Plant Beneficial Bacteria and Their Potential Applications in Vertical Farming Systems

PGPB-driven bioenrichment and metabolic modulation of Salicornia europaea under marine Aquaponic conditions

This study analyzed the secondary metabolite profile of Salicornia europaea inoculated with Brevibacterium casei EB3 and Pseudomonas oryzihabitans RL18 in aquaponic systems, exploring the metabolic mechanisms responsible for the observed shifts. Experiments were conducted in both microcosm and pilot-scale aquaponic setups to evaluate how these metabolic shifts vary across different system scales and their potential contributions to the observed increased accumulation of bioactive compounds with antioxidant and antimicrobial properties, including some phenolic acids, such as caffeic acid (154-fold), flavonoids (2.85-fold), and some unsaturated fatty acids, such as oct-3-enoic acid (32-fold). Metabolic profiling revealed shifts in pathways associated with plant growth and stress resilience, such as amino acid and phenolic biosynthesis. Additionally, differences in metabolic responses observed between microcosm and pilot-scale systems underscored the importance of understanding scaling effects. These findings highlight the potential for optimizing aquaponic systems by leveraging microbial-plant interactions to enhance ecological and economic outcomes. This approach offers valuable applications in nutrient recycling, phytopharmaceutical development, and the advancement of saline agriculture within integrated aquaculture frameworks.

Plant Colonization by Biocontrol Bacteria and Improved Plant Health: A Review

The use of biological control agents is one of the best strategies available to combat the plant diseases in an ecofriendly manner. Biocontrol bacteria capable of providing beneficial effect in crop plant growth and health, have been developed for several decades. It highlights the need for a deeper understanding of the colonization mechanisms employed by biocontrol bacteria to enhance their efficacy in plant pathogen control. The present review deals with the in-depth understanding of steps involved in host colonization by biocontrol bacteria. The colonization process starts from the root zone, where biocontrol bacteria establish initial interactions with the plant's root system. Moving beyond the roots, biocontrol bacteria migrate and colonize other plant organs, including stems, leaves, and even flowers. Also, the present review attempts to explore the mechanisms facilitating bacterial movement within the plant such as migrating through interconnected spaces such as vessels or in the apoplast, and applying quorum sensing or extracellular enzymes during colonization and what is needed to establish a long-term association within a plant. The impacts on microbial community dynamics, nutrient cycling, and overall plant health are discussed, emphasizing the intricate relationships between biocontrol bacteria and the plant's microbiome and the benefits to the plant's above-ground parts, the biocontrol 40 bacteria confer. By unraveling these mechanisms, researchers can develop targeted strategies for enhancing the colonization efficiency and overall effectiveness of biocontrol bacteria, leading to more sustainability and resilience.

In vitro and In silico investigation deciphering novel antifungal activity of endophyte Bacillus velezensis CBMB205 against Fusarium oxysporum

Endophytes from medicinal plants are potential biocontrol agents against Fusarium oxysporum f. sp. cubense (Foc), which is the causative fungus of banana wilt disease. In the present study, the endophytic bacterium was isolated from Globba racemosa and their antagonistic activities against Foc were studied, and the probable molecular mechanism of antagonism was predicted by molecular docking studies. The 16SrRNA sequencing confirmed the endophytic isolate to be Bacillus velezensis CBMB205 (EG2). The antagonistic activities of the isolates by distortion of fungal hyphae were illustrated in SEM. The probable metabolites present in endophytic isolate were identified by FTIR, suggesting the presence of C-H, CH3 and O-H groups. Two major metabolites such as β-amyrin and dihydroxy octadecenoic acid (DA) were confirmed by LC-MS analysis. Molecular docking studies suggested that these metabolites showed potential binding with chitin synthase 1 and fungal 1,3-glucan synthase of pathogenic fungi. The binding energy (BE) of the molecular interaction between β-amyrin and chitin synthase-1 (CS-1), and 1,3-glucan synthase (1,3-GS) were estimated to be -10.17 kcal/mol and - 9.5 kcal/mol, respectively. The BE of the interaction between β-amyrin and CS-1 and 1,3-GS were determined to be -2.43 kcal/mol and 3.4 kcal/mol, respectively. The current study demonstrated the antagonistic activities of EG2 towards Foc and provided a probable molecular mechanism by in silico studies. The study also provides a potential insight into developing endophytic metabolite-based antifungal agents for various agricultural applications.

Paraburkholderia tropica Primes a Multilayered Transcriptional Defense Response to the Nematode Meloidogyne spp. in Tomato

Meloidogyne causes a devastating disease known as root-knot that affects tomatoes and other cash crops worldwide. Conversely, Paraburkholderia tropica has proven beneficial in mitigating the effects of various pathogens in plants. We aimed to unravel the molecular events that underlie the beneficial effects of the bacterium and the detrimental impacts of the nematode when inoculated separately or together in tomato plants. The transcriptional responses induced by P. tropica (TB group (tomato-bacteria group)), Meloidogyne spp. (TN group (tomato-nematode group)) or by the two agents (TBN group (tomato-bacteria-nematode group)) in tomato were assessed by RNA-seq. We implemented a transcript discovery pipeline which allowed the identification of 2283 putative novel transcripts. Differential expression analysis revealed that upregulated transcripts were much more numerous than downregulated ones. At the gene ontology level, the most activated term was 'hydrolase activity acting on ester bonds' in all groups. In addition, when both microbes were inoculated together, 'hydrolase activity acting on O-glycosyl compounds' was activated. This finding suggests defense responses related to lipid and carbohydrate metabolism, membrane remodeling and signal transduction. Notably, defense genes, transcription factors and protein kinases stood out. Differentially expressed transcripts suggest the activation of a multifaceted plant defense response against the nematode occurred, which was exacerbated by pre-inoculation of P. tropica.

Fungal endophytes Fusarium solani SGGF14 and Alternaria tenuissima SGGF21 enhance the glycyrrhizin production by modulating its key biosynthetic genes in licorice (Glycyrrhiza glabra L.)

AIMS

To identify promising fungal endophytes that are able to produce glycyrrhizin and enhance it in licorice and the mechanisms involved.

METHODS AND RESULTS

Fifteen fungal endophytes were isolated from Glycyrrhiza glabra L. rhizomes among which SGGF14 and SGGF21 isolates were found to produce glycyrrhizin by 4.29 and 2.58 µg g-1 dry weight in the first generation of their culture. These isolates were identified as Fusarium solani and Alternaria tenuissima, respectively, based on morphological characteristics and sequence analysis of internal transcribed spacer, TEF1, ATPase, and CAL regions. Subsequently, G. glabra plants were inoculated with these fungal isolates to examine their effect on glycyrrhizin production, plant growth parameters and the expression of key genes involved in glycyrrhizin pathway: SQS1, SQS2, bAS, CAS, LUS, CYP88D6, and CYP72A154. Endophytes were able to enhance glycyrrhizin content by 133%-171% in the plants. Natural control (NC) plants, harboring all natural endophytes, had better growth compared to SGGF14- and SGGF21-inoculated and endophyte-free (EF) plants. Expression of SQS1, SQS2, CYP88D6, and CYP72A154 was upregulated by inoculation with endophytes. LUS and CAS were downregulated after endophyte inoculation. Expression of bAS was higher in SGGF21-inoculated plants when compared with NC, EF, and SGGF14-inoculated plants.

CONCLUSIONS

Two selected fungal endophytes of G. glabra can produce glycyrrhizin and enhance glycyrrhizin content in planta by modulating the expression of key genes in glycyrrhizin biosynthetic pathway.

Feasibility of using vertical farming in northern Iran: A multiple necessity

Agricultural production in vertical farms (VF) will play a prominent role in preventing environmental crises, its good governance and maintaining food security for everyone in the world. The ecological footprint in Guilan province significantly exceeds its biological capacity, indicating considerable pressure on its natural resources and ecosystems. This problem, which is mostly due to the use of traditional production methods in the agricultural sector, requires a change in lifestyle and production methods. The purpose of the current research is the feasibility of VF in Guilan province with the help of the Strengths, Weaknesses, Opportunities, and Threats (SWOT) model and Quantitative Strategic Planning Matrix (QSPM). After identifying internal factors (strengths and weaknesses) and external factors (opportunities and threats) affecting production in VF, the necessary strategies were determined and then prioritized using the QSPM matrix. Necessary information through written scientific sources and survey studies based on key questions between two groups of professors of geography and rural planning, water resources engineering, soil, architecture and experts from the plant production department and the head of the environment department, Jihad Agricultural Organization of Guilan province and the organization Food hygiene was achieved. The statistical population participating in the survey was 30 people. The results of the research showed that 7 strategies were formulated based on strengths, weaknesses, opportunities, and threats and were prioritized based on the importance of four strategies in the QSPM table. The first priority for ensuring food security in Guilan province is to focus on increasing agricultural productivity per unit area. This strategy is crucial considering the challenges of low ownership and limited land availability in the region. Thus, enhancing productivity per unit area should be given utmost priority to meet the food demands of the population. The appropriate strategy for VF production in Guilan province is a competitive-aggressive strategy and being in this position requires attracting the necessary funds. This study fills research gaps by providing a comprehensive assessment of the feasibility of vertical farming in Guilan province. The emphasis on methodology, strategic planning, and addressing food security and environmental challenges contributes to the existing body of knowledge. By highlighting the transferability and adaptability of the research findings, other researchers can utilize the methods and adapt the strategies to their own regions, promoting further research and advancement in the field of sustainable agriculture.

Unlocking the potential of bacterial endophytes from medicinal plants for drug discovery

Among the plant-associated microorganisms, the so-called endophytes continue to attract much attention because of their ability not only to protect host plants from biotic and abiotic stress factors, but also the potential to produce bioactive secondary metabolites. The latter property can elicit growth-promoting effects on plants, as well as boost the production of plant-specific secondary metabolites with valuable pharmacological properties. In addition, endophyte-derived secondary metabolites may be a rich source for the discovery of drugs to treat various diseases, including infections and cancer. However, the full potential of endophytes to produce bioactive secondary metabolites is often not revealed upon conventional cultivation in the laboratory. New advances in genomics and metabolic engineering offer exciting opportunities for the exploration and exploitation of endophytes' biosynthetic potential. This review focuses on bacterial endophytes of medicinal plants, some of their secondary metabolites and recent advances in deciphering their biosynthesis. The latter may assist in genetic engineering efforts aimed at the discovery of novel bioactive compounds with the potential to be developed into drugs.

The Microbial Connection to Sustainable Agriculture

Microorganisms are an important element in modeling sustainable agriculture. Their role in soil fertility and health is crucial in maintaining plants' growth, development, and yield. Further, microorganisms impact agriculture negatively through disease and emerging diseases. Deciphering the extensive functionality and structural diversity within the plant-soil microbiome is necessary to effectively deploy these organisms in sustainable agriculture. Although both the plant and soil microbiome have been studied over the decades, the efficiency of translating the laboratory and greenhouse findings to the field is largely dependent on the ability of the inoculants or beneficial microorganisms to colonize the soil and maintain stability in the ecosystem. Further, the plant and its environment are two variables that influence the plant and soil microbiome's diversity and structure. Thus, in recent years, researchers have looked into microbiome engineering that would enable them to modify the microbial communities in order to increase the efficiency and effectiveness of the inoculants. The engineering of environments is believed to support resistance to biotic and abiotic stressors, plant fitness, and productivity. Population characterization is crucial in microbiome manipulation, as well as in the identification of potential biofertilizers and biocontrol agents. Next-generation sequencing approaches that identify both culturable and non-culturable microbes associated with the soil and plant microbiome have expanded our knowledge in this area. Additionally, genome editing and multidisciplinary omics methods have provided scientists with a framework to engineer dependable and sustainable microbial communities that support high yield, disease resistance, nutrient cycling, and management of stressors. In this review, we present an overview of the role of beneficial microbes in sustainable agriculture, microbiome engineering, translation of this technology to the field, and the main approaches used by laboratories worldwide to study the plant-soil microbiome. These initiatives are important to the advancement of green technologies in agriculture.