Isolation, taxonomic analysis, and phenotypic characterization of bacterial endophytes present in alfalfa (Medicago sativa) seeds

López, José Luis; Álvarez, Florencia; Príncipe, Analía; Salas, María Eugenia; Lozano, Mauricio Javier; Draghi, Walter Omar; Jofré, Edgardo; Lagares, Antonio

doi:10.1016/j.jbiotec.2017.12.020

Cited by 53 publications

(27 citation statements)

References 39 publications

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“…The synthetic community was designed to include the three phyla that dominated our wild M. sativa leaf samples and plant endophytes in general: Proteobacteria, Actinobacteria and Firmicutes (Figure S2; Vorholt, ). Nutrient and plant associated traits measured include: indole‐acetic acid (IAA) production, siderophore production, phosphate and potassium solubilization, and survival in nitrogen free media (Figure S1, Szkop et al ., ; Lynne et al ., ; Li et al ., ; López et al ., ). Because 10 of 12 distinct isolates display survival in media without nitrogen addition, we decided to determine the ability of these isolates to colonize plants provided with varying nitrogen concentrations (Figure S1): ‘no added nitrogen’, ‘standard Yoshida’ and ‘high nitrogen’ (see Supporting Information for calculation of fertilizer levels based on crops rotated with M. sativa ; Callahan et al ., ; Hughes, ; Klindworth et al ., ) (Fig.…”

Section: Resultsmentioning

confidence: 97%

“…While our endophyte culture collection is small, many of the members are found consistently in plant phyllosphere, root tissue and seed endophytes (Vorholt, ; Kaewkla and Franco, ; Stiefel et al ., ; Horn et al ., ; López et al ., ), as well as the 16S rRNA gene amplicon survey from the source material for our isolate collection (Figure S2). In one review, three of the eight genera represented in our synthetic community, Pantoea , Streptomyces and Arthrobacter were among the most abundant genera detected in the phyllosphere of both legumes (e.g.…”

Section: Resultsmentioning

confidence: 99%

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Distinguishing nutrient‐dependent plant driven bacterial colonization patterns in alfalfa

Moccia

Willems

Papoulis

et al. 2019

Environ Microbiol Rep

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To understand factors that influence the assembly of microbial communities, we inoculated Medicago sativa with a series of nested bacterial synthetic communities and grew plants in distinct nitrogen concentrations. Two isolates in our eight-member synthetic community, Williamsia sp. R60 and Pantoea sp. R4, consistently dominate community structure across nitrogen regimes. While Pantoea sp. R4 consistently colonizes plants to a higher degree compared to the other six organisms across each community and each nutrient level, Williamsia sp. R60 exhibits nutrient specific colonization differences. Williamsia sp. R60 is more abundant in plants grown at higher nitrogen concentrations, but exhibits the opposite trend when no plant is present, indicating plant-driven influence over colonization. Our research discovered unique, repeatable colonization phenotypes for individual microbes during plant microbiome assembly, and identified alterations caused by the host plant, microbes, and available nutrients.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Distinguishing nutrient‐dependent plant driven bacterial colonization patterns in alfalfa

Moccia

Willems

Papoulis

et al. 2019

Environ Microbiol Rep

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“…Other genera represented were species of Rhizobium , Pseudomonas, and Serratia . Similarly, identification of Medicago sativa seed endophytes (from surface-sterilized seeds) also found members of Enterobacter , Pantoea , non-nodulating rhizobia, and Pseudomonas species, among others [ 54 ]. A recent microbiome study of M. truncatula found various species of Pseudomonas and Rhizobium species associated with M. truncatula roots, although these were from soil-grown plants [ 55 ].…”

Section: Discussionmentioning

confidence: 99%

The Presence of Plant-Associated Bacteria Alters Responses to N-acyl Homoserine Lactone Quorum Sensing Signals that Modulate Nodulation in Medicago Truncatula

Veliz-Vallejos¹,

Kawasaki

Mathesius³

2020

Plants

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Bacteria use quorum sensing signaling for cell-to-cell communication, which is also important for their interactions with plant hosts. Quorum sensing via N-acyl-homoserine lactones (AHLs) is important for successful symbioses between legumes and nitrogen-fixing rhizobia. Previous studies have shown that plant hosts can recognize and respond to AHLs. Here, we tested whether the response of the model legume Medicago truncatula to AHLs from its symbiont and other bacteria could be modulated by the abundance and composition of plant-associated microbial communities. Temporary antibiotic treatment of the seeds removed the majority of bacterial taxa associated with M. truncatula roots and significantly altered the effect of AHLs on nodule numbers, but lateral root density, biomass, and root length responses were much less affected. The AHL 3-oxo-C14-HSL (homoserine lactone) specifically increased nodule numbers but only after the treatment of seeds with antibiotics. This increase was associated with increased expression of the early nodulation genes RIP1 and ENOD11 at 24 h after infection. A 454 pyrosequencing analysis of the plant-associated bacteria showed that antibiotic treatment had the biggest effect on bacterial community composition. However, we also found distinct effects of 3-oxo-C14-HSL on the abundance of specific bacterial taxa. Our results revealed a complex interaction between plants and their associated microbiome that could modify plant responses to AHLs.

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“…Seed-borne pathogens spread and perpetuate bacteria in new plant generations, similarly seeds may also carry beneficial bacteria that may be inherited to new generations. Non-pathogenic seed bacteria have been identified in Phaseolus vulgaris , maize, rice, wheat, alfalfa, and other plants ( Okunishi et al, 2005 ; Rijavec et al, 2007 ; Johnston-Monje and Raizada, 2011 ; Hardoim et al, 2012 ; López-López et al, 2012 ; Liu et al, 2017b ; López et al, 2018 ). Previous analyses of seed endophytes have shown a large diversity of bacteria ( Rijavec et al, 2007 ; Johnston-Monje and Raizada, 2011 ; López-López et al, 2012 ; Rosenblueth et al, 2012 ; Chimwamurombe et al, 2016 ).…”

Section: Sources Of Diazotrophic Bacteriamentioning

confidence: 99%

Nitrogen Fixation in Cereals

et al. 2018

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Cereals such as maize, rice, wheat and sorghum are the most important crops for human nutrition. Like other plants, cereals associate with diverse bacteria (including nitrogen-fixing bacteria called diazotrophs) and fungi. As large amounts of chemical fertilizers are used in cereals, it has always been desirable to promote biological nitrogen fixation in such crops. The quest for nitrogen fixation in cereals started long ago with the isolation of nitrogen-fixing bacteria from different plants. The sources of diazotrophs in cereals may be seeds, soils, and even irrigation water and diazotrophs have been found on roots or as endophytes. Recently, culture-independent molecular approaches have revealed that some rhizobia are found in cereal plants and that bacterial nitrogenase genes are expressed in plants. Since the levels of nitrogen-fixation attained with nitrogen-fixing bacteria in cereals are not high enough to support the plant’s needs and never as good as those obtained with chemical fertilizers or with rhizobium in symbiosis with legumes, it has been the aim of different studies to increase nitrogen-fixation in cereals. In many cases, these efforts have not been successful. However, new diazotroph mutants with enhanced capabilities to excrete ammonium are being successfully used to promote plant growth as commensal bacteria. In addition, there are ambitious projects supported by different funding agencies that are trying to genetically modify maize and other cereals to enhance diazotroph colonization or to fix nitrogen or to form nodules with nitrogen-fixing symbiotic rhizobia.

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Isolation, taxonomic analysis, and phenotypic characterization of bacterial endophytes present in alfalfa (Medicago sativa) seeds

Cited by 53 publications

References 39 publications

Distinguishing nutrient‐dependent plant driven bacterial colonization patterns in alfalfa

Distinguishing nutrient‐dependent plant driven bacterial colonization patterns in alfalfa

The Presence of Plant-Associated Bacteria Alters Responses to N-acyl Homoserine Lactone Quorum Sensing Signals that Modulate Nodulation in Medicago Truncatula

Nitrogen Fixation in Cereals

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