Biochemical and biophysical changes associated with magnetopriming in germinating cucumber seeds

Ultrasonic treatment can improve maize seed germination and abiotic stress resistance

Constant-frequency ultrasonic treatment helped to improve seed germination. However, variable-frequency ultrasonic treatment on maize seed germination were rarely reported. In this study, maize seeds were exposed to 20-40 kHz ultrasonic for 40 s. The germination percentage and radicle length of maize seeds increased by 10.4% and 230.5%. Ultrasonic treatment also significantly increased the acid protease, α-amylase, and β-amylase contents by 96.4%, 73.8%, and 49.1%, respectively. Transcriptome analysis showed that 11,475 differentially expressed genes (DEGs) were found in the ultrasonic treatment and control groups, including 5,695 upregulated and 5,780 downregulated. Metabolic pathways and transcription factors (TFs) were significantly enriched among DEGs after ultrasonic treatment. This included metabolism and genetic information processing, that is, ribosome, proteasome, and pyruvate metabolism, sesquiterpenoid, triterpenoid, and phenylpropanoid biosynthesis, and oxidative phosphorylation, as well as transcription factors in the NAC, MYB, bHLH, WRKY, AP2, bZIP, and ARF families. Variable-frequency ultrasonic treatment increased auxin, gibberellin, and salicylic acid by 5.5%, 37.3%, and 28.9%, respectively. Abscisic acid significantly decreased by 33.2%. The related DEGs were upregulated and downregulated to varying degrees. Seed germination under the abiotic stress conditions of salt stress (NaCl solution), drought (PEG solution), and waterlogging (water-saturated sand bed) under ultrasonic treatment were promoted, radicle length was significantly increased by 30.2%, 30.5%, and 27.3%, respectively; and germination percentage by 14.8%, 20.1%, and 21.6%, respectively. These findings provide new insight into the mechanisms through ultrasonic to promote maize seed germination.

Effect of magnetic field pretreatment on germination characteristics, phenolic biosynthesis, and antioxidant capacity of quinoa

The development of quinoa-based functional foods with cost-effective methods has gained considerable attention. In this study, the effects of magnetic field pretreatment on the germination characteristics, phenolic synthesis, and antioxidant system of quinoa (Chenopodium quinoa Willd.) were investigated. The results showed that the parameters of magnetic field pretreatment had different effects on the germination properties of five quinoa varieties, in which Sanjiang-1 (SJ-1) was more sensitive to magnetic field pretreatment. The content of total phenolics and phenolic acids in 24-h germinated seeds increased by 20.48% and 26.54%, respectively, under the pretreatment of 10 mT magnetic fields for 10 min compared with the control. This was closely related to the activation of the phenylpropanoid pathway by increasing enzyme activities and gene expression. In addition, magnetic field improved 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) free radicals scavenging capacities and increased peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione peroxidase (GSH-Px) activities. This study suggests that magnetic field pretreatment enhanced gene expression of phenylalanine ammonia lyase (PAL), 4-coumarate-CoA ligase (4CL), chalcone synthase (CHS) and chalcone isomerase (CHI), increased antioxidant enzyme activity and phenolics content. Thereby lead to an increase in the antioxidative capacity of quinoa.

Comparative transcriptomic analysis revealed important processes underlying the static magnetic field effects on Arabidopsis

Static magnetic field (SMF) plays important roles in various biological processes of many organisms including plants, though the molecular mechanism remains largely unclear. Here in this study, we evaluated different magnetic setups to test their effects on growth and development on Arabidopsis (Arabidopsis thaliana), and discovered that plant growth was significantly enhanced by inhomogeneous SMF generated by a regular triangular prism magnet perpendicular to the direction of gravity. Comparative transcriptomic analysis revealed that auxin synthesis and signal transduction genes were upregulated by SMF exposure. SMF also facilitated plants to maintain the iron homeostasis. The expression of iron metabolism-related genes was downregulated by SMF, however, the iron content in plant tissues remains relatively unchanged. Furthermore, SMF exposure also helped the plants to reduce ROS level and synergistically maintain the oxidant balance by enhanced activity of antioxidant enzymes and accumulation of nicotinamide. Taken together, our data suggested that SMF is involved in regulating the growth and development of Arabidopsis thaliana through maintaining iron homeostasis and balancing oxidative stress, which could be beneficial for plant survival and growth. The work presented here would extend our understanding of the mechanism and the regulatory network of how magnetic field affects the plant growth, which would provide insights into the development of novel plant synthetic biology technologies to engineer stress-resistant and high-yielding crops.

Enhancing iron content and growth of cucumber seedlings with MgFe-LDHs under low-temperature stress

The development of cost-effective and eco-friendly fertilizers is crucial for enhancing iron (Fe) uptake in crops and can help alleviate dietary Fe deficiencies, especially in populations with limited access to meat. This study focused on the application of MgFe-layered double hydroxide nanoparticles (MgFe-LDHs) as a potential solution. We successfully synthesized and characterized MgFe-LDHs and observed that 1-10 mg/L MgFe-LDHs improved cucumber seed germination and water uptake. Notably, the application of 10 mg/L MgFe-LDHs to roots significantly increased the seedling emergence rate and growth under low-temperature stress. The application of 10 mg/L MgFe-LDHs during sowing increased the root length, lateral root number, root fresh weight, aboveground fresh weight, and hypocotyl length under low-temperature stress. A comprehensive analysis integrating plant physiology, nutrition, and transcriptomics suggested that MgFe-LDHs improve cold tolerance by upregulating SA to stimulate CsFAD3 expression, elevating GA3 levels for enhanced nitrogen metabolism and protein synthesis, and reducing levels of ABA and JA to support seedling emergence rate and growth, along with increasing the expression and activity of peroxidase genes. SEM and FTIR further confirmed the adsorption of MgFe-LDHs onto the root hairs in the mature zone of the root apex. Remarkably, MgFe-LDHs application led to a 46% increase (p < 0.05) in the Fe content within cucumber seedlings, a phenomenon not observed with comparable iron salt solutions, suggesting that the nanocrystalline nature of MgFe-LDHs enhances their absorption efficiency in plants. Additionally, MgFe-LDHs significantly increased the nitrogen (N) content of the seedlings by 12% (p < 0.05), promoting nitrogen fixation in the cucumber seedlings. These results pave the way for the development and use of LDH-based Fe fertilizers.

Seed Priming with Zinc Oxide Nanoparticles to Enhance Crop Tolerance to Environmental Stresses

Drastic climate changes over the years have triggered environmental challenges for wild plants and crops due to fluctuating weather patterns worldwide. This has caused different types of stressors, responsible for a decrease in plant life and biological productivity, with consequent food shortages, especially in areas under threat of desertification. Nanotechnology-based approaches have great potential in mitigating environmental stressors, thus fostering a sustainable agriculture. Zinc oxide nanoparticles (ZnO NPs) have demonstrated to be biostimulants as well as remedies to both environmental and biotic stresses. Their administration in the early sowing stages, i.e., seed priming, proved to be effective in improving germination rate, seedling and plant growth and in ameliorating the indicators of plants' well-being. Seed nano-priming acts through several mechanisms such as enhanced nutrients uptake, improved antioxidant properties, ROS accumulation and lipid peroxidation. The target for seed priming by ZnO NPs is mostly crops of large consumption or staple food, in order to meet the increased needs of a growing population and the net drop of global crop frequency, due to climate changes and soil contaminations. The current review focuses on the most recent low-cost, low-sized ZnO NPs employed for seed nano-priming, to alleviate abiotic and biotic stresses, mitigate the negative effects of improper storage and biostimulate plants' growth and well-being. Taking into account that there is large variability among ZnO NPs and that their chemico-physical properties may play a role in determining the efficacy of nano-priming, for all examined cases, it is reported whether the ZnO NPs are commercial or lab prepared. In the latter cases, the preparation conditions are described, along with structural and morphological characterizations. Under these premises, future perspectives and challenges are discussed in relation to structural properties and the possibility of ZnO NPs engineering.

Growth, physiological, biochemical and molecular changes in plants induced by magnetic fields: A review

The Earth's geomagnetic field (GMF) is an inescapable environmental factor for plants that affects all growth and yield parameters. Both strong and weak magnetic fields (MF), as compared to the GMF, have specific roles in plant growth and development. MF technology is an eco-friendly technique that does not emit waste or generate harmful radiation, nor require any external power supply, so it can be used in sustainable modern agriculture. Thus, exposure of plants to MF is a potential affordable, reusable and safe practice for enhancing crop productivity by changing physiological and biochemical processes. However, the effect of MF on plant physiological and biochemical processes is not yet well understood. This review describes the effects of altering MF conditions (higher or lower values than the GMF) on physiological and biochemical processes of plants. The current contradictory and inconsistent outcomes from studies on varying effects of MF on plants could be related to species and/or MF exposure time and intensity. The reviewed literature suggests MF have a role in changing physiological processes, such as respiration, photosynthesis, nutrient uptake, water relations and biochemical attributes, including genes involved in ROS, antioxidants, enzymes, proteins and secondary metabolites. MF application might efficiently increase growth and yield of many crops, and as such, should be the focus for future research.

Combined transcriptome and metabolome analyses reveal the mechanisms of ultrasonication improvement of brown rice germination

This study investigated the effects of ultrasonication treatment on the germination rate of brown rice. Brown rice grains were subjected to ultrasound (40 kHz/30 min) and then incubated for 36 h at 37 °C to germinate the seeds. Ultrasonic treatment increased the germination rate of brown rice by up to ∼28 % at 30 h. Transcriptomic and metabolomic analyses were performed to explore the mechanisms underlying the effect of ultrasonic treatment on the brown rice germination rate. Comparing the treated and control check samples, 867 differentially expressed genes (DEGs) were identified, including 638 upregulated and 229 downregulated), as well as 498 differentially accumulated metabolites (DAMs), including 422 up accumulated and 76 down accumulated. Multi-omics analysis revealed that the germination rate of brown rice was promoted by increased concentrations of low-molecular metabolites (carbohydrates and carbohydrate conjugates, fatty acids, amino acids, peptides, and analogues), and transcription factors (ARR-B, NAC, bHLH and AP2/EREBP families) as well as increased carbon metabolism. These findings provide new insights into the mechanisms of action of ultrasound in improving the brown rice germination rate and candidate DEGs and DAMs responsible for germination have been identified.

Nanoparticle's uptake and translocation mechanisms in plants via seed priming, foliar treatment, and root exposure: a review

Nanotechnology is one of the promising techniques and shares wide ranges of applications almost in every field of life. Nanomaterials are getting continuous attractions due to specific physical and chemical properties and being applied as multifunctional material. The use of nanomaterials/nanoparticles in agriculture sector for crop improvement and protection against various environmental threats have attained greater significance. Size and nature of nanoparticles, mode of application, environmental conditions, rhizospheric and phyllospheric environment, and plant species are major factors that influence the action of nanoparticles. The mode or method of nanoparticle applications to plants is attaining greater attentions. Recently, different methods for nanoparticle applications (seed priming, foliar, and root application) are being used to improve crop growth. It is of quite worth that which method is suitable for nanoparticle application, and how nanoparticles can possibly translocate to various plant tissues from root to shoot or vice versa. These information's are poorly understood and need more investigations to explore the comprehensive mechanism by which nanoparticles make their possible entry through different plant organs and how they transport to regulate various physiological and molecular functions in plant cells. Therefore, this study comprehensively provides the knowledge of nanoparticles uptake via seed priming, foliar exposure, and root application, and their possible translocation mechanism within plants influenced by various factors that has not clearly presented. This study will provide new insights to find out an actual uptake and translocation mechanism of nanoparticles that may help researchers to develop nanoparticle-based new strategies for plants to cope with various environmental challenges. This study also focuses on different soil factors or above ground factors that are involved in nanoparticles uptake and translocation and ultimately their functioning in plants.

Impact of Foliar Application of ZnO and Fe3O4 Nanoparticles on Seed Yield and Physio-Biochemical Parameters of Cucumber (Cucumis sativus L.) Seed under Open Field and Protected Environment vis a vis during Seed Germination

Nutritionally rich cucumber seeds remain in demand in the agricultural, health and cosmetic sectors as they are essential for a successful crop stand establishment and seed-based products. However, the production of cucumber seeds is impeded by source limitation and nutrient deficiency. The foliar application of micronutrients can supplement this deficiency and overcome the physiological setback. An experiment was undertaken to compare the impacts of the foliar application of Fe and Zn, as nanoparticles and fertilizers, on the yield and seed quality of cucumber under open and protected environments. A foliar spray of nano-ZnO (ZnNPs) and nano-Fe3O4 (FeNPs) at 100, 200 and 300 mg L-1, as well as ZnSO4 and FeSO4 as fertilizer (0.5%), was conducted at the vegetative stage and pre- and post-flowering stages. The NPs had a greater efficacy in an open field than in the protected (naturally ventilated poly house) environment. The application of both NPs increased seed yield (51.7-52.2%), total chlorophyll content (15.9-17.3%) and concentration of Zn and Fe in the fruit and the seed, by 2.0-58.5% and 5.0-30.5%, respectively. A significant increase in starch, soluble proteins, soluble sugars and oil content was observed in the seeds from the NP treated plants. NP treatment also enhanced the germination-related parameters, such as percent germination (16.8-17.0%), rate of germination (18.0-22.2%) and seedling vigor (59.8-72.6%). The biochemical characterization showed a significant improvement in the seed water uptake and the activity of hydrolytic enzymes (amylase and protease) in the germinating seed. The involvement of reactive oxygen species (superoxide anion and hydrogen peroxide) and antioxidant enzymes (Superoxide dismutase, Catalase and Peroxidase) in the germination process was indicated by an increase in their activities in the seeds from NP treated plants. Hence, the study proposes the potential benefit of the foliar application of 300 mg L-1 ZnNPs and 200 mg L-1 FeNPs at crucial stages of plant growth to improve the yield and seed quality in cucumbers.

Effects of non-ionizing electromagnetic fields on flora and fauna, Part 2 impacts: how species interact with natural and man-made EMF

Ambient levels of nonionizing electromagnetic fields (EMF) have risen sharply in the last five decades to become a ubiquitous, continuous, biologically active environmental pollutant, even in rural and remote areas. Many species of flora and fauna, because of unique physiologies and habitats, are sensitive to exogenous EMF in ways that surpass human reactivity. This can lead to complex endogenous reactions that are highly variable, largely unseen, and a possible contributing factor in species extinctions, sometimes localized. Non-human magnetoreception mechanisms are explored. Numerous studies across all frequencies and taxa indicate that current low-level anthropogenic EMF can have myriad adverse and synergistic effects, including on orientation and migration, food finding, reproduction, mating, nest and den building, territorial maintenance and defense, and on vitality, longevity and survivorship itself. Effects have been observed in mammals such as bats, cervids, cetaceans, and pinnipeds among others, and on birds, insects, amphibians, reptiles, microbes and many species of flora. Cyto- and geno-toxic effects have long been observed in laboratory research on animal models that can be extrapolated to wildlife. Unusual multi-system mechanisms can come into play with non-human species - including in aquatic environments - that rely on the Earth's natural geomagnetic fields for critical life-sustaining information. Part 2 of this 3-part series includes four online supplement tables of effects seen in animals from both ELF and RFR at vanishingly low intensities. Taken as a whole, this indicates enough information to raise concerns about ambient exposures to nonionizing radiation at ecosystem levels. Wildlife loss is often unseen and undocumented until tipping points are reached. It is time to recognize ambient EMF as a novel form of pollution and develop rules at regulatory agencies that designate air as 'habitat' so EMF can be regulated like other pollutants. Long-term chronic low-level EMF exposure standards, which do not now exist, should be set accordingly for wildlife, and environmental laws should be strictly enforced - a subject explored in Part 3.

The Static Magnetic Field Regulates the Structure, Biochemical Activity, and Gene Expression of Plants

The purpose of this paper is to review the scientific results and summarise the emerging topic of the effects of statistic magnetic field on the structure, biochemical activity, and gene expression of plants. The literature on the subject reports a wide range of possibilities regarding the use of the magnetic field to modify the properties of plant cells. MFs have a significant impact on the photosynthesis efficiency of the biomass and vigour accumulation indexes. Treating plants with SMFs accelerates the formation and accumulation of reactive oxygen species. At the same time, the influence of MFs causes the high activity of antioxidant enzymes, which reduces oxidative stress. SMFs have a strong influence on the shape of the cell and the structure of the cell membrane, thus increasing their permeability and influencing the various activities of the metabolic pathways. The use of magnetic treatments on plants causes a higher content of proteins, carbohydrates, soluble and reducing sugars, and in some cases, lipids and fatty acid composition and influences the uptake of macro- and microelements and different levels of gene expression. In this study, the effect of MFs was considered as a combination of MF intensity and time exposure, for different varieties and plant species. The following article shows the wide-ranging possibilities of applying magnetic fields to the dynamics of changes in the life processes and structures of plants. Thus far, the magnetic field is not widely used in agricultural practice. The current knowledge about the influence of MFs on plant cells is still insufficient. It is, therefore, necessary to carry out detailed research for a more in-depth understanding of the possibilities of modifying the properties of plant cells and achieving the desired effects by means of a magnetic field.

The Effect on the Germination Vigour of Cucumber Seeds after Receiving Magnetic Field Treatment Pre-Sowing

In the experiment, the impact of magnetisation on cucumber seeds is examined with the use of Bitter magnets with a constant magnetic field. The magnetisation process is performed in three magnetic fields: low—200 mT, medium—1 T, and high—9 T for 15 and 60 min. After germination, the biometric parameters are determined. The results of this research show that cucumber after pre-treatment in a magnetic field of 1 T for 60 min has a similar germination capacity and root length as the control sample. However, cucumber seeds magnetised in a 1 T field for 60 min have a significantly higher dry weight than the control sample (5.50 ± 0.32 mg vs. 3.01 ± 0.18 mg). The magnetisation in 9 T for both 15 and 60 min shows that these samples have a significantly lower germination capacity (86.8 ± 4.4% and 81.4 ± 7.3% vs. 91.8 a ± 3.2%) and root length (1.78 ± 0.02 cm and 4.42 ± 0.83 cm vs. 8.21 ± 0.34 cm) compared to the control sample. The cucumber seeds pre-treated at 9 T have a significantly greater dry weight than the control sample. Additionally, our research shows that some magnetic field intensities and magnetisation durations inhibit root growth and limit germination. These results are also important as they indicate which values of magnetic fields should be avoided.

Seed priming with non-ionizing physical agents: plant responses and underlying physiological mechanisms

Seed priming has long been explored as an effective value-added potential technique that results in improved germination, reduced seedling emergence time, shortened crop duration, increased stress tolerance and eventually increased higher grain production. However, the wider applicability of water or chemical-based conventional methods of seed priming is often restricted considering its deleterious effects on post-treatment storability or agricultural pollution due to the persistence of chemicals in plant systems or in the environment. In this context, the utilization of physical methods of seed priming for enhancing plant productivity has created a new horizon in the domain of seed technology. Being eco-friendly and cost-effective approaches, priming with extra-terrestrial or physical agents such as ionizing radiation such as X-rays and gamma rays and non-ionizing radiation such as ultrasonic wave, magnetic field, microwaves, and infrared light offers many advantages along with ensuring enhanced production over conventional methods. Ultraviolet radiations, bridging between ionizing and non-ionizing radiation, are important electromagnetic waves that would also be an effective priming agent. Non-ionizing radiation has certain biological advantages over ionizing radiation since it does not generate charged ions while passing through a subject, but has enough energy to cause biological effects. Extensive research works to study the effects of various non-ionizing physical priming methods are required before their wider exploitation in agriculture. With this background, this review aims to highlight the current understanding of non-ionizing physical methods of seed priming and its applicability to combat present-day challenges to achieve agro-ecological resilience.

Causal theory on acceleration of seed germination in the vicinity of high voltage direct current transmission line

Seed germination is the primary stage of growth in a seed. A wealth of experiments exist in literature to support the existence of correlation between seed germination to the electric and magnetic fields. This becomes more important as researchers have suggested to develop technologies to build ecologically clean and environment-friendly solutions to agricultural practices. Although the literature supports the existence of seed germination acceleration, the lack of a definite causal theory has been observed by numerous researchers over decades. After considering all the existing experimental data, we have formulated a causal theory to explain the factors influencing seed germination around high voltage DC transmission lines. This work opens new avenues of research in this field.

Nanoceria seed priming enhanced salt tolerance in rapeseed through modulating ROS homeostasis and α-amylase activities

BACKGROUND

Salinity is a big threat to agriculture by limiting crop production. Nanopriming (seed priming with nanomaterials) is an emerged approach to improve plant stress tolerance; however, our knowledge about the underlying mechanisms is limited.

RESULTS

Herein, we used cerium oxide nanoparticles (nanoceria) to prime rapeseeds and investigated the possible mechanisms behind nanoceria improved rapeseed salt tolerance. We synthesized and characterized polyacrylic acid coated nanoceria (PNC, 8.5 ± 0.2 nm, -43.3 ± 6.3 mV) and monitored its distribution in different tissues of the seed during the imbibition period (1, 3, 8 h priming). Our results showed that compared with the no nanoparticle control, PNC nanopriming improved germination rate (12%) and biomass (41%) in rapeseeds (Brassica napus) under salt stress (200 mM NaCl). During the priming hours, PNC were located mostly in the seed coat, nevertheless the intensity of PNC in cotyledon and radicle was increased alongside with the increase of priming hours. During the priming hours, the amount of the absorbed water (52%, 14%, 12% increase at 1, 3, 8 h priming, respectively) and the activities of α-amylase were significantly higher (175%, 309%, 295% increase at 1, 3, 8 h priming, respectively) in PNC treatment than the control. PNC primed rapeseeds showed significantly lower content of MDA, H2O2, and •O2- in both shoot and root than the control under salt stress. Also, under salt stress, PNC nanopriming enabled significantly higher K+ retention (29%) and significantly lower Na+ accumulation (18.5%) and Na+/K+ ratio (37%) than the control.

CONCLUSIONS

Our results suggested that besides the more absorbed water and higher α-amylase activities, PNC nanopriming improves salt tolerance in rapeseeds through alleviating oxidative damage and maintaining Na+/K+ ratio. It adds more knowledge regarding the mechanisms underlying nanopriming improved plant salt tolerance.

Priming Strategies for Benefiting Plant Performance under Toxic Trace Metal Exposure

Combating environmental stress related to the presence of toxic elements is one of the most important challenges in plant production. The majority of plant species suffer from developmental abnormalities caused by an exposure to toxic concentrations of metals and metalloids, mainly Al, As, Cd, Cu, Hg, Ni, Pb, and Zn. However, defense mechanisms are activated with diverse intensity and efficiency. Enhancement of defense potential can be achieved though exogenously applied treatments, resulting in a higher capability of surviving and developing under stress and become, at least temporarily, tolerant to stress factors. In this review, I present several already recognized as well as novel methods of the priming process called priming, resulting in the so-called “primed state” of the plant organism. Primed plants have a higher capability of surviving and developing under stress, and become, at least temporarily, tolerant to stress factors. In this review, several already recognized as well as novel methods of priming plants towards tolerance to metallic stress are discussed, with attention paid to similarities in priming mechanisms activated by the most versatile priming agents. This knowledge could contribute to the development of priming mixtures to counteract negative effects of multi-metallic and multi-abiotic stresses. Presentation of mechanisms is complemented with information on the genes regulated by priming towards metallic stress tolerance. Novel compounds and techniques that can be exploited in priming experiments are also summarized.

Magnetic Field Induced Changes in the Shoot and Root Proteome of Barley (Hordeum vulgare L.)

The geomagnetic field (GMF) has been present since the beginning of plant evolution. Recently, some researchers have focused their efforts on employing magnetic fields (MFs) higher than GMF to improve the seed germination, growth, and harvest of agriculturally important crop plants, as the use of MFs is an inexpensive and environment-friendly technique. In this study, we have employed different treatments of MF at 7 mT (milliTesla) at different time points of exposure, including 1, 3, and 6 h. The extended exposure was followed by five consecutive days at 6 h per day in barley seeds. The results showed a positive impact of MF on growth characteristics for 5-day-old seedlings, including seed germination rate, root and shoot length, and biomass weight. Furthermore, ~5 days of delay of flowering in pre-treated plants was also observed. We used a shotgun proteomics approach to identify changes in the protein signatures of root and shoot tissues under MF effects. In total, we have identified 2,896 proteins. Thirty-eight proteins in the shoot and 15 proteins in the root showed significant changes under the MF effect. Proteins involved in primary metabolic pathways were increased in contrast to proteins with a metal ion binding function, proteins that contain iron ions in their structure, and proteins involved in electron transfer chain, which were all decreased significantly in the treated tissues. The upregulated proteins' overall biological processes included carbohydrate metabolic process, oxidation-reduction process, and cell redox homeostasis, while down-regulated processes included translation and protein refolding. In general, shoot response was more affected by MF effect than root tissue, leading to the identification of 41 shoot specific proteins. This study provides an initial insight into the proteome regulation response to MF during barley's seedling stage.

Use of polymeric nanoparticles to improve seed germination and plant growth under copper stress

Plant seedlings are susceptible to copper (Cu) toxicity. As copper levels in soil continue to rise with the use of Cu-based agrochemicals, alleviation of Cu stress is of paramount importance. Traditional approaches to allay Cu stress are well documented but are typically found to be either costly or inefficient. Given their small size, ionic character, and high biocompatibility, specific polymeric nanoparticles (NPs) may have the potential for mitigating metal toxicity to crops. In this pioneering study, we investigated the effects of newly synthesized polysuccinimide NPs (PSI-NPs) on corn (Zea mays L.) seed germination and seedling growth under different levels of Cu stress. The results showed that PSI-NPs influenced seed germination in a dose-dependent manner with an optimal rate of 200 mg L^-1. In addition, the positive effects of PSI-NPs on seed germination indexes were found to be positively correlated with enhanced seed imbibition (r = 0.82). The addition of PSI-NPs significantly mitigated Cu stress as indicated by improved growth of shoots and roots, and higher antioxidant enzyme activity observed with co-exposure to PSI-NPs as compared to Cu stress treatment only. Cu concentrations in seedling root and shoot significantly increased with increasing Cu treatment rate. Higher uptake of Cu by plant was observed in the Cu-PSI-NPs co-treatment than single Cu treatment. The alleviation effect of PSI-NPs could be explained by the enhanced antioxidant enzyme activities and storage of Cu as Cu-PSI complexes in plants with reduced phytotoxicity. These findings will open the opportunity of using PSI-NPs as a regulator to enhance seed germination and improve seedling growth under stress of heavy metals like Cu.

Carbon Nanotubes Improved the Germination and Vigor of Plant Species from Peatland Ecosystem Via Remodeling the Membrane Lipidome

Application of the nanopriming technique to alleviate seed dormancy has shown promising results in various agricultural crop species. However, there is a dearth of knowledge regarding its potential use in native peatland boreal forest species to alleviate seed dormancy and improve their propagation or vigor for forest reclamation activities. Herein, we demonstrate the use of nanopriming with carbon nanotubes (CNT) to alleviate seed dormancy, improved seed germination, and seedling vigor in two boreal peatland species. Bog birch (Betula pumila L.) and Labrador tea (Rhododendron groenlandicum L.) seeds with embryo or seed coat dormancy were nanoprimed with either 20 or 40 µg/mL CNT, cold stratified at 2–4 °C for 15 days, and allowed to germinate at room temperature. The emerged seedlings’ lipidome was assessed to decipher the role of lipid metabolism in alleviating seed dormancy. We observed significant (p < 0.05) improvement in seedling germination and seedling vigor in seeds primed with multiwalled carbon nanotubes functionalized with carboxylic acids. Phosphatidylcholine (PC 18:1/18:3), phosphatidylglycerol (PG 16:1/18:3), and lysophosphatidylcholine (LPC 18:3) molecular species (C18:3 enriched) were observed to be highly correlated with the increased seed germination percentages and the enhanced seedling vigor. Mechanistically, it appears that carbon nanoprimed seeds following stratification are effective in mediating seed dormancy by remodeling the seed membrane lipids (C18:3 enriched PC, PG, and LPC) in both peatland boreal forest species. The study results demonstrate that nanopriming may provide a solution to resolve seed dormancy issues by enhancing seed germination, propagation, and seedling vigor in non-resource boreal forest species ideally suited for forest reclamation following anthropogenic disturbances.

Magnetic Field (MF) Applications in Plants: An Overview

Crop yield can be raised by establishment of adequate plant stand using seeds with high germination ratio and vigor. Various pre-sowing treatments are adopted to achieve this objective. One of these approaches is the exposure of seeds to a low-to-medium level magnetic field (MF), in pulsed and continuous modes, as they have shown positive results in a number of crop seeds. On the basis of the sensitivity of plants to MF, different types of MF have been used for magnetopriming studies, such as weak static homogeneous magnetic fields (0–100 μT, including GMF), strong homogeneous magnetic fields (milliTesla to Tesla), and extremely low frequency (ELF) magnetic fields of low-to-moderate (several hundred μT) magnetic flux densities. The agronomic application of MFs in plants has shown potential in altering conventional plant production systems; increasing mean germination rates, and root and shoot growth; having high productivity; increasing photosynthetic pigment content; and intensifying cell division, as well as water and nutrient uptake. Furthermore, different studies suggest that MFs prevent the large injuries produced/inflicted by diseases and pests on agricultural crops and other economically important plants and assist in reducing the oxidative damage in plants caused by stress situations. An improved understanding of the interactions between the MF and the plant responses could revolutionize crop production through increased resistance to disease and stress conditions, as well as the superiority of nutrient and water utilization, resulting in the improvement of crop yield. In this review, we summarize the potential applications of MF and the key processes involved in agronomic applications. Furthermore, in order to ensure both the safe usage and acceptance of this new opportunity, the adverse effects are also discussed.

Effect of Extremely Low Power Time-Varying Electromagnetic Field on Germination and Other Characteristics in Foxtail Millet (Setaria italica) Seeds

The ability of extremely low, time-varying electromagnetic field (EMF) to improve germination efficacy was studied in Foxtail millet (Setaria italica) seeds using response surface methodology. An optimal factorial central composite design was chosen to optimize the EMF with three critical factors, viz. frequency, intensity, and duration. The adequacy of the model and fitness was evaluated by analysis of variance and regression coefficients. This model suggested that the factors, frequency, and intensity had a significant impact on germination. Optimal conditions for germination were observed to be 10 Hz frequency, 30,007 nT intensity, and 30-min duration with an observed germination percentage of 93.0, and a predicted germination percentage of 92.92. Magneto-priming was found to increase the germination efficacy (15.66%), shoot length (27.78%), total seedling length (20.30%), seedling dry mass (26.49%), and water uptake (34.48% at 80 min) showing significant output when compared with the control and positive controls. Remarkable improvements were observed in germination parameters such as vigor index-1 (39.14%), vigor index-2 (46.28%), speed of germination (27.52%), and emergence index (12.50%). Magneto-priming was found to reduce the levels of germination-specific enzymes, viz. α-amylase, protease, and dehydrogenase, while it enhanced the levels of antioxidant enzymes, viz. catalase (114.63%) and superoxide dismutase (19.62%), triggering fast germination and early vigor of seedlings. This study clearly showed that EMF priming significantly improved the germination effect and other characteristics of Foxtail millet seeds. Bioelectromagnetics. © 2020 Bioelectromagnetics Society.

Ameliorative Effects of a Static Magnetic Field on Hyssop (Hyssopus officinalis L.) Growth and Phytochemical Traits Under Water Stress

The present study was carried out in order to evaluate the promoting effect of a static magnetic field (SMF) on drought tolerance and medicinal properties in Hyssopus officinalis. In the current work, the effect of seed priming with SMF (45, 90, 200, and 250 mT for 5 min) was investigated in 60-day-old hyssop (H. officinalis) plants that were irrigated every 8 days. The assessments consisted of total dry mass, membrane integrity, photosynthetic pigment concentrations, polyphenol content, antioxidant enzyme activities, and antioxidant capacity. Compared with exclusively water stress, magnetopriming, particularly at 200 mT, significantly altered these parameters in the grown plants. At this intensity, the level of total dry mass, total chlorophyll, and polyphenol content increased by 94%, 2.5- and 7.7-fold, respectively. Also, the level of electrolyte leakage and malondialdehyde decreased by 35% and 33%. The reducing power, DPPH (1,1-diphenyl-2-picrylhydrozyl), and superoxide anion-scavenging activities were highly augmented as well. Magnetopriming at 200 mT increased catalase (+92%) and ascorbate peroxidase (+2.3-fold) activities. However, the highest activity of guaiacol peroxidase was recorded at 90 mT. Generally, the present study illustrated the positive effect of magnetopriming (200 mT) on improvement of drought tolerance in H. officinalis through protection of cellular membrane integrity, maintenance of photosynthetic pigment content, and alternation of antioxidant enzyme activities. Furthermore, the data showed this treatment (200 mT) not only had no negative effect on medicinal properties of H. officinalis, but also improved it via increasing total phenolic content and antioxidant capacity. Bioelectromagnetics. 2020;41:403-412. © 2020 Bioelectromagnetics Society.

Impact of pulsed electric field treatments on the growth parameters of wheat seeds and nutritional properties of their wheat plantlets juice

This study was designed to explore the impacts of the pulsed electric field (PEF; 2 to 6 kV/cm; a number of pulses 25 and 50) on wheat (Tritium aestivum L.) seeds before imbibition to improve the germination, growth, and their nutritional profile in juice form. It was observed that the PEF treatment at 6 kV/cm at 50 pulses increased water uptake, germination of seeds, and growth parameters of seedlings. A significant increase in total phenolic contents, DPPH, chlorophylls, carotenoids, soluble proteins, minerals, and amino acids in PEF-treated seeds plantlets juice as compared to the untreated seeds plantlets juice was observed. The results indicate that the PEF may effectively stimulate the growth of the wheat kernels and positively affect their metabolism, optimize the nutrients, and enhance the strength of the wheat kernels plantlets.

Impact of polystyrene nanoplastics (PSNPs) on seed germination and seedling growth of wheat (Triticum aestivum L.)

Microplastics and nanoplastics are emerging pollutants of global concern. However, the understanding of their ecological effects on terrestrial plants is still limited. We conducted the systematic research to reveal the impact of polystyrene nanoplastics (PSNPs) (0.01-10 mg/L) on seed germination and seedling growth of wheat (Triticum aestivum L.). The results showed that PSNPs had no discernible effect on seed germination rate whereas significantly (p < 0.01) increased root elongation by 88.6 %-122.6 % when compared with the control. Similarly, remarkable increases in carbon, nitrogen contents, and plant biomass were also observed after exposure to PSNPs. Moreover, PSNPs could reduce the shoot to root biomass ratio (S:R ratio) of wheat seedlings. Furthermore, the imagings of a 3D laser confocal scanning microscopy (LCSM) and scanning electron microscopy (SEM) indicated that PSNPs were taken up and subsequently down-top transported to shoot. The absorption and accumulation of four micronutrients (Fe, Mn, Cu and Zn) in wheat were generally reduced in varying degrees. Notably, metabolomics analysis revealed that all PSNPs treatments altered the leaf metabolic profiles mainly by regulating energy metabolisms and amino acid metabolisms. These findings are expected to provide new insights into the effects of PSNPs on crop plants.

Carbon Nanoparticles Functionalized with Carboxylic Acid Improved the Germination and Seedling Vigor in Upland Boreal Forest Species

Nanopriming has been shown to significantly improve seed germination and seedling vigor in several agricultural crops. However, this approach has not been applied to native upland boreal forest species with complex seed dormancy to improve propagation. Herein, we demonstrate the effectiveness of carbon nanoparticles functionalized with carboxylic acids in resolving seed dormancy and improved the propagation of two native upland boreal forest species. Seed priming with carbon nanoparticles functionalized with carboxylic acids followed by stratification were observed to be the most effective in improving germination to 90% in green alder (Alnus viridis L.) compared to 60% in the control. Conversely, a combination of carbon nanoparticles (CNPs), especially multiwall carbon nanoparticles functionalized with carboxylic acid (MWCNT–COOH), cold stratification, mechanical scarification and hormonal priming (gibberellic acid) was effective for buffaloberry seeds (Shepherdia canadensis L.). Both concentrations (20 µg and 40 µg) of MWCNT–COOH had a higher percent germination (90%) compared to all other treatments. Furthermore, we observed the improvement in germination, seedling vigor and resolution of both embryo and seed coat dormancy in upland boreal forest species appears to be associated with the remodeling of C18:3 enriched fatty acids in the following seed membrane lipid molecular species: PC18:1/18:3, PG16:1/18:3, PE18:3/18:2, and digalactosyldiacylglycerol (DGDG18:3/18:3). These findings suggest that nanopriming may be a useful approach to resolve seed dormancy issues and improve the seed germination in non-resource upland boreal forest species ideally suited for forest reclamation following resource mining.

Hydrogen peroxide signaling integrates with phytohormones during the germination of magnetoprimed tomato seeds

Seeds of tomato were magnetoprimed at 100 mT for 30 min followed by imbibition for 12 and 24 h, respectively, at 20 °C, to examine the biochemical and molecular changes involved in homeostasis of hydrogen peroxide (H₂O₂) and its signaling associated with hormone interactions for promoting vigor. The relative transcript profiles of genes involved in the synthesis of H₂O₂ like Cu-amine oxidase (AO), receptor for activated C kinase 1 (RACK1) homologue (ArcA2) and superoxide dismutase (SOD1 and SOD9) increased in magnetoprimed tomato seeds as compared to unprimed ones with a major contribution (21.7-fold) from Cu-amine oxidase. Amongst the genes involved in the scavenging of H₂O₂ i.e, metallothionein (MT1, MT3 and MT4), catalase (CAT1) and ascorbate peroxidase (APX1 and APX2), MT1 and MT4 exhibited 14.4- and 15.4-fold increase respectively, in the transcript abundance, in primed seeds compared to the control. We report in our study that metallothionein and RACK1 play a vital role in the reactive oxygen species mediated signal transduction pathway to enhance the speed of germination in magnetoprimed tomato seeds. Increased enzymatic activities of catalase and ascorbate peroxidase were observed at 12 h of imbibition in the magnetoprimed seeds indicating their roles in maintaining H₂O₂ levels in the primed seeds. The upregulation of ABA 8′-hydroxylase and GA3 oxidase1 genes eventually, lead to the decreased abscisic acid/gibberellic acid (ABA/GA₃) ratio in the primed seeds, suggesting the key role of H₂O₂ in enhancing the germination capacity of magnetoprimed tomato seeds.

Priming of Silybum marianum (L.) Gaertn seeds with H2O2 and magnetic field ameliorates seawater stress

Silybum marianum (L.) Gaertn is an important medicinal plant and has been used as a traditional medicine for diseases of the liver and biliary tract. The effects of seed priming by H2O2 (Haloprimig) and magnetic field (Magnetopriming, MF) on the impacts of seawater concentration were tested using S. marianum at the vegetative stage. These plant species accumulate flavonoids especially slimarine that is used in liver treatment. Some soaked S. marianum seeds were subjected to 0.18 T MF for different time durations (0, 10, 20 and 30 min) and other seeds were soaked in different concentrations of H2O2 (0, 80,160 and 240μM) for 8h. H2O2 priming increased growth and development under water irrigation more than under sea water stress. Moreover, our results uncovered statistical evidence that the priming seeds with H2O2 and MF increased the tolerance of S. marianum to salinity. In summary, we provide clear evidence that seawater stress caused a highly significant reduction in the growth parameters and stimulation in proline and phenolic compounds. It was concluded that, application of H2O2 and MF of S. marianum could scavenge or alleviate the harmful effects of salinity stress at early seedling stage and alleviate the oxidative damage leading to improvements in physiological attributes for the plant growth under sea water stress.

Seed germination of medicinal sage is affected by gibberellic acid, magnetic field and laser irradiation

Proper priming techniques are among the most important methods for increasing seed germination and seedling growth. Three experiments were conducted to investigate the effects of plant hormone (500 and 1000 mg/L gibberellic acid (GA)), magnetic field (3, 15, 30 mili Tesla (mT)) and laser irradiation at 650 nm (200 mW) on the germination and the growth of Salvia officinalis. We examined the plumule and radical length, plumule and radical fresh weight, plumule and radical dry weight, germination percentage, germination rate and seed vigor. The two concentrations of GA significantly increased seed germination and seedling growth. The magnetic field at 15 mT significantly increased radical length. The effect of laser irradiation was also significant on plumule length, and fresh and dry weight, radicle fresh weight, germination percentage and rate and seed vigor. Such results may be of practical use in the field, especially in arid and semiarid areas, but more research must determine the response of medicinal sage, treated with the priming techniques tested in our experiments, under stress conditions.

Influence of magnetopriming on germination, growth, physiology, oil and essential contents of cumin (Cuminum cyminum L.)

An environment friendly technique is desirable for enhancing of crop production. In this study, seeds of cumin (Cuminum cyminum L.) Yazd accession were treated with 0, 150 mT, 250 mT, 500 mT and 1 T magnetic field strengths for min and germination parameters were determined. All of the treatments improved germination parameters and seedling growth as compared with the control. However, 500 and 150 mT were the most effective treatments and thus selected for field studies. Seeds were exposed to 150 mT and 500 mT static magnetic field of strengths for 12 min, planted in the field during 2010-2012 in Isfahan, Iran. Static magnetic field treatment shortened the days to emergence, flowering and maturity, increased chlorophyll and reduced proline contents. Highest biological, seed and essential oil yield, oil content, and oil yield were recorded under 500 mT followed by 150 mT and control, respectively. The results suggested that the pretreatment of cumin seeds with static magnetic field can improve germination, growth and oil and essential contents of the cumin seed under the field.

Nanopriming technology for enhancing germination and starch metabolism of aged rice seeds using phytosynthesized silver nanoparticles

Application of nanomaterials for agriculture is relatively new as compared to their use in biomedical and industrial sectors. In order to promote sustainable nanoagriculture, biocompatible silver nanoparticles (AgNPs) have been synthesized through green route using kaffir lime leaf extract for use as nanopriming agent for enhancing seed germination of rice aged seeds. Results of various characterization techniques showed the successful formation of AgNPs which were capped with phytochemicals present in the plant extract. Rice aged seeds primed with phytosynthesized AgNPs at 5 and 10 ppm significantly improved germination performance and seedling vigor compared to unprimed control, AgNO₃ priming, and conventional hydropriming. Nanopriming could enhance α-amylase activity, resulting in higher soluble sugar content for supporting seedlings growth. Furthermore, nanopriming stimulated the up-regulation of aquaporin genes in germinating seeds. Meanwhile, more ROS production was observed in germinating seeds of nanopriming treatment compared to unprimed control and other priming treatments, suggesting that both ROS and aquaporins play important roles in enhancing seed germination. Different mechanisms underlying nanopriming-induced seed germination were proposed, including creation of nanopores for enhanced water uptake, rebooting ROS/antioxidant systems in seeds, generation of hydroxyl radicals for cell wall loosening, and nanocatalyst for fastening starch hydrolysis.

Nanopriming technology for enhancing germination and starch metabolism of aged rice seeds using phytosynthesized silver nanoparticles

Application of nanomaterials for agriculture is relatively new as compared to their use in biomedical and industrial sectors. In order to promote sustainable nanoagriculture, biocompatible silver nanoparticles (AgNPs) have been synthesized through green route using kaffir lime leaf extract for use as nanopriming agent for enhancing seed germination of rice aged seeds. Results of various characterization techniques showed the successful formation of AgNPs which were capped with phytochemicals present in the plant extract. Rice aged seeds primed with phytosynthesized AgNPs at 5 and 10 ppm significantly improved germination performance and seedling vigor compared to unprimed control, AgNO₃ priming, and conventional hydropriming. Nanopriming could enhance α-amylase activity, resulting in higher soluble sugar content for supporting seedlings growth. Furthermore, nanopriming stimulated the up-regulation of aquaporin genes in germinating seeds. Meanwhile, more ROS production was observed in germinating seeds of nanopriming treatment compared to unprimed control and other priming treatments, suggesting that both ROS and aquaporins play important roles in enhancing seed germination. Different mechanisms underlying nanopriming-induced seed germination were proposed, including creation of nanopores for enhanced water uptake, rebooting ROS/antioxidant systems in seeds, generation of hydroxyl radicals for cell wall loosening, and nanocatalyst for fastening starch hydrolysis.

Pulsed magnetic field improves seed quality of aged green pea seeds by homeostasis of free radical content

To elucidate the mechanism responsible for magnetic field induced seed invigoration in aged seeds an experiment was conducted on six year old garden pea seeds stored under controlled (20 °C and 40% RH) condition. Aged seeds were magnetoprimed by exposing to pulsed magnetic field (PMF) of 100 mT for 1 h in three pulsed modes. The 6 min on and off PMF showed significant improvement in germination (7.6%) and vigor (84.8%) over aged seeds. Superoxide and hydrogen peroxide production increased in germinating primed seeds by 27 and 52%, respectively, over aged seeds. Nicotinamide adenine dinucleotide (reduced) (NADH) peroxidase and superoxide dismutase involved in generation of hydrogen peroxide showed increased activity in PMF primed seeds. Increase in catalase, ascorbate peroxidase and glutathione reductase activity after 36 h of imbibition in primed seeds demonstrated its involvement in seed recovery during magnetopriming. An increase in total antioxidants also helped in maintaining the level of free radicals for promoting germination of magnetoprimed seeds. A 44% increase in level of protein carbonyls after 36 h indicated involvement of protein oxidation for counteracting and/or utilizing the production of ROS and faster mobilization of reserve proteins. Higher production of free radicals in primed seeds did not cause lipid peroxidation as malondialdehyde content was low. Lipoxygenase was involved in the germination associated events as the magnitude of activity was higher in primed aged seeds compared to aged seeds. Our study elucidated that PMF mediated improvement in seed quality of aged pea seeds was facilitated by fine tuning of free radicals by the antioxidant defense system and protein oxidation.

Static magnetic field treatment of seeds improves carbon and nitrogen metabolism under salinity stress in soybean

The effectiveness of magnetopriming was assessed for alleviation of salt-induced adverse effects on soybean growth. Soybean seeds were pre-treated with static magnetic field (SMF) of 200 mT for 1 h to evaluate the effect of magnetopriming on growth, carbon and nitrogen metabolism, and yield of soybean plants under different salinity levels (0, 25, and 50 mM NaCl). The adverse effect of NaCl-induced salt stress was found on growth, yield, and various physiological attributes of soybeans. Results indicate that SMF pre-treatment significantly increased plant growth attributes, number of root nodules, nodules, fresh weight, biomass accumulation, and photosynthetic performance under both non-saline and saline conditions as compared to untreated seeds. Polyphasic chlorophyll a fluorescence (OJIP) transients from magnetically treated plants gave a higher fluorescence yield at J-I-P phase. Nitrate reductase activity, PIABS , photosynthetic pigments, and net rate of photosynthesis were also higher in plants that emerged from SMF pre-treated seeds as compared to untreated seeds. Leghemoglobin content and hemechrome content in root nodules were also increased by SMF pre-treatment. Thus pre-sowing exposure of seeds to SMF enhanced carbon and nitrogen metabolism and improved the yield of soybeans in terms of number of pods, number of seeds, and seed weight under saline as well as non-saline conditions. Consequently, SMF pre-treatment effectively mitigated adverse effects of NaCl on soybeans. It indicates that magnetopriming of dry soybean seeds can be effectively used as a pre-sowing treatment for alleviating salinity stress. Bioelectromagnetics. 37:455-470, 2016. © 2016 Wiley Periodicals, Inc.

Physical Methods for Seed Invigoration: Advantages and Challenges in Seed Technology

In the context of seed technology, the use of physical methods for increasing plant production offers advantages over conventional treatments based on chemical substances. The effects of physical invigoration treatments in seeds can be now addressed at multiple levels, ranging from morpho-structural aspects to changes in gene expression and protein or metabolite accumulation. Among the physical methods available, "magneto-priming" and irradiation with microwaves (MWs) or ionizing radiations (IRs) are the most promising pre-sowing seed treatments. "Magneto-priming" is based on the application of magnetic fields and described as an eco-friendly, cheap, non-invasive technique with proved beneficial effects on seed germination, vigor and crop yield. IRs, as γ-rays and X-rays, have been widely regarded as a powerful tool in agricultural sciences and food technology. Gamma-rays delivered at low dose have showed to enhance germination percentage and seedling establishment, acting as an actual 'priming' treatment. Different biological effects have been observed in seeds subjected to MWs and X-rays but knowledge about their impact as seed invigoration agent or stimulatory effects on germination need to be further extended. Ultraviolet (UV) radiations, namely UV-A and UV-C have shown to stimulate positive impacts on seed health, germination, and seedling vigor. For all mentioned physical treatments, extensive fundamental and applied research is still needed to define the optimal dose, exposition time, genotype- and environment-dependent irradiation conditions. Electron paramagnetic resonance has an enormous potential in seed technology not fully explored to monitor seed invigoration treatments and/or identifying the best suitable irradiation dose or time-point to stop the treatment. The present manuscript describes the use of physical methods for seed invigoration, while providing a critical discussion on the constraints and advantages. The future perspectives related to the use of these approaches to address the need of seed technologists, producers and trade markers will be also highlighted.

How membranes organize during seed germination: three patterns of dynamic lipid remodelling define chilling resistance and affect plastid biogenesis

Imbibitional chilling injury during germination causes agricultural losses, but this can be overcome by osmopriming. It remains unknown how membranes reorganize during germination. Herein, we comparatively profiled changes of membrane lipids during imbibition under normal and chilling temperatures in chilling-tolerant and -sensitive soybean seeds. We found three patterns of dynamic lipid remodelling during the three phases of germination. Pattern 1 involved a gradual increase in plastidic lipids during phases I and II, with an abrupt increase during phase III. This abrupt increase was associated with initiation of photosynthesis. Pattern 3 involved phosphatidic acid (PA) first decreasing, then increasing, and finally decreasing to a low level. Patterns 1 and 3 were interrupted in chilling-sensitive seeds under low temperature, which lead a block in plastid biogenesis and accumulation of harmful PA, respectively. However, they were rescued and returned to their status under normal temperature after polyethylene glycol osmopriming. We specifically inhibited phospholipase D (PLD)-mediated PA formation in chilling-sensitive seeds of soybean, cucumber, and pea, and found their germination under low temperature was significantly improved. These results indicate that membranes undergo specific and functional reorganization of lipid composition during germination and demonstrate that PLD-mediated PA causes imibibitional chilling injury.

Magnetic field effects on plant growth, development, and evolution

The geomagnetic field (GMF) is a natural component of our environment. Plants, which are known to sense different wavelengths of light, respond to gravity, react to touch and electrical signaling, cannot escape the effect of GMF. While phototropism, gravitropism, and tigmotropism have been thoroughly studied, the impact of GMF on plant growth and development is not well-understood. This review describes the effects of altering magnetic field (MF) conditions on plants by considering plant responses to MF values either lower or higher than those of the GMF. The possible role of GMF on plant evolution and the nature of the magnetoreceptor is also discussed.