Plant-microbe-microbe interactions influenced the faba bean nodule colonization by diverse endophytic bacteria

2021 ◽  
Author(s):  
Sameh H Youseif ◽  
Fayrouz H Abd El-Megeed ◽  
Ali S Abdelaal ◽  
Amr Ageez ◽  
Esperanza Martínez-Romero
Keyword(s):  
Faba Bean ◽  
Root Nodules ◽  
N Uptake ◽  
Nifh Gene ◽  
Housekeeping Genes ◽  
Soil Conditions ◽  
Pgp Traits ◽  
Plant Growth Promoting ◽  
Legume Symbiosis ◽  
Microbe Interactions

Abstract Legume root nodules harbor rhizobia and other non-nodulating endophytes known as nodule-associated bacteria (NAB) whose role in the legume symbiosis is still unknown. We analyzed the genetic diversity of thirty-four NAB isolates obtained from the root nodules of faba bean grown under various soil conditions in Egypt using 16S rRNA and concatenated sequences of three housekeeping genes. All isolates were identified as members of the family Enterobacteriaceae belonging to the genera Klebsiella, Enterobacter, and Raoultella. We identified nine enterobacterial genospecies, most of which have not been previously reported as NAB. All isolated strains harbored nifH gene sequences and most of them possessed plant growth-promoting (PGP) traits. Upon co-inoculation with an N2 fixing rhizobium (Rlv NGB-FR128), two strains (E. sichanensis NGB-FR97 and K. variicola NGB-FR116) significantly increased nodulation, growth, and N-uptake of faba bean plants over the single treatments or the uninoculated control. The presence of these enterobacteria in nodules was significantly affected by the host plant genotype, symbiotic rhizobium genotype, and endophyte genotype, indicating that the nodule colonization process is regulated by plant-microbe-microbe interactions. This study emphasizes the importance of nodule-associated enterobacteria and suggests their potential role in improving the effectiveness of rhizobial inoculants.

scholarly journals Diversity, Phylogeny and Plant Growth Promotion Traits of Nodule Associated Bacteria Isolated from Lotus parviflorus

2020 ◽  
Vol 8 (4) ◽  
pp. 499 ◽  
Author(s):  
Ricardo Soares ◽  
Jesús Trejo ◽  
Maria J. Lorite ◽  
Etelvina Figueira ◽  
Juan Sanjuán ◽  
...  
Keyword(s):  
Plant Growth ◽  
Plant Growth Promotion ◽  
Growth Promotion ◽  
Root Nodules ◽  
Nifh Gene ◽  
Bacterial Strains ◽  
Lytic Enzymes ◽  
Taxonomic Assignment ◽  
Pgp Traits ◽  
Associated Bacteria

Lotus spp. are widely used as a forage to improve pastures, and inoculation with elite rhizobial strains is a common practice in many countries. However, only a few Lotus species have been studied in the context of plant-rhizobia interactions. In this study, forty highly diverse bacterial strains were isolated from root nodules of wild Lotus parviflorus plants growing in two field locations in Portugal. However, only 10% of these isolates could nodulate one or more legume hosts tested, whereas 90% were thought to be opportunistic nodule associated bacteria. Phylogenetic studies place the nodulating isolates within the Bradyrhizobium genus, which is closely related to B. canariense and other Bradyrhizobium sp. strains isolated from genistoid legumes and Ornithopus spp. Symbiotic nodC and nifH gene phylogenies were fully consistent with the taxonomic assignment and host range. The non-nodulating bacteria isolated were alpha- (Rhizobium/Agrobacterium), beta- (Massilia) and gamma-proteobacteria (Pseudomonas, Lysobacter, Luteibacter, Stenotrophomonas and Rahnella), as well as some bacteroidetes from genera Sphingobacterium and Mucilaginibacter. Some of these nodule-associated bacteria expressed plant growth promotion (PGP) traits, such as production of lytic enzymes, antagonistic activity against phytopathogens, phosphate solubilization, or siderophore production. This argues for a potential beneficial role of these L. parviflorus nodule-associated bacteria.

scholarly journals Multiple metabolic phenotypes as screening criteria are correlated with the plant growth-promoting ability of rhizobacterial isolates

2021 ◽  
Author(s):  
Peng Shi ◽  
Jianli Zhang ◽  
Xingyue Li ◽  
Liyun Zhou ◽  
Hui Luo ◽  
...  
Keyword(s):  
Plant Growth ◽  
Root Exudate ◽  
Screening Criteria ◽  
Pgp Traits ◽  
Preliminary Screening ◽  
Rhizosphere Colonization ◽  
Metabolic Phenotypes ◽  
Plant Growth Promoting ◽  
Microbe Interactions ◽  
Growth Promoting

Abstract Aims Most preliminary screening criteria for plant growth-promoting (PGP) rhizobacteria (PGPR) are based on traditional knowledge of PGP mechanisms and do not always work well due to complex plant–microbe interactions. The aim of this study was to analyze the correlation between the metabolic phenotypes of rhizobacterial isolates and their PGP ability. The feasibility of using these phenotypes as preliminary screening criteria for PGPR was also evaluated. Methods Twenty-one rhizobacterial isolates were screened for their PGP ability, traditional PGP traits, and multiple metabolic phenotypes that are not directly related to PGP mechanisms, but are possibly related to rhizosphere colonization. Correlations between the PGP traits or metabolic phenotypes and increases in plant agronomic parameters were analyzed to find the indicators that are most closely related to PGP ability. Results The utilization of 11 nutrient substrates commonly found in root exudates, such as D-salicin, β-methyl-D-glucoside, D-cellobiose, D-maltose, D-trehalose, and dextrin, was significantly positively correlated with the PGP ability of the rhizobacterial isolates. The utilization of one amino acid and two organic acids, namely L-aspartic acid, α-keto-glutaric acid, and formic acid, was negatively correlated with PGP ability. There were no significant correlations between four PGP traits tested in this study and the PGP ability. Conclusion The ability of rhizobacterial isolates to metabolize nutrient substrates that are identical or similar to root exudate components may act as better criteria than PGP traits for the primary screening of PGPR, because rhizosphere colonization is a prerequisite for PGPR to affect plants.

scholarly journals Rhizobial Microsymbionts of Kamchatka Oxytropis Species Possess Genes of the Type III and VI Secretion Systems, Which Can Affect the Development of Symbiosis

2020 ◽  
Vol 33 (10) ◽  
pp. 1232-1241
Author(s):  
Vera I. Safronova ◽  
Polina V. Guro ◽  
Anna L. Sazanova ◽  
Irina G. Kuznetsova ◽  
Andrey A. Belimov ◽  
...  
Keyword(s):  
Host Specificity ◽  
Ribosomal Rna ◽  
Root Nodules ◽  
Kamchatka Peninsula ◽  
Secretion Systems ◽  
Nod Factor ◽  
Type Iii ◽  
Type Vi Secretion ◽  
Legume Symbiosis ◽  
Microbe Interactions

A collection of rhizobial strains isolated from root nodules of the narrowly endemic legume species Oxytropis erecta, O. anadyrensis, O. kamtschatica, and O. pumilio originating from the Kamchatka Peninsula (Russian Federation) was obtained. Analysis of the 16S ribosomal RNA gene sequence showed a significant diversity of isolates belonging to families Rhizobiaceae (genus Rhizobium), Phyllobacteriaceae (genera Mesorhizobium, Phyllobacterium), and Bradyrhizobiaceae (genera Bosea, Tardiphaga). A plant nodulation assay showed that only strains belonging to genus Mesorhizobium could form nitrogen-fixing nodules on Oxytropis plants. The strains M. loti 582 and M. huakuii 583, in addition to symbiotic clusters, possessed genes of the type III and type VI secretion systems (T3SS and T6SS, respectively), which can influence the host specificity of strains. These strains formed nodules of two types (elongated and rounded) on O. kamtschatica roots. We suggest this phenomenon may result from Nod factor–dependent and –independent nodulation strategies. The obtained strains are of interest for further study of the T3SS and T6SS gene function and their role in the development of rhizobium-legume symbiosis. The prospects of using rhizobia having both gene systems related to symbiotic and nonsymbiotic nodulation strategies to enhance the efficiency of plant-microbe interactions by expanding the host specificity and increasing nodulation efficiency are discussed.

scholarly journals Rhizobial microsymbionts of the narrowly endemic Oxytropis species growing in Kamchatka possess a set of genes that are associated with T3SS and T6SS secretion systems and can affect the development of symbiosis

2020 ◽  
Author(s):  
P. Guro ◽  
V. Safronova ◽  
A. Sazanova ◽  
I. Kuznetsova ◽  
A. Belimov ◽  
...  
Keyword(s):  
Host Specificity ◽  
Root Nodules ◽  
Kamchatka Peninsula ◽  
Rrna Gene ◽  
Nitrogen Fixing ◽  
Symbiotic Genes ◽  
Secretion Systems ◽  
Legume Symbiosis ◽  
Microbe Interactions ◽  
Different Strains

A collection of rhizobial strains isolated from root nodules of the narrowly endemic legume species Oxytropis erecta, O. anadyrensis, O. kamtschatica and O. pumilio growing on the Kamchatka Peninsula (Russian Federation) was obtained. Analysis of the 16S rRNA gene sequence showed a significant diversity of isolates belonging to the families Rhizobiaceae (Rhizobium), Phyllobacteriaceae (Mesorhizobium, Phyllobacterium) and Bradyrhizobiaceae (Bosea, Tardiphaga). Pairs of taxonomically different strains in various combinations were isolated from some nodules of Oxytropis plants. Plant nodulation assays showed that only strains belonging to the genus Mesorhizobium (M. jarvisii, M. loti and M. huakuii) could form nitrogen-fixing nodules. The nitrogen-fixing activity of the strains was more associated with the host plant than with the species of strains. The whole genome sequences analysis showed that the strains M. loti 582 and M. huakuii 583 possessed symbiotic genes necessary for the formation of effective symbiosis and grouped into Sym-clusters. In contrast, the strain T. robiniae 581 had only a reduced number of fix genes, while the strains Phyllobacterium sp. 628 and R. lusitanum 629 possesed only individual symbiotic genes, which obviously did not participate in the formation of nodules. It was also stated that the strains M. loti 582 and M. huakuii 583 had a significantly larger set of genes related to the secretion systems T3SS and T6SS that can affect the host specificity of strains, compared with 6 commercial strains used as reference. These two strains formed nodules of two types (typical elongated and atypical rounded) on Oxytropis plants. We suggest that a possible cause of the observed phenomenon is the availability of different nodulation strategies in these strains (dependent and independent of Nod-factors). Thus, as a result of studying the collection of strains isolated from the narrow endemic species of Kamchatka Oxytropis, interesting objects were selected to study the functions of the T3SS and T6SS genes, and their role in the development of rhizobia-legume symbiosis. The prospects of using strains with gene systems for both symbiotic and non-symbiotic nodulation to enhance the efficiency of plant-microbe interactions by expanding the host specificity and increasing the efficiency of nodulation are discussed.

scholarly journals Expression and function of the cdgD gene, encoding a CHASE–PAS-DGC-EAL domain protein, in Azospirillum brasilense

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
José Francisco Cruz-Pérez ◽  
Roxana Lara-Oueilhe ◽  
Cynthia Marcos-Jiménez ◽  
Ricardo Cuatlayotl-Olarte ◽  
María Luisa Xiqui-Vázquez ◽  
...  
Keyword(s):  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Soil Conditions ◽  
Wild Type ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Genes Encoding ◽  
In The Wild ◽  
Plant Growth Promoting

AbstractThe plant growth-promoting bacterium Azospirillum brasilense contains several genes encoding proteins involved in the biosynthesis and degradation of the second messenger cyclic-di-GMP, which may control key bacterial functions, such as biofilm formation and motility. Here, we analysed the function and expression of the cdgD gene, encoding a multidomain protein that includes GGDEF-EAL domains and CHASE and PAS domains. An insertional cdgD gene mutant was constructed, and analysis of biofilm and extracellular polymeric substance production, as well as the motility phenotype indicated that cdgD encoded a functional diguanylate protein. These results were correlated with a reduced overall cellular concentration of cyclic-di-GMP in the mutant over 48 h compared with that observed in the wild-type strain, which was recovered in the complemented strain. In addition, cdgD gene expression was measured in cells growing under planktonic or biofilm conditions, and differential expression was observed when KNO3 or NH4Cl was added to the minimal medium as a nitrogen source. The transcriptional fusion of the cdgD promoter with the gene encoding the autofluorescent mCherry protein indicated that the cdgD gene was expressed both under abiotic conditions and in association with wheat roots. Reduced colonization of wheat roots was observed for the mutant compared with the wild-type strain grown in the same soil conditions. The Azospirillum-plant association begins with the motility of the bacterium towards the plant rhizosphere followed by the adsorption and adherence of these bacteria to plant roots. Therefore, it is important to study the genes that contribute to this initial interaction of the bacterium with its host plant.

Molecular imaging of plant-microbe interactions on the Brachypodium seed surface

The Analyst ◽  
2021 ◽  
Author(s):  
Yuchen Zhang ◽  
Rachel Komorek ◽  
Jiyoung Son ◽  
Shawn Riechers ◽  
Zihua Zhu ◽  
...  
Keyword(s):  
Biological Control ◽  
Molecular Imaging ◽  
Plant Growth ◽  
Crucial Role ◽  
Plant Growth Promoting Rhizobacteria ◽  
Plant Tissues ◽  
Seed Surface ◽  
Plant Growth Promoting ◽  
Microbe Interactions ◽  
Growth Promoting

Plant growth-promoting rhizobacteria (PGPR) play a crucial role in biological control and pathogenic defense on and within plant tissues, however the mechanism(s) by which plants associate with PGPR to elicit...

scholarly journals Foliar-Applied Potassium Silicate Coupled with Plant Growth-Promoting Rhizobacteria Improves Growth, Physiology, Nutrient Uptake and Productivity of Faba Bean (Vicia faba L.) Irrigated with Saline Water in Salt-Affected Soil

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 894
Author(s):  
Emad M. Hafez ◽  
Hany S. Osman ◽  
Usama A. Abd El-Razek ◽  
Mohssen Elbagory ◽  
Alaa El-Dein Omara ◽  
...  
Keyword(s):  
Plant Growth ◽  
Fresh Water ◽  
Faba Bean ◽  
Saline Water ◽  
Plant Growth Promoting Rhizobacteria ◽  
Control Treatment ◽  
Combined Application ◽  
Bean Plants ◽  
Plant Growth Promoting ◽  
Growth Promoting

The continuity of traditional planting systems in the last few decades has encountered its most significant challenge in the harsh changes in the global climate, leading to frustration in the plant growth and productivity, especially in the arid and semi-arid regions cultivated with moderate or sensitive crops to abiotic stresses. Faba bean, like most legume crops, is considered a moderately sensitive crop to saline soil and/or saline water. In this connection, a field experiment was conducted during the successive winter seasons 2018/2019 and 2019/2020 in a salt-affected soil to explore the combined effects of plant growth-promoting rhizobacteria (PGPR) and potassium (K) silicate on maintaining the soil quality, performance, and productivity of faba bean plants irrigated with either fresh water or saline water. Our findings indicated that the coupled use of PGPR and K silicate under the saline water irrigation treatment had the capability to reduce the levels of exchangeable sodium percentage (ESP) in the soil and to promote the activity of some soil enzymes (urease and dehydrogenase), which recorded nearly non-significant differences compared with fresh water (control) treatment, leading to reinstating the soil quality. Consequently, under salinity stress, the combined application motivated the faba bean vegetative growth, e.g., root length and nodulation, which reinstated the K+/Na+ ions homeostasis, leading to the lessening or equalizing of the activity level of enzymatic antioxidants (CAT, POD, and SOD) compared with the controls of both saline water and fresh water treatments, respectively. Although the irrigation with saline water significantly increased the osmolytes concentration (free amino acids and proline) in faba bean plants compared with fresh water treatment, application of PGPR or K-silicate notably reduced the osmolyte levels below the control treatment, either under stress or non-stress conditions. On the contrary, the concentrations of soluble assimilates (total soluble proteins and total soluble sugars) recorded pronounced increases under tested treatments, which enriched the plant growth, the nutrients (N, P, and K) uptake and translocation to the sink organs, which lastly improved the yield attributes (number of pods plant−1, number of seeds pod−1, 100-seed weight). It was concluded that the combined application of PGPR and K-silicate is considered a profitable strategy that is able to alleviate the harmful impact of salt stress alongside increasing plant growth and productivity.

scholarly journals PGPR Characteristics of Rhizospheric Bacteria to Understand the Mechanisms of Faba Bean Growth

Proceedings ◽  
2021 ◽  
Vol 66 (1) ◽  
pp. 27
Author(s):  
Rim Tinhinen Maougal ◽  
Maya Kechid ◽  
Chaima Ladjabi ◽  
Abdelhamid Djekoun
Keyword(s):  
Plant Growth ◽  
Faba Bean ◽  
Biochemical Characterization ◽  
Plant Growth Promoting Rhizobacteria ◽  
Bacterial Strains ◽  
Rhizospheric Bacteria ◽  
Plant Growth Promoting ◽  
Pgpr Traits ◽  
Taxonomic Groups ◽  
High Degree

Rhizobacteria play an important role in maintaining soil balance. Among these bacteria, there are those taht have shown their ability to promote the growth of plants, known as Plant Growth Promoting Rhizobacteria (PGPR). In our work, we are interested in characterizing 110 bacterial strains isolated in the field in the region of Ben Badis (Constantine Algeria) from 5 varieties of faba bean. Phenotypic and biochemical characterization showed that most of the isolates are cream-colored, slightly raised, flat and opaque, Gram−, catalase+ and oxidase−, and Bacillus form. PCA analysis allowed us to select 40 isolates with a high degree of variability to continue our work. The results obtained have directed us towards different taxonomic groups (rhizobium, Pseudomonas, Bacillus etc.). The evaluation of the PGPR potential of bacteria (phytostimulation, biofertilization and biocontrol), showed that 100% of bacteria are able to produce auxin at different concentrations, with the highest concentration (177.77 µg/mL) for the isolate 6, and that more than 50% of isolates are capable of producing nitrogen, ammonia and phytate mineralization. These PGPR traits have a direct effect on plant growth of five varieties of the faba bean and can be used to select the best performing bacteria for inoculation tests.

scholarly journals Role of Two Plant Growth-Promoting Bacteria in Remediating Cadmium-Contaminated Soil Combined with Miscanthus floridulus (Lab.)

Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 912
Author(s):  
Shuming Liu ◽  
Hongmei Liu ◽  
Rui Chen ◽  
Yong Ma ◽  
Bo Yang ◽  
...  
Keyword(s):  
Plant Growth ◽  
Contaminated Soils ◽  
Translocation Factor ◽  
Plant Growth Promoting Bacteria ◽  
Bacterial Strains ◽  
Pgp Traits ◽  
Cd Tolerance ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Cd Translocation

Miscanthus spp. are energy plants and excellent candidates for phytoremediation approaches of metal(loid)s-contaminated soils, especially when combined with plant growth-promoting bacteria. Forty-one bacterial strains were isolated from the rhizosphere soils and roots tissue of five dominant plants (Artemisia argyi Levl., Gladiolus gandavensis Vaniot Houtt, Boehmeria nivea L., Veronica didyma Tenore, and Miscanthus floridulus Lab.) colonizing a cadmium (Cd)-contaminated mining area (Huayuan, Hunan, China). We subsequently tested their plant growth-promoting (PGP) traits (e.g., production of indole-3-acetic acid, siderophore, and 1-aminocyclopropane-1-carboxylate deaminase) and Cd tolerance. Among bacteria, two strains, Klebsiella michiganensis TS8 and Lelliottia jeotgali MR2, presented higher Cd tolerance and showed the best results regarding in vitro growth-promoting traits. In the subsequent pot experiments using soil spiked with 10 mg Cd·kg−1, we investigated the effects of TS8 and MR2 strains on soil Cd phytoremediation when combined with M. floridulus (Lab.). After sixty days of planting M. floridulus (Lab.), we found that TS8 increased plant height by 39.9%, dry weight of leaves by 99.1%, and the total Cd in the rhizosphere soil was reduced by 49.2%. Although MR2 had no significant effects on the efficiency of phytoremediation, it significantly enhanced the Cd translocation from the root to the aboveground tissues (translocation factor > 1). The combination of K. michiganensis TS8 and M. floridulus (Lab.) may be an effective method to remediate Cd-contaminated soils, while the inoculation of L. jeotgali MR2 may be used to enhance the phytoextraction potential of M. floridulus.

scholarly journals Mutation in the ntrR Gene, a Member of the vap Gene Family, Increases the Symbiotic Efficiency of Sinorhizobium meliloti

2001 ◽  
Vol 14 (7) ◽  
pp. 887-894 ◽  
Author(s):  
Boglárka Oláh ◽  
Erno Kiss ◽  
Zoltán Györgypál ◽  
Judit Borzi ◽  
Gyöngyi Cinege ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Pathogenic Bacteria ◽  
Sinorhizobium Meliloti ◽  
Root Nodules ◽  
Nifh Gene ◽  
Dry Weight ◽  
Nodule Occupancy ◽  
Gene Encoding ◽  
Symbiotic Efficiency ◽  
Host Interactions

In specific plant organs, namely the root nodules of alfalfa, fixed nitrogen (ammonia) produced by the symbiotic partner Sinorhizobium meliloti supports the growth of the host plant in nitrogen-depleted environment. Here, we report that a derivative of S. meliloti carrying a mutation in the chromosomal ntrR gene induced nodules with enhanced nitrogen fixation capacity, resulting in an increased dry weight and nitrogen content of alfalfa. The efficient nitrogen fixation is a result of the higher expression level of the nifH gene, encoding one of the subunits of the nitrogenase enzyme, and nifA, the transcriptional regulator of the nif operon. The ntrR gene, controlled negatively by its own product and positively by the symbiotic regulator syrM, is expressed in the same zone of nodules as the nif genes. As a result of the nitrogen-tolerant phenotype of the strain, the beneficial effect of the mutation on efficiency is not abolished in the presence of the exogenous nitrogen source. The ntrR mutant is highly competitive in nodule occupancy compared with the wild-type strain. Sequence analysis of the mutant region revealed a new cluster of genes, termed the “ntrPR operon,” which is highly homologous to a group of vap-related genes of various pathogenic bacteria that are presumably implicated in bacterium-host interactions. On the basis of its favorable properties, the strain is a good candidate for future agricultural utilization.

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