ABSTRACT In the composition of the soil microbiome, there are numerous microorganisms capable of promoting plant growth, better known as plant growth-promoting microorganisms. The study aimed to determine the effects of multifunctional microorganisms, alone or in combination, on shoot, root, and total biomass production, gas exchange, macronutrient content, yield components, and grain yield of corn plants. The experiment was carried out in a greenhouse in a completely randomized design, with four replications. Twenty-six treatments consisted of isolated or combined microbiolization of corn seeds with the rhizobacteria Bacillus sp. (BRM 32109, BRM 32110, and BRM 63573), Burkholderia cepacea (BRM 32111), Pseudomonas sp. (BRM 32112), Serratia marcenses BRM 32113, Serratia sp. (BRM 32114), Azospirillum brasilense (Ab-V5), and Azospirillum sp. (BRM 63574), an isolated of fungus Trichoderma koningiopsis (BRM 53736), and a control treatment (without the application of microorganisms). At seven and 21 days, two more applications of the same treatments were carried out in the soil and the plants, respectively. The microorganisms applied alone or in combination promoted significant increases of 49% in corn plant biomass, 30% in gas exchange, 36% in macronutrient content, and 33% in grain yield. Isolates BRM 32114, Ab-V5, BRM 32110, and BRM 32112 and the combinations BRM 32114 + BRM 53736, BRM 63573 + Ab-V5, and BRM 32114 + BRM 32110 promoted better benefits to corn, allowing us to infer that the use of beneficial microorganisms significantly affects the development of corn plants.

RESUMO Na composição do microbioma do solo tem-se inúmeros microrganismos, capazes de promover o crescimento vegetal, mais conhecidos como microrganismos promotores de crescimento de plantas. Objetivamos determinar os efeitos de microrganismos multifuncionais, isoladamente ou em combinação, na produção de biomassa da parte aérea, raiz e total, nas trocas gasosas, no teor de macronutrientes, componentes de produção e produtividade de grãos de plantas de milho. O experimento foi conduzido em casa de vegetação em delineamento inteiramente casualizado, com quatro repetições. Utilizou-se 26 tratamentos que consistiram na microbiolização isolada ou combinada das sementes de milho com as rizobactérias BRM 32109, BRM 32110 e BRM 63573 (Bacillus sp.), BRM 32111 (Burkholderia cepacea), BRM 32112 (Pseudomonas sp.), BRM 32113 (Serratia marcenses) and BRM 32114 (Serratia sp.), Ab-V5 (Azospirillum brasilense) e BRM 63574 (Azospirillum sp.), um isolado de fungo BRM 53736 (Trichoderma koningiopsis) e um tratamento controle (sem a aplicação de microrganismos). Aos sete e 21 dias, foram realizadas mais duas aplicações dos mesmos tratamentos, no solo e nas plantas, respectivamente. Os microrganismos aplicados isoladamente ou em combinação promoveram incrementos significativos de 49% na biomassa das plantas de milho, 30% nas trocas gasosas, 36% no teor de macronutrientes e 33% na produtividade. Os isolados BRM 32114, Ab-V5, BRM 32110 e BRM 32112 e as combinações BRM 32114 + BRM 53736, BRM 63573 + Ab-V5 e 32114 + BRM 32110 promoveram melhores benefícios ao milho, nos permitindo inferir que o uso de microrganismos benéficos afetam significativamente o desenvolvimento das plantas de milho.

RESUMO As inoculações em plantas com mix de microrganismos benéficos podem melhorar significativamente o crescimento dessas e contribuir para uma agricultura sustentável. Entretanto, ainda existem questionamentos se inoculações em mix poderiam proporcionar resultados ainda melhores do que na forma isolada, sendo necessários estudos adicionais. Desta forma, objetivou-se avaliar os efeitos de microrganismos benéficos no desempenho da cultura do arroz de terras altas, em experimento conduzido em casa de vegetação, usando delineamento inteiramente casualizado, com três repetições e 26 tratamentos, que consistiram da inoculação de microrganismos isolados ou em mix de Bacillus sp., Serratia sp., Azospirillum sp., Bacillus spp., Azospirillum brasilense (Ab-V5) e um pool de Trichoderma asperellum, além do tratamento controle (sem aplicação de microrganismos). Os microrganismos afetaram significativamente as trocas gasosas, produção de biomassa e teor de nutrientes em plantas de arroz de terras altas. Os tratamentos mix BRM32114 + pool de T. asperellum, e Ab-V5 + pool de T. asperellum, foram mais efetivos, com destaque para as variáveis de trocas gasosas e teor de nutrientes. O tratamento mix 1301 + Ab-V5, apresentou maiores médias para produção de biomassa, com diferença significativa em relação ao tratamento controle.

ABSTRACT Inoculating plants with a mix of beneficial microorganisms can significantly improve plant growth and contribute to sustainable agriculture. However, it is unclear if mixed inoculations of microorganisms provide better results than inoculations of a single beneficial microorganism. Thus, the objective of this study was to evaluate the effects of beneficial microorganisms on the performance of upland rice in a greenhouse experiment using a completely randomized design with three repetitions and 26 treatments. The treatments consisted of inoculations of Bacillus sp. (BRM32110), Serratia sp. (BRM32114), Azospirillum sp. (1381), Bacillus sp. (1301), A. brasilense (Ab-V5) and a pool of Trichoderma asperellum in isolation or in a mixture in addition to a control treatment (without application of microorganisms). Microorganisms significantly affected gas exchange, biomass production and nutrient accumulation in upland rice plants. The mixed treatments of BRM32114 + pool of T. asperellum and Ab-V5 + pool of T. asperellum were more effective than the other treatments, with improved gas exchange variables and nutrient concentration. The 1301 + Ab-V5 mixed treatment showed higher averages for biomass production than the other treatments, and these values were significantly different from those of the control treatment.

This study aimed to assess the ability of silicon (Si) to potentiate defense enzyme activities in rice leaf sheaths and thus reduce sheath blight, caused by Rhizoctonia solani, development. Rice plants of BR-Irga 409 and Labelle cultivars were grown in a hydroponic solution containing 0 (-Si) or 2 mM (+Si) Si and inoculated with R. solani. Silicon concentration in the leaf sheaths was significantly higher in the +Si plants than the -Si plants by 727% for BR-Irga 409 and 714% for Labelle. The area under relative lesion expansion progress curve was significantly lower for +Si plants than -Si plants, by 34.2% for BR-Irga 409 and 30.59% for Labelle. Increases in the activities of phenylalanine ammonia-lyases, peroxidases, polyphenoloxidases and chitinases in the leaf sheaths of plants supplied with Si, especially of those from BR-Irga 409, led to reduced progress of sheath blight lesions.

Crude extract of an isolate of the fungus Sarocladium oryzae (CNPAF So 20G), containing the antimicrobial cerulenin, was produced and its antagonistic potential on the rice blast pathogen Magnaporthe oryzae was asessed. Cerulenin was detected in crude extract of S. oryzae through thin layer chromatography showing a Rf value of 0.63. The quantity of cerulenin in the crude extract was 237 µg.mL-1. The in vitro inhibition of germination and appressorial formation of M. oryzae was assessed on an artificial hydrophobic surface, using eight different doses of cerulenin ranging from 0.05 to 30.0 µg.mL-1. The LD50 values calculated based on the Probit-log analysis for germination and appressorial formation were 1.298 ± 0.123 µg.mL-1 and 0.0705 ± 0.0062 µg.mL-1 of cerulenin, respectively. The 30.0 µg.mL-1 of cerulenin dose inhibited 98% and 99%, germination and appressorial formation, respectively. The mode of action of cerulenin was studied by staining conidia with Calcofluor White and fluorescent microscopy showing its effect on plasma membrane. Crude extract of S. oryzae suppressed 63% of rice blast disease in greenhouse conditions. The results indicate that a product based on cerulenin and/or S. oryzae has a great potential to be used in biological control of rice blast.

A collection of Gaeumannomyces graminis var. graminis isolates obtained from symptomatic rice and grass plants in central and northern Brazil were studied in regard to pathogenicity on rice and cultural characteristics. For all isolates, only one type of lobed hyphopodia was observed both in the field and artificially inoculated plants. Perithecia were formed on artificial media and inoculated leaf sheaths. Hyphopodia were formed from ascosporic germ tubes. The hyphae under moist stress conditions produced dark brown chlamydospores that were initially hyaline. Large variation in the number of chlamydospores produced and duration of perithecia formation was observed among the isolates. Pathogenicity assays showed that 60-day old rice plants were more susceptible than 35-day old plants. The isolates from rice and grasses varied significantly in regard to disease severity on both rice seedlings and adult rice plants. In general, the isolates from rice were more aggressive than the isolates from grasses. Spontaneous infection of rice plants by ascosporic inoculum from perithecia on rice stubbles was observed in the greenhouse, suggesting their role as a source of primary inoculum in the field, which deserves further investigation.

Foi constatada a ocorrência de uma epidemia de brusone, na safra 1998/99 nas cultivares de arroz (Oryza sativa) irrigado Epagri 108 e 109, nos municípios de Lagoa da Confusão e Duerê, do Estado do Tocantins, na safra 1998-99. Foram utilizados "DNA fingerprinting" e análise fenotípica de virulência para determinar a diversidade entre isolados de Pyricularia grisea coletados nestas duas cultivares no ano de epidemia. A análise de DNA dos isolados foi realizada utilizando rep-PCR para amplificação das sequências entre os elementos repetitivos Pot2. Dois grupos distintos de bandas polimórficas ou linhagens foram identificados entre os 53 isolados coletados em nove diferentes lavouras comerciais. O padrão de virulência dos isolados foi estudado através de inoculações artificiais em 32 genótipos, em casa de vegetação. O dendrograma construído com base nos dados de virulência fenotípica, permitiu distinguir apenas um grupo, considerando o nível de similaridade de 77%. O patótipo predominante IB-45 foi representado por 47 dos 53 isolados correspondendo a 83%. Foram identificados quatro patótipos (IB-1, IB-9, IB-13 e IB-41) entre isolados coletados nestas duas cultivares. Não houve relação entre agrupamento dos isolados por rep-PCR e patótipos. Os resultados ainda demonstraram que os isolados de P. grisea provenientes das cultivares Epagri 108 e 109 apresentaram estreita diversidade fenotípica e genética. A epidemia da brusone nestas duas cultivares, um ano após o lançamento, pode ser atribuída ao surgimento do novo patótipo IB-45 ou à sua preexistência em baixa freqüência e rápido aumento no campo.

An epidemic of rice (Oryza sativa) blast occurred on cultivars Epagri 108 and 109 in the municipalities of Lagoa da Confusão and Duerê in the State of Tocantins, during the rice-growing season 1998-99. DNA fingerprinting and virulence phenotype analysis were utilized to determine the diversity of Pyricularia grisea isolates collected from these cultivars in one epidemic year. Rep-PCR analysis of isolates was done by using two primer sequences from Pot2. Two distinct fingerprint groups or lineages were identified among 53 isolates collected from nine different commercial fields. The virulence pattern of isolates retrieved from these two cultivars was analyzed in artificial inoculation tests utilizing 32 genotypes in the greenhouse. A dendrogram constructed from virulence phenotype data showed a single group considering 77% similarity level. The predominant pathotype IB-45 was represented by 47 of the 53 isolates corresponding to 83%. Four other pathotypes (IB-1, IB-9, IB-13 and IB-41) were identified at random among the isolates from these cultivars. There was no relation between rep-PCR grouping and pathotypes. The results showed that the isolates of P. grisea recovered from cultivars Epagri108 and 109 in farmers' fields had narrow phenotypic and genetic diversity. The blast outbreak on these two cultivars one year after their introduction could be attributed to the new pathotype IB-45 or its increase, which was hitherto existing in low frequency.

Foi estudada a diversidade patogênica de isolados de Pyricularia grisea coletados de 14 cultivares de arroz (Oryza sativa) de terras altas, em campos experimentais durante um período de cinco anos no Brasil. Foram realizadas inoculações em 32 genótipos com 85 isolados monospóricos em condições de casa de vegetação. Com base nas reações das oito diferenciadoras internacionais, onze patótipos de P. grisea foram identificados. Os patótipos internacionais predominantes foram IB-9 (56.4%), IB-1 (16.4%) e IB-41 (11.8%). Oito cultivares locais ('Carajás', 'Confiança', 'Maravilha', 'Primavera', 'Progresso', 'Caiapó', 'IAC-47' e 'IAC-201') foram utilizadas como diferenciadoras para descrever o padrão de virulência de isolados de P. grisea. Foram identificados 26 patótipos locais com base no tipo de reação nestas diferenciadoras, em contraste com os 11 patótipos internacionais. Os patótipos brasileiros mais predominantes, BB-21 e BB-41, representaram 28,2% e 17,6%, dos isolados testados, respectivamente. Isolados virulentos e avirulentos com a cultivar 'Primavera' foram encontrados dentro do patótipo IB-1. Os 14 isolados do patótipo IB-1 foram subdivididos em oito patótipos locais, BB-41, BB-13, BB-21, BB-9, BB-29, BB-61, BD-9 e BG-1. A virulência para as cultivares melhoradas como 'Canastra', 'Confiança', 'Carisma', 'Maravilha', 'Primavera' e 'Bonança' foi freqüente na população do patógeno. Alguns patótipos brasileiros que apresentaram reações diferenciais em cultivares comerciais poderão ser utilizados para incorporação de genes de resistência nas cultivares suscetíveis melhoradas para qualidade de grãos pelo método de melhoramento convencional.

A study was undertaken to examine the pathogenic diversity of Pyricularia grisea isolates retrieved from 14 upland rice (Oryza sativa) cultivars in experimental plots during a period of five years. Inoculations were performed on 32 genotypes with 85 monoconidial isolates under controlled greenhouse conditions. Based on the reaction pattern of eight international differentials, eleven pathotypes of P. grisea were identified. The predominant international races or pathotypes were IB-9 (56.4%), IB-1 (16.4%) and IB-41 (11.8%). A set of eight commercial upland rice cultivars ('Carajás', 'Confiança', 'Maravilha', 'Primavera', 'Progresso', 'Caiapó', 'IAC-47', 'IAC-201') was utilized as additional differentials for describing the virulence pattern of P. grisea. Twenty-six Brazilian pathotypes were identified on the basis of disease reaction on these differentials, in contrast to the 11 international pathotypes. The most predominant Brazilian pathotypes, BB-21 and BB-41 were represented by 28.2% and 17.6% of the isolates tested, respectively. Isolates virulent and avirulent to cultivar 'Primavera' were encountered within the pathotype IB-1. Utilizing Brazilian cultivars as differentials, the 14 isolates of the pathotype IB-1could be further classified into eight local pathotypes, BB-41, BB-13, BB-21, BB-9, BB-29, BB-61, BD-9 and BG-1. Virulence to improved rice cultivars 'Canastra', 'Confiança', 'Carisma', 'Maravilha', 'Primavera' and 'Bonança' was frequent in pathogen population. Some of the Brazilian pathotypes that showed differential reaction on commercial rice cultivars could be utilized for incorporating resistance genes in susceptible cultivars improved for grain quality, by conventional breeding methods.

Foram avaliados 39 híbridos de arroz (Oryza sativa) desenvolvidos a partir das linhagens 046I e IR 58025A com macho esterilidade genético citoplasmática derivado do citoplasma WA e seus restauradores, para resistência vertical a Pyricularia grisea. Os testes foram realizados em viveiro de brusone e em condições artificiais de inoculação com dois patotipos, em casa de vegetação. Em viveiro de brusone, todos os híbridos apresentaram reação suscetível variando de 5 a 9 em uma escala de 0 a 9. Reações compatíveis e incompatíveis à brusone nas folhas foram observadas para os dois patotipos IC-1 e IB-45, em inoculações controladas. A maioria dos híbridos foi resistente quando o restaurador utilizado como pai foi resistente. Entretanto, sete dos 25 híbridos F1 apresentaram reação suscetível mesmo quando um dos pais foi resistente para um patótipo. A resistência parcial de 11 híbridos e seus pais que apresentaram reação compatível foi analisada para resistência parcial. Foi observada interação diferencial entre isolados e genótipos para resistência parcial em relação a severidade e número de lesões esporulativas, indicando a natureza especifica da resistência parcial.

Thirty-nine rice (Oryza sativa) hybrids and their restorers were assessed for vertical resistance to Pyricularia grisea in the rice blast nursery, and in artificial inoculation tests with two pathotypes, under controlled greenhouse conditions. The hybrids were developed from cytoplasmic genetic male sterile lines 046I and IR 58025A, derived from WA cytoplasm. In the rice blast nursery all hybrids showed susceptible reaction varying from 5 to 9. Compatible and incompatible leaf blast reactions of hybrids to two pathotypes, IC-1 and IB-45, were observed in inoculation tests. A majority of the hybrids were resistant when the restorer was resistant. However, seven of the 25 F1 hybrids exhibited susceptible reactions even when one of the parents was resistant to a pathotype. The partial resistance of 11 hybrids and their parents that showed compatible reactions to two pathotypes was analyzed. Differential interaction between isolates and genotypes was observed for partial resistance in relation to both disease severity and lesion number indicating the specific nature of partial resistance.

O mal-do-pé em arroz (Oryza sativa) foi constatado em lavouras de terras altas nos municípios de Unaí (MG), Palmeiras (GO), Itaberaí (GO), Humaitá (AM) e em lavouras irrigadas nos Estados de Goiás, Tocantins e Rio Grande de Sul. O agente causal foi identificado como Gaeumannomyces graminis var. graminis baseado em características morfológicas, culturais e testes de patogenicidade utilizando diferentes isolados brasileiros. O método de inoculação e avaliação da doença em de casa de vegetação foi descrito. Este é o primeiro registro desta enfermidade na cultura do arroz no Brasil.

Crown sheath rot also known as black sheath rot has been found to occur in upland rice (Oryza sativa) in the municipalities of Unaí (MG), Palmeiras(GO), Itaberaí (GO), Humaitá (AM) and in flooded rice in the States of Goiás, Tocantins and Rio Grande de Sul. The causal agent was identified as Gaeumannomyces graminis var. graminis based on morphological and cultural characteristics of the fungus as well as pathogenicity tests conducted utilizing different Brazilian isolates. This constitutes the first report of the disease occurrence in rice in Brazil.

O gene Pi-ar confere resistência para a raça IB-45 de Pyricularia grisea no somaclone derivado de panículas imaturas da cultivar de arroz (Oryza sativa) Araguaia. A técnica RAPD foi usada para identificar marcadores ligados a este gene utilizando a análise de misturas segregantes. Inicialmente o DNA do pai doador resistente SC09 e da cultivar Araguaia foram analisados usando primers arbitrários. Dos 240 primers, 203 produziram produtos amplificados. O DNA dos pais e dos bulks resistente e suscetível da população F2 foram testados usando 48 primers que diferenciaram os pais resistente e suscetível. Enquanto oito primers diferenciaram o bulk resistente do suscetível bem como o somaclone SC09 e Araguaia, somente o primer OPC02 ('GTGAGGCGTC') estava fortemente ligado (1,7cM) ao gene de resistência do somaclone SC09.

The gene Pi-ar confers resistance to Pyricularia grisea race IB-45 in a somaclone derived from immature panicles of the susceptible rice (Oryza sativa) cultivar Araguaia. RAPD technique was used to identify molecular markers linked to this gene utilizing bulked segregant analysis. Initially, the two parental DNAs from the resistant donor SC09 and 'Araguaia' were analyzed using random primers. Of the 240 primers tested, 203 produced amplification products. The two parental DNAs along with the resistant and susceptible bulks of F2 population were screened using 48 primers that differentiated resistant and susceptible parents. Even though eight primers differentiated the resistant bulk from the susceptible bulk, as well as somaclone SC09 and 'Araguaia', only one primer, OPC02 ('GTGAGGCGTC'), was found to be tightly linked (1.7cM) to the resistance gene of somaclone SC09.

Seven sources of resistance to the two predominant races IB-1 and IB-9 of the rice blast pathogen Pyricularia grisea were selected based on leaf blast reaction in tests conducted under controlled greenhouse conditions. Crosses involving resistant and susceptible parents were made to study the inheritance of the disease reaction for different sources of resistance. The F1 and F2 progenies of all crosses, including backcrosses to resistant and susceptible parents, were tested for reaction to leaf blast. The data showed that resistance is controlled by one to three genes that segregate independently in most of the donors. Non-allelic interaction among resistance genes, including dominant epistasis, was identified.