Academic literature on the topic 'Root-Microorganism interaction'

A variety of methods to detect cellulase secretion by microorganisms has been developed over the years, none of which enables the real-time visualization of cellulase activity on a surface. This visualization is critical to study the interaction between soil-borne cellulase-secreting microorganisms and the surface of plant roots and specifically, the effect of surface features on this interaction. Here, we modified the known carboxymethyl cellulase (CMC) hydrolysis visualization method to enable the real-time tracking of cellulase activity of microorganisms on a surface. A surface was formed using pure CMC with acridine orange dye incorporated in it. The dye disassociated from the film when hydrolysis occurred, forming a halo surrounding the point of hydrolysis. This enabled real-time visualization, since the common need for post hydrolysis dyeing was negated. Using root-knot nematode (RKN) as a model organism that penetrates plant roots, we showed that it was possible to follow microorganism cellulase secretion on the surface. Furthermore, the addition of natural additives was also shown to be an option and resulted in an increased RKN response. This method will be implemented in the future, investigating different microorganisms on a root surface microstructure replica, which can open a new avenue of research in the field of plant root–microorganism interactions.

In the face of climate change, progressive degradation of the environment, including agricultural land negatively affecting plant growth and development, endangers plant productivity. Seeking efficient and sustainable agricultural techniques to replace agricultural chemicals is one of the most important challenges nowadays. The use of plant growth-promoting microorganisms is among the most promising approaches; however, molecular mechanisms underneath plant–microbe interactions are still poorly understood. In this review, we summarized the knowledge on plant–microbe interactions, highlighting the role of microbial and plant proteins and metabolites in the formation of symbiotic relationships. This review covers rhizosphere and phyllosphere microbiomes, the role of root exudates in plant–microorganism interactions, the functioning of the plant’s immune system during the plant–microorganism interactions. We also emphasized the possible role of the stringent response and the evolutionarily conserved mechanism during the established interaction between plants and microorganisms. As a case study, we discussed fungi belonging to the genus Trichoderma. Our review aims to summarize the existing knowledge about plant–microorganism interactions and to highlight molecular pathways that need further investigation.

Photoperiod, which regulates the duration of vegetative and generative development, and the plant-microorganism interaction, which influences the metabolic status of plant organisms, are important factors in the regulating plant growth and development. The aim of the study was to determine the influence of Glycine max (L.) Merr. genotype and seed pre-bacterization with a virulent and active strain of Bradyrhizobium japonicum 634b on the plant growth and development, and on the soluble carbohydrate content in leaves of isogenic by E-genes lines under field conditions. Nearly isogenic lines (NILs) of soybean, in which the E1, E2, and E3 genes are located at different allelic loci, were used. Sterile seeds were pretreated with distilled water (control) and Bradyrhizobium japonicum 634b cell suspension (experiment). Plants were grown under natural long-day conditions (16 hours). The growth and development of the soybean were evaluated by phenological observations, morphometric indicators fixed at the V3 and V5 developmental stages, relative growth rate (RGR), and the content of soluble sugars ‒ mono- and oligosaccharides. The effect of the factors studied (genotype, bacterization, and their interaction) was calculated. The results of the experiment and the calculation of the effect of the factor showed that the isoline genotype has the greatest effect on seed germination, phenological development of the plant and duration of the VE-R1 phase, growth of the root system in the V3 and V5 phases, and the content of monosaccharides involved in forming the plant-microorganism interaction. The effect of bacterization is most evident in the RGR, shoot development, and the oligosaccharide content of the leaves of NILs in the V3 and V5 phases. Among the isolines studied, L 80-5879, which has the E1 gene (flowering repressor) in a dominant state, was characterized by minimal sensitivity to bacterization. It was found that bacterization and genotype interaction didn't influence the VE-R1 duration stage and the shoot and root length. The results obtained therefore prove that the E-series genes, which determine the photoperiodic sensitivity of soya beans, can also be indirectly involved in establishing plant-microorganism interactions.

Abstract Cabbage, a widely cultivated cruciferous vegetable, generates substantial waste material during its harvest and processing. This study was conducted to analyse the effectiveness of three decomposer types and their concentration to break down cabbage waste compost on the cultivation of lettuce (Lactuca sativa L.). The research employed randomized complete block design with two factors and three replications. The first factor was the cabbage waste compost amount: 20 g, 30 g, and 40 g per plant. The second factor was type of compost decomposers: without decomposers, EM4, Thiobacillus sp., and indigenous microorganism. Variables observed included leaf length, number of leafs, leaf fresh weight, leaf dry weight, root fresh weight, root dry weight, and root length. Data were analysed using analysis of variance and means were separated using Duncan’s multiple range test. There was no interaction between the decomposer and the amount of cabbage waste compost on all parameters. The type of cabbage waste compost decomposer had a very significant effect on the number of leaves and root length. The amount of cabbage waste compost did not significantly affect all parameters. Indigenous microorganism (IMO) decomposer resulted in the number of leaf 14.36 and leaf length of 5.79 cm.

The root system of the plant is essential for taking up water and nutrients, serves as an anchor and is the organ where plant-microorganism interaction takes place. When the Plant Growth Promoting Rhizobacteria (PGPR) Azospirillum brasilense Sp245 colonizes the root of the plants, it halts the growth of the primary root and stimulates the development of the lateral roots and root hairs which support vegetative, green biomass. Target of Rapamycin (TOR) is a highly conserved protein in all eukaryotes, and it controls anabolic processes, such as cell cycle, ribosome biogenesis, protein synthesis, cell wall changes and photosynthesis among others. TOR in plants forms part of the TORC1 complex, which when is activated by auxins and light, activates anabolic processes and represses autophagy. TOR regulates the growth of the primary root of Arabidopsis through cell proliferation and elongation. In the present investigation, the participation of TOR during the Arabidopsis-Azospirillum interaction was determined using two approaches, a pharmacology and other genetic. The results showed that TOR is involved in the development of the lateral roots of A. thaliana seedlings inoculated with A. brasilense.

Abstract Aims Microstructure plays an important role in biological systems. Microstructural features are critical in the interaction between two biological organisms, for example, a microorganism and the surface of a plant. However, isolating the structural effect of the interaction from all other parameters is challenging when working directly with the natural system. Replicating microstructure of leaves was recently shown to be a powerful research tool for studying leaf-environment interaction. However, no such tool exists for roots. Roots present a special challenge because of their delicacy (specifically of root hairs) and their 3D structure. We aim at developing such a tool for roots. Methods Biomimetics use synthetic systems to mimic the structure of biological systems, enabling the isolation of structural function. Here we present a method which adapts tools from leaf microstructure replication to roots. We introduce new polymers for this replication. Results We find that Polyurethane methacrylate (PUMA) with fast UV curing gives a reliable replication of the tomato root surface microstructure. We show that our system is compatible with the pathogenic soilborne bacterium Ralstonia solanacearum. Conclusions This newly developed tool may be used to study the effect of microstructure, isolated from all other effects, on the interaction of roots with their environment.

The plant root is the primary site of interaction between plants and associated microorganisms and constitutes the main components of plant microbiomes that impact crop production. The endophytic bacteria in the root zone have an important role in plant growth promotion. Diverse microbial communities inhabit plant root tissues, and they directly or indirectly promote plant growth by inhibiting the growth of plant pathogens, producing various secondary metabolites. Mechanisms of plant growth promotion and response of root endophytic microorganisms for their survival and colonization in the host plants are the result of complex plant-microbe interactions. Endophytic microorganisms also assist the host to sustain different biotic and abiotic stresses. Better insights are emerging for the endophyte, such as host plant interactions due to advancements in ‘omic’ technologies, which facilitate the exploration of genes that are responsible for plant tissue colonization. Consequently, this is informative to envisage putative functions and metabolic processes crucial for endophytic adaptations. Detection of cell signaling molecules between host plants and identification of compounds synthesized by root endophytes are effective means for their utilization in the agriculture sector as biofertilizers. In addition, it is interesting that the endophytic microorganism colonization impacts the relative abundance of indigenous microbial communities and suppresses the deleterious microorganisms in plant tissues. Natural products released by endophytes act as biocontrol agents and inhibit pathogen growth. The symbiosis of endophytic bacteria and arbuscular mycorrhizal fungi (AMF) affects plant symbiotic signaling pathways and root colonization patterns and phytohormone synthesis. In this review, the potential of the root endophytic community, colonization, and role in the improvement of plant growth has been explained in the light of intricate plant-microbe interactions.

Fertilization is an important practical measure in agricultural production. As an important nutrient element of plants, nitrogen (N) has a significant impact on the plant productivity and microbial function. Rhizosphere microorganisms affect plant growth and development, nitrogen uptake and utilization, and ecological adaptability. The interaction mechanism between plant and rhizosphere microorganisms is one of the hotspots in life science research and the key program of agricultural microorganism utilization. In this article, the relationship among plant root morphology and physiology, rhizosphere microorganisms, and nitrogen is reviewed, summarized, and prospected.

Avocado is one of the most in-demand fruits worldwide and the trend towards its sustainable production, regulated by international standards, is increasing. One of the most economically important diseases is root rot, caused by Phythopthora cinnamomi. Regarding this problem, antagonistic microorganism use is an interesting alternative due to their phytopathogen control efficiency. Therefore, the interaction of arbuscular mycorrhizal fungi of the phylum Glomeromycota, native to the Peruvian coast (GWI) and jungle (GFI), and avocado rhizospheric bacteria, Bacillus subtilis and Pseudomonas putida, was evaluated in terms of their biocontrol capacity against P. cinnamomi in the “Zutano” variety of avocado plants. The results showed that the GWI and Bacillus subtilis combination increased the root exploration surface by 466.36%. P. putida increased aerial biomass by 360.44% and B. subtilis increased root biomass by 433.85%. Likewise, P. putida rhizobacteria showed the highest nitrogen (24.60 mg ∙ g−1 DM) and sulfur (2.60 mg ∙ g−1 DM) concentrations at a foliar level. The combination of GWI and Bacillus subtilis was the treatment that presented the highest calcium (16.00 mg ∙ g−1 DM) and magnesium (8.80 mg ∙ g−1 DM) concentrations. The microorganisms’ multifunctionality reduced disease severity by 85 to 90% due to the interaction between mycorrhizae and rhizobacteria. In conclusion, the use of growth promoting microorganisms that are antagonistic to P. cinnamomi represents a potential strategy for sustainable management of avocado cultivation.

The interaction between plant, soil and microorganism plays a crucial role in sustainable development of terrestrial ecosystem function and diversity. However, little information is known about how plant growth, soil organic carbon (C) fractions and microorganism respond to exogenous C addition in soils with low organic C content. Three levels of 13C-glucose (equal to 0, 100% and 500% of initial microbial biomass C) were added to non-sterilized (corresponding to treatment abbreviation of CK, Glu-1, Glu-2, respectively) and sterilized soils (corresponding to treatment abbreviation of SS, SS+Glu-1, SS+Glu-2, respectively) planted with apple rootstock (Malus baccata (L.) Borkh.) seedings. The objectives of this study were to analyse the dynamics of soil organic C (SOC) fractions and soil bacterial community diversity with glucose levels and soil sterilization, and to explore the morphology of roots and nitrogen (N) metabolism by plant after glucose addition to sterilized/non-sterilized soils. Results showed that the contents of labile organic C fractions were significantly varied (P<0.05) with the levels of glucose addition and soil sterilization. SS+Glu-2 and Glu-2 treatments increased the contents of labile organic C fractions, on average, by 48.47% and 35.33% compared with no glucose addition, respectively. About 21.42% and 16.17% of glucose-C remained in sterilized and non-sterilized soils, respectively at the end of experiment (day 45). Regardless of soil sterilized or not, the glucose addition increased the richness and diversity indices of soil bacterial community compared with no-glucose addition. The glucose addition optimized root zone conditions, and enhanced root vitality, morphology and biomass. Both SS+Glu-2 and Glu-2 treatments significantly enhanced (P<0.05) the contents of nitrate (NO3—N) and nitrite (NO2—N), but sharply decreased (P<0.05) the ammonium (NH4+-N) content compared with no glucose addition. Also, these two treatments significantly (P<0.05) increased the enzymic activities and gene transcript levels involved in root N metabolism, which demonstrated that the high level of glucose addition promoted N assimilation and transformation into free amino acids by root. Overall, the addition of exogenous C to not only promotes its fixation and bacterial community diversity in C-poor soils, but also improves root morphology and N absorption by plant.

Les cellules de la coiffe racinaire et les cellules bordantes et apparentées (AC-DC) libèrent un mucilage principalement composé de glycopolymères, mais également d’ADN extracellulaire. Cette matrice mucilagineuse associée aux AC-DC forme une structure dense, connue sous le nom de piège extracellulaire de racine ou RET, qui entoure l'apex racinaire. Dans cette étude nous avons caractérisé la composition du RET du soja (Glycine max) et du pois (Pisum sativum) par immunomarquages de surface et par chromatographie gazeuse. Les résultats ont montré que les polysaccharides majoritairement présents dans le RET sont les pectines, en majorité des RG-I très ramifiés, et les xyloglucanes. Les zones de l’apex racinaire et d’élongation, et le RET ont une composition différente, ce qui suggère une spécificité des tissus, capable d’assurer des fonctions particulières, notamment dans les interactions entre la racine et les microorganismes. Par la suite, nous avons étudié l’effet du RET du soja et du pois sur le comportement de deux bactéries, Pseudomonas fluorescens et Bacillus subtilis, ainsi que sur les zoospores d’un oomycète, Phytophthora parasitica. Pour ce faire, des tests de confrontation ont été menés, puis chaque microorganisme a été suivi à l'aide d'un logiciel d’imagerie et son déplacement a été caractérisé. Ainsi, les observations au microscope ont notamment révélé que les bactéries sont filtrées par le RET, alors que les zoospores ne le sont pas. Toutefois, lorsque les microorganismes pénètrent le réseau mucilagineux, ils présentent une mobilité très fortement affectée, par rapport à ceux restant à l'extérieur du RET. A l’intérieur du réseau, les vitesses de déplacement sont considérablement réduites, d’un facteur trois pour les bactéries et d’un facteur quatre pour les zoospores, avec des trajectoires très fortement altérées. Ces résultats indiquent que le RET du soja et du pois entrave le déplacement des microorganismes et, par conséquent, leur migration vers la racine. Enfin, nous avons tenté de déconstruire le RET via l’utilisation d’enzymes hydrolytiques et suivi les changements par imagerie et par chromatographie d’exclusion stérique. Les résultats ont révélé que le RET était particulièrement résistant aux différents traitements enzymatiques, ce qui est très probablement dû à la composition et l’organisation des polymères dans le RET
Root cap cells and root associated, cap-derived cells (AC-DC) release a dense mucilage composed mainly of glycopolymers, and extracellular DNA. This mucilaginous matrix associated with the AC-DC forms a complex structure, known as the Root Extracellular Trap (RET), which surrounds the root tip. In this study we characterized the composition of the RET of soybean (Glycine max) and pea (Pisum sativum) by using immunocytochemistry and gas chromatography. The results showed that the polysaccharides predominantly present in the RET are pectins, mainly highly branched RG-I, and xyloglucans. The root elongation and meristematic zones and the RET exhibit different composition, which suggests a specificity of the tissues, able to ensuring specific functions, particularly in the interactions between the root and soil microorganisms. Then, we studied the effect of RET from soybean and pea on the behaviour of two bacteria, Pseudomonas fluorescens and Bacillus subtilis, and on the zoospores of an oomycete, Phytophthora parasitica. To this end, comparison tests were carried out, then microorganisms were tracked using imaging software and their movements were characterized. Microscopic observations revealed that bacteria are seived by the RET, while zoospores are not. However, when the microorganisms penetrate the mucilaginous network, their mobility is greatly affected compared with those remaining outside the RET. Within the RET, the speeds are considerably reduced, by a factor of three for bacteria and a factor of four for zoospores, with very strongly altered trajectories. These results indicate that the RET of soybean and pea hinders the movement of microorganisms and, consequently, their migration towards the root. Finally, we attempted to deconstruct the RET using hydrolytic enzymes (i.e. glycosidases and DNase) and monitored the changes using imaging and steric exclusion chromatography. The data revealed that the RET was particularly resistant to the various enzymatic treatments, which is most likely due to the composition and complex organization of the polymers within the RET

The introduction of species into exotic areas has increased, although it results in serious impacts on novel ecosystems. In Portugal, Eucalyptus globulus (exotic species) and Acacia longifolia (exotic invasive species) occupy a vast forested area. Eucalyptus globulus was extensively planted due to its role in pulpwood industries and, while the majority of plantations are managed, some are poorly managed along with isolated trees dispersed in the landscape (seed-trees) that are very huge and old, potentially increasing the risk of dispersal. Acacia longifolia was introduced for dune stabilization, but quickly expanded, becoming invasive without human intervention. As a leguminous species, the ability to establish symbiosis with nitrogen-fixing bacteria seems to be crucial to potentiate this invasiveness; however, these mutualistic interactions will interfere with soil microbiota, altering plant communities and affecting local biodiversity. Being two species adapted to post-fire regeneration, their behavior changes after fire occurrence, however after off-season fires, there is a gap in knowledge about their establishment dynamics. Eucalyptus globulus plantations and surrounding areas of seed-trees affected by June and October 2017 fire events were sampled, as well as unburnt areas. Acacia longifolia root-nodules were collected from unburnt and burnt areas affected by 2017 October fire and bacterial community was isolated and identified. Our results showed that the fire date and pre-fire management restrained E. globulus natural regeneration, with greater establishment in unmanaged plantations affected by the October fire. The presence of seed-trees seems to be less influenced by these factors (fire date and management), and can be considered an important seed source. Also, A. longifolia bacteriome has lower diversity after fire, but the main symbionts seem to be nitrogen-fixing bacteria, indicating a more specialized symbiosis that could enhance post-fire invasion. Bradyrhizobium spp. were the main partners in both studied zones, revealing its role as a facilitating microorganism. Off-season fires specific conditions seem to create more favourable conditions for E. globulus establishment, while A. longifolia seems to be able to establish promiscuous symbioses, but simultaneously adapt to a disturbed environment, managing to outcompete effectively with other plant species