Maurício Marini Kopp

Tandem repeat distribution of gene transcripts in three plant families

Tandem repeats (microsatellites or SSRs) are molecular markers with great potential for plant genetic studies. Modern strategies include the transfer of these markers among widely studied and orphan species. In silico analyses allow for studying distribution patterns of microsatellites and predicting which motifs would be more amenable to interspecies transfer. Transcribed sequences (Unigene) from ten species of three plant families were surveyed for the occurrence of micro and minisatellites. Transcripts from different species displayed different rates of tandem repeat occurrence, ranging from 1.47% to 11.28%. Both similar and different patterns were found within and among plant families. The results also indicate a lack of association between genome size and tandem repeat fractions in expressed regions. The conservation of motifs among species and its implication on genome evolution and dynamics are discussed.

Repetibilidade de características agronômicas e número de cortes necessários para seleção de Urochloa ruziziensis

O objetivo deste trabalho foi estimar a repetibilidade de caracteristicas agronomicas e determinar a quantidade adequada de cortes para selecao de Urochloa ruziziensis. Foram avaliadas 118 progenies de meio-irmaos de U. ruziziensis, alem das cultivares Basilisk (U. decumbens), Marandu (U. brizantha), Comum (U. ruziziensis) e um acesso de Urochloa sp. como testemunhas. Utilizou-se o delineamento em blocos ao acaso, com duas repeticoes, parcelas de uma linha com 3,0 m e espacamento de 1,0x0,5 m. Foram realizados sete cortes, em intervalos medios de 60 e 90 dias, nas epocas chuvosas e secas, respectivamente. Avaliaram-se: altura de planta, massa de materia seca (MS), massa de materia verde (MV) e percentagem de materia seca (PMS). A repetibilidade foi estimada pelos seguintes metodos: analise de variância; componentes principais, pela matriz de covariâncias e pela matriz de correlacoes; e analise estrutural pela matriz de correlacoes. As estimativas de repetibilidade variaram de 0,31-0,38 para altura de plantas, 0,31-0,43 para MV, 0,16-0,50 para PMS, e 0,23-0,43 para MS; com coeficientes de determinacao entre 57-87%. O numero de cortes necessarios para estimar o valor real das caracteristicas variou entre 7-8 para MV e altura de plantas, e 10-14 para MS e PMS, com coeficientes de determinacao igual ou superior a 80%.

Associação entre caracteres e análise de trilha na seleção de progênies de meios-irmãos de Brachiaria ruziziensis

Association between traits and path analysis in half-sib progeny selection of Brachiaria ruziziensis High association between fresh and dry mass weight can facilitate early selection of superior genotypes of B. ruziziensis R. Germ. & C.M. Evrard. The aim of this study was to verify the associations between traits in the selection of B. ruziziensis genotypes. The experiment was arranged in a complete randomized block design with two replications. The traits evaluated were height and vigor of plants; weight of fresh mass and percentage of dry matter of the whole plant, stem and leaf; dry mass weight of total herbage, stem, and leaf and the ratio between productivity of leaf and stem. Estimation of simple correlations and path analysis were performed considering the dry mass weight as the main variable. The correlations were mostly low, but significant higher correlations were observed between fresh mass weight and dry mass weight, dry weight of the stem and dry weight of leaves. The path coefficients showed that the direct effects of different explanatory variables on the dry mass weight were mostly low. More significant direct ef fects were obtained with fresh mass weight, stem dry weight and leaf dry weight, indicating that the fresh mass weight allows for the indirect selection for dry mass weight.

Estacionalidade e estabilidade de produção de forragem de progênies de Brachiaraia ruziziensis

Conduziu-se este trabalho, com o objetivo de avaliar a produtividade de biomassa de forragem de progenies de Brachiaria ruziziensis e a estabilidade de producao ao longo de diferentes cortes, representativos de epocas favoraveis e desfavoraveis ao desenvolvimento das forrageiras. Foram avaliadas 118 progenies de B. ruziziensis, juntamente com as testemunhas B. decumbens cv. Basilisk, B. brizantha cv. Marandu, B. ruziziensis cv. Comum e Brachiaria sp., em delineamento de blocos casualisados, com duas repeticoes. Realizaram-se sete cortes de avaliacao com intervalos medios de 60 e 90 dias nas epocas das aguas (5 cortes) e das secas (2 cortes). Em cada um deles mensurou-se a altura das plantas (ALT) e as produtividades de biomassa de forragem verde (PBV) e seca (PBS). As medias dos diferentes cortes, nas epocas das aguas ou das secas, foram utilizadas para a realizacao de analises de variância, em esquema fatorial (progenies x epocas), para a avaliacao dos efeitos de estacionalidade de producao das progenies. Tambem foi realizada a avaliacao da estabilidade das progenies. Apesar da grande concentracao da PBV e PBS na epoca das aguas, detectou-se a existencia de variabilidade genetica entre progenies de B. ruziziensis para ALT, PBV e PBS, tanto na epoca das aguas como na seca. Alguns materiais avaliados apresentaram estabilidades de producao superiores as principais cultivares comerciais de Brachiaria, indicando ser possivel a identificacao e selecao de materiais de B. ruziziensis com medias mais elevadas e com producao mais estavel ao longo do ano.

Avaliação de genótipos de arroz sob efeito do ácido butírico

Hydromorphic soils have low drainage capacity and are used mainly for growing irrigated rice.. This condition favors the development of anaerobic microorganisms that produce phytotoxic substances. The objective of this work was to evaluate the response of 25 rice genotypes to butyric acid, a phytotoxic compound produced in low-drainage soils with high organic matter content. This work was performed by hydroponics with four acid doses as treatments using a random block design with three replications. The variables measured were root (CR) and shoot (CPA) length, number of roots (NR) and root (MSR) and shoot (MSPA) dry matter. Analysis of variance, relative performance and regression fitting were performed. Significance for genotype and dose was found for all variables. Significance for the interaction (genotype vs. dose) was found only for CR and MSR. The variable CR was the most influenced by the acid and the regression established for these variables revealed nine tolerant and 16 sensitive genotypes. Genotypes developed for irrigated systems were more tolerant.

Avaliação de genótipos de aveia branca sob estresse de ácidos orgânicos

The association of anaerobic conditions with high organic matter content in hydromorphic soils favors the development of anaerobic microorganisms that produce phytotoxic substances, especially short chain organic acids. The objective of this investigation was to evaluate the response of 20 oat (Avena sativa L.) genotypes to the exposure of acetic, propionic and butyric acids in hydroponic system. Three doses (0; 3 and 6 mM) of a mixture of the three acids at a 6:3:1 ratio, respectively were tested. The experimental design was randomized blocks with three replications on a factorial scheme. Measured variables were root (CR) shoot (CPA) length, root number (NR), root (MSR) and shoot (MSPA) dry matter. Variance analyses and regression fitness were performed. The effects of the interaction between doses and genotypes were significant for the variables CR and MSR. The regression curves indicated two genotypes (OR-3 e FAPA-5) with stable root growth and three (OR-3, UFRGS-17 e UPF-15) with stable dry matter accumulation under organic acid stresses. The characterization of these genotypes regarding organic acid phytotoxic action is an important resource for breeding programs aiming at to develop high yielding cultivars for no-tillage or minimal tillage systems in hydromorphic soils of southern Brazil.

Identification of variability for agronomically important traits in rice mutant families

The increase of yield potential in new rice (Oryza sativa L.) varieties has been a major challenge for genetic improvement. The generation of mutants, followed by their characterization, constitutes a great possibility to isolate and select genes and genotypes that present agronomic traits of interest. This study aimed to evaluate the effect of chemical mutagen ethyl methane sulphonate (EMS) on agronomic traits in 340 M3 families of rice derived from BRS Querencia cultivar. Seeds from each family and the original genotype BRS Querencia were sown in the experimental field, and the characters main panicle length, main panicle weight, main panicle grain weight, flag leaf width and plant height were evaluated. Data were subjected to analysis of variance (p ≤ 0.05), and a comparison of means was carried out by Dunnetts test at 5% significance. The results show that there is genetic variability among the mutant families, suggesting that the mutagen EMS at 1.5% is effective for generating mutants for all assessed traits. Among the characters, plant height was the most affected by the mutagen, which provided an increase in the character. For the main panicle length character, seven families showed means above the control; for main panicle weight and grain weight, four and six mutant families were observed, respectively, with a superior performance in comparison to the control.

Dissimilaridade genética em população segregante de soja com variabilidade para caracteres morfológicos de semente

The soybean seed coat is a structure associated with seed germination, vigor and longevity. Soybean genotypes show genetic variability regarding the seed coat traits, which can be used in soybean breeding programs. The objectives of this study were: to analyze the genetic similarity of a segregant soybean population for morphological seed traits using morphological and molecular markers (AFLP, RAPD and SSR) and to establish the correlation between the dissimilarity matrices obtained using different marker classes. The population was obtained by crossing between two contrasting soybean genotypes: the cultivar CD 202 (female parent) with a yellow coat, and the genotype TP (male parent) with a black coat. The morphological traits evaluated were coat and hilum colors, hilum spread, pubescence and flower colors. Molecular markers were obtained by AFLP, RAPD and SSR techniques. Based on estimated similarity matrices, dendrograms were developed and the correlations between all matrix pairs and dendrograms estimated. The results showed that AFLP markers are more efficient for accessing the genetic variability of this population. Only the dissimilarity matrix and the dendrogram obtained by AFLP markers showed a positive correlation with the dissimilarity matrix and dendrogram obtained by morphological data.

Rice Genotype Responses to Acetate to Improve No‐Tillage and Minimal‐Tillage Systems

The goal of this work was to evaluate the response of 25 rice genotypes to the toxic effect of acetate, which is commonly produced in low‐drainage and organic‐matter‐rich soils. The work was performed in hydroponics with four acetate doses. The experimental design was random blocks with three replications on a factorial scheme. The variables root (RL) and shoot (SL) length, number of roots (NR), and root (RDM) and shoot (SDM) dry matter were measured. Analyses of variance, relative performance, and regression adjustments were used. Only the dose × genotype interaction effect for SL, NR, and SDM were not significant. Among the variables analyzed, RL was influenced the most by the acetate treatments. The regressions established for this variable revealed 6 tolerant and 19 sensitive genotypes. Most of the tolerant genotypes were irrigated japonica.

Organic Acid Effects on Nutrient Uptake by Rice

The purpose of this work was to evaluate the responses of 20 rice cultivars to the phytotoxic effects of acetic, propionic, and butyric acids produced in soils under anaerobic conditions. The study was conducted in a hydroponic system, with four levels (0, 3, 6, and 9 mM) of the three organic acids in the ratio of 6:3:1 in a factorial of complete randomized block design with three replications. The evaluated variables were phosphorus (P) and potassium (K) contents. The analysis of variance revealed a significant interaction, and the established regressions showed differences among the genotypes as evaluated for both variables. Four genotypes were classified as tolerant in relation to P content and three genotypes as tolerant in relation to K. The best performance was verified with japonica genotypes and the irrigation-based growing system.