scholarly journals Manipulation of Ascorbate Biosynthetic, Recycling, and Regulatory Pathways for Improved Abiotic Stress Tolerance in Plants

2020 ◽  
Vol 21 (5) ◽  
pp. 1790 ◽  
Author(s):  
Ronan C. Broad ◽  
Julien P. Bonneau ◽  
Roger P. Hellens ◽  
Alexander A.T. Johnson

Abiotic stresses, such as drought, salinity, and extreme temperatures, are major limiting factors in global crop productivity and are predicted to be exacerbated by climate change. The overproduction of reactive oxygen species (ROS) is a common consequence of many abiotic stresses. Ascorbate, also known as vitamin C, is the most abundant water-soluble antioxidant in plant cells and can combat oxidative stress directly as a ROS scavenger, or through the ascorbate–glutathione cycle—a major antioxidant system in plant cells. Engineering crops with enhanced ascorbate concentrations therefore has the potential to promote broad abiotic stress tolerance. Three distinct strategies have been utilized to increase ascorbate concentrations in plants: (i) increased biosynthesis, (ii) enhanced recycling, or (iii) modulating regulatory factors. Here, we review the genetic pathways underlying ascorbate biosynthesis, recycling, and regulation in plants, including a summary of all metabolic engineering strategies utilized to date to increase ascorbate concentrations in model and crop species. We then highlight transgene-free strategies utilizing genome editing tools to increase ascorbate concentrations in crops, such as editing the highly conserved upstream open reading frame that controls translation of the GDP-L-galactose phosphorylase gene.

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 623
Author(s):  
Sidra Habib ◽  
Yee Yee Lwin ◽  
Ning Li

Adverse environmental factors like salt stress, drought, and extreme temperatures, cause damage to plant growth, development, and crop yield. GRAS transcription factors (TFs) have numerous functions in biological processes. Some studies have reported that the GRAS protein family plays significant functions in plant growth and development under abiotic stresses. In this study, we demonstrated the functional characterization of a tomato SlGRAS10 gene under abiotic stresses such as salt stress and drought. Down-regulation of SlGRAS10 by RNA interference (RNAi) produced dwarf plants with smaller leaves, internode lengths, and enhanced flavonoid accumulation. We studied the effects of abiotic stresses on RNAi and wild-type (WT) plants. Moreover, SlGRAS10-RNAi plants were more tolerant to abiotic stresses (salt, drought, and Abscisic acid) than the WT plants. Down-regulation of SlGRAS10 significantly enhanced the expressions of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) to reduce the effects of reactive oxygen species (ROS) such as O2− and H2O2. Malondialdehyde (MDA) and proline contents were remarkably high in SlGRAS10-RNAi plants. Furthermore, the expression levels of chlorophyll biosynthesis, flavonoid biosynthesis, and stress-related genes were also enhanced under abiotic stress conditions. Collectively, our conclusions emphasized the significant function of SlGRAS10 as a stress tolerate transcription factor in a certain variety of abiotic stress tolerance by enhancing osmotic potential, flavonoid biosynthesis, and ROS scavenging system in the tomato plant.


Author(s):  
Ali Razzaq ◽  
Ghulam Mustafa ◽  
Muhammad Amjad Ali ◽  
Muhammad Sarwar Khan ◽  
Faiz Ahmad Joyia

Abstract This chapter discusses the applications of CRISPR-mediated genome editing to improve the abiotic stress tolerance (such as drought, heat, waterlogging and cold tolerance) of maize. CRISPR/Cas9 has great potential for maize genome manipulation at desired sites. By using CRISPR/Cas9-mediated genome editing, numerous genes can be targeted to produce elite maize cultivars that minimize the challenges of abiotic stresses. In the future, more precise and accurate variants of the CRISPR/Cas9 toolbox are expected to be used for maize yield improvement.


2019 ◽  
Author(s):  
Nouf Owdah Alshareef ◽  
Elodie Rey ◽  
Holly Khoury ◽  
Mark Tester ◽  
Sandra M. Schmöckel

AbstractChenopodium quinoa Willd. (quinoa) is a pseudocereal with high nutritional value and relatively high tolerance to several abiotic stresses, including water deficiency and salt stress, making it a suitable plant for the study of mechanisms of abiotic stress tolerance. NAC (NAM, ATAF and CUC) transcription factors are involved in a range of plant developmental processes and in the response of plants to biotic and abiotic stresses. In the present study, we perform a genome-wide comprehensive analysis of the NAC transcription factor gene family in quinoa. In total, we identified 107 quinoa NAC transcription factor genes, distributed equally between sub-genomes A and B. They are phylogenetically clustered into two major groups and 18 subgroups. Almost 75% of the identified CqNAC genes were duplicated two to seven times and the remaining 25% of the CqNAC genes were found as a single copy. We analysed the transcriptional responses of the identified quinoa NAC TF genes in response to various abiotic stresses. The transcriptomic data revealed 28 stress responsive CqNAC genes, where their expression significantly changed in response to one or more abiotic stresses, including salt, water deficiency, heat and phosphate starvation. Among these stress responsive NACs, some were previously known to be stress responsive in other species, indicating their potentially conserved function in response to abiotic stress across plant species. Six genes were differentially expressed specifically in response to phosphate starvation but not to other stresses, and these genes may play a role in controlling plant responses to phosphate deficiency. These results provide insights into quinoa NACs that could be used in the future for genetic engineering or molecular breeding.


2021 ◽  
Vol 22 (20) ◽  
pp. 11032
Author(s):  
Jamie A. O’Rourke ◽  
Michael J. Morrisey ◽  
Ryan Merry ◽  
Mary Jane Espina ◽  
Aaron J. Lorenz ◽  
...  

The soybean (Glycine max L. merr) genotype Fiskeby III is highly resistant to a multitude of abiotic stresses, including iron deficiency, incurring only mild yield loss during stress conditions. Conversely, Mandarin (Ottawa) is highly susceptible to disease and suffers severe phenotypic damage and yield loss when exposed to abiotic stresses such as iron deficiency, a major challenge to soybean production in the northern Midwestern United States. Using RNA-seq, we characterize the transcriptional response to iron deficiency in both Fiskeby III and Mandarin (Ottawa) to better understand abiotic stress tolerance. Previous work by our group identified a quantitative trait locus (QTL) on chromosome 5 associated with Fiskeby III iron efficiency, indicating Fiskeby III utilizes iron deficiency stress mechanisms not previously characterized in soybean. We targeted 10 of the potential candidate genes in the Williams 82 genome sequence associated with the QTL using virus-induced gene silencing. Coupling virus-induced gene silencing with RNA-seq, we identified a single high priority candidate gene with a significant impact on iron deficiency response pathways. Characterization of the Fiskeby III responses to iron stress and the genes underlying the chromosome 5 QTL provides novel targets for improved abiotic stress tolerance in soybean.


Agronomy ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 788 ◽  
Author(s):  
Youngdae Yoon ◽  
Deok Hyun Seo ◽  
Hoyoon Shin ◽  
Hui Jin Kim ◽  
Chul Min Kim ◽  
...  

Abiotic stresses, such as drought, high temperature, and salinity, affect plant growth and productivity. Furthermore, global climate change may increase the frequency and severity of abiotic stresses, suggesting that development of varieties with improved stress tolerance is critical for future sustainable crop production. Improving stress tolerance requires a detailed understanding of the hormone signaling and transcriptional pathways involved in stress responses. Abscisic acid (ABA) and jasmonic acid (JA) are key stress-response hormones in plants, and some stress-responsive transcription factors such as ABFs and MYCs function as direct components of ABA and JA signaling, playing a pivotal role in plant tolerance to abiotic stress. In addition, extensive studies have identified other stress-responsive transcription factors belonging to the NAC, AP2/ERF, MYB, and WRKY families that mediate plant response and tolerance to abiotic stress. These suggest that transcriptional regulation of stress-responsive genes is an essential step to determine the mechanisms underlying plant stress responses and tolerance to abiotic stress, and that these transcription factors may be important targets for development of crops with enhanced abiotic stress tolerance. In this review, we briefly describe the mechanisms underlying plant abiotic stress responses, focusing on ABA and JA metabolism and signaling pathways. We then summarize the diverse array of transcription factors involved in plant responses to abiotic stress, while noting their potential applications for improvement of stress tolerance.


AoB Plants ◽  
2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Komivi Dossa ◽  
Marie A Mmadi ◽  
Rong Zhou ◽  
Aili Liu ◽  
Yuanxiao Yang ◽  
...  

Abstract An increasing number of candidate genes related to abiotic stress tolerance are being discovered and proposed to improve the existing cultivars of the high oil-bearing crop sesame (Sesamum indicum L.). However, the in planta functional validation of these genes is remarkably lacking. In this study, we cloned a novel sesame R2-R3 MYB gene SiMYB75 which is strongly induced by drought, sodium chloride (NaCl), abscisic acid (ABA) and mannitol. SiMYB75 is expressed in various sesame tissues, especially in root and its protein is predicted to be located in the nucleus. Ectopic over-expression of SiMYB75 in Arabidopsis notably promoted root growth and improved plant tolerance to drought, NaCl and mannitol treatments. Furthermore, SiMYB75 over-expressing lines accumulated higher content of ABA than wild-type plants under stresses and also increased sensitivity to ABA. Physiological analyses revealed that SiMYB75 confers abiotic stress tolerance by promoting stomatal closure to reduce water loss; inducing a strong reactive oxygen species scavenging activity to alleviate cell damage and apoptosis; and also, up-regulating the expression levels of various stress-marker genes in the ABA-dependent pathways. Our data suggested that SiMYB75 positively modulates drought, salt and osmotic stresses responses through ABA-mediated pathways. Thus, SiMYB75 could be a promising candidate gene for the improvement of abiotic stress tolerance in crop species including sesame.


2021 ◽  
Vol 22 (23) ◽  
pp. 12970
Author(s):  
Jagadish Rane ◽  
Ajay Kumar Singh ◽  
Mahesh Kumar ◽  
K. M. Boraiah ◽  
Kamlesh K. Meena ◽  
...  

Abiotic stresses, including drought, extreme temperatures, salinity, and waterlogging, are the major constraints in crop production. These abiotic stresses are likely to be amplified by climate change with varying temporal and spatial dimensions across the globe. The knowledge about the effects of abiotic stressors on major cereal and legume crops is essential for effective management in unfavorable agro-ecologies. These crops are critical components of cropping systems and the daily diets of millions across the globe. Major cereals like rice, wheat, and maize are highly vulnerable to abiotic stresses, while many grain legumes are grown in abiotic stress-prone areas. Despite extensive investigations, abiotic stress tolerance in crop plants is not fully understood. Current insights into the abiotic stress responses of plants have shown the potential to improve crop tolerance to abiotic stresses. Studies aimed at stress tolerance mechanisms have resulted in the elucidation of traits associated with tolerance in plants, in addition to the molecular control of stress-responsive genes. Some of these studies have paved the way for new opportunities to address the molecular basis of stress responses in plants and identify novel traits and associated genes for the genetic improvement of crop plants. The present review examines the responses of crops under abiotic stresses in terms of changes in morphology, physiology, and biochemistry, focusing on major cereals and legume crops. It also explores emerging opportunities to accelerate our efforts to identify desired traits and genes associated with stress tolerance.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Islam A. Abd El-Daim ◽  
Sarosh Bejai ◽  
Johan Meijer

Abstract Abiotic stresses are main limiting factors for agricultural production around the world. Plant growth promoting rhizobacteria (PGPR) have been shown to improve abiotic stress tolerance in several plants. However, the molecular and physiological changes connected with PGPR priming of stress management are poorly understood. The present investigation aimed to explore major metabolic and molecular changes connected with the ability of Bacillus velezensis 5113 to mediate abiotic stress tolerance in wheat. Seedlings treated with Bacillus were exposed to heat, cold/freezing or drought stress. Bacillus improved wheat survival in all stress conditions. SPAD readings showed higher chlorophyll content in 5113-treated stressed seedlings. Metabolite profiling using NMR and ESI-MS provided evidences for metabolic reprograming in 5113-treated seedlings and showed that several common stress metabolites were significantly accumulated in stressed wheat. Two-dimensional gel electrophoresis of wheat leaves resolved more than 300 proteins of which several were differentially expressed between different treatments and that cold stress had a stronger impact on the protein pattern compared to heat and drought. Peptides maps or sequences were used for database searches which identified several homologs. The present study suggests that 5113 treatment provides systemic effects that involve metabolic and regulatory functions supporting both growth and stress management.


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