Biostimulants and environmental stress mitigation in crops: A novel and emerging approach for agricultural sustainability under climate change

Environmental and safety aspects of nanotechnology in genetically modified crops for sustainable agriculture

The rising global demand for food poses a significant threat to environmental health through both biotic (e.g., pests, pathogens) and abiotic (e.g., drought, salinity) stresses. Therefore, the adoption of innovative strategies is essential to ensure the sustainability of agricultural practices and to enhance crop resilience against environmental challenges. This review investigates how the integration of nanotechnology with genetically modified (GM) crops can offer solutions to agricultural challenges by improving crop resilience and productivity. While genetic modification has faced limitations in achieving consistent results due to environmental variability and species-specific differences, nanotechnology has emerged as a transformative tool to enhance GM crop performance. In this study we critically explore the underlying mechanisms of combining nanotechnology with GM crops to enhance plant growth and development and their resilience against biotic and abiotic stresses. Furthermore, nanotechnology also play a crucial role in targeted gene delivery, precise genome editing, and controlled regulation of gene expression in GM plant cells. Overall, the emerging role of nanotechnology in GM crops is paving the way for innovative solutions in agriculture. By leveraging nanotechnology, researchers are exploring novel approaches to enhance productivity, combat plant diseases, and improve plant resilience to environmental stress for sustainable agriculture. Furthermore, in this review we also highlighted the environmental impacts and safety issues associated with using nanotechnology in crops in order to establish more resilient and sustainable farming practices.

Biostimulant modulate the physiological and biochemical activities, improving agronomic characteristics of bell pepper plants under salt stress

Salinity is a significant environmental stress impacting plant growth and metabolism in irrigated areas of arid and semi-arid regions; the use of biostimulants is an effective alternative to enhance plant productivity under saline conditions. This study examined the effects of salinity stress by applying various electrical conductivities (0.5, 1.5, 2.5, 3.5, and 4.5 dS m- 1) of irrigation water combined with foliar application of the in combination with foliar application of biostimulant VIUSID Agro (0, 0.3, and 0.6 mL L- 1) on the growth, productivity, physiological, and biochemical responses of bell pepper plants in a greenhouse. Conducted in a factorial design with a completely randomized layout and five replications, and the results indicated that salinity caused a significant reduction in growth, decreased chlorophyll levels, and increased malondialdehyde levels, osmoregulators, and antioxidant enzyme activity. Plants treated with biostimulant demonstrated relatively superior growth parameters, such as plant height, dry matter, leaf area and number of leaves, as well as fruit quality, such as fruit size, firmness, ascorbic acid and soluble solids. Both doses of the biostimulant effectively mitigated the effects of salt stress by maintaining higher chlorophyll levels (15% increase), enhancing photosynthetic performance (20% increase), and improving fruit size and quality, as well as leaf water status, ultimately leading to better crop performance. The biochemical mechanisms through which these effects occur include enhanced osmoregulation and increased antioxidant activity. The foliar application of the biostimulant was an effective strategy to enhance the tolerance of bell pepper plants under salt stress conditions and can serve as a sustainable solution for agricultural production in saline irrigation water.

Endophytic and Rhizospheric Microorganisms: An Alternative for Sustainable, Organic, and Regenerative Bioinput Formulations for Modern Agriculture

Large amounts of chemical fertilizers are still used to suppress pathogens and boost agricultural productivity and food generation. However, their use can cause harmful environmental imbalance. Furthermore, plants typically absorb limited amounts of the nutrients provided by chemical fertilizers. Recent studies are recommending the use of microbiota present in the soil in different formulations, considering that several microorganisms are found in nature in association with plants in a symbiotic, antagonistic, or synergistic way. This ecological alternative is positive because no undesirable significant alterations occur in the environment while stimulating plant nutrition development and protection against damage caused by control pathogens. Therefore, this review presents a comprehensive discussion regarding endophytic and rhizospheric microorganisms and their interaction with plants, including signaling and bio-control processes concerning the plant's defense against pathogenic spread. A discussion is provided about the importance of these bioinputs as a microbial resource that promotes plant development and their sustainable protection methods aiming to increase resilience in the agricultural system. In modern agriculture, the manipulation of bioinputs through Rhizobium contributes to reducing the effects of greenhouse gases by managing nitrogen runoff and decreasing nitrous oxide. Additionally, mycorrhizal fungi extend their root systems, providing plants with greater access to water and nutrients.

Plant-microbiome interactions for enhanced crop production under cadmium stress: A review

Cadmium (Cd) is a toxic heavy metal that has detrimental effects on agriculture crops and human health. Both natural and anthropogenic processes release Cd into the environment, elevating its contents in soils. Under Cd stress, strong plant-microbiome interactions are important in improving crop production, but a systematic review is still missing. This review demonstrates the importance of microbiomes and their interactions with plants in mitigating Cd toxicity and promoting crop growth. Endogenous and exogenous microbiomes play a role to enhance plant's ability to respond to Cd stress. Specifically, the rhizosphere microbiome, which includes plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi, endosphere microbiome, and phyllosphere microbiome, are involved in Cd accumulation, immobilization, and translocation, and Cd-induced stress management. The mechanisms underlying these plant-microbiome interactions vary depending on the species and varieties of crops, composition and diversity of the microbiome, and level of Cd stress. Among the microbiome-mediated approaches, biosorption, bioprecipitation, and bioaccumulation are promising for Cd remediation in soil. Additionally, the endosphere microbiome, particularly Cd resistant endophytes, reduces Cd toxicity, increases the expression of Cd efflux genes, and enhances crop growth through regulating crops' antioxidant machinery and endogenous hormones. Furthermore, improved agricultural practices modulate the soil and plant microbiomes, thereby reducing Cd stress and increasing crop productivity.

Foliar application of biostimulants improves nutritional and bioactive quality of walnuts

BACKGROUND

Owing to their health benefits, walnuts are attracting interest as a good option for nutritious meals, thereby promoting their production. Furthermore, the adoption of ecologically and environmentally friendly agriculture strengthens biostimulant use as a sustainable complement to traditional fertilizers. This study evaluated the effects of different foliar-applied biostimulants in walnut tree orchards, in northeastern Portugal, on walnuts' chemical composition and bioactivity.

RESULTS

Walnut samples were rich in fat (particularly the polyunsaturated linoleic acid), dietary fiber and protein. Sucrose was the most prevalent soluble sugar, followed by glucose and fructose. Studied samples also showed an antioxidant activity comparable (or superior) to that of Trolox. Some plant biostimulants (e.g. Sprint Plus®) had a positive impact on the nutritional composition of walnuts, more specifically by boosting tocopherol levels, besides improving the bioactivity of walnut extracts against specific bacteria.

CONCLUSION

Overall, this research demonstrated that important quality traits of walnuts can be improved using sustainable agricultural bioproducts and practices. © 2024 Society of Chemical Industry.

Plant Biostimulants to Enhance Abiotic Stress Resilience in Crops

The escalating impact of abiotic stress on crop productivity requires innovative strategies to ensure sustainable agriculture. This review examines the promising role of biostimulants in mitigating the adverse effects of abiotic stress on crops. Biostimulants, ranging from simple organic compounds to complex living microorganisms, have demonstrated significant potential in enhancing plant resilience, stress tolerance, and overall performance. The mechanisms underlying biostimulant action-such as enhancing antioxidant defenses, regulating hormonal pathways, and inducing metabolic adjustments-are reviewed. Furthermore, we incorporate the latest research findings, methodologies, and advancements in biostimulant applications for addressing abiotic stressors, including drought, salinity, high temperatures, and nutrient deficiencies. This review also highlights current challenges and future opportunities for optimizing biostimulant use in sustainable crop production. This revision aims to guide researchers and agronomists in applying biostimulants to improve crop resilience in the context of climate change.

Molecular Communication of Microbial Plant Biostimulants in the Rhizosphere Under Abiotic Stress Conditions

Microbial plant biostimulants offer a promising, sustainable solution for enhancing plant growth and resilience, particularly under abiotic stress conditions such as drought, salinity, extreme temperatures, and heavy metal toxicity. These biostimulants, including plant growth-promoting rhizobacteria, mycorrhizal fungi, and nitrogen-fixing bacteria, enhance plant tolerance through mechanisms such as phytohormone production, nutrient solubilization, osmotic adjustment, and antioxidant enzyme activation. Advances in genomics, metagenomics, transcriptomics, and proteomics have significantly expanded our understanding of plant-microbe molecular communication in the rhizosphere, revealing mechanisms underlying these interactions that promote stress resilience. However, challenges such as inconsistent field performance, knowledge gaps in stress-related molecular signaling, and regulatory hurdles continue to limit broader biostimulant adoption. Despite these challenges, microbial biostimulants hold significant potential for advancing agricultural sustainability, particularly amid climate change-induced stresses. Future studies and innovation, including Clustered Regularly Interspaced Short Palindromic Repeats and other molecular editing tools, should optimize biostimulant formulations and their application for diverse agro-ecological systems. This review aims to underscore current advances, challenges, and future directions in the field, advocating for a multidisciplinary approach to fully harness the potential of biostimulants in modern agriculture.

Antioxidant activity and comparative RNA-seq analysis support mitigating effects of an algae-based biostimulant on drought stress in tomato plants

Drought is a significant global environmental stress. Biostimulants offer a sustainable solution to enhance crop tolerance and mitigate productivity losses. This study assessed the impact of foliar application of ERANTHIS®, a biostimulant derived from the algae Ascophyllum nodosum and Laminaria digitata and yeast extracts, on tomato plants under mild water stress. Evaluations were conducted at 5 and 24 hours after the third treatment. Under optimal water conditions, the biostimulant showed a priming effect, with an early increase of stress markers and a timing-specific modulation of ROS non enzymatic and enzymatic ROS scavenging activities. Under drought stress, the biostimulant later decreased stress markers, by aligning the majority of analyzed ROS scavengers closer to levels in well-irrigated plants. Transcriptome analysis using RNA-seq data revealed differentially expressed genes (DEGs) and multivariate data highlighted groups of co-regulated genes (k-means clustering). Genes involved in water channel activity, transcription regulator activity, and oxidoreductase activity were significantly modulated. Cluster analysis identified distinct gene clusters influenced by the biostimulant under optimal conditions, including early responses (cell wall modification, hormone signaling) and late responses (RNA modification, nutrient uptake process). Under water stress, early responses involved actin filament organization and MAPK signaling, while late responses were related to plasma membrane components and cell wall organization. This study, integrating biochemical and transcriptomic data, provides a comprehensive understanding of how a biostimulant primes plants under optimal conditions and mitigates water stress effects, offering valuable insights for sustainable agriculture.

Sucrose supplements modulate the Pseudomonas chlororaphis-Arabidopsis thaliana interaction via decreasing the production of phenazines and enhancing the root auxin response

Management of the plant microbiome may help support food needs for the human population. Bacteria influence plants through enhancing nutrient uptake, metabolism, photosynthesis, biomass production and/or reinforcing immunity. However, information into how these microbes behave under different growth conditions is missing. In this work, we tested how carbon supplements modulate the interaction of Pseudomonas chlororaphis with Arabidopsis thaliana. P. chlororaphis streaks strongly repressed primary root growth, lateral root formation and ultimately, biomass production. Noteworthy, increasing sucrose availability into the media from 0 to 2.4% restored plant growth and promoted lateral root formation in bacterized seedlings. This effect could not be observed by supplementing sucrose to leaves only, indicating that the interaction was strongly modulated by bacterial access to sugar. Total phenazine content decreased in the bacteria grown in high (2.4%) sucrose medium, and conversely, the expression of phzH and pslA genes were diminished by sugar supply. Pyocyanin antagonized the promoting effects of sucrose in lateral root formation and biomass production in inoculated seedlings, indicating that this virulence factor accounts for growth repression during the plant-bacterial interaction. Defence reporter transgenes PR-1::GUS and LOX2::GUS were induced in leaves, while the expression of the auxin-inducible, synthetic reporter gene DR5::GUS was enhanced in the roots of bacterized seedlings at low and high sucrose treatments, which suggests that growth/defence trade-offs in plants are critically modulated by P. chlororaphis. Collectively, our data suggest that bacterial carbon nutrition controls the outcome of the relation with plants.

Pseudomonas putida configures Arabidopsis root architecture through modulating the sensing systems for phosphate and iron acquisition

Iron (Fe) and phosphate (Pi) are two essential nutrients that are poorly available in the soil and should be supplemented either as fertilizers or organic amendments to sustain crop production. Currently, determining how rhizosphere bacteria contribute to plant mineral nutrient acquisition is an area of growing interest regarding its potential application in agriculture. The aim of this study was to investigate the influence of root colonization by Pseudomonas putida for Arabidopsis growth through Fe and Pi nutritional signaling. We found that root colonization by the bacterium inhibits primary root elongation and promotes the formation of lateral roots. These effects could be related to higher expression of two Pi starvation-induced genes and AtPT1, the major Pi transporter in root tips. In addition, P. putida influenced the accumulation of Fe in the root and the expression of different elements of the Fe uptake pathway. The loss of function of the protein ligase BRUTUS (BTS), and the bHLH transcription factors POPEYE (PYE) and IAA-LEUCINE RESISTANT3 (ILR3) compromised the root branching stimulation triggered by bacterial inoculation while the leaf chlorosis in the fit1 and irt1-1 mutant plants grown under standard conditions could be bypassed by P. putida inoculation. The WT and both mutant lines showed similar Fe accumulation in roots. P. putida repressed the expression of the IRON-REGULATED TRANSPORTER 1 (IRT1) gene suggesting that the bacterium promotes an alternative Fe uptake mechanism. These results open the door for the use of P. putida to enhance nutrient uptake and optimize fertilizer usage by plants.

A New Era of Sustainability: Plant Biostimulants

Today, environmental sustainability has become a fundamental concern in nearly every aspect of our daily lives, including the food sector [...].

The Application of Arbuscular Mycorrhizal Fungi as Microbial Biostimulant, Sustainable Approaches in Modern Agriculture

Biostimulant application can be considered an effective, practical, and sustainable nutritional crop supplementation and may lessen the environmental problems related to excessive fertilization. Biostimulants provide beneficial properties to plants by increasing plant metabolism, which promotes crop yield and improves the quality of crops; protecting plants against environmental stresses such as water shortage, soil salinization, and exposure to sub-optimal growth temperatures; and promoting plant growth via higher nutrient uptake. Other important benefits include promoting soil enzymatic and microbial activities, changing the architecture of roots, increasing the solubility and mobility of micronutrients, and enhancing the fertility of the soil, predominantly by nurturing the development of complementary soil microbes. Biostimulants are classified as microbial, such as arbuscular mycorrhizae fungi (AMF), plant-growth-promoting rhizobacteria (PGPR), non-pathogenic fungi, protozoa, and nematodes, or non-microbial, such as seaweed extract, phosphite, humic acid, other inorganic salts, chitin and chitosan derivatives, protein hydrolysates and free amino acids, and complex organic materials. Arbuscular mycorrhizal fungi are among the most prominent microbial biostimulants and have an important role in cultivating better, healthier, and more functional foods in sustainable agriculture. AMF assist plant nutrient and water acquisition; enhance plant stress tolerance against salinity, drought, and heavy metals; and reduce soil erosion. AMF are proven to be a sustainable and environmentally friendly source of crop supplements. The current manuscript gives many examples of the potential of biostimulants for the production of different crops. However, further studies are needed to better understand the effectiveness of different biostimulants in sustainable agriculture. The review focuses on how AMF application can overcome nutrient limitations typical of organic systems by improving nutrient availability, uptake, and assimilation, consequently reducing the gap between organic and conventional yields. The aim of this literature review is to survey the impacts of AMF by presenting case studies and successful paradigms in different crops as well as introducing the main mechanisms of action of the different biostimulant products.

Cultivable Endophyte Resources in Medicinal Plants and Effects on Hosts

With the increasing demand for medicinal plants and the increasing shortage of resources, improving the quality and yield of medicinal plants and making more effective use of medicinal plants has become an urgent problem to be solved. During the growth of medicinal plants, various adversities can lead to nutrient loss and yield decline. Using traditional chemical pesticides to control the stress resistance of plants will cause serious pollution to the environment and even endanger human health. Therefore, it is necessary to find suitable pesticide substitutes from natural ingredients. As an important part of the microecology of medicinal plants, endophytes can promote the growth of medicinal plants, improve the stress tolerance of hosts, and promote the accumulation of active components of hosts. Endophytes have a more positive and direct impact on the host and can metabolize rich medicinal ingredients, so researchers pay attention to them. This paper reviews the research in the past five years, aiming to provide ideas for improving the quality of medicinal plants, developing more microbial resources, exploring more medicinal natural products, and providing help for the development of research on medicinal plants and endophytes.