Caracterização genômica (taxonomia e simbiose) e fenotípica (controle biológico de fitopatógenos) de bactérias isoladas de feijoeiro da Coleção SEMIA : revisão taxonômica da Ordem Rhizobiales (Hyphomicrobiales)

A Coleção SEMIA existe oficialmente desde 1975 e é referência internacional na área de inoculantes. Essa coleção mantém mais de 1.200 estirpes de bactérias isoladas de nódulos de 171 leguminosas de importância agrícola, das quais 98 são recomendadas para o uso em inoculantes. Grande parte da Coleção SEMIA foi identificada utilizando características bioquímicas, PCR baseada em elementos repetitivos, identificações sorológicas e de planta hospedeira, e, menor número, o sequenciamento parcial do gene do 16S rRNA. Entretanto, ainda faltam informações taxonômicas das estirpes SEMIA, com base nos métodos moleculares baseados em análise de genomas aceitos atualmente. Em vista disso, o presente trabalho se propôs a i) elucidar o potencial das estirpes SEMIA para o controle biológico de fungos patogênicos e ii) resolver problemas de taxonomia dentro da Coleção SEMIA e da própria ordem Rhizobiales (Hyphomicrobiales). O capítulo I, “Rhizobia for biological control of plant diseases”, é uma revisão sobre os mecanismos empregados para a eficácia dos rizóbios no biocontrole de doenças causadas por diferentes classes de fitopatógenos. O capítulo II, intitulado “Rhizobium strains in the biological control of the phytopathogenic fungi Sclerotium (Athelia) rolfsii on the common bean” é um artigo de pesquisa que avaliou 78 isolados de feijão da coleção de cultura SEMIA para identificar agentes de biocontrole contra o fitopatógeno S. rolfsii. Demonstramos que estirpes estirpes isoladas de nódulos podem ser fortes antagonistas ao crescimento S. rolfsii e ser eficazes no controle da doença provocada pelo mesmo à campo. No Capítulo III, “Reclassification of Ochrobactrum lupini as a later heterotypic synonym of Ochrobactrum anthropi based on whole-genome sequence analysis”, demonstramos com dados filogenéticos, genômicos, fenotípicos e quimiotaxonômicos que O. lupini deve ser considerado a mesma espécie de O anthropi. O Capítulo IV, “Genomic metrics applied to Rhizobiales (Hyphomicrobiales): species reclassification, identification of unauthentic genomes and false type strains”, apresenta a taxonomia atualizada da ordem Hyphomicrobiales, com base em 270.400 comparações analisadas com um corte de 95% de ANI para extrair clusters de genoma com alta identidade através do uso da ferramenta ProKlust descrita. Esse trabalho originou uma série de propostas de reclassificações taxonômicas, além da descoberta de acessos de genoma que não era das estirpes-tipo genuínas utilizadas para as respectivas descrições de “suas espécies”, bem como casos de uso indevido do termo “estirpe-tipo” no banco de dados. No Capítulo IV, "Analysis of 95+ genomes from the common-bean branch from SEMIA collection: new genomospecies, alternative nitrogenases, horizontal gene transfer events, and unexpected genera of nodule-associated bacteria", sequenciamos os genomas de 96 estirpes SEMIA, relatando 15 clusters de genoespécies, bem como, 12 genoespécies isoladas, que surgiram de 1.322.500 comparações de ANI em pares entre as estirpes SEMIA e 1.053 genomas pertencentes a Burkholderiaceae, Comamonadaceae, Mycobacteriaceae, Rhizobiaceae, e Xanthomonadaceae. As estirpes foram identificadas como pertencentes a nove espécies diferentes de Rhizobium, Agrobacterium radiobacter, Pararhizobium giardinii, Paraburkholderia fungorum e as espécies putativas associadas a nódulos Mycobacterium monacense, Stenotrophomonas maltophilia e Variovorax guangxiensis. Cerca de um terço da coleção foi identificado como novas espécies potenciais. A análise do pangenoma das estirpes SEMIA resultou em 50.221 clusters de genes contendo 604.752 genes. A presença de genes relacionados às nitrogenases alternativas foi detectada entre representantes pertencentes a M. monacense, P. fungorum e V. guangxiens, bem como nas novas espécies putativas G11 e G9. A presença de homólogos nifH foi exclusiva para 55 estirpes pertencentes a Rhizobium. A detecção de sobreposição com sequências extracromossômicas foi encontrada apenas entre representantes de Rhizobium e P. fungorum. Vários genes de transposase foram localizados a montante e a jusante dos operons nifHDKENX e nifHDKE detectados, indicando eventos de transferência horizontal. Uma ampla distribuição filogenética foi encontrada no nível da família e um número notável (≥40) de genes transferidos putativos foram encontrados especialmente entre 12 estirpes, incluindo eventos de transferência putativos de outros domínios, como a família botânica Euphorbiaceae, Aspergillaceae e Siphoviridae. Conjuntos de genes biossintéticos putativos foram identificados. A reclassificação de mais de 25 espécies bacterianas também foi proposta com base nas comparações entre os genomas das estirpes-tipo.The SEMIA Collection has officially existed since 1975 and is an international reference in the field of inoculants. This collection holds more than 1,200 strains of bacteria isolated from the nodules of 171 legumes of agricultural importance, 98 of which are recommended for use in inoculants. A large part of the SEMIA Collection was identified using biochemical characteristics, PCR based on repetitive elements, serological and host plant identification, and, to a lesser extent, the partial sequencing of the 16S rRNA gene. However, taxonomic information on SEMIA strains is still lacking, based on currently accepted molecular genome-based methods. In view of this, the present work aimed to i) elucidate the potential of SEMIA strains for the biological control of pathogenic fungi and ii) solve taxonomy problems within the SEMIA Collection and the order Rhizobiales (Hyphomicrobiales) itself. Chapter I, “Rhizobia for biological control of plant diseases”, is a review regarding rhizobial mechanisms and efficacy to biocontrol diseases caused by different classes of plant pathogens. Chapter II, entitled “Rhizobium strains in the biological control of the phytopathogenic fungi Sclerotium (Athelia) rolfsii on the common bean” is a research article that evaluated 78 common bean isolates from SEMIA culture collection to identify biocontrol agents against the plant pathogen S. rolfsii. We demonstrated that root-isolated strains can be strong antagonists to S. rolfsii growth and be effective in controlling the disease caused by this pathogen in the field. In the Chapter III, “Reclassification of Ochrobactrum lupini as a later heterotypic synonym of Ochrobactrum anthropi based on whole-genome sequence analysis”, we demonstrated with phylogenetic, genomic, phenotypic, and chemotaxonomic data that O. lupini should be considered the same species of O. anthropi. The Chapter IV, “Genomic metrics applied to Rhizobiales (Hyphomicrobiales): species reclassification, identification of unauthentic genomes and false type strains”, presents the updated taxonomy of the order Hyphomicrobiales, based on 270,400 comparisons analyzed with a 95% ANI cut-off to extract high identity genome clusters using the described ProKlust tool. This work has led to a series of proposals for taxonomic reclassifications, in addition to discover of genome accessions that are not from the genuine type strains used for the respective species descriptions as well as cases of misuse of the term “type strain”. In the Chapter IV, “Analysis of 95+ genomes from the common-bean branch from SEMIA collection: new genomospecies, alternative nitrogenases, horizontal gene transfer events, and unexpected genera of nodule-associated bacteria”, we sequenced the genomes from 96 SEMIA strains, reporting 15 genospecies clusters as well as 12 isolated genospecies that arised from the 1,322,500 ANI pairwise comparisons between the SEMIA strains and 1,053 genomes belonging to Burkholderiaceae, Comamonadaceae, Mycobacteriaceae, Rhizobiaceae, and Xanthomonadaceae. The strains were identified as belonging to nine different Rhizobium species, Agrobacterium radiobacter, Pararhizobium giardinii, Paraburkholderia fungorum and the putative nodule-associated species Mycobacterium monacense, Stenotrophomonas maltophilia, and Variovorax guangxiensis. Around one-third of the collection were identified as new potential species. The pangenome analysis of SEMIA resulted in 50,221 gene clusters containing 604,752 genes. The presence of alternative nitrogenases relatedgenes was detected among representatives belonging to M. monacense, P. fungorum and V. guangxiens, as well as in the putative new species G11 and G9. The presence of nifH homologs was as exclusive to 55 strains belonging to Rhizobium. The detection of overlap with extrachromosomal sequences was found only among representatives from Rhizobium and P. fungorum. Multiple transposase genes were located upstream and downstream of the detected nifHDKENX and nifHDKE operons, indicating HGT events. A wide phylogenetic distribution was found at the family level and an outstanding number (≥40) of putative transferred genes were found especially among 12 strains, including putative transfer events from other Domains such as the botanical family Euphorbiaceae, Aspergillaceae, and Siphoviridae. Putative biosynthetic gene clusters were identified. Reclassification of over 25 bacterial species was also proposed based on the comparisons between the type-strain genomes

Rhizobium spp. para o controle biológico do fungo fitopatogênico Sclerotium (Athelia) rolfsii no feijoeiro (Phaseolus vulgaris L.)

Rizóbios são bactérias fixadoras de nitrogênio utilizadas com sucesso como inoculante microbiano para diminuir a utilização de fertilizantes nitrogenados no cultivo do feijoeiro (Phaseolus vulgaris L.) e outras leguminosas. Sclerotium rolfsii (sin. Athelia rolfsii) é um fungo onipresente que causa perdas severas em culturas importantes, inclusive em espécies de Phaseolus. Assim, o objetivo deste estudo foi avaliar a coleção de Rhizobium SEMIA para identificar o primeiro agente rizobial para o biocontrole da doença promovida por S. rolfsii no feijoeiro. Duplas culturas foram primeiramente realizadas para identificar propriedades de biocontrole entre as estirpes. Entre as 151 estirpes SEMIA testadas, 33 (~22%) mostraram atividade antagonista, sendo 16 delas capazes de % do crescimento micelial. As estirpes antagonistas produziram de 1,2 a 36,5 -1 de ácido indol-acético (IAA), um fitohormônio mais conhecido por promover o crescimento de plantas do que por inibir diretamente patógenos. Contudo, obteve-se um r=0,447 (p=0,011) entre a produção de IAA das estirpes antagonistas e a capacidade de inibição do micélio. As estirpes SEMIA 436, 4077, 4088 e 460 foram produtoras de sideróforos, e a atividade antagonista de SEMIA 4088 pode ser, em parte, relacionada a isso. Além de compostos antimicrobianos difusíveis no meio de cultura, SEMIA 460 também inibiu 45% do crescimento micelial através da produção de compostos voláteis. A análise do 16S rRNA possibilitou a identificação das estirpes SEMIA 456, 4026, 436, 439, 4032, 460, 4085, 4080, 4077 e 4088 como Rhizobium spp. Considerando o alto grau de conservação do 16S rRNA dentro do gênero Rhizobium, as linhagens SEMIA 436 e 439 apresentaram similaridades menores que 98,65% com o banco de dados, possivelmente representando um novo táxon. Apesar de terem sido isoladas de nódulos de feijão, as estirpes SEMIA 436, 439, 456, 4026 e 4032 foram alocadas em um ramo filogenético com estirpes de Rhizobium tumorigênicas (agrobacteria). Finalmente, para testar a eficiência de biocontrole das estirpes antagonistas selecionadas, plantas de feijão foram individualmente inoculadas e cultivadas em vasos com solo infectado com S. rolfsii. Para os parâmetros i) porcentagem de doença e ii) massas secas da parte área os tratamentos com SEMIA 4032, 4077, 4088, 4080, 4085 ou 439 não apresentaram diferenças estatisticamente significativas quando comparadas com o controle (plantas de feijão cultivadas em solo não infectado), demonstrando a grande potencialidade destas estirpes no controle biológico de S. rolfsii mediante inoculação de sementes de feijão.Rhizobia are nitrogen-fixing bacteria successfully used as microbial inoculant attempting to diminish synthetic nitrogen fertilizers inputs on the common bean (Phaseolus vulgaris L.) and others legume crops. Sclerotium rolfsii (syn. Athelia rolfsii) is a ubiquitous fungus that causes several losses on important crops, including Phaseolus species. In this way, the aim of this study was to evaluate SEMIA Rhizobium Culture Collection to identify the first rhizobial biocontrol agent for the S. rolfsii-promoted disease on the common bean. Dual cultures were first performed to screening strains for biocontrol proprieties. Among of the 151 SEMIA strains, 33 (~22%) of them showed antagonistic activity on dual cultures % of mycelial growth. Antagonistic -1 of indole-acetic acid (IAA), a phytohormone best known to promote plant growth than to direct inhibit plant pathogens. However, a r=0.447 (p=0.011) was obtained between antagonistic strains IAA production and mycelium inhibition ability. Strains SEMIA 436, 4077, 4088 and 460 were siderophore producers, and SEMIA 4088 antagonistic activity can be related to this. Besides antimicrobial diffusible compounds, SEMIA 460 inhibited 45% of mycelial growth through volatiles compounds production. Analysis of 16S rRNA identified strains SEMIA 456, 4026, 436, 439, 4032, 460, 4085, 4080, 4077 and 4088 as Rhizobium spp. Considering the high degree of 16S rRNA conservation in Rhizobium genus. SEMIA 436 and 439 were found to represent new taxa for presenting gene similarities less than 98.65% with the database. Despite being isolated from nodules, SEMIA 436, 439, 456, 4026 and 4032 were placed in a phylogenetic branch with tumorigenic Rhizobium (agrobacteria). Finally, to evaluate biocontrol efficiency of the selected antagonists strains, common bean plants were individually inoculated and grown in pots with S. rolfsii infected soil. For the parameters i) disease percentage and ii) shoot dry masses, treatments with SEMIA 4032, 4077, 4088, 4080, 4085 and 439 were not found with statistically significant differences from the control (plants grown on uninfected soil), demonstrating the great potentiality of these strains for biological control of S. rolfsii through inoculation of common bean seeds

Plant growth-promoting bacteria effect in withstanding drought in wheat cultivars

Plant growth-promoting bacteria (PGPB) have been used as biofertilizer. However, considering the specificity of the plant-bacteria interaction, the effect of PGPB inoculation in wheat under water stress is still poorly understood. The aim of this work was to evaluate wheat genotypes under water shortage inoculated with Azospirillum brasilense and Herbaspirillum seropedicae, with and without nitrogen fertilization. Therefore, samples for relative water content (RWC) and membrane stability index (MSI) evaluations were collected at the 1st and 8th days of a total water restriction at booting stage. In addition, biomass, total nitrogen (TN) and yield parameters were determined at the harvesting. As results, genotypes showed a distinct performance. RWC and MSI data revealed that A. brasilense and H. seropedicae inoculation are able to lead CD 120 to drought tolerance. In addition, grain index was improved in all conditions where H. seropedicae was present under both different water regimes. H. seropedicae with nitrogen fertilizer also increased grain yield under water shortage regime. Furthermore, A. brasilense with nitrogen fertilizer was also able to improve 1000-grain mass of plants under water shortage. Frontana exhibited the maintenance of cellular integrity and RWC only when H. seropedicae and with both bacteria plus nitrogen were applied, however this cultivar did not present differences in terms of biomass, TN or productivity. These results pointed out H. seropedicae as promising to inoculation in cereals and CD120 as a good plant model to study plant-bacteria interaction

Genomic and phylogenomic insights into the family Streptomycetaceae lead to the proposal of six novel genera

The family Streptomycetaceae is a large and diverse family within the phylum Actinomycetota . The members of the family are known for their ability to produce medically important secondary metabolites, notably antibiotics. In this study, 19 type strains showing low 16S rRNA gene similarity (<97.3 %) to other members of the family Streptomycetaceae were identified and their high genetic diversity was reflected in a phylogenomic analysis using conserved universal proteins. This analysis resulted in the identification of six distinct genus-level clades, with two separated from the genus Streptacidiphilus and four separated from the genus Streptomyces . Compared with members of the genera Streptacidiphilus and Streptomyces , average amino acid identity (AAI) analysis of the novel genera identified gave values within the range of 63.9–71.3 %, as has been previously observed for comparisons of related but distinct bacterial genera. The whole-genome phylogeny was reconstructed using PhyloPhlAn 3.0 based on an optimized subset of conserved universal proteins, the results of AAI and percentage of conserved proteins (POCP) analyses indicated that these phylogenetically distinct taxa may be assigned to six novel genera, namely Actinacidiphila gen. nov., Mangrovactinospora gen. nov., Peterkaempfera gen. nov., Phaeacidiphilus gen. nov., Streptantibioticus gen. nov. and Wenjunlia gen. nov

Genome-based reclassification of azospirillum brasilense SP245 as the type strain of azospirillum baldaniorum sp. nov

Azospirillum sp. strain Sp245T, originally identified as belonging to Azospirillum brasilense, is recognized as a plant-growth-promoting rhizobacterium due to its ability to fix atmospheric nitrogen and to produce plant-beneficial compounds. Azospirillum sp. Sp245T and other related strains were isolated from the root surfaces of different plants in Brazil. Cells are Gram-negative, curved or slightly curved rods, and motile with polar and lateral flagella. Their growth temperature varies between 20 to 38 °C and their carbon source utilization is similar to other Azospirillum species. A preliminary 16S rRNA sequence analysis showed that the new species is closely related to A. brasilense Sp7T and A. formosense CC-Nfb-7T. Housekeeping genes revealed that Azospirillum sp. Sp245T, BR 12001 and Vi22 form a separate cluster from strain A. formosense CC-Nfb-7T, and a group of strains closely related to A. brasilense Sp7T. Overall genome relatedness index (OGRI) analyses estimated based on average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) between Azospirillum sp. Sp245T and its close relatives to other Azospirillum species type strains, such as A. brasilense Sp7T and A. formosense CC-Nfb-7T, revealed values lower than the limit of species circumscription. Moreover, core-proteome phylogeny including 1079 common shared proteins showed the independent clusterization of A. brasilense Sp7T, A. formosense CC-Nfb-7T and Azospirillum sp. Sp245T, a finding that was corroborated by the genome clustering of OGRI values and housekeeping phylogenies. The DNA G+C content of the cluster of Sp245T was 68.4–68.6%. Based on the phylogenetic, genomic, phenotypical and physiological analysis, we propose that strain Sp245T together with the strains Vi22 and BR12001 represent a novel species of the genus Azospirillum, for which the name Azospirillum baldaniorum sp. nov. is proposed. The type strain is Sp245T (=BR 11005T=IBPPM 219T) (GCF_007827915.1, GCF_000237365.1, and GCF_003119195.2).Fil: Ferreira, Natalia Dos Santos. Universidade Federal Rural Do Rio de Janeiro; BrasilFil: Sant´Anna, Fernando Hayashi. Universidade Federal do Rio Grande do Sul; BrasilFil: Reis, Veronica Massena. Ministerio da Agricultura Pecuaria e Abastecimento de Brasil. Empresa Brasileira de Pesquisa Agropecuaria; BrasilFil: Ambrosini, Adriana. Universidade Federal do Rio Grande do Sul; BrasilFil: Volpiano, Camila Gazolla. Universidade Federal do Rio Grande do Sul; BrasilFil: Rothballer, Michael. Helmholtz Center Munich German Research Center For Environmental Health; AlemaniaFil: Schwab, Stefan. Ministerio da Agricultura Pecuaria e Abastecimento de Brasil. Empresa Brasileira de Pesquisa Agropecuaria; BrasilFil: Baura, Valter Antonio. Universidade Federal do Paraná; BrasilFil: Balsanelli, Eduardo. Universidade Federal do Paraná; BrasilFil: Pedrosa, Fabio de Oliveira. Universidade Federal do Paraná; BrasilFil: Passaglia, Luciane Maria Pereira. Universidade Federal do Rio Grande do Sul; BrasilFil: de Souza, Emanuel Maltempi. Universidade Federal do Paraná; BrasilFil: Hartmann, Anton. Ludwig Maximilians Universitat; AlemaniaFil: Cassan, Fabricio Dario. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigaciones Agrobiotecnológicas - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Agrobiotecnológicas; ArgentinaFil: Zilli, Jerri Edson. Ministerio da Agricultura Pecuaria e Abastecimento de Brasil. Empresa Brasileira de Pesquisa Agropecuaria; Brasi

Soil-plant-microbiota interactions to enhance plant growth

The nature of the soil is shaped by the presence of roots and the soil microbiota. Bacteria, archaea and fungi profoundly alter plant growth and, in turn, depend on root exudation of carbon-rich and energy-yielding compounds. The microbial communities act as facilitators of plant processes by secreting plant growth regulators, solubilizing minerals, providing N for plant growth, altering plant immune responses and competing with plant pathogens. Characterizing and engineering the processes driven by the multiple microbial taxa that make up a “plant growth-promoting soil” represents an ecologically friendly solution that may lead to unprecedented increases in agronomic efficiency. This review outlines the characteristics of soil-plant-microbiota interactions that would lead to enhanced plant growth and the importance of characterizing the soil microbial communities with metabarcoding and shotgun metagenomics allied to machine learning analytics. Although much is still needed to be understood about soil microbial ecology, it is possible to choose the best soil management practices to take advantage of beneficial microbial activity with our current knowledge

Plant growth-promoting bacteria effect in withstanding drought in wheat cultivars

Plant growth-promoting bacteria (PGPB) have been used as biofertilizer. However, considering the specificity of the plant-bacteria interaction, the effect of PGPB inoculation in wheat under water stress is still poorly understood. The aim of this work was to evaluate wheat genotypes under water shortage inoculated with Azospirillum brasilense and Herbaspirillum seropedicae, with and without nitrogen fertilization. Therefore, samples for relative water content (RWC) and membrane stability index (MSI) evaluations were collected at the 1st and 8th days of a total water restriction at booting stage. In addition, biomass, total nitrogen (TN) and yield parameters were determined at the harvesting. As results, genotypes showed a distinct performance. RWC and MSI data revealed that A. brasilense and H. seropedicae inoculation are able to lead CD 120 to drought tolerance. In addition, grain index was improved in all conditions where H. seropedicae was present under both different water regimes. H. seropedicae with nitrogen fertilizer also increased grain yield under water shortage regime. Furthermore, A. brasilense with nitrogen fertilizer was also able to improve 1000-grain mass of plants under water shortage. Frontana exhibited the maintenance of cellular integrity and RWC only when H. seropedicae and with both bacteria plus nitrogen were applied, however this cultivar did not present differences in terms of biomass, TN or productivity. These results pointed out H. seropedicae as promising to inoculation in cereals and CD120 as a good plant model to study plant-bacteria interaction

Efeito de bactérias promotoras de crescimento vegetal na resistência à seca em cultivares de trigo

This work evaluated wheat genotypes under water deficit inoculated with Azospirillum brasilense and Herbaspirillum seropedicae, with and without nitrogen fertilization. Samples of the plants were collected to evaluate its relative water content (RWC) and membrane stability index (MSI) at the 1st and 8th day of total water restriction at the booting stage. The plant biomass, total nitrogen (TN) and grain yield were determined at harvesting. The genotypes showed different performances. According to the results of RWC and MSI, inoculation with A. brasilense and H. seropedicae can make the cultivar CD-120 more tolerant to drought. Grain index was improved with H. seropedicae in all conditions and water regimes. H. seropedicae with nitrogen fertilization increased grain yield under water deficit. A. brasilense with nitrogen fertilization improved the 1000-grain weight of plants under water deficit. The cultivar Frontana maintained its cellular integrity and RWC with nitrogen fertilization combined with H. seropedicae and with both bacteria, however the shoot and root fresh and dry weights, TN and yield of this cultivar showed no differences. These results show the inoculation with H. seropedicae as promising to cereals, and the cultivar CD-120 as a good plant model to study plant-bacteria interaction.Este trabalho avaliou genótipos de trigo em condições de escassez de água inoculados com Azospirillum brasilense e Herbaspirillum seropedicae, com e sem adubação nitrogenada. Para tanto, amostras para determinação do conteúdo relativo de água na folha (CRA) e do índice de estabilidade da membrana (IEM) foram coletadas no 1º e 8º dias de uma restrição total de água no estágio de emborrachamento. Além disso, os parâmetros de biomassa, nitrogênio total (NT) e produtividade foram determinados na colheita. Como resultado, os genótipos mostraram um desempenho distinto. Os dados de CRA e IEM revelaram que a inoculação de A. brasilense e H. seropedicae são capazes de conduzir o genótipo CD 120 à tolerância à seca. Além disso, o índice de grãos foi melhorado em todas as condições em que H. seropedicae estava presente em ambos os diferentes regimes de água. O H. seropedicae inoculado juntamente com adubo nitrogenado também aumentou o rendimento de grãos sob o regime de escassez de água. Além disso, A. brasilense inoculado com adubo nitrogenado foi capaz de melhorar a massa de 1000 grãos de plantas sob escassez de água. O cultivar Frontana exibiu a capacidade de manutenção do IEM e CRA apenas quando H. seropedicae ou ambas as bactérias mais adubo nitrogenado foram aplicados, no entanto, esta cultivar não apresentou diferenças em termos de massa fresca e seca da parte aérea e radicular, NT ou produtividade. Estes resultados apontaram H. seropedicae como promissora para inoculação em cereais e o CD120 como um bom modelo de planta para estudar a interação de plantas e bactérias