Enhancing quinoa growth under severe saline-alkali stress by phosphate solubilizing microorganism Penicillium funicuiosum P1

Exploring extremophilic fungi in soil mycobiome for sustainable agriculture amid global change

As the Earth warms, alternatives to traditional farming are crucial. Exploring fungi, especially poly extremophilic and extremotolerant species, to be used as plant probiotics, represents a promising option. Extremophilic fungi offer avenues for developing and producing innovative biofertilizers, effective biocontrol agents against plant pathogens, and resilient enzymes active under extreme conditions, all of which are crucial to enhance agricultural efficiency and sustainability through improved soil fertility and decreased reliance on agrochemicals. Yet, extremophilic fungi's potential remains underexplored and, therefore, comprehensive research is needed to understand their roles as tools to foster sustainable agriculture practices amid climate change. Efforts should concentrate on unraveling the complex dynamics of plant-fungi interactions and harnessing extremophilic fungi's ecological functions to influence plant growth and development. Aspects such as plant's epigenome remodeling, fungal extracellular vesicle production, secondary metabolism regulation, and impact on native soil microbiota are among many deserving to be explored in depth. Caution is advised, however, as extremophilic and extremotolerant fungi can act as both mitigators of crop diseases and as opportunistic pathogens, underscoring the necessity for balanced research to optimize benefits while mitigating risks in agricultural settings.

Isolation of the inorganic phosphorus-solubilizing bacteria Lysinibacillus sphaericus and assessing its role in promoting rice growth

Soluble phosphorus scarcity severely limits plant growth and crop yield. In this study, a strain of inorganic phosphorus-solubilizing bacteria, Lysinibacillus sphaericus, was isolated from rice rhizosphere soil. The available phosphorus content in liquid inorganic phosphorus identification medium and in L. sphaericus-inoculated soil increased from 204.28 mg/L to 1124.68 mg/L and from 4.75 mg/kg to 7.04 mg/kg, respectively. The pH decreased significantly from 6.87 to 6.14. Incubation with L. sphaericus significantly increased malic and succinic acid content in the liquid inorganic phosphorus identification medium and increased acid phosphatase and alkaline phosphatase activity in the soil. Inoculation with L. sphaericus significantly increased rice growth, chlorophyll a/b content, and photosynthesis by increasing the soluble phosphorus content in the rice rhizosphere soil under phosphorus-deficient conditions. Further analysis revealed that L. sphaericus improved soil phosphorus release by decreasing soil pH and promoting acid phosphatase and alkaline phosphatase activity. This study supports the production of microbial fertilizers to improve rice yield in phosphorus-deficient conditions.

Fungi beyond limits: The agricultural promise of extremophiles

Global climate changes threaten food security, necessitating urgent measures to enhance agricultural productivity and expand it into areas less for agronomy. This challenge is crucial in achieving Sustainable Development Goal 2 (Zero Hunger). Plant growth-promoting microorganisms (PGPM), bacteria and fungi, emerge as a promising solution to mitigate the impact of climate extremes on agriculture. The concept of the plant holobiont, encompassing the plant host and its symbiotic microbiota, underscores the intricate relationships with a diverse microbial community. PGPM, residing in the rhizosphere, phyllosphere, and endosphere, play vital roles in nutrient solubilization, nitrogen fixation, and biocontrol of pathogens. Novel ecological functions, including epigenetic modifications and suppression of virulence genes, extend our understanding of PGPM strategies. The diverse roles of PGPM as biofertilizers, biocontrollers, biomodulators, and more contribute to sustainable agriculture and environmental resilience. Despite fungi's remarkable plant growth-promoting functions, their potential is often overshadowed compared to bacteria. Arbuscular mycorrhizal fungi (AMF) form a mutualistic symbiosis with many terrestrial plants, enhancing plant nutrition, growth, and stress resistance. Other fungi, including filamentous, yeasts, and polymorphic, from endophytic, to saprophytic, offer unique attributes such as ubiquity, morphology, and endurance in harsh environments, positioning them as exceptional plant growth-promoting fungi (PGPF). Crops frequently face abiotic stresses like salinity, drought, high UV doses and extreme temperatures. Some extremotolerant fungi, including strains from genera like Trichoderma, Penicillium, Fusarium, and others, have been studied for their beneficial interactions with plants. Presented examples of their capabilities in alleviating salinity, drought, and other stresses underscore their potential applications in agriculture. In this context, extremotolerant and extremophilic fungi populating extreme natural environments are muchless investigated. They represent both new challenges and opportunities. As the global climate evolves, understanding and harnessing the intricate mechanisms of fungal-plant interactions, especially in extreme environments, is paramount for developing effective and safe plant probiotics and using fungi as biocontrollers against phytopathogens. Thorough assessments, comprehensive methodologies, and a cautious approach are crucial for leveraging the benefits of extremophilic fungi in the changing landscape of global agriculture, ensuring food security in the face of climate challenges.

Phosphate solubilizing microorganisms: a sustainability strategy to improve urban ecosystems

Intensification of urban construction has gradually destroyed human habitat ecosystems. Plants, which serve as the foundation of ecosystems, require green, low-cost, and effective technologies to sustain their growth in stressful environments. A total of 286 keywords and 10 clusters from the bibliometric analysis of 529 articles (1999-2023) indicate the increasing importance of research on microbial functionality in landscape ecosystems. Phosphate solubilizing microorganisms (PSMs) also improve plant disease resistance, adaptability, and survival. PSMs are widely used to promote plant growth and improve ecological quality. They can increase the availability of phosphorus in the soil and reduce the dependence of plants on chemical fertilizers. Microorganisms regulate phosphorus as key tools in landscape ecosystems. Most importantly, in urban and rural landscape practices, PSMs can be applied to green spaces, residential landscapes, road greening, and nursery planting, which play significant roles in improving vegetation coverage, enhancing plant resistance, improving environmental quality, and mitigating the heat island effect. PSMs are also helpful in restoring the ecological environment and biodiversity of polluted areas, such as brownfields, to provide residents with a more liveable living environment. Therefore, the multiple efficacies of PSM are expected to play increasingly important roles in the construction of urban and rural landscape ecosystems.

Isolation and Identification of a Phosphate-Solubilizing Pantoea dispersa with a Saline-Alkali Tolerance and Analysis of Its Growth-Promoting Effects on Silage Maize Under Saline-Alkali Field Conditions

Phosphate-solubilizing bacteria (PSB) are microorganisms that can dissolve insoluble phosphorus (P) to accessible forms. This study aimed to screen saline-alkali-tolerant PSB and analyze its growth promoting properties, and evaluate its effects on the growth, quality, soil nutrient balance, and enzyme activities of silage maize in the field. We isolated six phosphate-solubilizing strains from rhizosphere soil of silage maize planted in saline-alkali land, and FC-1 with the best P-solubilizing effect was used for further study. The morphological, physiological and biochemical analysis, and 16S rDNA and housekeeping gene atpD sequencing were performed for identification. FC-1 was identified as Pantoea dispersa and had high P solubility. The phosphate solubility of FC-1 using four P sources ranged from 160.79 to 270.22 mg l-1. FC-1 produced indole-3-acetic acid (IAA) and decreased the pH of the growth media by secreting organic acids, including citric acid, malic acid, succinic acid, and acetic acid. The results of a field experiment indicated that FC-1 treatment increased the height, stem diameter, fresh weight, dry weight, starch content, crude protein content, and total P content of silage maize by 9.8, 9.2, 12.6, 11.7, 12.6, 18.3, and 17.4%, respectively. The nitrogen, potassium, phosphorus, and organic matter contents in the rhizosphere soil of silage maize increased by 29.8, 17.1, 17.9, and 25.3%, respectively; urease, catalase, sucrase, and alkaline phosphatase levels also increased by 24.7, 26.7, 24.0, and 19.5%, respectively. FC-1 promoted the growth of silage maize by improving nutrient metabolism and enzyme activities in saline-alkali soil and may be an effective alternative to fertilizers.