Bioprospecting and Challenges of Plant Microbiome Research for Sustainable Agriculture, a Review on Soybean Endophytic Bacteria.

This review evaluates oilseed crop soybean endophytic bacteria, their prospects, and challenges for sustainable agriculture. Soybean is one of the most important oilseed crops with about 20-25% protein content and 20% edible oil production. The ability of soybean root-associated microbes to restore soil nutrients enhances crop yield. Naturally, the soybean root endosphere harbors root nodule bacteria, and endophytic bacteria, which help increase the nitrogen pool and reclamation of another nutrient loss in the soil for plant nutrition. Endophytic bacteria can sustain plant growth and health by exhibiting antibiosis against phytopathogens, production of enzymes, phytohormone biosynthesis, organic acids, and secondary metabolite secretions. Considerable effort in the agricultural industry is focused on multifunctional concepts and bioprospecting on the use of bioinput from endophytic microbes to ensure a stable ecosystem. Bioprospecting in the case of this review is a systemic overview of the biorational approach to harness beneficial plant-associated microbes to ensure food security in the future. Progress in this endeavor is limited by available techniques. The use of molecular techniques in unraveling the functions of soybean endophytic bacteria can explore their use in integrated organic farming. Our review brings to light the endophytic microbial dynamics of soybeans and current status of plant microbiome research for sustainable agriculture.

A metagenomic lens into endosphere microbial communities, promises, and discoveries.

The word endosphere represents the internal tissues of plants harboring diverse microbes capable of producing active biological products for various biotechnological and agricultural applications. The discreet standalone genes and interdependent association of microbial endophytes with plants can be an underlining factor in predicting their ecological functions. Yet-to-be-cultured endophytic microbes have geared the invention of metagenomics in various environmental studies to determine their structural diversity and functional genes with novel attributes. This review presents an overview of the general concept of metagenomics in microbial endophytic studies. First, the endosphere microbial communities were introduced, followed by metagenomic insights in endosphere biology, a promising technology. Also, the major application of metagenomics and a short brief on DNA stable isotope probing in determining functions and metabolic pathways of microbial metagenome were highlighted. Therefore, the use of metagenomics promises to provide answers to yet-to-be-cultured microbes by unraveling their diversity, functional attributes, and metabolic pathways with prospects in integrated and sustainable agriculture.

Genomic assessment of Stenotrophomonas indicatrix for improved sunflower plant.

Diverse agriculturally important microbes have been studied with known potential in plant growth promotion. Providing several opportunities, Stenotrophomonas species are characterized as promising plant enhancers, inducers, and protectors against environmental stressors. The S. indicatrix BOVIS40 isolated from the sunflower root endosphere possessed unique features, as genome insights into the Stenotrophomonas species isolated from oilseed crops in Southern Africa have not been reported. Plant growth-promotion screening and genome analysis of S. indicatrix BOVIS40 were presented in this study. The genomic information reveals various genes underlining plant growth promotion and resistance to environmental stressors. The genome of S. indicatrix BOVIS40 harbors genes involved in the degradation and biotransformation of organic molecules. Also, other genes involved in biofilm production, chemotaxis, and flagellation that facilitate bacterial colonization in the root endosphere and phytohormone genes that modulate root development and stress response in plants were detected in strain BOVIS40. IAA activity of the bacterial strain may be a factor responsible for root formation. A measurable approach to the S. indicatrix BOVIS40 lifestyle can strategically provide several opportunities in their use as bioinoculants in developing environmentally friendly agriculture sustainably. The findings presented here provide insights into the genomic functions of S. indicatrix BOVIS40, which has set a foundation for future comparative studies for a better understanding of the synergism among microbes inhabiting plant endosphere. Hence, highlighting the potential of S. indicatrix BOVIS40 upon inoculation under greenhouse experiment, thus suggesting its application in enhancing plant and soil health sustainably.

The endosphere microbial communities, a great promise in agriculture.

Agricultural food production and sustainability need intensification to address the current global food supply to meet human demand. The continuous human population increase and other anthropogenic activities threaten food security. Agrochemical inputs have long been used in conventional agricultural systems to boost crop productivity, but they are disadvantageous to a safe environment. Towards developing environmentally friendly agriculture, efforts are being directed in exploring biological resources from soil and plant microbes. The survival of the rhizosphere and endosphere microbiota is influenced by biotic and abiotic factors. Plant microbiota live interdependently with the host plants. Endophytes are regarded as colonizer microbes inhabiting and establishing microbial communities within the plant tissue. Their activities are varied and include fixing atmospheric nitrogen, solubilizing phosphate, synthesis of siderophores, secretion of metabolite-like compounds containing active biocontrol agents in the control of phytopathogens, and induced systemic resistance that stimulates plant response to withstand stress. Exploring beneficial endophyte resources in the formulation of bio-inoculants, such as biofertilizers, as an alternative to agrochemicals (fertilizers and pesticides) in developing environmentally friendly agriculture and for incorporation into crop breeding and disease control program is promising. Therefore, in this review, endosphere microbial ecology, associating environmental factors, and their roles that contribute to their effectiveness in promoting plant growth for maximum agricultural crop productivity were highlighted.

16S rRNA gene sequencing data of plant growth-promoting jute-associated endophytic and rhizobacteria from coastal-environment of Ondo State, Nigeria.

This study provides sequence datasets of endophytic and rhizobacteria of jute using 16S rRNA gene sequencing. The plant samples were first surface sterilized and DNA of the bacteria from soil and jute roots and stem was extracted using Quick-DNA™ Fungal/Bacterial Miniprep Kit. The purified DNA was amplified and subjected to polymerase chain reaction using forward and reverse primers. The PCR products were sequenced on Applied Biosystems ABI 3500XL Genetic Analyser (Applied Biosystems, ThermoFisher Scientific). The sequences were analyzed using BioEdit version 7.2.5 and then BLAST on NCBI. The identifiable bacteria include the rhizobacteria, Citrobacter fruendii RZS23 (accession number: CP024673.1), endophytic bacteria, Bacillus cereus EDR23 (accession number: LN890242.1), and Morganella morganii EDS23 (accession number: KR094121.1). The plant growth-promoting traits exhibited by these bacteria suggest their future exploration as bioinoculants.

The seed microbiomes of staple food crops.

The scientific community increasingly recognized that seed microbiomes are important for plant growth and nutrition. The versatile roles and modulating properties that microbiomes hold in the context of seeds seem to be an inherited approach to avert adverse conditions. These discoveries attracted extensive interest, especially in staple food crops (SFCs) where grain was consumed as food. Along with the rapid expansion of population and industrialization that posed a severe challenge to the yield of SFCs, microbiologists and botanists began to explore and engineer seed microbiomes, for safer and more fruitful grain production. To utilize seed microbiomes, we present an overall review of the most updated scientific literature on three representative SFCs (wheat, rice and maize) using the 5W1H (Which, Where, What, Why, When and How) method that provides a comprehensive understanding of the issue. These include which factors determine the composition of seed microbiomes? Where do seed microbiomes come from? What are these seed microbes? Why do these microbes choose seeds as their destination and when do microbes settle down and become seed communists? In addition, how do seed microbiomes work and can be manipulated effectively? Therefore, answering the aforementioned questions regarding SFCs seed microbiomes remain fundamental in bridging endophytic research gaps and harnessing their ecological services.

The plant endosphere-hidden treasures: a review of fungal endophytes.

The endosphere represents intracellular regions within plant tissues colonize by microbial endophytes without causing disease symptoms to host plants. Plants harbor one or two endophytic microbes capable of synthesizing metabolite compounds. Environmental factors determine the plant growth and survival as well as the kind of microorganisms associated with them. Some fungal endophytes that symbiotically colonize the endosphere of medicinal plants with the potential of producing biological products have been employed in traditional and modern medicine. The bioactive resources from endophytic fungi are promising; biotechnologically to produce cheap and affordable commercial bioactive products as alternatives to chemical drugs and other compounds. The exploration of bioactive metabolites from fungal endophytes has been found applicable in agriculture, pharmaceutical, and industries. Thus, fungal endophytes can be engineered to produce a substantive quantity of pharmacological drugs through the biotransformation process. Hence, this review shall provide an overview of fungal endophytes, ecology, their bioactive compounds, and exploration with the biosystematics approach.

Pharmacological Potential of Fungal Endophytes Associated with Medicinal Plants: A Review.

Endophytic microbes are microorganisms that colonize the intracellular spaces within the plant tissues without exerting any adverse or pathological effects. Currently, the world population is facing devastating chronic diseases that affect humans. The resistance of pathogens to commercial antibiotics is increasing, thus limiting the therapeutic potential and effectiveness of antibiotics. Consequently, the need to search for novel, affordable and nontoxic natural bioactive compounds from endophytic fungi in developing new drugs with multifunction mechanisms to meet human needs is essential. Fungal endophytes produce invaluable bioactive metabolic compounds beneficial to humans with antimicrobial, anticancer, antidiabetic, anti-inflammatory, antitumor properties, etc. Some of these bioactive compounds include pestacin, taxol, camptothecin, ergoflavin, podophyllotoxin, benzopyran, isopestacin, phloroglucinol, tetrahydroxy-1-methylxanthone, salidroside, borneol, dibenzofurane, methyl peniphenone, lipopeptide, peniphenone etc. Despite the aforementioned importance of endophytic fungal metabolites, less information is available on their exploration and pharmacological importance. Therefore, in this review, we shall elucidate the fungal bioactive metabolites from medicinal plants and their pharmacological potential.

Bacterial community structure of the sunflower (Helianthus annuus) endosphere.

Agrochemical applications on farmland aim to enhance crop yield; however, the consequence of biodiversity loss has caused a reduction in ecological functions. The positive endosphere interactions and crop rotation systems may function in restoring a stable ecosystem. Employing culture-independent techniques will help access the total bacteria community in the sunflower endosphere. Limited information is available on the bacteria diversity in sunflower plants cultivated under different agricultural practices. Hence, this study was designed to investigate the endophytic bacterial community structure of sunflower at the growing stage. Plant root and stem samples were sourced from two locations (Itsoseng and Lichtenburg), for DNA extraction and sequenced on the Illumina Miseq platform. The sequence dataset was analyzed using online bioinformatics tools. Saccharibacteria and Acidobacteria were dominant in plant roots, while the stem is dominated by Proteobacteria, Bacteriodetes, and Gemmatimonadetes across the sites. Bacterial genera, Acidovorax, Flavobacterium, Hydrogenophaga, and Burkholderia-Paraburkhoderia were found dominant in the root, while the stem is dominated by Streptomyces. The diverse bacterial community structure at phyla and class levels were significantly different in plant organs across the sites. The influence of soil physical and chemical parameters analyzed was observed to induce bacterial distribution across the sites. This study provides information on the dominant bacteria community structure in sunflowers at the growing stage and their predictive functions, which suggest their future exploration as bioinoculants for improved agricultural yields.

Draft Genome Sequencing of Stenotrophomonas indicatrix BOVIS40 and Stenotrophomonas maltophilia JVB5, Two Strains with Identifiable Genes Involved in Plant Growth Promotion.

Here, plant growth-promoting Stenotrophomonas strains isolated from the sunflower root endosphere were studied. Bacterial DNA was sequenced on Illumina's NextSeq platform. The gene prediction reveals diverse functional genes involved in plant growth promotion from each bacterial genome. The exploration of bacterial resources as bioinoculants is promising for agricultural biotechnology.

16S rRNA gene amplicon sequence data from sunflower endosphere bacterial community.

Insights into plant endosphere bacterial diversity and exploration of their bioincentives in the formulation of biofertilizers promise to avert ecological disturbances. Here, we presented the sequence dataset of the endophytic bacterial community from the roots and stems of sunflower obtained from farmlands in Itsoseng and Lichtenburg, North West Province of South Africa, using 16S rRNA gene amplicon sequencing. The climatic conditions of this region are characterized by an annual rainfall of about 600 mm and a temperature range of 3 to 21°C during winter and 22 to 34°C during summer. The genomic DNA was obtained from 1 g of each macerated sample using commercial DNA kits (DNeasy® Plant Mini kit, Qiagen, USA). The DNA was amplified through polymerase chain reaction at the V4 region using the specific forward and reverse primers. Amplicon sequencing was performed on the Miseq Illumina platform. Sequence read processing was performed using QIIME 1 16S-based pipeline implemented on Nephele microbial bioinformatics platform using default parameters. The sequence has been deposited in the Sequence Read Archive (SRA) of the National Center for Biotechnology Information (NCBI) with assigned Bioproject accession numbers. The data reveals the endophytic bacterial community structure and functions in sunflower cultivated in organic and nonorganic soils at growing and flowering stages.

Genomic Analysis of Endophytic Bacillus cereus T4S and Its Plant Growth-Promoting Traits.

Insights into plant endophytic microbes and their exploration in agriculture have provided opportunities for sustainable plant health and food safety. Notable endophytic Bacillus species with plant growth-promoting traits have been documented; nevertheless, information on genome analysis of B. cereus associated with the sunflower in South Africa has not been studied. Therefore, we present whole-genome sequence of agriculturally important B. cereus strain T4S isolated from sunflower plants. The NextSeq Illumina sequencing yielded 7,255,762 bp sequence reads, 151 bp average read length, 5,945,881 bp genome size, 56 tRNA, 63 rRNA, and G + C content of 34.8%. The phylogeny analysis of strain T4S was similar to B. cereus NJ-W. Secondary metabolites, such as petrobactin, bacillibactin, bacitracin, molybdenum factor, zwittermicin, and fengycin underlining bacterial biocontrol efficacy against phytopathogens were found in the T4S genome. The predicted novel genes in the bacterial genome mediating the complex metabolic pathways can provide a genetic basis in understanding endosphere biology and their multiple functions thereof in crop improvement. Interestingly, seed and root inoculation with strain T4S contributed to sunflower yield under greenhouse experiments. Hence, the detection of notable genes specific for plant growth promotion as validated under in vitro screening, promisingly, suggests the relevance of strain T4S in agricultural biotechnology.

Whole Genome Sequencing of Sunflower Root-Associated Bacillus cereus.

In recent times, diverse agriculturally important endophytic bacteria colonizing plant endosphere have been identified. Harnessing the potential of Bacillus species from sunflower could reveal their biotechnological and agricultural importance. Here, we present genomic insights into B. cereus T4S isolated from sunflower sourced from Lichtenburg, South Africa. Genome analysis revealed a sequence read count of 7 255 762, a genome size of 5 945 881 bp, and G + C content of 34.8%. The genome contains various protein-coding genes involved in various metabolic pathways. The detection of genes involved in the metabolism of organic substrates and chemotaxis could enhance plant-microbe interactions in the synthesis of biological products with biotechnological and agricultural importance.

Plant Disease Management: Leveraging on the Plant-Microbe-Soil Interface in the Biorational Use of Organic Amendments.

Agriculture is faced with many challenges including loss of biodiversity, chemical contamination of soils, and plant pests and diseases, all of which can directly compromise plant productivity and health. In addition, inadequate agricultural practices which characterize conventional farming play a contributory role in the disruption of the plant-microbe and soil-plant interactions. This review discusses the role of organic amendments in the restoration of soil health and plant disease management. While the use of organic amendments in agriculture is not new, there is a lack of knowledge regarding its safe and proper deployment. Hence, a biorational approach of organic amendment use to achieve sustainable agricultural practices entails the deployment of botanicals, microbial pesticides, and organic minerals as organic amendments for attaining plant fitness and disease suppression. Here, the focus is on the rhizosphere microbial communities. The role of organic amendments in stimulating beneficial microbe quorum formation related to the host-plant-pathogen interactions, and its role in facilitating induced systemic resistance and systemic-acquired resistance against diseases was evaluated. Organic amendments serve as soil conditioners, and their mechanism of action needs to be further elaborated to ensure food safety.

Oilseed crop sunflower (Helianthus annuus) as a source of food: Nutritional and health benefits.

The use of biofertilizers in developing environmentally friendly agriculture as an alternative to chemical-based fertilizers in enhancing food production is promising in sustainable agriculture for the improvement in the yield of some commercial crops such as sunflowers and other oilseed crops in terms of quality and quantity. Sunflower is an important oilseed crop native to South America and currently cultivated throughout the world. Generally, the sunflower is considered important based on its nutritional and medicinal value. Due to its beneficial health effects, sunflower has been recognized as functional foods or nutraceutical, although not yet fully harnessed. Sunflower contains mineral elements and phytochemicals such as dietary fiber, manganese, vitamins, tocopherols, phytosterols, triterpene glycosides, α-tocopherol, glutathione reductase, flavonoids, phenolic acids, carotenoids, peptides, chlorogenic acid, caffeic acid, alkaloids, tannins, and saponins; and these compounds contribute to their functional and nutraceutical development. The extract from sunflower is known to be a potential source of antimicrobial, anti-inflammatory, antitumor, and antioxidants agents that protect human cells against harmful reactive oxygen molecules and pathogenic microorganisms. Also, the pharmacological survey on sunflower had revealed its curative power to different kinds of diseases. The health benefits of sunflower include blood pressure and diabetic control, skin protection, and lowering cholesterol and other functions. This review is written with appropriate referencing to previously published work and provides updated information regarding the new method of organic farming for sunflower production, nutritional and health benefits, and its by-products as human diet and livestock feed. Also, the constraints of sunflower production are elucidated.