stress at the seedling stage in direct-seeded indica rice

Heavy Metals Stress and Plants Defense Responses