scholarly journals Pairwise Interactions of Three Related Pseudomonas Species in Plant Roots and Inert Surfaces

2021 ◽  
Vol 12 ◽  
Author(s):  
Nesli Tovi ◽  
Tomer Orevi ◽  
Maor Grinberg ◽  
Nadav Kashtan ◽  
Yitzhak Hadar ◽  
...  
Keyword(s):  
Bacterial Colonization ◽  
Plant Roots ◽  
Microbial Consortia ◽  
Root Tip ◽  
Interaction Patterns ◽  
Interspecies Interactions ◽  
Wheat Roots ◽  
Pairwise Interactions ◽  
Inert Surfaces ◽  
External Stimuli

Bacteria are social organisms that interact extensively within and between species while responding to external stimuli from their environments. Designing synthetic microbial communities can enable efficient and beneficial microbiome implementation in many areas. However, in order to design an efficient community, one must consider the interactions between their members. Using a reductionist approach, we examined pairwise interactions of three related Pseudomonas species in various microenvironments including plant roots and inert surfaces. Our results show that the step between monoculture and co-culture is already very complex. Monoculture root colonization patterns demonstrate that each isolate occupied a particular location on wheat roots, such as root tip, distance from the tip, or scattered along the root. However, pairwise colonization outcomes on the root did not follow the bacterial behavior in monoculture, suggesting various interaction patterns. In addition, we show that interspecies interactions on a microscale on inert surface take part in co-culture colonization and that the interactions are affected by the presence of root extracts and depend on its source. The understanding of interrelationships on the root may contribute to future attempts to manipulate and improve bacterial colonization and to intervene with root microbiomes to construct and design effective synthetic microbial consortia.

scholarly journals Persistence of Functional Microbiota Composition Across Generations

2020 ◽  
Author(s):  
Christian Ramos Uria ◽  
Mario Calus ◽  
Dirkjan Schokker
Keyword(s):  
Alternative Stable States ◽  
Simulated Data ◽  
Functional Composition ◽  
Interaction Patterns ◽  
Interspecies Interactions ◽  
Stable States ◽  
Units Of Selection ◽  
Pairwise Interactions ◽  
The Stability ◽  
Over Time

Abstract Background: Holobionts are defined as a host and its microbiota, and there is not a consensus about their status as a unit of selection. The “it’s the song, not the singer” theory proposes that functional traits, instead of taxonomical composition, could be preserved across generations if interspecies interaction patterns perpetuate themselves. We used a novel combination of community level analysis on the functional composition of microbiota-communities to test this theory by using empirical and simulated data. We tested the conservation of functional composition across generations using mosquito and plant datasets. Then, we tested if there is a change of functional composition over time within a generation in human datasets. Finally, we simulated microbiota communities with different amounts of pairwise interspecies interactions and initial configurations to investigate if the interactions can lead to multiple stable community compositions. Results: Our results suggest that the vertically transmitted microbiota starts a predictable change of functions performed by the microbiota over time (i.e. an ecological succession) whose robustness depends on the arrival of diverse migrants. This succession culminates in a stable functional composition state. The pairwise interactions between species of the community are not sufficient to explain the stability of the final community and the existence of alternative stable states, which suggests that the host-microbiota interaction and non-pairwise interactions in general have an important contribution to the robustness of the final community.Conclusions: If the proposed mechanism proves to be valid for a diverse array of host species, this would support the concept of holobionts being used as units of selection, suggesting this has a wider applicability, including animal breeding.

Effect of 24-epibrassinolide on localization of ABA, AZP, and dehydrins in wheat plant roots during dehydration

Biomics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 329-336
Author(s):  
A.R. Lubyanova ◽  
F.M. Shakirova ◽  
M.V. Bezrukova
Keyword(s):  
Triticum Aestivum ◽  
Wheat Germ ◽  
Wheat Plant ◽  
Triticum Aestivum L ◽  
Immunohistochemical Localization ◽  
Plant Roots ◽  
Wheat Roots ◽  
Wheat Seedlings ◽  
Apoplastic Barrier ◽  
Protective Proteins

We studied the immunohistochemical localization of abscisic acid (ABA), wheat germ agglutinin (WGA) and dehydrins in the roots of wheat seedlings (Triticum aestivum L.) during 24-epibrassinolide-pretreatment (EB-pretreatment) and PEG-induced dehydration. It was found coimmunolocalization of ABA, WGA and dehydrins in the cells of central cylinder of basal part untreated and EB-pretreated roots of wheat seedlings under normal conditions and under osmotic stress. Such mutual localization ABA and protective proteins, WGA and dehydrins, indicates the possible effect of their distribution in the tissues of EB-pretreated wheat roots during dehydration on the apoplastic barrier functioning, which apparently contributes to decrease the water loss under dehydration. Perhaps, the significant localization of ABA and wheat lectin in the metaxylem region enhances EB-induced transport of ABA and WGA from roots to shoots under stress. It can be assumed that brassinosteroids can serve as intermediates in the realization of the protective effect of WGA and wheat dehydrins during water deficit.

scholarly journals Higher-order temporal network effects through triplet evolution

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Qing Yao ◽  
Bingsheng Chen ◽  
Tim S. Evans ◽  
Kim Christensen
Keyword(s):  
Real World ◽  
Link Prediction ◽  
Higher Order ◽  
Prediction Algorithm ◽  
Interaction Patterns ◽  
Temporal Networks ◽  
World Systems ◽  
Order Interaction ◽  
Space And Time ◽  
Pairwise Interactions

AbstractWe study the evolution of networks through ‘triplets’—three-node graphlets. We develop a method to compute a transition matrix to describe the evolution of triplets in temporal networks. To identify the importance of higher-order interactions in the evolution of networks, we compare both artificial and real-world data to a model based on pairwise interactions only. The significant differences between the computed matrix and the calculated matrix from the fitted parameters demonstrate that non-pairwise interactions exist for various real-world systems in space and time, such as our data sets. Furthermore, this also reveals that different patterns of higher-order interaction are involved in different real-world situations. To test our approach, we then use these transition matrices as the basis of a link prediction algorithm. We investigate our algorithm’s performance on four temporal networks, comparing our approach against ten other link prediction methods. Our results show that higher-order interactions in both space and time play a crucial role in the evolution of networks as we find our method, along with two other methods based on non-local interactions, give the best overall performance. The results also confirm the concept that the higher-order interaction patterns, i.e., triplet dynamics, can help us understand and predict the evolution of different real-world systems.

Gradients of pH, ammonium, and phosphorus between the fertiliser band and wheat roots

1999 ◽  
Vol 50 (3) ◽  
pp. 365 ◽  
Author(s):  
Xike Zhang ◽  
Zdenko Rengel
Keyword(s):  
Ammonium Phosphate ◽  
Dry Weight ◽  
Plant Roots ◽  
Ammonia Toxicity ◽  
Phosphorus Concentration ◽  
Wheat Roots ◽  
Shoot Dry Weight ◽  
Nylon Mesh ◽  
Extractable P ◽  
Fertiliser Use

Di-ammonium phosphate (DAP) band application generally improves phosphorus (P) fertiliser use efficiency but can cause ammonia toxicity to plants. We used specially constructed pots to study P and ammonium (NH4+) gradients between the DAP band and plant roots grown in 2 soils. The pots were with or without a 30-mm nylon mesh between the roots and the fertiliser band, and had a movable side to enable sampling of soil layers at various distances from the fertiliser band and/or plant roots. After 28 days, ammonia toxicity symptoms occurred in plants grown in Lancelin soil in both mesh and no-mesh pots with the band placed 1 cm from the seed. Smaller root and shoot dry weights and a shorter root length were measured in both soils in no-mesh pots when the banding distance from the seed was 1 cm compared with 2.5 cm. In contrast, no differences in root and shoot dry weight occurred when direct contact between the roots and the fertiliser band was prevented in mesh pots; however, roots were shorter in mesh pots when fertiliser was banded 1 cm, compared with 2.5 cm, from the seed. The highest values for pH, NH4+ concentration, and bicarbonate-extractable P level occurred 4–5 cm from the seed in mesh pots, and in the layer between the fertiliser band and the seed in no-mesh pots. Phosphorus concentration in shoots was greater when plants were grown in Lancelin than in New Norcia soil, and when grown in no-mesh compared with mesh pots. In conclusion, large gradients of pH, ammonium, and bicarbonate-extractable P existed around plant roots when DAP and ammonium sulfate were banded in the vicinity of the seed. The frequently employed practice of growing plants in mesh pots to characterise nutrient gradients in soil close to roots, including the rhizosphere soil, results in plants with altered growth and nutrient accumulation characteristics in comparison to plants with no physical restriction for root growth within the pot.

FACTORS GOVERNING ZOOSPORE RESPONSES OF PHYTOPHTHORA MEGASPERMA VAR. SOJAE TO PLANT ROOTS

1967 ◽  
Vol 45 (11) ◽  
pp. 1983-1994 ◽  
Author(s):  
H. H. Ho ◽  
C. J. Hickman
Keyword(s):  
Root Exudate ◽  
Chemical Nature ◽  
Root Surface ◽  
Plant Roots ◽  
Root Tip ◽  
Phytophthora Megasperma ◽  
Negative Pole ◽  
New Feature ◽  
Germ Tubes ◽  
Cyst Germination

In the presence of plant roots, zoospores of Phytophthora megasperma var. sojae reacted in general as do other fungal zoospores: they were attracted to, and trapped in the immediate vicinity of the root surface, on which they encysted rapidly. Encysted zoospores formed a continuous sheath around the root, thickest just behind the root tip. Cyst germination was stimulated. Germ tubes were always initiated from the side of cysts closest to the root and grew towards it. In addition, a new feature was observed, suppression of repeated emergence of zoospores. Zoospore accumulation was nonspecific with respect to host and non-host, resistance, and susceptibility.Tests with exudates and extracts from roots of resistant and susceptible soybean varieties and a non-host, pea, confirmed the chemical nature of the stimulus inducing these responses. Zoospores observed in an electric field were not attracted towards either pole, but they were trapped and encysted rapidly around the negative pole. Cyst germination was not stimulated. Nevertheless, since encystment was more pronounced on root exudate agar mounted on the negative pole, electric charges on roots may also contribute to inducing early encystment of zoospores there.In an investigation of ions on zoospore responses, with ionic resins, all phases of zoospore response to roots, with the exception of attraction, occurred in the presence of hydrogen resin particles.

Changes in the Ultrastructure of the Root Tip of Wheat Following Exposure to Aluminium

1994 ◽  
Vol 21 (1) ◽  
pp. 85 ◽  
Author(s):  
MLD Lima ◽  
L Copeland
Keyword(s):  
Triticum Aestivum ◽  
Prolonged Exposure ◽  
Morphological Changes ◽  
Triticum Aestivum L ◽  
Root Tip ◽  
Cortical Layers ◽  
Wheat Roots ◽  
Wheat Seedlings ◽  
Meristematic Cells ◽  
Fermentative Metabolism

Investigations have been carried out on morphological changes induced by aluminium ions in roots of wheat seedlings (Triticum aestivum L. cv. Vulcan). Lesions were evident on the surface of the roots after 4-8 h of exposure, and within 24 h there was increased vacuolation, loss of turgor, and severe cytoplasmic disorganisation in epidermal and peripheral cap cells. The central cap and cortical layers were also severely damaged by aluminium, but changes in the meristematic cells became evident only after more prolonged exposure of roots to aluminium. Mobilisation of starch in amyloplasts of peripheral and central cap cells of aluminium-stressed roots was particularly noticeable, and this was accompanied by an increase in the amount of extractable activity of starch-degrading enzymes. The possibility that the mobilisation of starch is linked to a coincident increase in fermentative metabolism in Al-stressed wheat roots is considered.

scholarly journals Paenibacillus polymyxa Invades Plant Roots and Forms Biofilms

2005 ◽  
Vol 71 (11) ◽  
pp. 7292-7300 ◽  
Author(s):  
Salme Timmusk ◽  
Nina Grantcharova ◽  
E. Gerhart H. Wagner
Keyword(s):  
Plant Growth ◽  
Fluorescent Protein ◽  
Paenibacillus Polymyxa ◽  
Plant Roots ◽  
Root Tip ◽  
Broad Host Range ◽  
Plant Growth Promoting Bacteria ◽  
Soil System ◽  
Plant Growth Promoting ◽  
Growth Promoting

ABSTRACT Paenibacillus polymyxa is a plant growth-promoting rhizobacterium with a broad host range, but so far the use of this organism as a biocontrol agent has not been very efficient. In previous work we showed that this bacterium protects Arabidopsis thaliana against pathogens and abiotic stress (S. Timmusk and E. G. H. Wagner, Mol. Plant-Microbe Interact. 12:951-959, 1999; S. Timmusk, P. van West, N. A. R. Gow, and E. G. H. Wagner, p. 1-28, in Mechanism of action of the plant growth promoting bacterium Paenibacillus polymyxa, 2003). Here, we studied colonization of plant roots by a natural isolate of P. polymyxa which had been tagged with a plasmid-borne gfp gene. Fluorescence microscopy and electron scanning microscopy indicated that the bacteria colonized predominantly the root tip, where they formed biofilms. Accumulation of bacteria was observed in the intercellular spaces outside the vascular cylinder. Systemic spreading did not occur, as indicated by the absence of bacteria in aerial tissues. Studies were performed in both a gnotobiotic system and a soil system. The fact that similar observations were made in both systems suggests that colonization by this bacterium can be studied in a more defined system. Problems associated with green fluorescent protein tagging of natural isolates and deleterious effects of the plant growth-promoting bacteria are discussed.

Bacterial colonization of seminal wheat roots

1980 ◽  
Vol 12 (6) ◽  
pp. 559-565 ◽  
Author(s):  
J.W.L. Van Vuurde ◽  
B. Schippers
Keyword(s):  
Bacterial Colonization ◽  
Wheat Roots

scholarly journals Theoretical guidelines for editing ecological communities

2020 ◽  
Author(s):  
Vu Nguyen ◽  
Dervis Can Vural
Keyword(s):  
Community Resilience ◽  
Optimization Process ◽  
Community Control ◽  
Ecological Communities ◽  
Interspecies Interactions ◽  
Cost Parameter ◽  
Pairwise Interactions ◽  
Species Abundances

Having control over species abundances and community resilience is of great interest for experimental, agricultural, industrial and conservational purposes. Here, we theoretically explore the possibility of manipulating ecological communities by modifying pairwise interactions. Specifically, we establish which interaction values should be modified, and by how much, in order to alter the composition or resilience of a community towards a favorable direction. While doing so, we also take into account the experimental difficulties in making such modifications by including in our optimization process, a cost parameter, which penalizes large modifications. In addition to prescribing what changes should be made to interspecies interactions given some modification cost, our approach also serves to establish the limits of community control, i.e. how well can one approach an ecological goal at best, even when not constrained by cost.

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