Cleber Morais Guimarães

Identification of drought-responsive genes in roots of upland rice (Oryza sativa L)

BackgroundRice (Oryza sativa L.) germplasm represents an extraordinary source of genes that control traits of agronomic importance such as drought tolerance. This diversity is the basis for the development of new cultivars better adapted to water restriction conditions, in particular for upland rice, which is grown under rainfall. The analyses of subtractive cDNA libraries and differential protein expression of drought tolerant and susceptible genotypes can contribute to the understanding of the genetic control of water use efficiency in rice.ResultsTwo subtractive libraries were constructed using cDNA of drought susceptible and tolerant genotypes submitted to stress against cDNA of well-watered plants. In silico analysis revealed 463 reads, which were grouped into 282 clusters. Several genes expressed exclusively in the tolerant or susceptible genotypes were identified. Additionally, proteome analysis of roots from stressed plants was performed and 22 proteins putatively associated to drought tolerance were identified by mass spectrometry.ConclusionSeveral genes and proteins involved in drought-response, as well as genes with no described homologs were identified. Genes exclusively expressed in the tolerant genotype were, in general, related to maintenance of turgor and cell integrity. In contrast, in the susceptible genotype, expression of genes involved in protection against cell damage was not detected. Several protein families identified in the proteomic analysis were not detected in the cDNA analysis. There is an indication that the mechanisms of susceptibility to drought in upland rice are similar to those of lowland varieties.

Compactação do solo na cultura do feijoeiro. I: efeitos nas propriedades físico-hídricas do solo

O problema de compactacao do solo vem aparecendo sistematicamente na regiao do Cerrado, onde os sistemas convencionais de manejo do solo tem causado desagregacao excessiva da camada aravel, o encrostamento superficial e a formacao de camadas coesas ou compactadas (pe-de-grade ou pe-de-arado). Como alternativa, os agricultores adotaram o Sistema Plantio Direto; entretanto, em varias situacoes vem sendo relatadas ocorrencias de aumento da densidade do solo e diminuicao da macroporosidade, o que tem sido diagnosticado como compactacao, fazendo com que o agricultor seja obrigado a movimentar o solo. Este trabalho teve por objetivo verificar como a compactacao do solo afeta as suas propriedades fisicas e de transmissao de agua. Para isto, utilizaram-se colunas de solo compactadas artificialmente, para produzir densidades do solo de 1,0; 1,2; 1,4 e 1,6 kg dm-3. As propriedades de transmissao de agua foram determinadas com infiltrometros de tensao, para as cargas de pressao de -0,5; -2,0 e -6,0 cm de agua. O aumento da densidade do solo aumentou sua resistencia a penetracao e reduziu linearmente a porosidade total e a macroporosidade. Houve ainda, reducao no tamanho dos poros para o fluxo de agua, reduzindo a condutividade hidraulica do solo. Esta reducao foi mais acentuada na maior carga de pressao testada. Com a carga de pressao de -2,0 cm de agua, a reducao no tamanho dos poros foi parcialmente compensada com aumento do seu numero. O metodo do infiltrometro de tensao mostrou-se adequado em distinguir diferencas nas propriedades de transmissao de agua de um solo submetido a diferentes niveis de compactacao.

Compactação do solo na cultura do feijoeiro. II: efeito sobre o desenvolvimento radicular e da parte aérea

This study was conducted with the objective of verifying how soil compaction affects root and shoot development of a bean crop. The experiment was carried out in a greenhouse of Embrapa Rice & Beans, in Santo Antonio de Goias, GO, Brazil, in soil columns packed in PVC tubes 40 cm high and 25 cm of internal diameter. The soil columns were artificially compacted to provide soil bulk densities of 1.0, 1.2, 1.4 and 1.6 kg dm-3 in the 0 - 20 cm soil layer. Bean varieties Perola and BAT 477 were grown in the soil columns. The soil water potential was maintained between -35 and -10 kPa. The evaluations were made at 15, 30, 45, 60, and 72 days after emergence. The root dry matter, root length density, root thickness, leaf area, shoot dry matter, and specific leaf weight were evaluated. The increase in soil compaction negatively affected root and shoot development of bean, the effect being more expressive at bulk density values higher than 1.2 kg dm-3. Perola variety showed more root and shoot development than BAT 477 when there was no physical restriction in the soil for root development. BAT 477, however, was more rustic being less affected by soil compaction and showing higher leaf area and shoot dry matter under this situation.

Adaptação do feijoeiro comum (Phaseolus vulgaris L.) à seca

Realizou-se este trabalho tendo em vista o proposito de se estudar a adaptacao de genotipos de feijoeiro comum (Phaseolus vulgaris L.) a seca, como suporte a programas de melhoramento que visem a criacao de cultivares para regioes sujeitas a deficiencia hidrica, mediante a avaliacao do potencial da agua nas folhas e da resistencia difusiva estomatica. Adicionalmente avaliou-se a tecnica de medicao da temperatura do dossel pela termometria de infravermelho para inferir o estado hidrico da planta. Os genotipos Carioca e RAB 96 foram submetidos, dos 20 dias apos a emergencia ate a colheita, a dois tratamentos hidricos: irrigacao adequada e com deficiencia hidrica. Em geral, a cultivar Carioca manteve potenciais de agua na folha mais altos e tambem melhor capacidade de recuperacao hidrica, alem de apresentar resistencia difusiva estomatica e temperatura do dossel mais baixas que a linhagem RAB 96 sendo, portanto, melhor adaptada a seca. A temperatura do dossel correlacionou-se significativamente com o potencial da agua nas folhas e, devido a sua medicao ser rapida e nao-destrutiva, mostrou tratar-se de uma tecnica util no processo de selecao de genotipos para regioes sujeitas a deficiencia hidrica.

Adubação nitrogenada do arroz de terras altas no Sistema Plantio Direto

Este trabalho objetivou determinar a dose e o modo de aplicacao de nitrogenio (N) mais adequados para o arroz cultivado apos pastagem ou soja, sob Sistema Plantio Direto (SPD). Os experimentos foram conduzidos em 1999/2000, em Santo Antonio de Goias, GO, depois da pastagem de Brachiaria decumbens, e em Campo Verde, MT, apos soja. Foi utilizado o delineamento de blocos casualizados, em esquema fatorial 5 x 3. Os tratamentos consistiram de cinco doses de N (12 ou 7, 40, 80, 120 e 160 kg ha-1) combinadas com tres modos de aplicacao: totalmente na semeadura, metade na semeadura e metade na cobertura, e dois tercos na semeadura e um terco na cobertura. A dose de 12 kg de N ha-1 foi aplicada no experimento apos pastagem que a de 7 kg de N ha-1, em seguida a soja. O arroz apresentou maior resposta a adubacao nitrogenada apos pastagem e depois de soja. A resposta da produtividade do arroz ao N apos pastagem, dependeu do modo de aplicacao deste nutriente, sendo 100 kg ha-1 a dose economica de N para a aplicacao total na semeadura. Em seguida a soja, o modo de aplicacao nao afetou a produtividade do arroz, sendo 68 kg ha-1 a dose economica de N.

Escala de sonolência de Epworth na síndroma de apneia obstrutiva do sono: uma subjetividade subestimada

Excessive daytime sleepiness is a major symptom in obstructive sleep apnea syndrome (OSAS) and can be evaluated using both subjective and objective methods. The Epworth Sleepiness Scale (ESS) is a simple and validated questionnaire for assessing subjective daytime sleepiness in the context of sleep disorders. Although its subjective character may limit the accurate expression of daytime sleepiness, the clinical benefit of sequential ESS is clear and demonstrates how ESS scores evolve in individual patients and how these scores may relate to various parameters. In this context we compared the severity of daytime sleepiness reported at baseline visit with severity of baseline sleepiness assessed, retrospectively, after treatment with automatic positive airway pressure (APAP). We conducted a prospective study that included 66 patients evaluated in a sleep clinic diagnosed with OSAS. The diagnosis was confirmed by in-laboratory or portable sleep studies. Their mean age was 53.3 years and the majority were men (88%, n=58). The ESS was answered during the first interview (baseline daytime sleepiness). During follow-up visits, after APAP treatment, the patient was asked to assess baseline sleepiness, retrospectively, as well as post-treatment sleepiness. The mean baseline ESS score was 11.8, mean retrospective baseline ESS 15.4, with a mean difference of 3.55 (p<0.001 t-Test) and post-treatment ESS 7.3. There was no significant correlation between the difference in ESS score (baseline - retrospective baseline) with the average daily (hours) use of APAP, the apnea-hypopnea index (AHI), the minimal recorded SatO(2), disease duration, body mass index (BMI) and age. Our findings confirm that the severity of subjective sleepiness reported before treatment with positive airway pressure is often underestimated by patients with OSAS.

Eficiência produtiva de cultivares de arroz com divergência fenotípica

The objective of this study was to phenotypically evaluate the traditional rice cultivars Guarani and Caiapo, and the modern rice cultivars CIRAD L-141, Maravilha, BR IRGA 409, and Metica 1 through association among various yield components to establish a genetic selection base in plant population. The study was conducted during the rainy season of 2003-2004, at the Embrapa Rice & Beans experimental station, in Santo Antonio de Goias, Goias, Brazil. With supplementary irrigation, the upland rice cultivars CIRAD L-141, Guarani, Caiapo, and Maravilha presented higher grain harvest indexes and lower spikelet sterility than the lowland cultivars BR IRGA 409 and Metica 1. It was concluded that the highest biomass yield of the lowland rice cultivars did not have an effect upon the grain yield. The upland cultivar CIRAD L-141, with high leaf area, panicles with high grain number and average performance of the agronomic components evaluated, such as harvest index, grain weight, tiller fertility, tillering, spikelet sterility and growth index, yielded 12.5% higher than Guarani, the second best cultivar. The increase in grain harvest index and weight of grain and the reduction in spikelet sterility, due to their high correlation with grain yield, are considered high priority in the upland rice breeding programs for higher yields.

Genótipos de feijoeiro comum sob deficiência hídrica

The objective of the work was to study the adaptation of common bean genotypes to water deficit. Fortynine genotypes were evaluated in a randomized block design, with three replications, in experiments with and without water deficit, conducted at the Experimental Station of SEAGRO, in Porangatu-GO during 2006 and 2007. Multivariable analysis was applied using de Ward’s method and the genotypes were divided in four groups based on the average grain yield of each water treatment, during the two years of the experimentation. The genotypes BRA 130583 CIAT G 6490 and FT 84 - 292 were classified as the most productive in the absence or under water deficit, while the genotypes BRA 283983 CIAT G 6492, BRA 129721 CIAT G 6896, and G 983 were classified as productive in the absence of water deficit, but they were more sensitive to this stress. It was also verified that the number of pods per plant was the most sensitive agronomic component to water deficit in common bean.

Tolerância à deficiência hídrica de genótipos de arroz de terras altas

Water deficit is one of the environmental factors that cause a great reduction in the upland rice grain yield. The objective of this study was to evaluate genotypes of upland rice with broad genetic diversity for tolerance to this stress and to identify secondary traits for evaluation of this tolerance. Sixty-four genotypes were evaluated during two years at the Experiment Station of EMATER, in Porangatu, GO, under well-watered and water deficit conditions. The genotypes showed differences in grain yield and were influenced differently by the water treatments, both under a mild water deficit in the first year and under a severe one in the second year. The genotype grain yield under water deficiency was significantly and positively correlated with tiller fertility, number of panicles m-2, 100-grain weight, and plant height, and negatively with spikelet sterility and the number of days for the occurrence of 50% panicle emergence. It was also observed that the most productive genotypes under water deficit conditions showed lower leaf temperature, indicating improved water status. Nine genotypes were productive in both water conditions and three were productive only when well-watered.

Infrared thermometry for drought phenotyping of inter and intra specific upland rice lines

Propos-se avaliar, no presente estudo, a tecnica da termometria ao infravermelho na caracterizacao de linhagens interespecificas (Oryza glaberrima x Oryza sativa cv Caiapo) e intraespecificas de arroz para tolerância a seca. O experimento, conduzido em Porangatu, GO, foi submetido a condicoes adequadas de umidade no solo ate 30 dias apos a emergencia, quando entao foi implantado um tratamento com deficiencia hidrica moderada (aproximadamente 50% da irrigacao aplicada em uma parcela testemunha, com condicoes adequadas de umidade no solo). Verificou-se que as linhagens mais produtivas em condicoes de deficiencia hidrica apresentaram plantas mais altas, com paniculas mais densas e com graos mais bem formados, com menor esterilidade de espiguetas. Observou-se, tambem, que a temperatura das folhas se correlacionou positivamente com a esterilidade de espiguetas e negativamente com a massa de 100 graos, altura das plantas, fertilidade de perfilhos e produtividade. Exceto a fertilidade de perfilhos, os demais componentes se correlacionaram com a produtividade de graos, sendo que com a esterilidade de espiguetas a correlacao foi negativa. Concluiu-se que a O. glaberrima confere, as suas progenies, maior rusticidade a deficiencia hidrica e que a termometria ao infravermelho e uma tecnica auxiliar importante na fenotipagem para tolerância a seca.