The Coevolution of Plants and Microbes Underpins Sustainable Agriculture

Terrestrial plants evolution occurred in the presence of microbes, the phytomicrobiome. The rhizosphere microbial community is the most abundant and diverse subset of the phytomicrobiome and can include both beneficial and parasitic/pathogenic microbes. Prokaryotes of the phytomicrobiome have evolved relationships with plants that range from non-dependent interactions to dependent endosymbionts. The most extreme endosymbiotic examples are the chloroplasts and mitochondria, which have become organelles and integral parts of the plant, leading to some similarity in DNA sequence between plant tissues and cyanobacteria, the prokaryotic symbiont of ancestral plants. Microbes were associated with the precursors of land plants, green algae, and helped algae transition from aquatic to terrestrial environments. In the terrestrial setting the phytomicrobiome contributes to plant growth and development by (1) establishing symbiotic relationships between plant growth-promoting microbes, including rhizobacteria and mycorrhizal fungi, (2) conferring biotic stress resistance by producing antibiotic compounds, and (3) secreting microbe-to-plant signal compounds, such as phytohormones or their analogues, that regulate aspects of plant physiology, including stress resistance. As plants have evolved, they recruited microbes to assist in the adaptation to available growing environments. Microbes serve themselves by promoting plant growth, which in turn provides microbes with nutrition (root exudates, a source of reduced carbon) and a desirable habitat (the rhizosphere or within plant tissues). The outcome of this coevolution is the diverse and metabolically rich microbial community that now exists in the rhizosphere of terrestrial plants. The holobiont, the unit made up of the phytomicrobiome and the plant host, results from this wide range of coevolved relationships. We are just beginning to appreciate the many ways in which this complex and subtle coevolution acts in agricultural systems.

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Anti-fungal secondary metabolites and hydrolytic enzymes from rhizospheric bacteria in crop protection: a review

Journal of Bangladesh Academy of Sciences ◽

10.3329/jbas.v44i2.51452 ◽

2021 ◽

Vol 44 (2) ◽

pp. 69-84

Author(s):

Farhana Tasnim Chowdhury ◽

Nazia Rifat Zaman ◽

Mohammad Riazul Islam ◽

Haseena Khan

Keyword(s):

Secondary Metabolites ◽

Plant Growth ◽

Fungal Pathogens ◽

Hydrolytic Enzymes ◽

Plant Growth Promoting Rhizobacteria ◽

Field Conditions ◽

Plant Host ◽

Wide Range ◽

Plant Growth Promoting ◽

Growth Promoting

Plant growth promoting rhizobacteria (PGPR) residing in soil rhizosphere provide enormous beneficial effects to a plant host producing diverse secondary metabolites and enzymes useful for plant growth and protection. Siderophores, antibiotics, volatile compounds and hydrolytic enzymes are the major molecules secreted by the PGPRs, which have substantial antifungal properties and can provide plant protection. These compounds are responsible for the lysis and hyperparasitism of antagonists against deleterious fungal pathogens. Siderophore-producing PGPRs function by depriving the pathogen of iron nutrition. Antibiotics have been reported to be involved in the suppression of different fungal pathogens by inducing fungistasis, inhibition of spore germination, lysis of fungal mycelia. The PGPRs also secrete a wide range of low molecular weight volatile organic compounds (VOCs) that inhibit mycelial growth, sporulation, germination of phytophathogenic fungi, etc. Hydrolytic enzymes, mostly chitinase, protease and cellulose, lyse the cell wall of fungi. Therefore, plant growth-promoting rhizobacteria can be considered as an effective, eco-friendly, and sustainable replacement to the chemical fungicides. There are many PGPRs that perform very well in controlled conditions but not in field conditions, and hence the commercializing of hese products is not easy. Development of formulations with increased shelf life, a broad spectrum of action and consistent performance under field conditions can pave the way for commercializing the PGPRs at a faster rate. Journal of Bangladesh Academy of Sciences, Vol. 44, No. 2, 69-84, 2020

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Research Advances of Beneficial Microbiota Associated with Crop Plants

International Journal of Molecular Sciences ◽

10.3390/ijms21051792 ◽

2020 ◽

Vol 21 (5) ◽

pp. 1792 ◽

Cited By ~ 4

Author(s):

Lei Tian ◽

Xiaolong Lin ◽

Jun Tian ◽

Li Ji ◽

Yalin Chen ◽

...

Keyword(s):

Plant Growth ◽

Stress Resistance ◽

Growth And Development ◽

Host Plants ◽

Crop Plant ◽

Plant Growth And Development ◽

Beneficial Bacteria ◽

Wide Range ◽

Microbe Interactions ◽

Bacteria And Fungi

Plants are associated with hundreds of thousands of microbes that are present outside on the surfaces or colonizing inside plant organs, such as leaves and roots. Plant-associated microbiota plays a vital role in regulating various biological processes and affects a wide range of traits involved in plant growth and development, as well as plant responses to adverse environmental conditions. An increasing number of studies have illustrated the important role of microbiota in crop plant growth and environmental stress resistance, which overall assists agricultural sustainability. Beneficial bacteria and fungi have been isolated and applied, which show potential applications in the improvement of agricultural technologies, as well as plant growth promotion and stress resistance, which all lead to enhanced crop yields. The symbioses of arbuscular mycorrhizal fungi, rhizobia and Frankia species with their host plants have been intensively studied to provide mechanistic insights into the mutual beneficial relationship of plant–microbe interactions. With the advances in second generation sequencing and omic technologies, a number of important mechanisms underlying plant–microbe interactions have been unraveled. However, the associations of microbes with their host plants are more complicated than expected, and many questions remain without proper answers. These include the influence of microbiota on the allelochemical effect caused by one plant upon another via the production of chemical compounds, or how the monoculture of crops influences their rhizosphere microbial community and diversity, which in turn affects the crop growth and responses to environmental stresses. In this review, first, we systematically illustrate the impacts of beneficial microbiota, particularly beneficial bacteria and fungi on crop plant growth and development and, then, discuss the correlations between the beneficial microbiota and their host plants. Finally, we provide some perspectives for future studies on plant–microbe interactions.

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Roles of Arbuscular Mycorrhizal Fungi on Plant Growth and Performance: Importance in Biotic and Abiotic Stressed Regulation

Diversity ◽

10.3390/d12100370 ◽

2020 ◽

Vol 12 (10) ◽

pp. 370 ◽

Cited By ~ 4

Author(s):

Nathalie Diagne ◽

Mariama Ngom ◽

Pape Ibrahima Djighaly ◽

Dioumacor Fall ◽

Valérie Hocher ◽

...

Keyword(s):

Plant Growth ◽

Arbuscular Mycorrhizal Fungi ◽

Mycorrhizal Fungi ◽

Abiotic Stresses ◽

Positive Impact ◽

Ion Selectivity ◽

Extreme Temperature ◽

Arbuscular Mycorrhizal ◽

Terrestrial Plants ◽

And Performance

Arbuscular mycorrhizal fungi (AMF) establish symbiotic associations with most terrestrial plants. These soil microorganisms enhance the plant’s nutrient uptake by extending the root absorbing area. In return, the symbiont receives plant carbohydrates for the completion of its life cycle. AMF also helps plants to cope with biotic and abiotic stresses such as salinity, drought, extreme temperature, heavy metal, diseases, and pathogens. For abiotic stresses, the mechanisms of adaptation of AMF to these stresses are generally linked to increased hydromineral nutrition, ion selectivity, gene regulation, production of osmolytes, and the synthesis of phytohormones and antioxidants. Regarding the biotic stresses, AMF are involved in pathogen resistance including competition for colonization sites and improvement of the plant’s defense system. Furthermore, AMF have a positive impact on ecosystems. They improve the quality of soil aggregation, drive the structure of plant and bacteria communities, and enhance ecosystem stability. Thus, a plant colonized by AMF will use more of these adaptation mechanisms compared to a plant without mycorrhizae. In this review, we present the contribution of AMF on plant growth and performance in stressed environments.

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Prospects for Abiotic Stress Tolerance in Crops Utilizing Phyto- and Bio-Stimulants

Frontiers in Sustainable Food Systems ◽

10.3389/fsufs.2021.754853 ◽

2021 ◽

Vol 5 ◽

Author(s):

Nidhi Rai ◽

Shashi Pandey Rai ◽

Birinchi Kumar Sarma

Keyword(s):

Plant Growth ◽

Environmental Conditions ◽

Mycorrhizal Fungi ◽

Protein Hydrolysate ◽

Abiotic Stress Tolerance ◽

Nutrient Use Efficiency ◽

Crop Plants ◽

Wide Range ◽

Use Efficiency ◽

Adverse Environmental Conditions

Environmental stressors such as salinity, drought, high temperature, high rainfall, etc. have already demonstrated the negative impacts on plant growth and development and thereby limiting productivity of the crops. Therefore, in the time to come, more sustainable efforts are required in agricultural practices to ensure food production and security under such adverse environmental conditions. A most promising and eco-friendly way to achieve this goal would be to apply biostimulants to address the environmental concerns. Non-microbial biostimulants such as humic substances (HA), protein hydrolysate, plant-based products and seaweed extracts (SWE), etc. and/or microbial inoculants comprising of plant growth-promoting microbes such as arbuscular mycorrhizal fungi (AMF), fluorescent and non-fluorescent Pseudomonas, Trichoderma spp., Bacillus spp. etc. have tremendous potentiality to enhance plant growth, flowering, crop productivity, nutrient use efficiency (NUE) and translocation, as well as enhancing tolerance to a wide range of abiotic stresses by modifying physiological, biological and biochemical processes of the crop-plants. Similarly, application techniques and timing are also important to achieve the desired results. In this article we discussed the prospects of using seaweed, microbial, and plant-based biostimulants either individually or in combination for managing environmental stresses to achieve food security in a sustainable way. Particular attention was given to the modifications that take place in plant's physiology under adverse environmental conditions and how different biostimulants re-program the host's physiology to withstand such stresses. Additionally, we also discussed how application of biostimulants can overcome the issue of nutrient deficiency in agricultural lands and improve their use efficiency by crop plants.

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Biological Activity of Naturally Derived Naphthyridines

Molecules ◽

10.3390/molecules26144324 ◽

2021 ◽

Vol 26 (14) ◽

pp. 4324

Author(s):

Gabriela Chabowska ◽

Ewa Barg ◽

Anna Wójcicka

Keyword(s):

Immune Response ◽

Biological Activity ◽

Heterocyclic Compounds ◽

Biological Properties ◽

Terrestrial Plants ◽

Bioactive Substances ◽

Natural Sources ◽

Chemical Structures ◽

Wide Range ◽

Terrestrial Environments

Marine and terrestrial environments are rich sources of various bioactive substances, which have been used by humans since prehistoric times. Nowadays, due to advances in chemical sciences, new substances are still discovered, and their chemical structures and biological properties are constantly explored. Drugs obtained from natural sources are used commonly in medicine, particularly in cancer and infectious diseases treatment. Naphthyridines, isolated mainly from marine organisms and terrestrial plants, represent prominent examples of naturally derived agents. They are a class of heterocyclic compounds containing a fused system of two pyridine rings, possessing six isomers depending on the nitrogen atom’s location. In this review, biological activity of naphthyridines obtained from various natural sources was summarized. According to previous studies, the naphthyridine alkaloids displayed multiple activities, i.a., antiinfectious, anticancer, neurological, psychotropic, affecting cardiovascular system, and immune response. Their wide range of activity makes them a fascinating object of research with prospects for use in therapeutic purposes.

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Plant Holobiont Theory: The Phytomicrobiome Plays a Central Role in Evolution and Success

Microorganisms ◽

10.3390/microorganisms9040675 ◽

2021 ◽

Vol 9 (4) ◽

pp. 675

Author(s):

Dongmei Lyu ◽

Jonathan Zajonc ◽

Antoine Pagé ◽

Cailun A. S. Tanney ◽

Ateeq Shah ◽

...

Keyword(s):

Microbial Community ◽

Growth Regulation ◽

Biotic And Abiotic Stress ◽

Natural Conditions ◽

Plant Host ◽

Wide Range ◽

Range Of Functions ◽

Plant Sciences ◽

Plant Signals ◽

And Function

Under natural conditions, plants are always associated with a well-orchestrated community of microbes—the phytomicrobiome. The nature and degree of microbial effect on the plant host can be positive, neutral, or negative, and depends largely on the environment. The phytomicrobiome is integral for plant growth and function; microbes play a key role in plant nutrient acquisition, biotic and abiotic stress management, physiology regulation through microbe-to-plant signals, and growth regulation via the production of phytohormones. Relationships between the plant and phytomicrobiome members vary in intimacy, ranging from casual associations between roots and the rhizosphere microbial community, to endophytes that live between plant cells, to the endosymbiosis of microbes by the plant cell resulting in mitochondria and chloroplasts. If we consider these key organelles to also be members of the phytomicrobiome, how do we distinguish between the two? If we accept the mitochondria and chloroplasts as both members of the phytomicrobiome and the plant (entrained microbes), the influence of microbes on the evolution of plants becomes so profound that without microbes, the concept of the “plant” is not viable. This paper argues that the holobiont concept should take greater precedence in the plant sciences when referring to a host and its associated microbial community. The inclusivity of this concept accounts for the ambiguous nature of the entrained microbes and the wide range of functions played by the phytomicrobiome in plant holobiont homeostasis.

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Linking plant growth promoting arbuscular mycorrhizal colonization with bacterial plant sulfur supply

10.1101/2021.06.22.449381 ◽

2021 ◽

Author(s):

Jacinta Gahan ◽

Achim Schmalenberger

Keyword(s):

Plant Growth ◽

Mycorrhizal Fungi ◽

Community Dynamics ◽

Plant Biomass ◽

Plantago Lanceolata ◽

Arbuscular Mycorrhizal ◽

Community Analysis ◽

Post Inoculation ◽

Plant Host ◽

Root Colonisation

Sulfur (S) exists in organically bound complexes (~95%), predominantly as sulfonates, and are not directly plant available. Specific soil bacteria can mobilise sulfonates but very little is known about these bacteria in the hyphosphere. Since mycorrhizal fungi support growth of the majority of land plants, hyphosphere desulfonating bacteria may be of substantial benefit to the plant host. This study analysed the effect of AM inoculation with Rhizophagus irregularis (former G. intraradices, Glomus) and a mix of six AM species (Mixed) on PGP, microbial communities and sulfonate mobilising bacteria with L. perenne, Agrostis stolonifera and Plantago lanceolata as plant hosts in bi-compartmental microcosms and A. stolonifera in PGP pot experiments. AM inoculation significantly increased plant growth, percentage root colonisation and the quantity of cultivable desulfonating bacteria in the hyphosphere over pre-inoculated soil for all plants. Community analysis via PCR-DGGE revealed significantly different bacterial and fungal communities post inoculation. Analysis of the sulfonate mobilising asfA gene revealed a significantly altered community and novel bacterial isolates with this important functional ability post-inoculation. The results demonstrate that AM inoculation increased plant biomass yield, AM root colonisation and altered bacterial and fungal community dynamics in the hyphosphere. AM inoculated microcosms had an increased abundance of desulfonating bacteria that may be beneficial for plant-S supply.

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Efectividad de hongos micorrízicos arbusculares nativos de rizósfera de Agave como promotores de crecimiento de papaya

REVISTA TERRA LATINOAMERICANA ◽

10.28940/terra.v37i2.397 ◽

2019 ◽

Vol 37 (2) ◽

pp. 163

Author(s):

Evangelina Esmeralda Quiñones Aguilar ◽

Laura Verónica Hernández Cuevas ◽

Luis López Pérez ◽

Gabriel Rincón Enríquez

Keyword(s):

Plant Growth ◽

Arbuscular Mycorrhizal Fungi ◽

Plant Height ◽

Analysis Of Variance ◽

Mycorrhizal Fungi ◽

Reference Strain ◽

Arbuscular Mycorrhizal ◽

Terrestrial Plants ◽

Relative Index ◽

Dry Biomass

Arbuscular mycorrhizal fungi (AMF) are benef icial symbionts of most terrestrial plants. This symbiosis brings benef its to both symbionts. The plant involved in the symbiosis is supplied with nutrients by the fungus that promotes plant growth, in exchange for energy for reproduction of the AMF. In this context, the effectiveness of multi-specif ic AMF inocula from the rhizosphere of Agave cupreata from Michoacán, Mexico, in promoting the growth of papaya plants was evaluated. An experiment was carried out in ten random blocks with eleven treatments: eight consortiums of AMF, a commercial biofertilizer based on AMF (EndoMic®), a reference strain (Claroideoglomus claroideum) and a control without AMF. One hundred days after establishing the experiment, we evaluated the variables plant height, stem diameter, dry biomass of foliage, root and total, foliar area, relative index of mycorrhizal dependence, mycorrhizal colonization and density of mycorrhizal spores. The data were analyzed through an analysis of variance and correlation. The results showed that two of the consortiums promoted plant growth eff iciently; the plants inoculated with the consortiums AD-MTu and CM-MT signif icantly increased (Tukey, P ≤ 0.05) dry biomass by 240 and 225%, respectively, relative to the control without AMF, while with the biofertilizer EndoMic® the increase for the same variable was only 12%. It is concluded that the use of consortiums of AMF promotes the growth of papaya and therefore could be used in nurseries or greenhouses.

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Ancient lineages of arbuscular mycorrhizal fungi provide little plant benefit

Mycorrhiza ◽

10.1007/s00572-021-01042-5 ◽

2021 ◽

Author(s):

Verena Säle ◽

Javier Palenzuela ◽

Concepción Azcón-Aguilar ◽

Iván Sánchez-Castro ◽

Gladstone Alves da Silva ◽

...

Keyword(s):

Plant Growth ◽

Arbuscular Mycorrhizal Fungi ◽

Nutrient Uptake ◽

Mycorrhizal Fungi ◽

Growth Promotion ◽

Arbuscular Mycorrhizal ◽

Allium Porrum ◽

Sand Mixture ◽

Wide Range ◽

The Impact

AbstractAlmost all land plants form symbiotic associations with arbuscular mycorrhizal fungi (AMF). Individual plants usually are colonized by a wide range of phylogenetically diverse AMF species. The impact that different AMF taxa have on plant growth is only partly understood. We screened 44 AMF isolates for their effect on growth promotion and nutrient uptake of leek plants (Allium porrum), including isolates that have not been tested previously. In particular, we aimed to test weather AMF lineages with an ancient evolutionary age differ from relatively recent lineages in their effects on leek plants. The AMF isolates that were tested covered 18 species from all five AMF orders, eight families, and 13 genera. The experiment was conducted in a greenhouse. A soil–sand mixture was used as substrate for the leek plants. Plant growth response to inoculation with AMF varied from − 19 to 232% and depended on isolate, species, and family identity. Species from the ancient families Archaeosporaceae and Paraglomeraceae tended to be less beneficial, in terms of stimulation plant growth and nutrient uptake, than species of Glomeraceae, Entrophosporaceae, and Diversisporaceae, which are considered phylogenetically more recent than those ancient families. Root colonization levels also depended on AMF family. This study indicates that plant benefit in the symbiosis between plants and AMF is linked to fungal identity and phylogeny and it shows that there are large differences in effectiveness of different AMF.

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Clohesyomyces symbioticus sp. nov., a fungal endophyte associated with roots of water smartweed (Persicaria amphibia)

Plant and Fungal Systematics ◽

10.35535/pfsyst-2021-0018 ◽

2021 ◽

Vol 66 (2) ◽

pp. 201-210

Author(s):

A. Elizabeth Arnold ◽

Dustin Sandberg

Keyword(s):

Aquatic Plant ◽

Fungal Endophytes ◽

Fungal Endophyte ◽

Western Hemisphere ◽

Plant Tissues ◽

Plant Responses ◽

Terrestrial Plants ◽

Living Plant ◽

Terrestrial Environments ◽

Lentic Waters

The widespread aquatic plant Persicaria amphibia (water smartweed, Polygonaceae) occurs in both flooded aquatic habitats and moist terrestrial environments. Its physiological versatility and wide geographic range highlight its resilience to stress and make the species intriguing for the study of fungal endophytes. Endophytes occur within living plant tissues and are known from diverse aquatic, marine, and terrestrial plants, where they often mitigate plant responses to stress. As part of a study evaluating endophyte communities associated with aquatic plants in lentic waters of Arizona, USA, we isolated a distinctive clade of endophytes from healthy, living roots of seasonally inundated P. amphibia, which we describe here on the basis of morphology and evidence from four loci as new species Clohesyomyces symbioticus (Lindgomycetaceae, Pleosporales, Dothideomycetes, Ascomycota). Clohesyomyces has long been considered a monotypic genus comprising the saprobic species C. aquaticus, presently known from submerged wood in freshwater systems in Asia and Australia. Description of Clohesyomyces symbioticus highlights the occurrence of endophytism in this genus and expands its geographic scope to the western hemisphere.

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