Genomic insights into the versatility of the plant growth-promoting bacterium Azospirillum amazonense

Sant’Anna, Fernando Hayashi; Almeida, Luiz Gonzaga Paula de; Cecagno, Ricardo; Reolon, Luciano Antonio; Siqueira, Franciele Maboni; Machado, Maicon Ricardo Stange; Vasconcelos, Ana Tereza Ribeiro de; Schrank, Irene Silveira

doi:10.1186/1471-2164-12-409

Cited by 46 publications

(25 citation statements)

References 77 publications

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“…The diazotroph Azospirillum brasilense is the best-studied species of the genus, is found in close association with many agriculturally important crops, and exerts beneficial effects on plant growth and productivity (2)(3)(4). Nitrogen fixation (5,6) and the production of the auxin 3-indoleacetic acid (IAA) by many representatives of the genus Azospirillum are related to the growth promotion effects observed in inoculated plants, such as increases in root length and the numbers of root hairs and lateral roots (3).…”

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confidence: 99%

Quantification of Azospirillum brasilense FP2 Bacteria in Wheat Roots by Strain-Specific Quantitative PCR

Stets

Alquéres

Souza

et al. 2015

Appl Environ Microbiol

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bAzospirillum is a rhizobacterial genus containing plant growth-promoting species associated with different crops worldwide. Azospirillum brasilense strains exhibit a growth-promoting effect by means of phytohormone production and possibly by N 2 fixation. However, one of the most important factors for achieving an increase in crop yield by plant growth-promoting rhizobacteria is the survival of the inoculant in the rhizosphere, which is not always achieved. The objective of this study was to develop quantitative PCR protocols for the strain-specific quantification of A. brasilense FP2. A novel approach was applied to identify strain-specific DNA sequences based on a comparison of the genomic sequences within the same species. The draft genome sequences of A. brasilense FP2 and Sp245 were aligned, and FP2-specific regions were filtered and checked for other possible matches in public databases. Strain-specific regions were then selected to design and evaluate strain-specific primer pairs. The primer pairs AzoR2.1, AzoR2.2, AzoR5.1, AzoR5.2, and AzoR5.3 were specific for the A. brasilense FP2 strain. These primer pairs were used to monitor quantitatively the population of A. brasilense in wheat roots under sterile and nonsterile growth conditions. In addition, coinoculations with other plant growth-promoting bacteria in wheat were performed under nonsterile conditions. The results showed that A. brasilense FP2 inoculated into wheat roots is highly competitive and achieves high cell numbers (ϳ10 7 CFU/g [fresh weight] of root) in the rhizosphere even under nonsterile conditions and when coinoculated with other rhizobacteria, maintaining the population at rather stable levels for at least up to 13 days after inoculation. The strategy used here can be applied to other organisms whose genome sequences are available.A zospirillum is one of the most important genera of plant growth-promoting rhizobacteria found worldwide under a variety of environmental and soil conditions (1). The diazotroph Azospirillum brasilense is the best-studied species of the genus, is found in close association with many agriculturally important crops, and exerts beneficial effects on plant growth and productivity (2-4). Nitrogen fixation (5, 6) and the production of the auxin 3-indoleacetic acid (IAA) by many representatives of the genus Azospirillum are related to the growth promotion effects observed in inoculated plants, such as increases in root length and the numbers of root hairs and lateral roots (3).The biotechnological use of A. brasilense inoculants in Latin American and in Brazil, in particular, has increased in recent years (7). Strain FP2 is a spontaneous mutant of A. brasilense Sp7 (8). Strain Sp7 has been shown to be capable of stimulating the growth of several members of the family Poaceae and increasing the productivities of wheat and maize crops (2). Strain FP2 can also promote the growth of wheat (9) and enhance maize and wheat productivity under field conditions (unpublished data). Most of the A. brasilense inoculants in B...

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confidence: 99%

Quantification of Azospirillum brasilense FP2 Bacteria in Wheat Roots by Strain-Specific Quantitative PCR

Stets

Alquéres

Souza

et al. 2015

Appl Environ Microbiol

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“…B510, A. amazonense Y2, and A. brasilense Sp245, CBG497, and Az39 (Kaneko et al 2010 ;Sant'Anna et al 2011 ;Wisniewski-Dyé et al 2011Rivera et al 2014 ). The complete genome sequences of the 3 A. brasilense strains and that of A. lipoferum 4B reveal no luxI homologue.…”

Section: Genome Analysesmentioning

confidence: 97%

“…Although allelic exchange is easy to perform with several PGPR bacteria ( Pseudomonas , Bacillus …), it remains tricky with Azospirillum probably due to the low frequency of double crossing-over events in several strains. However, a series of genetic tools was recently developed for A. amazonense (Sant'Anna et al 2011 ). An alternative approach is to insert a suicide vector into the gene of interest (only one crossingover event is needed).…”

Section: Obtention Of a Strain Defi Cient In Signal Productionmentioning

confidence: 99%

Cell–Cell Communication in Azospirillum and Related PGPR

Wisniewski‐Dyé¹,

Vial²

2015

Handbook for Azospirillum

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Quorum-sensing (QS) regulation based on N -acyl-L -homoserine lactones (AHL) is used to control various phenotypes that are often essential for interaction with a eukaryotic host, notably for plant-associated bacteria. Technical methodologies currently used to reveal AHL production in a specifi c strain and to decipher phenotypes under QS regulation are surveyed in this chapter. Analyses conducted on the genus Azospirillum and on other related PGPR are used to illustrate the different steps of the approach. Among the genus Azospirillum , a survey of 40 strains belonging to six species revealed AHL production for four strains belonging to the lipoferum species or to a close undefi ned species and isolated from a rice rhizosphere. Identifi cation of genes mediating QS and regulating functions indicate that (1) distinct QS networks are present in some strains and seem to have been acquired independently by horizontal gene transfer; (2) QS regulation is strain specifi c with several phenotypes and numerous proteins being regulated by AHL-based QS in A. lipoferum B518, whereas no change is observed in A. lipoferum TVV3 defi cient in AHL production; and (3) QS is dedicated to regulating functions linked to rhizosphere competence and adaptation to plant roots in A. lipoferum B518.

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“…In contrast to the model organism E. coli which possesses a single chemotaxis pathway encoded within a single operon and only fi ve different chemotaxis receptors, the genomes of Azospirillum species sequenced thus far indicate the presence of several chemotaxis signal transduction pathways encoded in operons and a very large number of receptors (Kaneko et al 2010 ;Sant'Anna et al 2011 ;WisniewskiDye et al 2011WisniewskiDye et al , 2012.…”

Section: Chemotaxis In Azospirillum Spp Genomesmentioning

confidence: 99%

Chemotaxis in Azospirillum

Alexandre

2015

Handbook for Azospirillum

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The ability of Azospirillum to colonize the roots of plants depends on motility and chemotaxis. Azospirillum cells are motile and capable of chemotaxis toward organic acids, sugars, and some aminoacids. Azospirillum is also able to navigate gradients of oxygen, alternative electron acceptors, and redox active compounds. Most attractants and repellents described thus far for this bacterial genus include compounds that affect intracellular metabolism, leading to the suggestion that most taxis responses correspond to energy taxis in Azospirillum spp. Several spatial and temporal gradient assays that can be implemented as quantitative methods are available to characterize taxis responses in Azospirillum species. The analysis of complete sequence genomes of several Azospirillum species reveals that taxis responses are coordinated by multiple chemotaxis pathways. All genomes also possess a chemotaxis pathway that is predicted to regulate alternative cellular functions other than fl agellar motility. Genome analyses indicate that all Azospirillum spp. sequenced to date encode for an extremely large repertoire of putative chemotaxis receptors, which is likely contributing to explaining their ubiquitous distribution.

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Genomic insights into the versatility of the plant growth-promoting bacterium Azospirillum amazonense

Cited by 46 publications

References 77 publications

Quantification of Azospirillum brasilense FP2 Bacteria in Wheat Roots by Strain-Specific Quantitative PCR

Quantification of Azospirillum brasilense FP2 Bacteria in Wheat Roots by Strain-Specific Quantitative PCR

Cell–Cell Communication in Azospirillum and Related PGPR

Chemotaxis in Azospirillum

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