The impact of stress on crop productivity and the ecosystem have been magnified by climate changes and mispractices in the agriculture field. Soil microbiome is a diverse system consisting of various microorganisms. Environmental control techniques like the use of arbuscular mycorrhizal fungi (AMF) are necessary to enhance crop productivity. AMF is known as stress regulating organisms that help plants within the nutrient uptake, biotic and abiotic stress management, plant protection, and consequently enhancement on crop yields. Also, host plants can tolerate many difficult situations such as water problems, salt stress, heavy metals, and temperature changes through AMF inoculation. Arbuscular mycorrhizae (AM) enhance plant growth under stress by mediating a series of complex contact events between the two symbiotic partners resulting in a good photosynthetic and gas exchange amelioration. Plants have several tolerance mechanisms to deal with the constraints of environmental changes. The antioxidant ability is the principal tolerance mechanism; it is assisted by osmolytes accumulation and exacting absorption of ions. In this review, we will discuss the effect of AMF colonization on the host plants at different stages of growth, with comprehensively updated knowledge, their roles, and applications for plant growth enhancement and mycorrhizae role on plant resistance induction and stress management.

With the expansion of the green products market and the worldwide policies and strategies directed toward a green revolution and ecological transition, the demand for innovative approaches is always on the rise. Among the sustainable agricultural approaches, microbial-based products are emerging over time as effective and feasible alternatives to agrochemicals. However, the production, formulation, and commercialization of some products can be challenging. Among the main challenges are the industrial production processes that ensure the quality of the product and its cost on the market. In the context of a circular economy, solid-state fermentation (SSF) might represent a smart approach to obtaining valuable products from waste and by-products. SSF enables the growth of various microorganisms on solid surfaces in the absence or near absence of free-flowing water. It is a valuable and practical method and is used in the food, pharmaceutical, energy, and chemical industries. Nevertheless, the application of this technology in the production of formulations useful in agriculture is still limited. This review summarizes the literature dealing with SSF agricultural applications and the future perspective of its use in sustainable agriculture. The survey showed good potential for SSF to produce biostimulants and biopesticides useful in agriculture.

The environmental conditions of caves shape microbiota. Within caves’ microbial communities, actinomycetes are among the most abundant bacteria. Cave actinomycetes have gained increasing attention during the last decades due to novel bioactive compounds with antibacterial, antioxidant and anticancer activities. However, their potential role in soil environments is still unknown. This review summarises the literature dealing with actinomycetes from caves, underlining for the first time their potential roles in soil environments. We provide an overview of their diversity and biotechnological properties, underling their potential role in soil environments applications. The contribution of caves’ actinomycetes in soil fertility and bioremediation and crops biostimulation and biocontrol are discussed. The survey on the literature show that several actinomycetes genera are present in cave ecosystems, mainly Streptomyces, Micromonospora, and Nocardiopsis. Among caves’ actinomycetes, Streptomyces is the most studied genus due to its ubiquity, survival capabilities, and metabolic versatility. Despite actinomycetes’ outstanding capabilities and versatility, we still have inadequate information regarding cave actinomycetes distribution, population dynamics, biogeochemical processes, and metabolisms. Research on cave actinomycetes needs to be encouraged, especially concerning environmental soil applications to improve soil fertility and health and to antagonise phytopathogens.

Manganese (Mn) is essential for plant growth, as it serves as a cofactor for enzymes involved in photosynthesis, antioxidant synthesis, and defense against pathogens. It also plays a role in nutrient uptake, root growth, and soil microbial communities. However, the availability of Mn in the soil can be limited due to factors like soil pH, redox potential, organic matter content, and mineralogy. The excessive use of chemical fertilizers containing Mn can lead to negative consequences for soil and environmental health, such as soil and water pollution. Recent research highlights the significance of microbial interactions in enhancing Mn uptake in plants, offering a more environmentally friendly approach to address Mn deficiencies. Microbes employ various strategies, including pH reduction, organic acid production, and the promotion of root growth, to increase Mn bioavailability. They also produce siderophores, anti-pathogenic compounds, and form symbiotic relationships with plants, thereby facilitating Mn uptake, transport, and stimulating plant growth, while minimizing negative environmental impacts. This review explores the factors impacting the mobility of Mn in soil and plants, and highlights the problems caused by the scarcity of Mn in the soil and the use of chemical fertilizers, including the consequences. Furthermore, it investigates the potential of different soil microbes in addressing these challenges using environmentally friendly methods. This review suggests that microbial interactions could be a promising strategy for improving Mn uptake in plants, resulting in enhanced agricultural productivity and environmental sustainability. However, further research is needed to fully understand these interactions’ mechanisms and optimize their use in agricultural practices.

Arbuscular mycorrhizal fungi (AMF) are widely distributed soil-borne microorganisms, which have a symbiotic relationship with several terrestrial plants. They play a key role in plant growth promotion and development, plant nutrient homeostasis, soil nutrient management, and induction of plant defense mechanisms against pest infestation and disease incidences. This interaction of AMF with rice plants has been studied in great detail, providing distinct perspectives on the natural basis of nutrient transport, stress management, improvement of soil health, and induction of systemic plant resistance. This review highlights the responses of (i) AMF interaction with rice plants, (ii) AMF colonization and sporulation potential in rice rhizosphere, (iii) AMF species as a source of inoculum for rice production, (iv) AMF for rice plant maintenance and durability, and (v) AMF responses to other soil microorganisms. Additionally, a new class of phytohormones known as strigolactone (SLs) has been briefly described covering the various forms of analogs, isomers, and membrane transporters. The role of SLs in pre-symbiotic molecular talks, induction of energy metabolism in mitochondria, spore germination, stimulation of hyphal branches, and the relationships of SLs synthesis with soil nutrient content provides in-depth insights into the mechanisms involved in improving AMF interactions with rice plants.

Excessive use of chemical products in agriculture is causing significant environmental pollution and the loss of lands and fertility of agricultural soils. Plant-growth-promoting bacteria are a valid alternative strategy for sustainable agriculture. The aim of this study was to select actinomycete strains based on their plant-growth-promoting traits and to investigate their root association abilities and biostimulant effects on Solanum lycopersicum. The strains were investigated for their phosphate solubilization ability, production of indole-3-acetic acid, hydrocyanic acid, and ammonia, and several enzymatic activities. Bacteria–plant-root associations were studied by scanning electron microscopy. A greenhouse experiment was carried out to assess inoculation effects. Of sixty isolates, fourteen strains showed significant plant-growth-promoting traits. All fourteen strains solubilized phosphate, produced ammonia, and showed several enzymatic activities at different rates. The production of indole-3-acetic acid was shown by nine strains, while hydrocyanic acid production was observed in eleven of them. Scanning electron microscopy revealed that strains have good in vitro plant root association and colonization abilities. In planta inoculation by actinomycete strains positively influenced plant growth parameters. The best results were shown by seven actinomycete strains, suggesting their possible utilization as biofertilizer agents for sustainable agriculture.