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6. Diverse Bacterial Genes Modulate Plant Root Association by Beneficial Bacteria

Author

do Amaral, Fernanda Plucani, Tuleski, Thalita Regina, Pankievicz, Vania Carla Silva, Melnyk, Ryan A, Arkin, Adam P, Griffitts, Joel, Tadra-Sfeir, Michelle Zibetti, de Souza, Emanuel Maltempi, Deutschbauer, Adam, Monteiro, Rose Adele, and Stacey, Gary

Subjects
Microbiology, Biological Sciences, Zero Hunger, Arabidopsis, Azoarcus, Bacterial Proteins, Herbaspirillum, Iron, Plant Roots, Rhizosphere, Setaria Plant, Soil Microbiology, bacterium-root colonization, beneficial bacteria, gene functionality, transposon mutagenesis, Biochemistry and cell biology, Medical microbiology
Abstract

The plant rhizosphere harbors a diverse population of microorganisms, including beneficial plant growth-promoting bacteria (PGPB), that colonize plant roots and enhance growth and productivity. In order to specifically define bacterial traits that contribute to this beneficial interaction, we used high-throughput transposon mutagenesis sequencing (TnSeq) in two model root-bacterium systems associated with Setaria viridis: Azoarcus olearius DQS4T and Herbaspirillum seropedicae SmR1. This approach identified ∼100 significant genes for each bacterium that appeared to confer a competitive advantage for root colonization. Most of the genes identified specifically in A. olearius encoded metabolism functions, whereas genes identified in H. seropedicae were motility related, suggesting that each strain requires unique functions for competitive root colonization. Genes were experimentally validated by site-directed mutagenesis, followed by inoculation of the mutated bacteria onto S. viridis roots individually, as well as in competition with the wild-type strain. The results identify key bacterial functions involved in iron uptake, polyhydroxybutyrate metabolism, and regulation of aromatic metabolism as important for root colonization. The hope is that by improving our understanding of the molecular mechanisms used by PGPB to colonize plants, we can increase the adoption of these bacteria in agriculture to improve the sustainability of modern cropping systems.IMPORTANCE There is growing interest in the use of associative, plant growth-promoting bacteria (PGPB) as biofertilizers to serve as a sustainable alternative for agriculture application. While a variety of mechanisms have been proposed to explain bacterial plant growth promotion, the molecular details of this process remain unclear. The current research supports the idea that PGPB use in agriculture will be promoted by gaining more knowledge as to how these bacteria colonize plants, promote growth, and do so consistently. Specifically, the research seeks to identify those bacterial genes involved in the ability of two, PGPB strains, Azoarcus olearius and Herbaspirillum seropedicae, to colonize the roots of the C4 model grass Setaria viridis. Applying a transposon mutagenesis (TnSeq) approach, we assigned phenotypes and function to genes that affect bacterial competitiveness during root colonization. The results suggest that each bacterial strain requires unique functions for root colonization but also suggests that a few, critical functions are needed by both bacteria, pointing to some common mechanisms. The hope is that such information can be exploited to improve the use and performance of PGPB in agriculture.

Published
2020

8. Understanding a Brazilian High School Blended Learning Environment from the Perspective of Complex Systems

Author

de Barros, Ana Paula Rodrigues Magalhães, Simmt, Elaine, and Maltempi, Marcus Vinicius

Abstract

The use of technological resources has the potential to make viable new and less traditional methodologies of teaching that take into account student differences. Blended learning can be a way to rethink classes so that students have more freedom in their processes of learning. The goal of this article is to understand a blended learning environment from the perspective of complex systems. We observed the classroom as a complex unit emerging from collective class member interactions. Data from one of two mathematics classes of first year high school students, in São Paulo, Brazil were used in this article. The results suggested that a high school blended learning environment, when seen as a complex system, not only frees students to make personal meaning in their learning processes, but it also provides for collective learning in virtual and face-to-face groups. Features of online discussion groups contributed to the teachers' knowledge about the collective learning, providing them valuable information for formative assessment and pedagogical actions. The blended learning environment seen from a complexity perspective provided evidence that such classrooms demand a different relationship between the teacher, the learner, and the curriculum than relationships observed in the traditional class.

Published
2017

17. Principals' Perceptions of the Barriers and Impediments to Distribute Leadership and Share Decision Making under an Era of Heightened Accountability: An Exploratory Study Using Q-Technique

Author

Maltempi, Michelle Grace

Abstract

Educational institutions--and, more specifically, principals--are faced with meeting the mandates and demands set forth by local, state, and federal initiatives. Accountability has forever changed the context in which the traditional role of a principal leads. This study examines the beliefs, attitudes, and opinions of public high school principals on distributed leadership within a context of accountability. In addition, it investigates their trust levels. The study of subjectivity can be employed utilizing a systematic mixed-methods approach called Q technique. This methodology has the power to reveal the shared viewpoints or intersubjectivity and models held by public high school principals. Data were analyzed from 28 suburban New York public high school principals located in Nassau, Suffolk, Rockland, or Westchester counties concerning their beliefs regarding the potential barriers and impediments in distributing leadership responsibilities within the context of heightened accountability. In addition, it assessed their trust levels as these levels related to distributing their leadership. This study identified and examined 3 models of shared viewpoints held by public high school principals. Background characteristics were utilized to describe the clusters of participating principals. These characteristics consisted of: years of experience as a public-school administrator, years of prior experience as a teacher, highest level of education, and decade graduated from high school. Information was also gathered regarding principals' beliefs in the effectiveness of distributed leadership. The 3 Q models revealed, consensus and disagreement. To identify and understand where changes in leadership must be made, it is necessary to research school leadership from an alternative perspective by understanding the intersubjectivity of high school principals. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]

Published
2019

19. Auxin-Mediated Modulation of Maize Rhizosphere Microbiome: Insights from AzospirillumInoculation and Indole-3-Acetic Acid Treatment

Author

Coniglio, Anahí, Larama, Giovanni, Nievas, Sofía, Cale, Natalie L., Mora, Verónica, Torres, Daniela, Lopez, Gastón, Donadio, Florencia, Rodriguez, Belén, Marin, Anelis, Rovere, Matias, Barra, Patricio Javier, Belmonte, Mark F., de Souza, Emanuel Maltempi, and Cassán, Fabricio

Abstract

Purpose: Auxins, especially indole-3-acetic acid (IAA), influences microbial physiology, but their effects on the plant microbiome are underreported. This study aimed to understand the impact of exogenously supplemented IAA or IAA produced by Azospirillum on maize rhizosphere microbiome. Methods: One-week-old maize seedlings were inoculated with Az39 (A. argentinense’s strain), Az39 + L-Trp (Azospirillum-produced IAA), L-Trp (rhizosphere-produced IAA), and exogenous IAA to study their effects on the maize microbiome. Rhizosphere samples were collected after 14 days for DNA extraction, sequencing via Illumina MiSeq, and bioinformatic analysis were made to explore prokaryotic community composition and predict metabolic functions. Results: Differences in the Shannon index were observed between Az39 inoculation and exogenous L-Trp application, and between Az39 inoculation and Az39 + L-Trp for phylogeny and observed features. Azospirillum inoculation influences on bacterial structure bacterial structure. Genus Actinospica and Bradyrhizobium were associated with IAA treatment, Rokubacteriales and Puia with L-Trp, and Cupriavidus and Pseudomonas with Az39 + L-Trp. Azospirillum and Sphingobium were linked to Az39 inoculation. We identified fifty microbial taxa following the exogenous application of IAA application and twenty-two with potential rhizosphere IAA production. Nitrogen fixation was the most abundant metabolic function in the prokaryotic rhizosphere. Conclusion: Our results show prokaryotic groups specifically increase in the maize rhizosphere following application of Azospirillum, the IAA produced by Azospirillum, or the rhizosphere community and the exogenous IAA. These groups could be considered specific markers of the IAA activity in the rhizosphere.

Published
2024
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26. Genetic, evolutionary and phylogenetic aspects of the plastome of annatto (Bixa orellana L.), the Amazonian commercial species of natural dyes

Author

Gomes Pacheco, Túlio, de Santana Lopes, Amanda, Monteiro Viana, Gélia Dinah, Nascimento da Silva, Odyone, Morais da Silva, Gleyson, do Nascimento Vieira, Leila, Guerra, Miguel Pedro, Nodari, Rubens Onofre, Maltempi de Souza, Emanuel, de Oliveira Pedrosa, Fábio, Otoni, Wagner Campos, and Rogalski, Marcelo

Published
2019
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31. Modulation of defence and iron homeostasis genes in rice roots by the diazotrophic endophyte Herbaspirillum seropedicae

Author

Brusamarello-Santos, Liziane Cristina Campos, Alberton, Dayane, Valdameri, Glaucio, Camilios-Neto, Doumit, Covre, Rafael, Lopes, Katia de Paiva, Zibetti Tadra-Sfeir, Michelle, Faoro, Helisson, Adele Monteiro, Rose, Barbosa-Silva, Adriano, John Broughton, William, Oliveira Pedrosa, Fabio, Wassem, Roseli, and Souza, Emanuel Maltempi de

Published
2019
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42. Nitrogen fixation control in Herbaspirillum seropedicae

Author

Chubatsu, Leda Satie, Monteiro, Rose Adele, de Souza, Emanuel Maltempi, de Oliveira, Marco Aurelio Schuler, Yates, Marshall Geoffrey, Wassem, Roseli, Bonatto, Ana Claudia, Huergo, Luciano Fernandes, Steffens, Maria Berenice Reynaud, Rigo, Liu Un, and Pedrosa, Fabio de Oliveira

Published
2012
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48. Controlling Protein Immobilization over Poly(3-hydroxybutyrate) Microparticles Using Substrate Binding Domain from PHA Depolymerase

Author

Dias, Isabela P., da Cunha, Regiane Stafim, Masaki, Ryu, Todo Bom, Maritza A., Ramos, Edneia A. S., dos Santos, Giovanna J. V. P., Furman, Giovanna, Lucena, Julia T., Jiacomini, Isabella G., Lo, Sze M., Schemczssen-Graeff, Zelinda, Beirão, Breno C. B., Zanata, Silvio M., Faria, Luiz M. de L., Gerhardt, Edileusa M., de Souza, Emanuel Maltempi, Müller-Santos, Marcelo, and Picheth, Guilherme F.

Abstract

Biointerface decoration with ligands is a crucial requirement to modulate biodistribution, increase half-life, and provide navigation control for targeted micro- or nanostructured systems. To better control the process of ligand functionalization over three-dimensional (3D) polyester surfaces, we report the characterization of hybrid proteins developed to enhance the anchoring efficiency over polymeric surfaces and preserve optimal spatial orientation: sfGFP, mRFP1, and the RBD proteins were attached to a polyester substrate binding domain (SBD) formed by the C-terminus region of PHA depolymerase. The binding ability was evaluated over poly(3-hydroxybutyrate) (PHB) microparticles (MP) and two-dimensional (2D) surfaces. The PHB interfaces revealed a high affinity toward the proteins linked with SBD, displaying higher protein contents compared to untagged proteins. The MP decorated with RBD-SBD exhibited limited MRC5 internalization and cytotoxicity without a significant impact caused by the RBD protein, suggesting that the system might be adapted for targeted drug delivery and vaccine applications.

Published
2025
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49. Characterization of glutamine synthetase from the ammonium-excreting strain HM053 of Azospirillum brasilense.

Author

Ghenov, Fernanda, Marques Gerhardt, Edileusa Cristina, Fernandes Huergo, Luciano, Oliveira Pedrosa, Fabio, Wassem, Roseli, and Maltempi Souza, Emanuel

Subjects
GLUTAMINE synthetase, AZOSPIRILLUM brasilense, ESCHERICHIA coli, AFFINITY chromatography, NITROGEN fixation, NITROGEN-fixing bacteria, GLUTAMINE
Abstract

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2022
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50. Modulation of Maize Rhizosphere Microbiota Composition by Inoculation with Azospirillum argentinenseAz39 (Formerly A. brasilenseAz39)

Author

Coniglio, Anahí, Larama, Giovanni, Molina, Romina, Mora, Verónica, Torres, Daniela, Marin, Anelis, Avila, Andrés Ignacio, Lede NoirCarlan, Coline, Erijman, Leonardo, Figuerola, Eva Lucía, de Souza, Emanuel Maltempi, and Cassán, Fabricio

Abstract

Azospirillumis one of the most important plant growths promoting rhizobacteria used in agriculture worldwide. However, few reports are available describing the effects of this bacterial genus on the inoculated plant microbiome. In order to determine whether A. argentinenseinoculation modifies the bacterial microbiota associated with the maize rhizosphere, we performed a high-throughput 16S rRNA gene sequence analysis under experimental controlled conditions. Rhizosphere metagenomic DNA was obtained from plants inoculated and non-inoculated with A. argentinenseAz39, and bulk soil was used as a reference treatment. Biodiversity, microbial community composition, co-occurrence network and predicted function analyses (FAPROTAX) were performed. Azospirillumwas the most abundant genus occurring in the rhizosphere of inoculated plants. Regarding the alpha diversity, a significant reduction in the bacteria evenness was observed in the inoculated rhizosphere. The beta diversity analysis showed a differential structure of the communities of each treatment. According to the LEfSe index, the three most abundant genera associated with Az39 inoculation were Burkholderia, Massiliaand Sphingobium. An increase in the relative abundance of some members of the Hyphomicrobiales(ex Rhizobiales) order was observed in inoculated plants. Co-occurrence networks showed a positive interaction between Azospirillumand Pseudomonasand a negative correlation with Hyphomicrobium. The FAPROTAX analysis associated Azospirilluminoculation with some functions related to chemoheterotrophy, phototrophy and the nitrogen cycle. Our results allowed us to conclude that Azospirillumis able to colonize the maize rhizosphere after inoculation and that this colonization process induces an increase in the relative abundance of beneficial bacterial genera, also commonly used as biofertilizers in agriculture.

Published
2022
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