Promotion of the growth and yield of Zea mays by synthetic microbial communities from Jala maize

A systematic discussion and comparison of the construction methods of synthetic microbial community

Synthetic microbial community has widely concerned in the fields of agriculture, food and environment over the past few years. However, there is little consensus on the method to synthetic microbial community from construction to functional verification. Here, we review the concept, characteristics, history and applications of synthetic microbial community, summarizing several methods for synthetic microbial community construction, such as isolation culture, core microbiome mining, automated design, and gene editing. In addition, we also systematically summarized the design concepts, technological thresholds, and applicable scenarios of various construction methods, and highlighted their advantages and limitations. Ultimately, this review provides four efficient, detailed, easy-to-understand and -follow steps for synthetic microbial community construction, with major implications for agricultural practices, food production, and environmental governance.

Genomic Insights into Pseudomonas protegens E1BL2 from Giant Jala Maize: A Novel Bioresource for Sustainable Agriculture and Efficient Management of Fungal Phytopathogens

The relationships between plants and bacteria are essential in agroecosystems and bioinoculant development. The leaf endophytic Pseudomonas protegens E1BL2 was previously isolated from giant Jala maize, which is a native Zea mays landrace of Nayarit, Mexico. Using different Mexican maize landraces, this work evaluated the strain's plant growth promotion and biocontrol against eight phytopathogenic fungi in vitro and greenhouse conditions. Also, a plant field trial was conducted on irrigated fields using the hybrid maize Supremo. The grain productivity in this assay increased compared with the control treatment. The genome analysis of P. protegens E1BL2 showed putative genes involved in metabolite synthesis that facilitated its beneficial roles in plant health and environmental adaptation (bdhA, acoR, trpE, speE, potA); siderophores (ptaA, pchC); and extracellular enzymes relevant for PGPB mechanisms (cel3, chi14), protection against oxidative stress (hscA, htpG), nitrogen metabolism (nirD, nit1, hmpA), inductors of plant-induced systemic resistance (ISR) (flaA, flaG, rffA, rfaP), fungal biocontrol (phlD, prtD, prnD, hcnA-1), pest control (vgrG-1, higB-2, aprE, pslA, ppkA), and the establishment of plant-bacteria symbiosis (pgaA, pgaB, pgaC, exbD). Our findings suggest that P. protegens E1BL2 significantly promotes maize growth and offers biocontrol benefits, which highlights its potential as a bioinoculant.

BioSolutions for Green Agriculture: Unveiling the Diverse Roles of Plant Growth-Promoting Rhizobacteria

The extensive use of chemical pesticides and fertilizers in conventional agriculture has raised significant environmental and health issues, including the emergence of resistant pests and pathogens. Plant growth-promoting rhizobacteria (PGPR) present a sustainable alternative, offering dual benefits as biofertilizers and biocontrol agents. This review delves into the mechanisms by which PGPR enhance plant growth, including nutrient solubilization, phytohormone production, and pathogen suppression. PGPR's commercial viability and application, particularly under abiotic stress conditions, are also examined. PGPR improves plant growth directly by enhancing nutrient uptake and producing growth-promoting substances and indirectly by inhibiting phytopathogens through mechanisms such as siderophore production and the secretion of lytic enzymes. Despite their potential, the commercialization of PGPR faces challenges, including strain specificity, formulation stability, and regulatory barriers. The review highlights the need for ongoing research to deepen our understanding of plant-microbe interactions and develop more robust PGPR formulations. Addressing these challenges will be crucial for integrating PGPR into mainstream agricultural practices and reducing reliance on synthetic agrochemicals. The successful adoption of PGPR could lead to more sustainable agricultural practices, promoting healthier crops and ecosystems.

Conserved patterns of sequence diversification provide insight into the evolution of two-component systems in Enterobacteriaceae

Two-component regulatory systems (TCSs) are a major mechanism used by bacteria to sense and respond to their environments. Many of the same TCSs are used by biologically diverse organisms with different regulatory needs, suggesting that the functions of TCS must evolve. To explore this topic, we analysed the amino acid sequence divergence patterns of a large set of broadly conserved TCS across different branches of Enterobacteriaceae, a family of Gram-negative bacteria that includes biomedically important genera such as Salmonella, Escherichia, Klebsiella and others. Our analysis revealed trends in how TCS sequences change across different proteins or functional domains of the TCS, and across different lineages. Based on these trends, we identified individual TCS that exhibit atypical evolutionary patterns. We observed that the relative extent to which the sequence of a given TCS varies across different lineages is generally well conserved, unveiling a hierarchy of TCS sequence conservation with EnvZ/OmpR as the most conserved TCS. We provide evidence that, for the most divergent of the TCS analysed, PmrA/PmrB, different alleles were horizontally acquired by different branches of this family, and that different PmrA/PmrB sequence variants have highly divergent signal-sensing domains. Collectively, this study sheds light on how TCS evolve, and serves as a compendium for how the sequences of the TCS in this family have diverged over the course of evolution.

Beneficial endophytic fungi improve the yield and quality of Salvia miltiorrhiza by performing different ecological functions

Background

Endophytic fungi can enhance the growth and synthesis of secondary metabolites in medicinal plants. Salvia miltiorrhiza Bunge is frequently employed for treating cardiovascular and cerebrovascular ailments, with the primary bioactive components being salvianolic acid and tanshinone. However, their levels in cultivated S. miltiorrhiza are inferior to that of the wild herbs, so the production of high-quality medicinal herbs is sharply declining. Consequently, the utilization of beneficial endophytic fungi to improve the yield and quality of S. miltiorrhiza holds great significance for the cultivation of medicinal plants.

Methods

In this study, nine non-pathogenic, endophytic fungal strains were introduced into sterile S. miltiorrhiza seedlings and cultivated both in vitro and in situ (the greenhouse). The effects of these strains on the growth indices, C and N metabolism, antioxidant activity, photosynthesis, and content of bioactive ingredients in S. miltiorrhiza were then evaluated.

Results

The results showed that the different genera, species, or strains of endophytic fungi regulated the growth and metabolism of S. miltiorrhiza in unique ways. These endophytic fungi primarily exerted their growth-promoting effects by increasing the net photosynthetic rate, intercellular CO2 concentration, and the activities of sucrose synthase, sucrose phosphate synthase, nitrate reductase, and glutamine synthetase. They also enhanced the adaptability and resistance to environmental stresses by improving the synthesis of osmoregulatory compounds and the activity of antioxidant enzymes. However, their regulatory effects on the growth and development of S. miltiorrhiza were affected by environmental changes. Moreover, the strains that significantly promoted the synthesis and accumulation of phenolic acids inhibited the accumulation of tanshinones components, and vice versa. The endophytic fungal strains Penicillium meloforme DS8, Berkeleyomyces basicola DS10, and Acremonium sclerotigenum DS12 enhanced the bioaccumulation of tanshinones. Fusarium solani DS16 elevated the rosmarinic acid content and yields in S. miltiorrhiza. The strain Penicillium javanicum DS5 improved the contents of dihydrotanshinone, salvianolic acid B, and rosmarinic acid. The strains P. meloforme DS8 and B. basicola DS10 improved resistance.

Conclusion

Various endophytic fungi affected the quality and yield of S. miltiorrhiza by regulating different physiological and metabolic pathways. This study also provides a novel and effective method to maximize the effects of beneficial endophytic fungi by selecting specific strains to design microbial communities based on the different ecological functions of endophytic fungi under varying environments and for specific production goals.

The phytomicrobiome: solving plant stress tolerance under climate change

With extraordinary global climate changes, increased episodes of extreme conditions result in continuous but complex interaction of environmental variables with plant life. Exploring natural phytomicrobiome species can provide a crucial resource of beneficial microbes that can improve plant growth and productivity through nutrient uptake, secondary metabolite production, and resistance against pathogenicity and abiotic stresses. The phytomicrobiome composition, diversity, and function strongly depend on the plant's genotype and climatic conditions. Currently, most studies have focused on elucidating microbial community abundance and diversity in the phytomicrobiome, covering bacterial communities. However, least is known about understanding the holistic phytomicrobiome composition and how they interact and function in stress conditions. This review identifies several gaps and essential questions that could enhance understanding of the complex interaction of microbiome, plant, and climate change. Utilizing eco-friendly approaches of naturally occurring synthetic microbial communities that enhance plant stress tolerance and leave fewer carbon-foot prints has been emphasized. However, understanding the mechanisms involved in stress signaling and responses by phytomicrobiome species under spatial and temporal climate changes is extremely important. Furthermore, the bacterial and fungal biome have been studied extensively, but the holistic interactome with archaea, viruses, oomycetes, protozoa, algae, and nematodes has seldom been studied. The inter-kingdom diversity, function, and potential role in improving environmental stress responses of plants are considerably important. In addition, much remains to be understood across organismal and ecosystem-level responses under dynamic and complex climate change conditions.

The Biosynthesis and Functions of Polyamines in the Interaction of Plant Growth-Promoting Rhizobacteria with Plants

Plant growth-promoting rhizobacteria (PGPR) are members of the plant rhizomicrobiome that enhance plant growth and stress resistance by increasing nutrient availability to the plant, producing phytohormones or other secondary metabolites, stimulating plant defense responses against abiotic stresses and pathogens, or fixing nitrogen. The use of PGPR to increase crop yield with minimal environmental impact is a sustainable and readily applicable replacement for a portion of chemical fertilizer and pesticides required for the growth of high-yielding varieties. Increased plant health and productivity have long been gained by applying PGPR as commercial inoculants to crops, although with uneven results. The establishment of plant-PGPR relationships requires the exchange of chemical signals and nutrients between the partners, and polyamines (PAs) are an important class of compounds that act as physiological effectors and signal molecules in plant-microbe interactions. In this review, we focus on the role of PAs in interactions between PGPR and plants. We describe the basic ecology of PGPR and the production and function of PAs in them and the plants with which they interact. We examine the metabolism and the roles of PAs in PGPR and plants individually and during their interaction with one another. Lastly, we describe some directions for future research.