Navigating microplastic-induced stress in plants: adaptations from physiology to gene regulation.

The R2R3-type MYB transcription factors have been shown to increase flavonoids accumulation by regulating the expression of key enzyme genes related to flavonoid biosynthesis pathway. However, the roles and underlying mechanisms of the soybean GmMYB12 gene in regulation of flavonoids accumulation and tolerance to abiotic stresses are rarely known. In the present study, the GmMYB12 gene was isolated and its function was characterized. Sequence and yeast one-hybrid analyses showed that GmMYB12 contained two MYB domains and belonged to R2R3-MYB protein with transactivation activity. Subcellular localization analysis in onion epidermal cells indicated that GmMYB12 was localized to the nucleus. Overexpression of GmMYB12 increased the production of downstream flavonoids and the expression of related genes in the flavonoid biosynthesis pathway. It also improved resistance to salt and drought stresses during seed germination, root development, and growing stage. Further component and enzymatic analyses showed significant increases of proline content, pyrroline-5-carboxylate synthase (P5CS), superoxide dismutase (SOD), and peroxidase (POD) activities, as well as significant reduction of H2O2 and malonaldehyde (MDA) content under salt and drought stresses in transgenic plants. Meanwhile, the expression level of AtP5CS, AtSOD and AtPOD genes was up-regulated against salt and drought stresses. Together, our finding indicated that changing the expression level of GmMYB12 in plants alters the accumulation of flavonoids and regulates plantlet tolerance to abiotic stress by regulating osmotic balance, protecting membrane integrity and maintaining ROS homeostasis. The GmMYB12 gene has the potential to be used to increase the content of valuable flavonoids and improve the tolerance to abiotic stresses in plants.

Small Ubiquitin-like MOdifier (SUMO) is a key regulator of abiotic stress, disease resistance, and development in plants. The identification of >350 plant SUMO targets has revealed many processes modulated by SUMO and potential consequences of SUMO on its targets. Importantly, highly related proteins are SUMO-modified in plants, yeast, and metazoans. Overlapping SUMO targets include heat-shock proteins (HSPs), transcription regulators, histones, histone-modifying enzymes, proteins involved in DNA damage repair, but also proteins involved in mRNA biogenesis and nucleo-cytoplasmic transport. Proteomics studies indicate key roles for SUMO in gene repression by controlling histone (de)acetylation activity at genomic loci. The responsible heavily sumoylated transcriptional repressor complexes are recruited by plant transcription factors (TFs) containing an (ERF)-associated Amphiphilic Repression (EAR) motif. These TFs are not necessarily themselves a SUMO target. Conversely, SUMO acetylation (Ac) prevents binding of downstream partners by blocking binding of their SUMO-interaction peptide motifs to Ac-SUMO. In addition, SUMO acetylation has emerged as a mechanism to recruit specifically bromodomains. Bromodomains are generally linked with gene activation. These findings strengthen the idea of a bi-directional sumo-acetylation switch in gene regulation. Quantitative proteomics has highlighted that global sumoylation provides a dynamic response to protein damage involving SUMO chain-mediated protein degradation, but also SUMO E3 ligase-dependent transcription of HSP genes. With these insights in SUMO function and novel technical advancements, we can now study SUMO dynamics in responses to (a)biotic stress in plants.

Growth and productivity of crop plants worldwide are often adversely affected by anthropogenic and natural stresses. Both biotic and abiotic stresses may impact future food security and sustainability; global climate change will only exacerbate the threat. Nearly all stresses induce ethylene production in plants, which is detrimental to their growth and survival when present at higher concentrations. Consequently, management of ethylene production in plants is becoming an attractive option for countering the stress hormone and its effect on crop yield and productivity. In plants, ACC (1-aminocyclopropane-1-carboxylate) serves as a precursor for ethylene production. Soil microorganisms and root-associated plant growth promoting rhizobacteria (PGPR) that possess ACC deaminase activity regulate growth and development of plants under harsh environmental conditions by limiting ethylene levels in plants; this enzyme is, therefore, often designated as a "stress modulator." TheACC deaminase enzyme, encoded by the AcdS gene, is tightly controlled and regulated depending upon environmental conditions. Gene regulatory components of AcdS are made up of the LRP protein-coding regulatory gene and other regulatory components that are activated via distinct mechanisms under aerobic and anaerobic conditions. ACC deaminase-positive PGPR strains can intensively promote growth and development of crops being cultivated under abiotic stresses including salt stress, water deficit, waterlogging, temperature extremes, and presence of heavy metals, pesticides and other organic contaminants. Strategies for combating environmental stresses in plants, and improving growth by introducing the acdS gene into crop plants via bacteria, have been investigated. In the recent past, some rapid methods and cutting-edge technologies based on molecular biotechnology and omics approaches involving proteomics, transcriptomics, metagenomics, and next generation sequencing (NGS) have been proposed to reveal the variety and potential of ACC deaminase-producing PGPR that thrive under external stresses. Multiple stress-tolerant ACC deaminase-producing PGPR strains have demonstrated great promise in providing plant resistance/tolerance to various stressors and, therefore, it could be advantageous over other soil/plant microbiome that can flourish under stressed environments.

Plants have acquired sophisticated stress response systems to adapt to changing environments. It is important to understand plants' stress response mechanisms in the effort to improve crop productivity under stressful conditions. The AP2/ERF transcription factors are known to regulate diverse processes of plant development and stress responses. In this study, the molecular characteristics and biological functions of AP2/ERFs in a variety of plant species were analyzed. AP2/ERFs, especially those in DREB and ERF subfamilies, are ideal candidates for crop improvement because their overexpression enhances tolerances to drought, salt, freezing, as well as resistances to multiple diseases in the transgenic plants. The comprehensive analysis of physiological functions is useful in elucidating the biological roles of AP2/ERF family genes in gene interaction, pathway regulation, and defense response under stress environments, which should provide new opportunities for the crop tolerance engineering.

Actin-depolymerizing factors (ADFs) are highly conserved small-molecule actin-binding proteins found throughout eukaryotic cells. In land plants, ADFs form a small gene family that displays functional redundancy despite variations among its individual members. ADF can bind to actin monomers or polymerized microfilaments and regulate dynamic changes in the cytoskeletal framework through specialized biochemical activities, such as severing, depolymerizing, and bundling. The involvement of ADFs in modulating the microfilaments' dynamic changes has significant implications for various physiological processes, including plant growth, development, and stress response. The current body of research has greatly advanced our comprehension of the involvement of ADFs in the regulation of plant responses to both biotic and abiotic stresses, particularly with respect to the molecular regulatory mechanisms that govern ADF activity during the transmission of stress signals. Stress has the capacity to directly modify the transcription levels of ADF genes, as well as indirectly regulate their expression through transcription factors such as MYB, C-repeat binding factors, ABF, and 14-3-3 proteins. Furthermore, apart from their role in regulating actin dynamics, ADFs possess the ability to modulate the stress response by influencing downstream genes associated with pathogen resistance and abiotic stress response. This paper provides a comprehensive overview of the current advancements in plant ADF gene research and suggests that the identification of plant ADF family genes across a broader spectrum, thorough analysis of ADF gene regulation in stress resistance of plants, and manipulation of ADF genes through genome-editing techniques to enhance plant stress resistance are crucial avenues for future investigation in this field.

Drought stress in plants has become one of the major abiotic stress that limits the growth and development of plants which also contributes to low yields. Biotechnology which has new and emerging techniques can be use to solve the problem of drought stress in plants. This review aimed at identifying drought stress tolerance in plants at different stages, how plants respond to drought stress using different methods and the application of different biotechnology methods to improve drought tolerance in plants. Some important parameters about drought stress in plants such as drought tolerance mechanisms, plants responses to drought stress, gene regulation for drought stress tolerance in plants, effects of drought stress at different stages of plant growth and biotechnology methods in developing drought tolerance in plants was reviewed. The use of biotechnology methods such as classical breeding, use of genetic manipulation, genes from resurrection plants and Protoplast fusion was discussed. Drought stress affects our plants seriously and it leads to wilts, reduction of yields and death of plants at different developmental stages. Plants have developed different mechanisms to respond to drought stress but these mechanisms are not sufficient enough without the application of biotechnology to greatly improve the growth, development and increase yield in pants. The use of biotechnology greatly improves plants ability to tolerate drought stress depending on the plant species and period of exposure. The use of biotechnology methods has become very vital in improving plants drought stress so as to overcome the major problems of plants which includes increase in population and climatic change.

Plant Stress and Biotechnology

High-temperature stress is a major abiotic stress that affects various biological processes of plants such as biochemical and physiological response, growth, development, and yield. High-temperature stress has critical effects at cellular and molecular levels also. The increased concentration of regulatory proteins such as heat shock transcription factors (Hsfs) is a major molecular response that occurs during heat stress. These regulatory proteins in turn regulate the expression of heat shock protein (HSP) genes that act as critical players during stress to maintain cell homeostasis. Besides HSPs, the other metabolic and regulatory genes, signaling compounds, compatible osmolytes, and antioxidants too play an important role during heat stress in plants. Apart from the protein-coding genes, recent studies have shown that noncoding microRNAs (miRNAs) also play a key role during heat stress by modulating the gene expression at the transcription and post-transcriptional level. The transcriptome approaches are important to understand the molecular and cellular changes occurring in response to heat stress. The approaches rely mostly by adopting the traditional methods like Northern blot/RNA blot and reverse transcription PCR (RT-PCR), where the expression of the genes can be studied in different tissues and cells, whereas the extent of their expression can be achieved by quantitative PCR or real time PCR. Further, the genome-wide expression profiling tools such as microarray analysis, next-generation sequencing, and RNA sequencing offer a great potential in this direction. This chapter primarily provides the current understanding on the role of regulatory genes (transcription factors), HSP genes, metabolic genes, signaling compounds, osmolytes, reactive oxygen species, and miRNAs as well as other small RNAs of plants under high temperature. In addition, it gives a brief account of various transcriptome approaches to study the expression profiling of genes during heat stress.

Chapter 13 - Role of glycine betaine in stress management in plants

Recent progress in the knowledge on the alleviating effect of nitric oxide on heavy metal stress in plants

Ion homeostasis during salt stress in plants

Abiotic stresses, including drought, salinity, extreme temperatures, and heavy metal toxicity encompassing adverse environmental conditions, poses a significant threat to plant growth, development, and productivity. These stress factors disrupt physiological and biochemical processes in plants, leading to reduce crop yields and posing a threat to global food security. To mitigate the detrimental effects of abiotic stresses, innovative agronomic practices are essential. Different methodologies have evolved over time for stress tolerance through conventional breeding and transgenesis. To enhance plant resilience against these stresses, priming strategies have emerged as a promising tool to improve plant stress tolerance. This review explores various priming approaches that precondition plants to better cope with subsequent stress exposure. Moreover, it discusses the underlying mechanisms involved in enhanced activation of antioxidant systems, improved osmotic balance, regulation of stress-responsive genes, and the strengthening of cellular defence systems. Additionally, priming induces stress memory in plants, enabling faster and more robust responses during recurrent stress events. This review also highlights recent advancements in priming techniques and their potential applications in sustainable agriculture. Integration of these strategies into crop management practices can improve plant performance and productivity in the face of increasing abiotic stresses. Overall, this review provides insights into the efficiency, sustainability, and applicability of different priming strategies as a means to mitigate abiotic stress in plants, offering a promising path toward sustainable agriculture in the face of changing environmental conditions.

Transcriptional regulation of salinity stress in plants: A short review

Exploring the critical role of non-coding RNAs in plant development and stress adaptation-current status and insights.

Emerging role of plant long non coding RNAs (lncRNAs) in salinity stress response