A Model for Mechanical Stress Limited Bacterial Growth and Resporulation in Confinement.

In this study, we propose a self-limiting growth model forBacillus subtilisspores confined within porous polyacrylamide (PA) hydrogels. We observed thatB. subtilisspores germinate into vegetative cells within the hydrogel matrix, forming spherical colonies. These colonies expand until the mechanical stress they exert on their environment surpasses the yield stress of the hydrogel, leading to formation of a nonpermeable layer that halts nutrient diffusion and forces the bacteria to resporulate. These novel observations suggest a model to explain why bacterial growth in confined environments and material interfaces may be limited, providing insight for natural phenomena and biotechnological applications involving bacterial encapsulation.

Andean Crops Germination: Changes in the Nutritional Profile, Physical and Sensory Characteristics. A Review.

Andean crops such as quinoa, amaranth, cañihua, beans, maize, and tarwi have gained interest in recent years for being gluten-free and their high nutritional values; they have high protein content with a well-balanced essential amino acids profile, minerals, vitamins, dietary fiber, and antioxidant compounds. During the germination bioprocess, the seed metabolism is reactivated resulting in the catabolism and degradation of macronutrients and some anti-nutritional compounds. Therefore, germination is frequently used to improve nutritional quality, protein digestibility, and availability of certain minerals and vitamins; furthermore, in specific cases, biosynthesis of new bioactive compounds could occur through the activation of secondary metabolic pathways. These changes could alter the technological and sensory properties, such as the hardness, consistency and viscosity of the formulations prepared with them. In addition, the flavor profile may undergo improvement or alteration, a critical factor to consider when integrating sprouted grains into food formulations. This review summarizes recent research on the nutritional, technological, functional, and sensory changes occur during the germination of Andean grains and analyze their potential applications in various food products.

Effects of discharge plasma on seed germination and volatile compounds content of Agropyron Mongolicum.

To investigate the effects of discharge plasma on Agropyron mongolicum seeds, various treatments including direct exposure to discharge plasma, combined treatment with discharge plasma and plasma-activated water (PAW) were applied to the seeds. The changes in germination rate, MDA content, and volatile compound levels of Agropyron mongolicum seeds after different treatments were examined. The results showed that the direct effect of plasma had no significant effect on the MDA content or germination rate of Agropyron mongolicum seeds due to the limited penetration depth. However, the combined effect of plasma and activated water could cause active nitrogen and oxygen particles to enter the seeds and cause oxidative stress damage. After 18 h of combined treatment, the MDA content increased significantly, and the germination rate decreased to below the semilethal dose, which was 33.44 %. After plasma treatment, 55 volatile compounds, mainly alcohols, aldehydes and ketones, were identified from the seeds of Agropyron mongolicum. Due to the oxidation and modification of the plasma, the content of most aldehydes increased with increasing reaction time. After screening, 13 volatile organic compounds could be used as potential markers to distinguish between different treatment methods. These results reveal the mechanism underlying the biological effects of plasma treatment on Agropyron mongolicum seeds.

Response of winter wheat genotypes to salinity stress under controlled environments.

This study was conducted in controlled environmental conditions to systematically evaluate multi-traits responses of winter wheat (Triticum aestivum L.) genotypes to different salinity levels. Responses were assessed at the germination to early seedling stage (Experiment 1). Seeds of different genotypes (n=292) were subjected to three salinity levels (0 [control], 60, and 120 mM NaCl). Principal Component Analysis (PCA) revealed that among studied traits seedling vigor index (SVI) contributed more towards the diverse response of genotypes to salinity stress. Based on SVI, eight contrasting genotypes assumed to be tolerant (Gage, Guymon, MTS0531, and Tascosa) and susceptible (CO04W320, Carson, TX04M410211) were selected for further physio-biochemical evaluation at the booting stage (Experiment 2) and to monitor grain yield. Higher level of salinity (120 mM NaCl) exposure at the booting stage increased thylakoid membrane damage, lipid peroxidation, sugars, proline, and protein while decreasing photosynthesis, chlorophyll index, starch, and grain yield. Based on grain yield, the assumed magnitude of the genotypic response shown in Experiment 1 was not analogous in Experiment 2. This indicates the necessity of individual screening of genotypes at different sensitive growth stages for identifying true salinity-tolerant and susceptible genotypes at a particular growth stage. However, based on higher grain yield and its least percentage reduction under higher salinity, Guymon and TX04M410211 were identified as tolerant, and Gage and CO04W320 as susceptible at the booting stage, and their biparental population can be used to identify genomic regions for booting stage-specific salinity response.

Elucidating the regulatory role of long non-coding RNAs in drought stress response during seed germination in leaf mustard.

Leaf mustard (Brassica juncea L. Czern & Coss), an important vegetable crop, experiences pronounced adversity due to seasonal drought stress, particularly at the seed germination stage. Although there is partial comprehension of drought-responsive genes, the role of long non-coding RNAs (lncRNAs) in adjusting mustard's drought stress response is largely unexplored. In this study, we showed that the drought-tolerant cultivar 'Weiliang' manifested a markedly lower base water potential (-1.073 MPa vs -0.437 MPa) and higher germination percentage (41.2% vs 0%) than the drought-susceptible cultivar 'Shuidong' under drought conditions. High throughput RNA sequencing techniques revealed a significant repertoire of lncRNAs from both cultivars during germination under drought stress, resulting in the identification of 2,087 differentially expressed lncRNAs (DELs) and their correspondingly linked 12,433 target genes. It was noted that 84 genes targeted by DEL exhibited enrichment in the photosynthesis pathway. Gene network construction showed that MSTRG.150397, a regulatory lncRNA, was inferred to potentially modulate key photosynthetic genes (Psb27, PetC, PetH, and PsbW), whilst MSTRG.107159 was indicated as an inhibitory regulator of six drought-responsive PIP genes. Further, weighted gene co-expression network analysis (WGCNA) corroborated the involvement of light intensity and stress response genes targeted by the identified DELs. The precision and regulatory impact of lncRNA were verified through qPCR. This study extends our knowledge of the regulatory mechanisms governing drought stress responses in mustard, which will help strategies to augment drought tolerance in this crop.

Synergistic effects of exogenous IAA and melatonin on seed priming and physiological biochemistry of three desert plants in saline-alkali soil.

To investigate the synergistic effect of IAA and melatonin (MT) on three plants to alleviate the effects of salt damage on plants, we aim to determine the optimal concentrations of exogenous hormone treatments that improve salinity resistance for each species. In this experiment, three desert plants, Sarcozygium xanthoxylon, Nitraria tangutorum, and Ammopiptanthus mongolicus, which are common in Wuhai City, were used as plant materials. Two time periods (12 h,24 h) of exogenous hormone IAA (100 µmol/L) and exogenous melatonin concentration (0, 100, 200, 300 µmol/L) were used to treat the three desert plants in saline soil under different conditions of exogenous IAA and exogenous melatonin. The results indicate that under different concentrations of exogenous IAA and melatonin, the germination rate and vigor of the three desert plant species in saline-alkaline soil improved. However, as the concentration of melatonin increased, the germination rate and vigor of these desert plants were inhibited. Whereas, plant height, root length, leaf length, fresh weight, dry weight, and root vigor of the three desert plants were alleviated under different conditions of exogenous IAA and exogenous melatonin. under the action of two exogenous hormones, the low concentration of melatonin decreased their malondialdehyde content and increased their proline content. As melatonin levels increased, the activity of antioxidant enzymes also rose initially, followed by a subsequent decline. This study highlights the synergistic effects of two exogenous hormones on the critical role of cell osmomodulators and antioxidant enzyme activity in combating salinity damage in three desert plants.

Physical seed damage, not rodent's saliva, accelerates seed germination of trees in a subtropical forest.

Many tree species adopt fast seed germination to escape the predation risk by rodents. Physical seed damage and the saliva of rodents on partially consumed seeds may act as cues for seeds to accelerate germination process. However, the impacts of these factors on seed germination rate and speed remain unclear. In this study, we investigated such impacts on the germination rate and speed (reversal of germination time) of four tree species (Quercus variabilis, Q. serrata, Q. acutissima, Q. glauca) after partial consumption by four rodent species (Leopoldamys edwards, Niviventer fulvescens, N. confucianus, Apodemus draco), through a series of experiments. We also examined how seed traits may affect the seed damage degree by rodents by analyzing the relationship between the germination rate and time of rodent-damaged seed and the traits. We found that, artificially- and rodent-damaged seeds exhibited a significantly higher seed germination rate and speed, compared to intact seeds. Also, the rodent saliva on seeds showed no significant effect on seed germination rate and speed. Furthermore, we observed significant positive correlations between several seed traits (including the seed mass, coat thickness, and protein content) and the seed germination rate and speed. These correlations are likely due to their beneficial traits countering seed damage by rodents. Overall, our results highlight the significant role of physical seed damage by rodents (rather than their saliva) in facilitating seed germination of tree species, and potential mutualism between rodents and trees. Additionally, our results may have some implications in forest restoration, such that intentionally sowing or dispersing slightly damaged seeds by humans or drones may increase the likelihood of successful seed regeneration.

Topping and NPK fertilization alter seed germination, plant growth and active components of Valeriana amurensis.

Introduction: Valeriana amurensis, a tall herbaceous plant, has been traditionally utilized as a herbal remedy both in China and Russia. Methods: This study was set to explore how to cultivate high quality seedlings, considering factors such as seedling time, seeding density, shading, and plastic film mulching. In addition, we investigated the impact of topping and fertilizer on the growth and quality of V. amurensis. Results: According to the percentage of seed germination, the seeds of V. amurensis were sowed with 0.88 g m-2 density using plastic film mulching from late April to mid-May (germination percentage was more than 30%). The optimal Transplanting time was identified as late September, ensuring a high survival rate of 98%. Generally, topping showed the most improved growth indices in late fruit period (21.87 for number of radical leaves) and withering period (6.50 for number of buds and 234.81 for number of roots). Topping increased the yields of valtrate (10.91 mg per plant), valepotriates (809.51 mg per plant) and essential oil (395.64 mg per plant) in withering period. Nitrogen fertilizer promoted maximum root growth and increased the biomass of V. amurensis. Meanwhile, N fertilizer significantly increased the yields of valtrate to 10.46 mg per plant and valepotriates to 772.32 mg per plant among three types of fertilizers. Seedlings are obtained according to rational sowing factors and transplanting time. Topping and nitrogen fertilization emerge as superior strategies to enhance the growth and medicinal quality of this valuable plant. Discussion: This study provides actionable insights for the cultivation V. amurensis.

Green-synthesized CuO and ZnO nanoparticles derived from Calotropis gigantea (Apple of Sodom): enhancing plant growth, efficient dye removal, and potent antibacterial applications.

Nanoparticles, owing to their unique physicochemical properties, have garnered significant attention in various scientific disciplines, including materials science, chemistry, biology, and environmental engineering. In recent years, the synthesis of metal oxide nanoparticles, such as NiO, Fe2O3, ZnO, SnO2, and CuO via green routes, has gained attraction due to their diverse applications in fields ranging from catalysis and electronics to medicine and environmental remediation. This study focuses on the green synthesis of copper oxide (CuO) and zinc oxide (ZnO) nanoparticles using Calotropis gigantea (Apple of Sodom) leaf extract as a reducing agent and stabilizer, with zinc nitrate (ZnNO3.6H2O) and copper nitrate (CuNO3.3H2O) as precursors. The hexagonal phase of ZnO and monoclinic plan structure of CuO with high crystallinity was confirmed by XRD and elemental composition by EDX analysis. With the help of an SEM image, particle size measured for CuO and ZnO using ImageJ software was found to be 56.08 nm and 46.49 nm, respectively. This study investigates the efficacy of nanoparticles in wastewater treatment, particularly focusing on methylene blue dye decolorization using the statistical processing of response surface methodology (RSM) using the Box-Behnken method. Additionally, it explores the impact of synthesized nanoparticles on seed growth enhancement, using Vigna radiata (green gram) seeds immersed in various doses of nanoparticles (0, 0.5, 1, 1.5, 2 mg/30 mL). Furthermore, the antibacterial activity of the nanoparticles against both gram-positive and gram-negative bacteria is evaluated. The results confirm the effectiveness of the materials for methylene blue dye removal, achieving 80.53% with CuO and 78.25% with ZnO. Significant seed growth was observed with a low nanoparticle dosage of 1.5 mg/30 mL, resulting in the highest seedling vigour index and germination percentage. This reduces the need for fertilizers and lessens environmental impact.

Intraspecific variation in responses to extreme and moderate temperature stress in the wild species, Solanum carolinense (Solanaceae).

Adaptation or acclimation to local temperature regimes has often been used as a proxy for predicting how plant populations will respond to impending novel conditions driven by human-caused climate change. To understand how plants may successfully respond to increasing air temperatures (extreme and moderate) in the future, we explored how temperature tolerance traits differ in populations of Solanum carolinense from northern (MN) and southern (TX) regions of the continental USA in a two-experiment study. In the first experiment, we compared the heat and cold tolerance in vegetative (sporophyte) and reproductive (male gametophyte) traits. In the second experiment, we studied if long-term heat influences plant development by examining how development in moderate heat affected reproductive structures and reproductive success. We found that temperature sensitivity differed between southern populations, which regularly experience extreme heat, and northern populations which do not. In contrast to our expectations, northern populations appeared more heat-tolerant than southern populations for vegetative traits such as chlorophyll stability and reproductive traits such as pollen germination. Our results are consistent with a heat-avoidance, rather than tolerance mechanism to mitigate extreme heat during pollen germination. In the second experiment, plants developing under the moderate heat treatment had significantly smaller reproductive structures and reduced seed production (27% fewer seeds on average than in the control treatment). Reproductive structures that developed in moderate heat were also reduced in size, particularly in the northern populations relative to populations from the south. We conclude that rising temperatures have the potential to incur substantial negative consequences for the reproductive success of individuals in this species and that some populations already mitigate stressful temperature conditions through phenotypic plasticity.

Exploring selection signatures in the divergence and evolution of lipid droplet (LD) associated genes in major oilseed crops.

BACKGROUND: Oil bodies or lipid droplets (LDs) in the cytosol are the subcellular storage compartments of seeds and the sites of lipid metabolism providing energy to the germinating seeds. Major LD-associated proteins are lipoxygenases, phospholipaseD, oleosins, TAG-lipases, steroleosins, caleosins and SEIPINs; involved in facilitating germination and enhancing peroxidation resulting in off-flavours. However, how natural selection is balancing contradictory processes in lipid-rich seeds remains evasive. The present study was aimed at the prediction of selection signatures among orthologous clades in major oilseeds and the correlation of selection effect with gene expression. RESULTS: The LD-associated genes from the major oil-bearing crops were analyzed to predict natural selection signatures in phylogenetically close-knit ortholog clusters to understand adaptive evolution. Positive selection was the major force driving the evolution and diversification of orthologs in a lineage-specific manner. Significant positive selection effects were found in 94 genes particularly in oleosin and TAG-lipases, purifying with excess of non-synonymous substitution in 44 genes while 35 genes were neutral to selection effects. No significant selection impact was noticed in Brassicaceae as against LOX genes of oil palm. A heavy load of deleterious mutations affecting selection signatures was detected in T-lineage oleosins and LOX genes of Arachis hypogaea. The T-lineage oleosin genes were involved in mainly anther, tapetum and anther wall morphogenesis. In Ricinus communis and Sesamum indicum > 85% of PLD genes were under selection whereas selection pressures were low in Brassica juncea and Helianthus annuus. Steroleosin, caleosin and SEIPINs with large roles in lipid droplet organization expressed mostly in seeds and were under considerable positive selection pressures. Expression divergence was evident among paralogs and homeologs with one gene attaining functional superiority compared to the other. The LOX gene Glyma.13g347500 associated with off-flavor was not expressed during germination, rather its paralog Glyma.13g347600 showed expression in Glycine max. PLD-α genes were expressed on all the tissues except the seed,δ genes in seed and meristem while ß and γ genes expressed in the leaf. CONCLUSIONS: The genes involved in seed germination and lipid metabolism were under strong positive selection, although species differences were discernable. The present study identifies suitable candidate genes enhancing seed oil content and germination wherein directional selection can become more fruitful.

Strengths of fertilizer and litter effects on seedling recruitment and growth of grassland species differ depending on functional groups and seed size.

Agricultural grasslands play an important role in conserving the biodiversity of the European cultural landscape. Both, litter cover and soil nutrient availability, change with grassland management, but it is not well-studied how seedling recruitment and growth of multiple grassland species are influenced by their single or combined effects. Therefore, we studied the effects of nitrogen fertilization (100 kg N per year and ha) and litter cover (250 gdw per m2) on seedling recruitment and growth of 75 temperate grassland species (16 graminoid species, 51 forb species, 8 legume species) in a full factorial microcosm experiment. Overall, fertilizer reduced seedling emergence, while litter cover increased it even when combined with fertilization. Fertilization increased seedling height and biomass, and the combination of fertilizer and litter resulted in even stronger responses. Litter cover alone did not influence seedling biomass or seedling height. While the overall direction of treatment effects was similar across functional groups, their strengths were mostly weaker in graminoids than in non-legume forbs and legumes. Positive litter effects on seedling emergence were stronger in large-seeded species. Positive fertilization effects on seedling growth were stronger in small-seeded species, while their seedling biomass was negatively affected by litter cover. In summary, our results show for multiple grassland species that the combination of litter cover and fertilization modulates their single effects. The varying sensitivity of how grassland species representing different functional groups and seed sizes respond with their seedling emergence and growth to litter cover and nitrogen fertilization indicates that the consequences of land-use change on grassland diversity and composition already start to manifest in the earliest stages of the plant life cycle.

Effect of water content on gelatinization functionality of flour from sprouted sorghum.

Sorghum starch granules are encapsulated in a rigid protein matrix that prevents the granules from fully swelling and gelatinizing. Sprouting and subsequent drying treatment can affect the gelatinization properties of sorghum starch. This study aimed to evaluate the gelatinization properties of flours from unsprouted (US) and sprouted (S50, S40) sorghum dried at 50 °C (6h) and 40 °C (12h), respectively. Swelling power (Sp), thermal properties (DSC) and 1H molecular mobility and dynamics were evaluated at different water contents (38-91%). Sp increased with increasing water content, with S40 showing the lowest values, probably due to prolonged amylase activity and thus starch breakdown. Sprouting increased gelatinization temperatures; however, these differences disappeared for high water contents (82 and 91%). From a molecular point of view, sprouted samples showed a decrease in protons associated to the rigid protein matrix and starch structures. 1H CPMG results showed the presence of 4 populations at 38% water content. The evolution of the more mobile population with increasing water content supported the assignment of more mobile water fraction to this population. Sprouting decreased the mobility of populations in unheated samples, suggesting an increase in molecular bonds between flour biopolymers and water. After heating, however, increased molecular mobility in S40 indicated the formation of a weaker network between starch, protein, and water at the molecular level. These results suggest that post-sprouting drying treatment influences sorghum gelatinization, with potential modulation by water content. This study contributes to understanding the application of sprouted sorghum in foods with different moisture content.

Assessing Seed Germination Response of Parasitic Plant Striga hermonthica with Small-Molecule Probes.

Seed germination of a parasitic plant Striga hermonthica is elicited by strigolactones which are exuded from roots of host plants. Here, we describe a high-throughput germination assay and a method for visualizing in vivo strigolactone receptor functions with a fluorogenic probe.

Assessment of Dormancy Level and Germination Ability of Seeds with Physiological Dormancy.

Germination test is fundamental and commonly used technique for seed dormancy and germination studies, and proper assessment of dormancy level and germination ability of a given set of seeds is prerequisite for most of the studies. However, germination is very sensitive to imbibition conditions, and dormancy development is also sensitive to growth conditions of the mother plants. In this chapter, we describe tips for plant growth and germination test mainly for physiological and molecular genetic studies with Arabidopsis. This protocol can be applied for other plant species with relatively small seeds and for various studies to analyze the effect of light, phytohormones, and other chemicals in seed germination.

Functional Analysis of Seed Dormancy Genes by Biolistic Transient Gene Expression in Immature Embryos of Wheat.

Seed dormancy genes typically suppress germination and cell division. Therefore, overexpressing these genes can negatively affect tissue culture, interfering with the generation of transgenic plants and thus hampering the analysis of gene function. Transient expression in target cells is a useful approach for studying the function of seed dormancy genes. Here, we describe a protocol for transiently expressing genes related to seed dormancy in the scutellum of immature wheat (Triticum aestivum) embryos to analyze their effects on germination.

A Seed Storage Protocol to Determine Longevity.

The longevity of seeds, also known as storability, is the period of time for which a seed lot maintains its viability during storage. The method aims to determine longevity of a seed lot during storage in a controlled environment. Seeds are first rehydrated to a preset water content (or relative humidity, RH) and then incubated under controlled conditions for various periods of time to allow for deterioration to occur. At increasing intervals during storage, seeds are retrieved and viability is tested by scoring germination of the seed lot (i.e., radicle protrusion). From these data, a survival curve can be drawn depicting loss of germination during time of storage from which different parameters estimating longevity can be inferred. These parameters can be used to compare longevity between different seed lots, genotypes, or species at similar storage conditions. This test can also be used as a proxy to measure seed vigor or physiological seed quality.

Evaluation Methods for Preharvest Sprouting Resistance in Japanese Wheat Breeding Programs.

Different methodologies have been applied for the selection of preharvest sprouting resistance in cereal breeding programs. We describe here a series of methods used in practical wheat breeding programs in Japan, including phenotyping based on germination score after artificial rain treatments and genotyping using DNA markers. These methods can be modified and applied to breeding programs in which preharvest sprouting is a problem during cereal cultivation.

Seed germination requirements of the rare Helosciadium repens (aka Apium repens) determine persistence of seeds in the soil seed bank.

The rare and threatened Heliosciadium repens grows in moist grasslands and has a distinct life cycle. Plants reproduce both clonally, although ramets tend to be short-lived, and sexually, with seeds that can form a persistent soil seed bank. The germination requirements of H. repens were investigated, yielding important information for its habitat management and conservation. We examined the soil seed bank in three populations and carried out germination experiments and embryo growth measurements with fresh seeds in laboratory, greenhouse and outdoor conditions. We also investigated the effects of storage and burial of seeds. H. repens formed a long-term persistent (>6 years) soil seed bank with very pronounced primary dormancy, but no secondary dormancy or dormancy cycles. Seeds can germinate throughout the growing season when temperatures are sufficiently high. Embryo growth and seed germination are triggered by light and, to a lesser extent, daily temperature fluctuations. Seeds of H. repens seem to have developed a unique germination syndrome with several strategies to remain dormant in the soil until optimal conditions are present for seedling establishment and survival. Both sexual reproduction and seed bank formation are crucial for the long-term survival of the populations.

Effect of GABA combined with ultrasound stress germination treatment on phenolic content and antioxidant activity of highland barley.

BACKGROUND: This study investigated the effects of γ-aminobutyric acid (GABA) combined with ultrasonic stress germination (AUG) treatment on the phenolic content and antioxidant activity of highland barley (HB). Key variables, including germination times (ranging from 0 to 96 h), ultrasonic power (200-500 W), and GABA concentration (5-20 mmol/L), were optimized using response surface methodology (RSM) to enhance the enrichment of phenolic compounds. Furthermore, the study assessed the content, composition, and antioxidant activities of phenolic compounds in HB under various treatment conditions such as germination alone (G), ultrasonic stress germination (UG), and AUG treatment. RESULTS: The study identified optimal conditions for the phenolic enrichment of HB, which included a germination time of 60 h, an ultrasound power of 300 W, and a GABA concentration of 15 mmol L-1. Under these conditions, the total phenolic content (TPC) in HB was measured at 7.73 milligrams of gallic acid equivalents per gram dry weight (mg GAE/g DW), representing a 34.96% enhancement compared to untreated HB. Notably, all treatment modalities - G, UG, and AUG - significantly increased the phenolic content and antioxidant activity in HB, with the AUG treatment proving to be the most effective. CONCLUSION: These obtained results suggest that AUG treatment is a promising processing method for enriching phenolic compounds and improving antioxidant activity in HB. Subsequently, the AUG-treated HB can be used to develop phenolic-rich germinated functional foods to further broaden the application of HB. © 2024 Society of Chemical Industry.