scholarly journals Experimental-Evolution-Driven Identification of Arabidopsis Rhizosphere Competence Genes in Pseudomonas protegens

mBio ◽  
2021 ◽  
Author(s):  
Erqin Li ◽  
Hao Zhang ◽  
Henan Jiang ◽  
Corné M. J. Pieterse ◽  
Alexandre Jousset ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Plant Performance ◽  
Plant Roots ◽  
Rhizosphere Competence

Beneficial root-associated microorganisms carry out many functions that are essential for plant performance. Establishment of a bacterium on plant roots, however, requires overcoming many challenges.

Root-to-shoot signalling: integration of diverse molecules, pathways and functions

2016 ◽  
Vol 43 (2) ◽  
pp. 87 ◽  
Author(s):  
Sergey Shabala ◽  
Rosemary G. White ◽  
Michael A. Djordjevic ◽  
Yong-Ling Ruan ◽  
Ulrike Mathesius
Keyword(s):  
Current Knowledge ◽  
Dynamic Environment ◽  
Plant Performance ◽  
Plant Roots ◽  
Specific Information ◽  
Plant Parts ◽  
Efficient Communication ◽  
Communication Modes ◽  
Below Ground ◽  
Signalling Systems

Plant adaptive potential is critically dependent upon efficient communication and co-ordination of resource allocation and signalling between above- and below-ground plant parts. Plant roots act as gatekeepers that sense and encode information about soil physical, chemical and biological factors, converting them into a sophisticated network of signals propagated both within the root itself, and also between the root and shoot, to optimise plant performance for a specific set of conditions. In return, plant roots receive and decode reciprocal information coming from the shoot. The communication modes are highly diverse and include a broad range of physical (electric and hydraulic signals, propagating Ca2+ and ROS waves), chemical (assimilates, hormones, peptides and nutrients), and molecular (proteins and RNA) signals. Further, different signalling systems operate at very different timescales. It remains unclear whether some of these signalling systems operate in a priming mode(s), whereas others deliver more specific information about the nature of the signal, or whether they carry the same ‘weight’. This review summarises the current knowledge of the above signalling mechanisms, and reveals their hierarchy, and highlights the importance of integration of these signalling components, to enable optimal plant functioning in a dynamic environment.

scholarly journals Preceding crop and tillage system affect winter survival of wheat and the fungal communities on young wheat roots and in soil

2019 ◽  
Vol 366 (15) ◽  
Author(s):  
Hanna Friberg ◽  
Paula Persson ◽  
Dan Funck Jensen ◽  
Göran Bergkvist
Keyword(s):  
Plant Growth ◽  
Plant Pathogens ◽  
Fusarium Culmorum ◽  
Winter Survival ◽  
Plant Performance ◽  
Plant Roots ◽  
Fungal Communities ◽  
Wheat Roots ◽  
Preceding Crop ◽  
Tillage System

ABSTRACT Agricultural practices like tillage and cropping sequence have profound influence on soil-living and plant-associated fungi, and thereby on plant growth. In a field experiment, we studied the effects of preceding crop and tillage on fungal communities in the soil and on young winter wheat roots in relation to plant winter survival and grain yield. We hypothesized that plant performance and fungal communities (described by amplicon sequencing) differ depending on tillage system and preceding crop; that the effect of preceding crop differs depending on tillage system, and that differences in fungal communities are reflected in plant performance. In line with our hypotheses, effects of preceding crop on plant growth and fungal communities on plant roots and in soil were more pronounced under non-inversion tillage than under inversion tillage (ploughing). Fungal communities on plant roots in treatments with low winter survival were different from those with better survival. In soil, several fungal OTUs (operational taxonomic units) differed significantly between tillage systems. OTUs representing putative plant pathogens were either more abundant (Parastagonospora sp._27) or less abundant (Fusarium culmorum/graminearum_5) after non-inversion tillage. Our findings highlight the influence of cultural practices on fungal communities and thereby on plant health and yield.

scholarly journals Successional Trajectories of Rhizosphere Bacterial Communities over Consecutive Seasons

mBio ◽  
2015 ◽  
Vol 6 (4) ◽  
Author(s):  
Shengjing Shi ◽  
Erin Nuccio ◽  
Donald J. Herman ◽  
Ruud Rijkers ◽  
Katerina Estera ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Growing Season ◽  
Avena Fatua ◽  
Plant Roots ◽  
Annual Grass ◽  
Phylogenetic Conservation ◽  
Growing Seasons ◽  
Rhizosphere Competence ◽  
The Many ◽  
Rhizosphere Bacterial Communities

ABSTRACT It is well known that rhizosphere microbiomes differ from those of surrounding soil, and yet we know little about how these root-associated microbial communities change through the growing season and between seasons. We analyzed the response of soil bacteria to roots of the common annual grass Avena fatua over two growing seasons using high-throughput sequencing of 16S rRNA genes. Over the two periods of growth, the rhizosphere bacterial communities followed consistent successional patterns as plants grew, although the starting communities were distinct. Succession in the rhizosphere was characterized by a significant decrease in both taxonomic and phylogenetic diversity relative to background soil communities, driven by reductions in both richness and evenness of the bacterial communities. Plant roots selectively stimulated the relative abundance of Alphaproteobacteria, Betaproteobacteria, and Bacteroidetes but reduced the abundance of Acidobacteria, Actinobacteria, and Firmicutes. Taxa that increased in relative abundance in the rhizosphere soil displayed phylogenetic clustering, suggesting some conservation and an evolutionary basis for the response of complex soil bacterial communities to the presence of plant roots. The reproducibility of rhizosphere succession and the apparent phylogenetic conservation of rhizosphere competence traits suggest adaptation of the indigenous bacterial community to this common grass over the many decades of its presence. IMPORTANCE We document the successional patterns of rhizosphere bacterial communities associated with a “wild” annual grass, Avena fatua, which is commonly a dominant plant in Mediterranean-type annual grasslands around the world; the plant was grown in its grassland soil. Most studies documenting rhizosphere microbiomes address “domesticated” plants growing in soils to which they are introduced. Rhizosphere bacterial communities exhibited a pattern of temporal succession that was consistent and repeatable over two growing seasons. There are few studies assessing the reproducibility over multiple seasons. Through the growing season, the rhizosphere community became progressively less diverse, likely reflecting root homogenization of soil microniches. Phylogenetic clustering of the rhizosphere dynamic taxa suggests evolutionary adaptation to Avena roots. The reproducibility of rhizosphere succession and the apparent phylogenetic conservation of rhizosphere competence traits suggest adaptation of the indigenous bacterial community to this common grass over the many decades of its presence.

scholarly journals Experimental evolution-driven identification of Arabidopsis rhizosphere competence genes in Pseudomonas protegens

2020 ◽  
Author(s):  
Erqin Li ◽  
Henan Jiang ◽  
Corné M.J. Pieterse ◽  
Alexandre Jousset ◽  
Peter A.H.M. Bakker ◽  
...  
Keyword(s):  
Experimental Evolution ◽  
Reverse Genetics ◽  
Plant Root ◽  
Plant Immunity ◽  
Plant Performance ◽  
Nucleotide Polymorphisms ◽  
Bacterial Adaptation ◽  
Global Regulators ◽  
Rhizosphere Colonization ◽  
Beneficial Microorganisms

AbstractBeneficial plant root-associated microorganisms carry out a range of functions that are essential for plant performance. Establishment of a bacterium on plant roots, however, requires overcoming several challenges, including the ability to outcompete neighboring microorganisms and suppression of plant immunity. Forward and reverse genetics approaches have led to the identification of diverse mechanisms that are used by beneficial microorganisms to overcome these challenges such as the production of iron-chelating compounds, biofilm formation, or downregulation of plant immunity. However, how such mechanisms have developed from an evolutionary perspective is much less understood. In an attempt to study bacterial adaptation in the rhizosphere, we employed an experimental evolution approach to track the physiological and genetic dynamics of root-dwelling Pseudomonas protegens CHA0 in the Arabidopsis thaliana rhizosphere under axenic conditions. This simplified binary one plant, and one bacterium system allows for the amplification of key adaptive mechanisms for bacterial rhizosphere colonization. We found that mutations in global regulators, as well as in genes for siderophore production, cell surface decoration, attachment, and motility accumulated in parallel in our evolutionary experiment, underlining several different strategies of bacterial adaptation to the rhizosphere. In total we identified 35 mutations, including single-nucleotide polymorphisms, smaller indels and larger deletions, distributed over 28 genes in total. Altogether these results underscore the strength of experimental evolution to identify key genes and pathways for bacterial rhizosphere colonization, as well as highlighting a methodology for the development of elite beneficial microorganisms with enhanced root-colonizing capacities that can support sustainable agriculture in the future.

scholarly journals Diversification of B. subtilis during experimental evolution on A. thaliana leads to synergism in root colonization of evolved subpopulations

2021 ◽  
Author(s):  
Christopher Blake ◽  
Mathilde Nordgaard Christensen ◽  
Gergely Maróti ◽  
Ákos T. Kovács
Keyword(s):  
Arabidopsis Thaliana ◽  
Bacillus Subtilis ◽  
Plant Growth ◽  
Plant Species ◽  
Experimental Evolution ◽  
Root Colonization ◽  
Plant Root ◽  
Plant Roots ◽  
Stable Strategy ◽  
Pellicle Formation

SummaryThe soil bacterium Bacillus subtilis is known to suppress pathogens as well as promote plant growth. However, in order to fully exploit the potential as natural fertilizer, we need a better understanding of the interactions between B. subtilis and plants. Here, B. subtilis was examined for root colonization through experimental evolution on Arabidopsis thaliana. The populations evolved rapidly, improved in root colonization and diversified into three distinct morphotypes. In order to better understand the adaptation that had taken place, single evolved isolates from the final transfer were randomly selected for further characterization, revealing changes in growth and pellicle formation in medium supplemented with plant polysaccharides. Intriguingly, certain evolved isolates showed improved root colonization only on the plant species they evolved on, but not on another plant species, namely tomato, suggesting A. thaliana specific adaption paths. Finally, synergism in plant root colonization was observed for a mix of all three morphotypes, as the mix performed better than the sum of its constituents in monoculture. Our results suggest, that genetic diversification occurs in an ecological relevant setting on plant roots and proves to be a stable strategy for root colonization.Significance StatementUnderstanding how plant-growth-promoting rhizobacteria colonize plant roots is crucial to fully utilize their potential for agricultural applications. Here, we utilized experimental evolution of the PGPR Bacillus subtilis on Arabidopsis thaliana to study root colonization. We revealed that evolving populations rapidly improve in root colonization and diversify into distinct morphotypes. Notably, improved root colonization by evolved isolates was observed on A. thaliana, not on tomato. Moreover, isolates of distinct morphotypes interacted during root colonization and the mixture of morphotypes showed higher productivity then predicted. These findings suggest that genetic diversification might be a stable strategy to maximize root colonization.

Effect of planting time on the performance of broccoli under Mizoram conditions

2017 ◽  
Vol 17 (1) ◽  
pp. 15-18
Author(s):  
Donnie Lalfakzuala Kawlni ◽  
Chhungpuii Khawlhring
Keyword(s):  
Commercial Production ◽  
Plant Performance ◽  
Average Weight ◽  
Plant Spacing ◽  
Vegetable Crop ◽  
Marketable Yield ◽  
Sowing Time ◽  
Planting Time ◽  
Significant Difference ◽  
Cultural Requirements

Broccoli (Brassica oleracea var. italica), a popular vegetable crop, has one of the most exacting climatic and cultural requirements, which limit its commercial production to a few favored locations. A field experiment was conducted at Mizoram University, Tanhril, Mizoram during winter of 2013/2014 to find out the effect of time of sowing on plant performance and yield of broccoli. Six sowing time was done viz. 17 October (T1), 24 October (T2), 31 October (T3), 7 November (T4), 14 November (T5) and 21 November (T6) with plant spacing of 45cm x 45cm. Yield and yield contributing characters were significantly influenced by the planting time. Highest average weight of marketable curd per plant (199.20 g) was obtained from T2, whereas lowest average weight obtained from T6 (75 g). The influence of planting time also showed significant difference on the calculated yield (tonnes per hectare) of broccoli, in which T2 showed highest marketable yield of 9.83 t/ha.

Acute and chronic toxicity studies on Polygonum glabrum in experimental animals

2020 ◽  
Vol 3 (1) ◽  
pp. 7-10
Author(s):  
Saravanakumar A ◽  
Gandhimathi R
Keyword(s):  
Chronic Toxicity ◽  
Clinical Stage ◽  
Herbal Medicines ◽  
Plant Roots ◽  
Root Extract ◽  
Experimental Animals ◽  
Toxicity Studies ◽  
Acute And Chronic Toxicity ◽  
Diuretic Agents

Polygonum glabrum is being used in traditional and folklore medicine to treat pneumonia and jaundice. Plant roots are used in ayurvedic preparations to treat fever and colic. The leaves are used as diuretic agents and process vermifuge action. Plant decoction is also used in the treatment of Rheumatism. Besides having many uses and folklore claims, herbal medicines are to be thoroughly investigated for their toxicity also. Therefore this work is being carried out to examine the toxicity of the drug and established dose is safe to use in the clinical stage. The current research studied the acute and chronic toxicity of Polygonum glabrum root extract in rats. It is proved that there was no change in any parameter tested both in acute and chronic toxicity, which means the extract is safe and non-toxic at the dose of 2g/kg also.

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