The potential role of microbial biostimulants in the amelioration of climate change-associated abiotic stresses on crops

4openInternationalInternational coauthor/editorCrop plants are more often exposed to abiotic stresses in the current age of fast-evolving climate change. This includes exposure to extreme and unpredictable changes in climatic conditions, phytosanitary hazards, and cultivation conditions, which results in drastic losses in worldwide agricultural productions. Plants coexist with microbial symbionts, some of which play key roles in the ecosystem and plant processes. The application of microbial biostimulants, which take advantage of symbiotic relationships, is a long-term strategy for improving plant productivity and performance, even in the face of climate change-associated stresses. Beneficial filamentous fungi, yeasts, and bacteria are examples of microbial biostimulants, which can boost the growth, yield, nutrition and stress tolerance in plants. This paper highlights recent information about the role of microbial biostimulants and their potential application in mitigating the abiotic stresses occurring on crop plants due to climate change. A critical evaluation for their efficient use under diverse climatic conditions is also made. Currently, accessible products generally improve cultural conditions, but their action mechanisms are mostly unknown, and their benefits are frequently inconsistent. Thus, further studies that could lead to the more precisely targeted products are discussedopenFadiji, Ayomide Emmanuel; Babalola, Olubukola Oluranti; Santoyo, Gustavo; Perazzolli, MicheleFadiji, A.E.; Babalola, O.O.; Santoyo, G.; Perazzolli, M

Understanding the plant-microbe interactions in environments exposed to abiotic stresses : an overview

Abiotic stress poses a severe danger to agriculture since it negatively impacts cellular homeostasis and eventually stunts plant growth and development. Abiotic stressors like drought and excessive heat are expected to occur more frequently in the future due to climate change, which would reduce the yields of important crops like maize, wheat, and rice which may jeopardize the food security of human populations. The plant microbiomes are a varied and taxonomically organized microbial community that is connected to plants. By supplying nutrients and water to plants, and regulating their physiology and metabolism, plant microbiota frequently helps plants develop and tolerate abiotic stresses, which can boost crop yield under abiotic stresses. In this present study, with emphasis on temperature, salt, and drought stress, we describe current findings on how abiotic stresses impact the plants, microbiomes, microbe-microbe interactions, and plant-microbe interactions as the way microorganisms affect the metabolism and physiology of the plant. We also explore crucial measures that must be taken in applying plant microbiomes in agriculture practices faced with abiotic stresses

Bacterial elicitors of the plant immune system : an overview and the way forward

A wide variety of root-associated bacterial mutualist species sensitize plant defenses to counteract pathogen infections. These beneficial bacteria produce myriad molecules that induce systemic resistance (ISR) in plants. Here, we review pioneering and recent studies describing the role of different ISR elicitors, including quorum sensing molecules, lipids, oligosaccharides, proteins, iron-chelating molecules, and volatiles. The concepts and differences between ISR and other plant immune responses, such as Localized Acquired Resistance (LAR) and Systemic Acquired Resistance (SAR) are also explored. We also highlight the necessity of understanding plant responses to such a wide chemical diversity of molecules. Finally, we discuss the urgency of using such elicitors to develop more sustainable agriculture by helping plant crops defend themselves from invading pathogens

Microbial mat ecosystems: Structure types, functional diversity, and biotechnological application

Microbial mats are horizontally stratified microbial communities, exhibiting a structure defined by physiochemical gradients, which models microbial diversity, physiological activities, and their dynamics as a whole system. These ecosystems are commonly associated with aquatic habitats, including hot springs, hypersaline ponds, and intertidal coastal zones and oligotrophic environments, all of them harbour phototrophic mats and other environments such as acidic hot springs or acid mine drainage harbour non-photosynthetic mats. This review analyses the complex structure, diversity, and interactions between the microorganisms that form the framework of different types of microbial mats located around the globe. Furthermore, the many tools that allow studying microbial mats in depth and their potential biotechnological applications are discussed

IrO2-Ta2O5|Ti electrodes prepared by electrodeposition from different Ir:Ta ratios for the degradation of polycyclic aromatic hydrocarbons

This work investigates the feasibility of producing IrO2-Ta2O5|Ti electrodes by electrodeposition. Using precursor solutions with Ir:Ta molar ratios from 0:100 to 100:0, followed by thermal treatment, the goal was to find the optimal composition for enhancing the formation of hydroxyl radicals and providing long service lives. Scanning electron microscopy (SEM), coupled with energy dispersive X-ray spectroscopy (EDX), revealed that the production of homogeneous coatings with a good surface coverage and absence of agglomerates was only possible for electrodes with 70% or 100% Ir. The potential for O2 evolution was similar for all the electrodes containing Ir, at about 0.90 V vs Ag|AgCl. However, the ability to produce M(¿OH) clearly increased with increasing Ir in the Ir:Ta ratios (100:0 > 70:30 > 30:70 > 0:100). This observation was confirmed by the transformation of coumarin to 7-hydroxycoumarin as determined by spectroscopic and chromatographic techniques after treatment. Once manufactured and characterized, the electrodes were tested, as anodes, for the electro-oxidation of polycyclic aromatic hydrocarbons in aqueous solutions at natural pH (i.e., without pH adjustment). The anodes prepared from 70:30 and 100:0 ratios produced the fastest and highest removal rates, reaching 86% and 93% for phenanthrene and naphthalene, respectively, after 120 min at 50 mA. This was accompanied by a high degree of mineralization, as the result of direct and M(¿OH)-mediated oxidation, with some refractory intermediates remaining in the final solutions. The interaction between IrO2 and Ta2O5 oxides appeared to be important. The 100:0 anode provided high electrocatalytic effectiveness, whereas the anode with the 70:30 ratio provided improved long-term stability, as confirmed by its service life of about 93 h

Agroecological management of the grey mould fungus Botrytis cinerea by plant growth-promoting bacteria

Botrytis cinerea is the causal agent of grey mould and one of the most important plant pathogens in the world because of the damage it causes to fruits and vegetables. Although the application of botrycides is one of the most common plant protection strategies used in the world, the application of plant-beneficial bacteria might replace botrycides facilitating agroecological production practices. Based on this, we reviewed the different stages of B. cinerea infection in plants and the biocontrol mechanisms exerted by plant-beneficial bacteria, including the well-known plant growth-promoting bacteria (PGPB). Some PGPB mechanisms to control grey mould disease include antibiosis, space occupation, nutrient uptake, ethylene modulation, and the induction of plant defence mechanisms. In addition, recent studies on the action of anti-Botrytis compounds produced by PGPB and how they damage the conidial and mycelial structures of the pathogen are reviewed. Likewise, the advantages of individual inoculations of PGPB versus those that require the joint action of antagonist agents (microbial consortia) are discussed. Finally, it should be emphasised that PGPB are an excellent option to prevent grey mould in different crops and their use should be expanded for environmentally friendly agricultural practices

Recent developments in the application of plant growth-promoting drought adaptive rhizobacteria for drought mitigation

Drought intensity that has increased as a result of human activity and global warming poses a serious danger to agricultural output. The demand for ecologically friendly solutions to ensure the security of the world’s food supply has increased as a result. Plant growth-promoting rhizobacteria (PGPR) treatment may be advantageous in this situation. PGPR guarantees the survival of the plant during a drought through a variety of processes including osmotic adjustments, improved phytohormone synthesis, and antioxidant activity, among others and these mechanisms also promote the plant’s development. In addition, new developments in omics technology have improved our understanding of PGPR, which makes it easier to investigate the genes involved in colonizing plant tissue. Therefore, this review addresses the mechanisms of PGPR in drought stress resistance to summarize the most current omics-based and molecular methodologies for exploring the function of drought-responsive genes. The study discusses a detailed mechanistic approach, PGPR-based bioinoculant design, and a potential roadmap for enhancing their efficacy in combating drought stress

Bioestimulación integral de un suelo contaminado por 60000 ppm de aceite residual automotriz

Waste motor oil (WMO) is a mixture of hydrocarbons (HICO) soil pollutants. An alternative solution for its elimination is the biostimulation (BIS), secuancial, complementary and accumulative or integral which requires at firstBIS by detergents to emulsify WMO, the second one following by enrichment by mineral solution, H2O2 as a O2 source for oxidation of WMO and controlling moisture soil content at 80% field capacity for exchange gases in soilto stimulate WMO mineralization The aim of the work was: i) analyze in the integral BIS of contaminated soil by60000 ppm of WMO. The first BIS was applying detergents to emulsify the WMO, the second BIS by mineralsolution, then by H2O2, under humidity control at 80% of field capacity, for the best oxidation of WMO. Additionally bacterial population oxidant WMO was measured, to select those which synthetized detergent related to WMOdegradation, finally the type of bacteria were molecular identify. Results showed than integral BIS by an anionic /nonionic detergent, then enrichment with mineral solution, and 0.5% H2O2, reduced WMO from 60000 ppm to27200 ppm in 23 days. Density of bacterial WMO oxidant population was 268 X 106 CFU/g dry soil, from whichthe dominant ones were selected and identified 47 bacterial genera divided into: Actinomycetes, Firmicutes andProteobacteria. These results showed that soil pollution by high concentration level of WMO demanded at integrated BIS, also was found some bacterial genus which synthetized detergent with potential used in soil polluted byWMO.El aceite residual automotriz (ARA) es una mezcla de hidrocarburos (HICO) contaminantes del suelo. Dado que elproblema es complejo así debe ser la solución una bioestimulación (BIS) secuencial, complementaria y acumulativa, o integral; una primer BIS con detergente que emulsifique el ARA, una segunda con solución de nutrientes inorgánicos que restituya la relación C (carbono): N (nitrógeno); una tercera con H2O2 como proveedor de O2 (oxigeno)para favorecer la oxidación del ARA, y el control de la humedad del suelo al 80% de la capacidad de campo pare elintercambio de gases en la mineralización de ARA. El objetivo de este trabajo fue: i) bioestimulación integral delsuelo contaminado por 60000 ppm de ARA. El suelo se bioestimuló integralmente con detergentes, una soluciónmineral (SOMI), H2O2, y la humedad del suelo se ajustó al 80% de la capacidad de campo. Además, se cuantificó lapoblación bacteriana oxidante de ARA, que sintetizo detergentes asociados con la emulsificación del ARA y realizosu identificación molecular. Los resultados probaron que la BIS secuencial complementaria y acumulativa o integral con un detergente aniónico/no iónico, la SOMI, el H2O2 al 0.5% redujeron el ARA de 60000 ppm a 27200 ppmen 23 días. Mientras que la densidad de la población oxidante de ARA fue de 268 X 106 UFC/g de suelo seco, deahí se seleccionaron las dominantes que sintetizaron detergentes relacionados con el ARA e identificaron 47 géneros bacterianos divididos en: Actinomicetos, Firmicutes y Proteobacterias. Lo anterior apoya que la alternativa pararemediar un suelo impactado con ARA demanda una solución compleja o integral; y que existen en ese ambientebacterias que sintetizan detergente, con un empleo potencial en suelo contaminado con ARA

Electrochemically assisted dewatering for the removal of oxyfluorfen from a coagulation/flocculation sludge

This work focuses on the evaluation of the electrochemical dewatering of sludge obtained in the coagulation of wastes polluted with oxyfluorfen. To do this, sludge samples were treated, aiming not only to reduce the sludge volume, but also to facilitate the degradation of oxyfluorfen contained in the cake via electrolysis with a boron-doped diamond anode. Results show that water can be effectively recovered through three sequential stages. First, a gravity-driven stage, that can recover around 60% of initial volume and where no oxyfluorfen is dragged. Then, a second stage that involves the application of pressure and which accounts for the recuperation of an additional 25% of the total volume of the water removed and in which oxyfluorfen also remained in the cake. Finally, an electrochemical stage, which involves the application of electricity with increasing electric fields (1.0, 2.0, 4.0, and 16.0 V cm−1), accounting for the recovery of the rest of water released and where an electrolytic degradation of oxyfluorfen is obtained, whose extension depends on the electrode configuration used in the electro-dewatering cell. This electrode configuration also influences the retention or loss of oxyfluorfen from the cake, being the optimum choice the placement of the cathode downstream, next to the outlet of the dewatering cell