Down-Regulation of Cytokinin Receptor Gene SlHK2 Improves Plant Tolerance to Drought, Heat, and Combined Stresses in Tomato

Environmental stresses negatively affect the growth and development of plants. Several previous studies have elucidated the response mechanisms of plants to drought and heat applied separately; however, these two abiotic stresses often coincide in environmental conditions. The global climate change pattern has projected that combined drought and heat stresses will tend to increase in the near future. In this study, we down-regulated the expression of a cytokinin receptor gene SlHK2 using RNAi and investigated the role of this gene in regulating plant responses to individual drought, heat, and combined stresses (drought + heat) in tomato. Compared to the wild-type (WT), SlHK2 RNAi plants exhibited fewer stress symptoms in response to individual and combined stress treatments. The enhanced abiotic stress tolerance of SlHK2 RNAi plants can be associated with increased membrane stability, osmoprotectant accumulation, and antioxidant enzyme activities. Furthermore, photosynthesis machinery was also protected in SlHK2 RNAi plants. Collectively, our results show that down-regulation of the cytokinin receptor gene SlHK2, and consequently cytokinin signaling, can improve plant tolerance to drought, heat, and combined stress.

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The Role of Stress-Responsive Transcription Factors in Modulating Abiotic Stress Tolerance in Plants

Agronomy ◽

10.3390/agronomy10060788 ◽

2020 ◽

Vol 10 (6) ◽

pp. 788 ◽

Cited By ~ 4

Author(s):

Youngdae Yoon ◽

Deok Hyun Seo ◽

Hoyoon Shin ◽

Hui Jin Kim ◽

Chul Min Kim ◽

...

Keyword(s):

Transcription Factors ◽

Abiotic Stress ◽

Stress Tolerance ◽

Stress Responses ◽

Abiotic Stresses ◽

Crop Production ◽

Global Climate ◽

Abiotic Stress Tolerance ◽

Plant Responses ◽

Plant Tolerance

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.

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Defining the combined stress response in wild Arachis

Scientific Reports ◽

10.1038/s41598-021-90607-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ana Paula Zotta Mota ◽

Ana Cristina Miranda Brasileiro ◽

Bruna Vidigal ◽

Thais Nicolini Oliveira ◽

Andressa da Cunha Quintana Martins ◽

...

Keyword(s):

Stress Tolerance ◽

Meta Analysis ◽

Plant Responses ◽

Combined Stress ◽

Root Knot Nematode ◽

Crop Breeding ◽

Combined Stresses ◽

Complex Regulation ◽

Encoding Gene ◽

Stress Responsive Genes

AbstractNematodes and drought are major constraints in tropical agriculture and often occur simultaneously. Plant responses to these stresses are complex and require crosstalk between biotic and abiotic signaling pathways. In this study, we explored the transcriptome data of wild Arachis species subjected to drought (A-metaDEG) and the root-knot nematode Meloidogyne arenaria (B-metaDEG) via meta-analysis, to identify core-stress responsive genes to each individual and concurrent stresses in these species. Transcriptome analysis of a nematode/drought bioassay (cross-stress) showed that the set of stress responsive DEGs to concurrent stress is distinct from those resulting from overlapping A- and B-metaDEGs, indicating a specialized and unique response to combined stresses in wild Arachis. Whilst individual biotic and abiotic stresses elicit hormone-responsive genes, most notably in the jasmonic and abscisic acid pathways, combined stresses seem to trigger mainly the ethylene hormone pathway. The overexpression of a cross-stress tolerance candidate gene identified here, an endochitinase-encoding gene (AsECHI) from Arachis stenosperma, reduced up to 30% of M. incognita infection and increased post-drought recovery in Arabidopsis plants submitted to both stresses. The elucidation of the network of cross-stress responsive genes in Arachis contributes to better understanding the complex regulation of biotic and abiotic responses in plants facilitating more adequate crop breeding for combined stress tolerance.

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Transgenic Breeding Approaches for Improving Abiotic Stress Tolerance: Recent Progress and Future Perspectives

International Journal of Molecular Sciences ◽

10.3390/ijms21082695 ◽

2020 ◽

Vol 21 (8) ◽

pp. 2695 ◽

Cited By ~ 5

Author(s):

Ali Anwar ◽

Ju-Kon Kim

Keyword(s):

Abiotic Stress ◽

Stress Tolerance ◽

Recent Progress ◽

Abiotic Stress Tolerance ◽

Antioxidant Enzyme Activities ◽

Great Success ◽

Plant Tolerance ◽

Future Perspectives ◽

Suitable Alternative ◽

Transgenic Breeding

The recent rapid climate changes and increasing global population have led to an increased incidence of abiotic stress and decreased crop productivity. Environmental stresses, such as temperature, drought, nutrient deficiency, salinity, and heavy metal stresses, are major challenges for agriculture, and they lead to a significant reduction in crop growth and productivity. Abiotic stress is a very complex phenomenon, involving a variety of physiological and biochemical changes in plant cells. Plants exposed to abiotic stress exhibit enhanced levels of ROS (reactive oxygen species), which are highly reactive and toxic and affect the biosynthesis of chlorophyll, photosynthetic capacity, and carbohydrate, protein, lipid, and antioxidant enzyme activities. Transgenic breeding offers a suitable alternative to conventional breeding to achieve plant genetic improvements. Over the last two decades, genetic engineering/transgenic breeding techniques demonstrated remarkable developments in manipulations of the genes for the induction of desired characteristics into transgenic plants. Transgenic approaches provide us with access to identify the candidate genes, miRNAs, and transcription factors (TFs) that are involved in specific plant processes, thus enabling an integrated knowledge of the molecular and physiological mechanisms influencing the plant tolerance and productivity. The accuracy and precision of this phenomenon assures great success in the future of plant improvements. Hence, transgenic breeding has proven to be a promising tool for abiotic stress improvement in crops. This review focuses on the potential and successful applications, recent progress, and future perspectives of transgenic breeding for improving abiotic stress tolerance and productivity in plants.

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Polyamines: Small Amines with Large Effects on Plant Abiotic Stress Tolerance

Cells ◽

10.3390/cells9112373 ◽

2020 ◽

Vol 9 (11) ◽

pp. 2373

Author(s):

Rubén Alcázar ◽

Milagros Bueno ◽

Antonio F. Tiburcio

Keyword(s):

Abiotic Stress ◽

Stress Tolerance ◽

Environmental Changes ◽

Genetic Manipulation ◽

Abiotic Stress Tolerance ◽

Seed Priming ◽

Crop Plants ◽

Plant Responses ◽

Plant Tolerance ◽

Plant Abiotic Stress

In recent years, climate change has altered many ecosystems due to a combination of frequent droughts, irregular precipitation, increasingly salinized areas and high temperatures. These environmental changes have also caused a decline in crop yield worldwide. Therefore, there is an urgent need to fully understand the plant responses to abiotic stress and to apply the acquired knowledge to improve stress tolerance in crop plants. The accumulation of polyamines (PAs) in response to many abiotic stresses is one of the most remarkable plant metabolic responses. In this review, we provide an update about the most significant achievements improving plant tolerance to drought, salinity, low and high temperature stresses by exogenous application of PAs or genetic manipulation of endogenous PA levels. We also provide some clues about possible mechanisms underlying PA functions, as well as known cross-talks with other stress signaling pathways. Finally, we discuss about the possible use of PAs for seed priming to induce abiotic stress tolerance in agricultural valuable crop plants.

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Down-Regulation of SlGRAS10 in Tomato Confers Abiotic Stress Tolerance

Genes ◽

10.3390/genes12050623 ◽

2021 ◽

Vol 12 (5) ◽

pp. 623

Author(s):

Sidra Habib ◽

Yee Yee Lwin ◽

Ning Li

Keyword(s):

Salt Stress ◽

Abiotic Stress ◽

Plant Growth ◽

Stress Tolerance ◽

Abiotic Stresses ◽

Abiotic Stress Tolerance ◽

Functional Characterization ◽

Flavonoid Biosynthesis ◽

Ros Scavenging ◽

Down Regulation

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.

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Potassium: A Vital Regulator of Plant Responses and Tolerance to Abiotic Stresses

Agronomy ◽

10.3390/agronomy8030031 ◽

2018 ◽

Vol 8 (3) ◽

pp. 31 ◽

Cited By ~ 73

Author(s):

Mirza Hasanuzzaman ◽

M. Bhuyan ◽

Kamrun Nahar ◽

Md. Hossain ◽

Jubayer Mahmud ◽

...

Keyword(s):

Abiotic Stress ◽

Stress Tolerance ◽

Molecular Mechanisms ◽

Abiotic Stress Tolerance ◽

Ion Homeostasis ◽

Enzyme Activation ◽

Regulatory Function ◽

Plant Responses ◽

Plant Structure ◽

Physiological Processes

Among the plant nutrients, potassium (K) is one of the vital elements required for plant growth and physiology. Potassium is not only a constituent of the plant structure but it also has a regulatory function in several biochemical processes related to protein synthesis, carbohydrate metabolism, and enzyme activation. Several physiological processes depend on K, such as stomatal regulation and photosynthesis. In recent decades, K was found to provide abiotic stress tolerance. Under salt stress, K helps to maintain ion homeostasis and to regulate the osmotic balance. Under drought stress conditions, K regulates stomatal opening and helps plants adapt to water deficits. Many reports support the notion that K enhances antioxidant defense in plants and therefore protects them from oxidative stress under various environmental adversities. In addition, this element provides some cellular signaling alone or in association with other signaling molecules and phytohormones. Although considerable progress has been made in understanding K-induced abiotic stress tolerance in plants, the exact molecular mechanisms of these protections are still under investigation. In this review, we summarized the recent literature on the biological functions of K, its uptake, its translocation, and its role in plant abiotic stress tolerance.

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The Arabidopsis Cys2/His2 zinc finger transcription factor ZAT18 is a positive regulator of plant tolerance to drought stress

Journal of Experimental Botany ◽

10.1093/jxb/erx157 ◽

2017 ◽

Vol 68 (11) ◽

pp. 2991-3005 ◽

Cited By ~ 27

Author(s):

Mingzhu Yin ◽

Yanping Wang ◽

Lihua Zhang ◽

Jinzhu Li ◽

Wenli Quan ◽

...

Keyword(s):

Drought Stress ◽

Zinc Finger ◽

Zinc Finger Protein ◽

Leaf Water ◽

Pathway Enrichment Analysis ◽

Antioxidant Enzyme Activities ◽

Sequencing Analysis ◽

Plant Tolerance ◽

Drought Treatment ◽

Positive Regulator

Abstract Environmental stress poses a global threat to plant growth and reproduction, especially drought stress. Zinc finger proteins comprise a family of transcription factors that play essential roles in response to various abiotic stresses. Here, we found that ZAT18 (At3g53600), a nuclear C2H2 zinc finger protein, was transcriptionally induced by dehydration stress. Overexpression (OE) of ZAT18 in Arabidopsis improved drought tolerance while mutation of ZAT18 resulted in decreased plant tolerance to drought stress. ZAT18 was preferentially expressed in stems, siliques, and vegetative rosette leaves. Subcellular location results revealed that ZAT18 protein was predominantly localized in the nucleus. ZAT18 OE plants exhibited less leaf water loss, lower content of reactive oxygen species (ROS), higher leaf water content, and higher antioxidant enzyme activities after drought treatment when compared with the wild type (WT). RNA sequencing analysis showed that 423 and 561 genes were transcriptionally modulated by the ZAT18 transgene before and after drought treatment, respectively. Pathway enrichment analysis indicated that hormone metabolism, stress, and signaling were over-represented in ZAT18 OE lines. Several stress-responsive genes including COR47, ERD7, LEA6, and RAS1, and hormone signaling transduction-related genes including JAZ7 and PYL5 were identified as putative target genes of ZAT18. Taken together, ZAT18 functions as a positive regulator and plays a crucial role in the plant response to drought stress.

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Arbuscular Mycorrhizal Fungal Diversity In Medicinal Plants Of Sirumalai Hills, Eastern Ghats And Their Role In Melia Dubia Cav

10.26524/royal.71 ◽

2021 ◽

Author(s):

Santhoshkumar S ◽

Nagarajan N

Keyword(s):

Arbuscular Mycorrhizal ◽

Eastern Ghats ◽

Nutrient Cycle ◽

Plant Responses ◽

Plant Interactions ◽

Plant Tolerance ◽

Agricultural Ecosystem ◽

Microbial World ◽

Melia Dubia ◽

Arbuscular Mycorrhizal Fungal

The microbial World is the largest unexplored reservoir of biodiversity on earth. Interest in the exploration of microbial diversity has been promoted by the fact that a microbe performs numerous functions essential for the biosphere that include nutrient cycle and environmental detoxification. Notably, under natural circumstances, plants frequently interact with microbes,which directly arbitrate plant responses to environmental adversities. Some microbe-plant interactions lead to a mitigation of stress-related damages and improvement of plant tolerance to stressful conditions. As a crucial element of soils, microbes are an integral part of the agricultural ecosystem.

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Energy Versus Stress Theories for Combined Stress—A Fatigue Experiment Using a Rotating Disk

Journal of Basic Engineering ◽

10.1115/1.3658878 ◽

1961 ◽

Vol 83 (1) ◽

pp. 10-14 ◽

Cited By ~ 17

Author(s):

W. N. Findley ◽

P. N. Mathur ◽

E. Szczepanski ◽

A. O. Temel

Keyword(s):

Fatigue Failure ◽

Strain Energy ◽

Fatigue Cracks ◽

Circular Disk ◽

Rotating Disk ◽

Constant Load ◽

Combined Stress ◽

Combined Stresses ◽

Critical Location ◽

Fatigue Experiment

An experiment is described in which the strain energy at the critical location for fatigue failure is maintained constant while the stresses on a given plane of the material at the same location are caused to fluctuate. Apparatus developed to produce this condition consisted of a circular disk with a wide flanged rim which was loaded along a diameter by means of pivot-pad bearings. The disk was then rotated under a constant load to produce the desired fluctuation in stresses at the center of the disk while maintaining a constant strain energy at the center. The fact that fatigue cracks were developed in the region of constant strain energy was considered to indicate that a concept of a fluctuating strain energy as a basic theory of failure by fatigue under combined stresses is not tenable.

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