ABSTRACT Drought is likely the main abiotic stress that affects wheat yield. The identification of drought-tolerant genotypes represents an effective way of dealing with the continuous decrease in water resources as well as the increase in world population. The aim of this study was to identify single nucleotide polymorphisms (SNP) associated with drought tolerance indices in wheat by using a genome-wide association study (GWAS) under fully irrigated and rain-fed conditions. The drought tolerance indices (i.e., Stress Susceptibility Index, Stress Tolerance Index, Tolerance Index and Yield Stability Index) were calculated based on grain yield, 1,000-kernel weight and kernels per spike. The association panel was genotyped using genotyping-by-sequencing (GBS). A total of 175 SNPs exhibited statistical evidence of association with at least one drought tolerance index, explaining up to 6 % of the phenotypic variation. Forty-five SNPs were associated with more than one tolerance index (up to 4 agronomic traits). Most associations were located on chromosome 4A, supporting the hypothesis that this chromosome has a key role in drought tolerance which should be exploited for wheat improvement. In addition, statistical analysis detected SNPs associated with tolerance indices in both growing seasons, providing information about genetic regions with stable effects under different environmental conditions. This GWAS experiment serves as one of the few studies on association mapping for drought tolerance indices in wheat, which could increase the efficiency of rain-fed and irrigated crop production.

ABSTRACT. The genetic differentiation of grapevine rootstock varieties was inferred by the Artificial Neural Network approach based on the Self-Organizing Map algorithm. A combination of RAPD and SSR molecular markers, yielding polymorphic informative loci, was used to determine the genetic characterization among the rootstock varieties 420-A, Schwarzmann, IAC-766 Campinas, Traviú, Kober 5BB, and IAC-572 Jales. A neural network algorithm, based on allelic frequency, showed that the individual grapevine rootstocks (n = 64) were grouped into three genetically differentiated clusters. Cluster 1 included only the Kober 5BB rootstock, Cluster 2 included rootstocks of the varieties Traviú and IAC-572, and Cluster 3 included 420-A, Schwarzmann and IAC-766 plants. Evidence from the current study indicates that, despite the morphological similarities of the 420-A and Kober 5BB varieties, which share the same genetic origin, two new varieties were generated that are genetically divergent and show differences in performance.

ABSTRACT Eucalyptus globulus is one of the most commonly planted hardwood species for industrial use in various temperate regions around the world. The present study aimed to evaluate 62 full-sib families of E. globulus in one of the southernmost progeny trials of the species in the south of Chile. Estimates of genetic parameters for stem straightness, branching quality and growth traits were based on a Bayesian modelling approach using Gibbs sampling. A Bayes Factor (BF) analysis supported the hypothesis of significant additive genetic variation for all traits under study. Conversely, the BF supported a model with significant dominance effects for the diameter at breast height and stem volume, which explained up to 25% of the phenotypic variation. The greatest narrow-sense heritability estimates were found for the tree height and stem straightness, which were 0.15 (0.08 to 0.26) and 0.18 (0.10 to 0.28), respectively (mean of posterior distributions and 90% credible sets). In turn, the branching quality had a low heritability (narrow-sense) that varied from 0.05 to 0.10 (90% Bayesian credible region). The mean posterior estimate of genetic correlation between both quality traits was 0.22 (0.01 to 0.63, 90% credible set from a bi-trait threshold model), which indicates that stem straightness is positively related to branching quality. Our findings reveal that the study population responds to common patterns of breeding populations of E. globulus. This information is valuable for the development of improved seeds in the southern zone of Chile.

ABSTRACT The development of commercial maize hybrids tolerant to herbicide and resistant to lepidopterans has allowed an important ex pansion of this crop in Brazil. The objective of this study was to field-evaluate the performance of eleven maize hybrids at three different growing locations in Brazil to find adapted and stable hybrids. The fields were desiccated using glyphosate (3 L ha-1) seven days before seeding. Each trial was arranged in a randomized complete block design with four replications per location. In the joint analysis of eight agronomic traits, the error variances were considered heterogeneous among locations. The eleven hybrids presented significant differences in all traits. The hybrid DKB340PRO2 had the highest grain yield, which could be a recommended hybrid to local farmers. In addition, the hybrid x location interaction was not statistically significant (p > 0.05), indicating stability of all the studied hybrids. Significant differences existed among the corn hybrids for eight agronomic traits, supporting our research hypothesis.

RESUMEN El desarrollo de híbridos comerciales de maíz tolerantes a herbicidas y resistentes a plagas ha permitido una importante expansión de este cultivo en Brasil. El objetivo de este estudio fue evaluar el desempeño de 11 híbridos comerciales de maíz en condiciones de campo, cultivados en tres localidades de Brasil, con el fin de identificar los híbridos mejor adaptados y estables. Los ensayos de campo fueron tratados con glifosato (3 L ha-1) siete días antes de la siembra. Cada ensayo se estableció de acuerdo a un diseño de bloques completamente aleatorizados, con cuatro repeticiones por tratamiento. La evaluación agronómica de los 11 híbridos consideró ocho características de importancia agrícola. De acuerdo a los resultados, hubo diferencia significativa entre tratamientos para todas las características estudiadas. Particularmente, el híbrido DKB340PRO2 obtuvo el mayor rendimiento de granos, por lo tanto, podría ser un híbrido recomendado para los productores locales. La interacción híbrido x sitio no fue significativa, lo cual implica que todos los híbridos estudiados tuvieron un desempeño estable.

Abstract Studies on genetic diversity and population structure provide basic information at the molecular level, which is a key input for breeding programs of crop species. This study evaluated the genetic diversity of 12 elite lines of sweet corn, using 20 microsatellite markers. To determine the genetic differentiation among lines, we used an artificial neural network with the self-organizing map (SOM) algorithm. This algorithm identified three genetically differentiated groups and produced relatively more accurate results than UPGMA, according to the indices of Davies-Bouldin and RMSSTD (Root Mean Square Standard Deviation). The expected heterozygosity was high (He>0.5) for 90% and the polymorphism information content high (PIC>0.6) for 40% of the SSR loci, indicating their potential to detect genetic differences among lines. The high genetic differentiation, detected by the neural network procedure, would allow the selection of promising divergent sweet corn genotypes.

Abstract This paper presents the results of the study of “Individual factors and their effect on school results. An analysis of data from the Simce TIC 2013” among Chilean students. The objective of this research was to describe the relationships among the self-perception of ICT skills, the attitude towards its use, and the type of use, based on tenth-grade student results on the Simce TICS 2013. Through a set of statistical analyses, we identified factors associated with dimensions of ICT skills for learning, attitude towards use and types of use. The study’s results suggest a relationship between the variables analyzed. The model explains 24.4% of the variance of the Simce TIC score.

Resumen Este trabajo presenta los resultados del estudio “Factores individuales y su efecto en los resultados escolares. Una medición a partir del Simce TIC 2013” en estudiantes chilenos. El objetivo de esta investigación fue describir las relaciones entre el tipo de uso, la autopercepción de habilidades TIC y la actitud frente al uso de las TIC, en relación con los resultados del Simce TIC 2013, en estudiantes chilenos de segundo año medio. A través de un conjunto de análisis estadísticos, se obtuvo como resultado la existencia de factores asociados a dimensiones de habilidades TIC para el aprendizaje, actitud frente al uso y tipos de uso. En cuanto a los resultados, es posible plantear que existe relación entre las variables analizadas en la investigación. El modelo explica el 24,4% de la varianza del puntaje Simce TIC.

Abstract This study aimed to evaluate hybrids obtained by the cross among temperate × tropical elite maize lines, and to determine the genetic diversity and population differentiation of these inbred lines. Forty-nine hybrids were evaluated for seed yield, plant and ear heights, and for severity of Phaeosphaeria maydis and Exserohilum turcicum in four environments in Brazil. Hybrids were obtained from a partial diallel that involved seven tropical and seven temperate lines. Twenty-two SSR primers were used to evaluate the genetic relationship among the lines. Diallel showed the existence of significance for GCA and SCA effects; the genetic control of the traits was associated with additive and non-additive genetic effect. Results showed that exotic and previously protected temperate maize germplasm may provide novel alleles for resistance to P. maydis and E. turcicum and increase yield in tropical maize. Tropical inbred lines were allocated in different heterotic groups, suggesting an admixture condition among temperate and tropical materials.

ABSTRACT Compared with the common corn, popcorn shows greater susceptibility to pests and diseases occurrence, being the use of resistant cultivars the most efficient strategy. In this regard, Germplasm Banks deserve special attention because they contain accessions that can be used as sources of resistance in breeding programs. The State University of Northern Rio de Janeiro (UENF) maintains a popcorn Germplasm Bank with accessions from tropical and temperate countries, including Diversity Centers for the species. In this study, we investigated the performance of 37 popcorn accessions landraces, hybrids, and inbreed lines ― from the Germplasm Collection of UENF’s Popcorn Breeding Program with respect to the fungal leaf diseases northern leaf blight (NLB) and southern leaf blight (SLB), caused by Exserohilum turcicum and Bipolaris maydis, aiming to select promising accessions for genetic resistance to be used in future crosses to generate new resistant cultivars for farmers. The dendrogram scattering by the UPGMA multivariate technique was efficient in discriminating resistant accessions. Satisfactory results were obtained for resistance to NLB in accessions L71, L75, L76, P7, and PARA-172, which can thus be considered remarkable sources of resistance. For resistance to SLB, the superior accessions that can be indicated as sources of resistance are ARZM-05083, ARZM-07049, and PARA-172.

RESUMO. O morango chileno [Fragaria chiloensis (L.) Mill.] é o progenitor materno do morangueiro comercial (Fragaria ( ananassa Duch.), caracterizado por frutos com alta qualidade organoléptica, sendo uma cultura bem adequada para áreas caracterizadas pela seca e a salinidade. Neste trabalho, foram examinados os padrões de desequilíbrio de ligação, diversidade genética e estrutura da populacional em 54 acessos de F. chiloensis, com o intuito de avaliar a base genética da espécie. Utilizou-se um conjunto de marcadores de microssatélites (n = 95) obtidos do mapa de ligação consenso do morango comercial. A taxa de transferibilidade foi de 82,1% (78/95). Dos marcadores transferidos, 38 foram selecionados e usados neste estudo, os quais produziram um total de 259 alelos, que variaram entre 112 e 342 pb. Encontrou-se uma menor diversidade genética ao nível da espécie (HE = 0,17, índice de Shannon = 0,28), em comparação com estudos prévios com a espécie. Não foi observado padrão de região climática para a diversidade genética. A análise da estrutura sugere que os acessos são agrupados em três grupos significativamente diferenciados. As estimativas de pares de φST indicaram baixo grau de diferenciação entre os três grupos genéticos (φST = 0,023 a 0,06). Esses grupos estão em concordância com os potenciais refúgios glaciários na região, sendo muitas adições uma mistura deles.

ABSTRACT. The Chilean strawberry [Fragaria chiloensis (L.) Mill.] is the maternal progenitor of the commercial strawberry (Fragaria ( ananassa Duch.), which is characterized by fruits with high organoleptic quality and is well-suited to areas where drought and salinity represent a constraint on crop growth and productivity. We examined the patterns of linkage disequilibrium, genetic diversity and population structure among 54 accessions of F. chiloensis to understand the genetic basis of this species. We used a core microsatellite marker set (n = 95) from a consensus linkage map of strawberry. A transferability rate of 82.1% (78/95) was found, and 38 markers were selected for this study. The SSR primers produced a total of 259 alleles, which varied between 112 and 342 bp. Lower genetic diversity at the species level (HE = 0.17, Shannon’s index = 0.28) was found compared to previous studies of this species. No climatic region pattern for SSR diversity was observed. Structure analysis suggests that the accessions are grouped into three significantly differentiated clusters. Pairwise estimates of φST indicated a low degree of differentiation between the three genetic groups (φST = 0.023 to 0.06). These groups are in concordance with potential glacial refugia in the region, with many accessions being an admixture of them.

RESUMO. Cevada (Hordeum vulgare L.) é uma cultura modelo para a avaliação genética dos mecanismos de tolerância à seca; a ameaça mais importante para a produção agrícola a nível mundial. Objetivou-se identificar polimorfismos de nucleotídeo único (SNP) associados a características agronômicas, morfológicas e fisiológicas numa população de 137 linhas recombinantes com substituição cromossômica (RCSL) de cevada, avaliadas sob condições de sequeiro, em Cauquenes, sul do Chile (35°58’ S, 72°17’ O). A precipitação anual foi de 299 mm durante o período vegetativo. Cinquenta e dois QTLs foram encontrados para as características estudadas, explicando entre 5% e 13.8% da variação fenotípica. A região genômica no cromossomo 1H (que compreende os SNPs 2711-234 e 1923-265) foi responsável de ~13% da variação no rendimento de grãos. Além disso, os SNPs 8388-578 e 7639-122 no cromossomo 5H teve um efeito moderado, explicando 12,8% da variação para altura da planta. Além disso, alguns SNPs foram associados com mais de uma característica, e grupos de QTLs para rendimento de grãos e características relacionadas também foram encontrados. Finalmente, os QTLs identificados no presente estudo podem ser de particular interesse para fins de melhoramento de cevada em ambiente de sequeiro.

ABSTRACT. Barley (Hordeum vulgare L.) is considered a good genetic model for evaluating mechanisms of drought tolerance, and it is the most important threat to crop production worldwide. This study aimed to identify single-nucleotide polymorphisms (SNPs) associated with agronomic, morphological and physiological traits in a population of 137 recombinant chromosome substitution lines (RCSL) of barley, which were evaluated under rainfed conditions, in Cauquenes, southern Chile (35°58’ S, 72°17’ W). The annual precipitation was 299 mm during the growing season. Fifty-two significant QTLs were detected for the studied traits, which explained between 5% and 13.8% of the phenotypic variation. A genomic region on chromosome 1H (that comprises SNPs 2711-234 and 1923-265) accounted for 13.4% and 13.8%, respectively, of the grain yield variation. In addition, SNPs 8388-578 and 7639-122 on the chromosome 5H had a moderate effect, explaining 12.8% of the plant height variation. Moreover, some SNPs were associated with more than one trait, and clusters of QTLs for yield and related traits were also found. Finally, the QTLs identified in the present study are of particular interest for barley-breeding purposes under rainfed conditions.

ABSTRACT The objective of this study was to present a classification proposal for coefficients of variation (CV) in Eucalyptus experiments, aiming at providing a useful tool for experiments involving growth, survival and wood quality traits. Ninety-four studies were selected from a search for peer-reviewed journals yielding a total of 508 data. The CVs were classified as low, moderate, high and very high. The mean, standard deviation, maximum and minimum values, skewness and kurtosis were estimated to describe the distribution shape. The Shapiro-Wilk test confirmed that all variables satisfied the assumption of normality (p < 0.05). The results indicated that the growth traits had the highest variability, being variables strongly affected by the environment. In contrast, all variables related to wood quality (except extractives) had the lowest range of CVs. In summary, the classification proposed in this report provides a useful tool for researchers interested in estimating the accuracy of their experiments.

The development of micropropagation techniques in orchid has many advantages such as the reproduction of elite, rare, sterile and/or disease-free genotypes. The aim of this study was to evaluate the use of organic supplements (coconut water and banana pulp) in the in vitro development of seedlings of Laeliocattleya (Hadrolaelia purpurata x Cattleya intermedia), comparing their response to plant growth regulators: auxins and cytokinins. For this, the following four experiments were carried out: 1. Organic supplements compared to different concentrations ofkinetin (N6-furfuryl aminopurine; KIN) and naphthaleneacetic acid (NAA), 2. Organic supplements compared to different concentrations of 3-indolebutyric acid (IBA) and N6-benzyladenine (6BA), 3. Organic supplements compared to different concentrations of IBA and KIN, and 4. Organic supplements compared with different concentrations ofANA and 6BA. Coconut water was statistically superior to the others (P <0.01) for the variable number of leaves, in all experiments performed with 7.3 leaves per seedling cultivated in vitro. While banana pulp showed the best results in the number of roots (P <0.01) for all experiments, with an average value of 7.4 roots. The addition of banana pulp and/or coconut water is suitable for the production of orchid hybrids, which present a positive effect on the development of seedlings. Its low cost is also a plus in relation to the use ofplant growth regulators.

El desarrollo de técnicas de micropropagación en orquídeas ofrece múltiples ventajas como la reproducción de genotipos superiores, raros, estériles o libres de enfermedades. El objetivo del presente trabajo fue evaluar el uso de suplementos orgánicos (agua de coco y pulpa de banana) en el crecimiento y desarrollo in vitro de plántulas del híbrido intergenérico Laeliocattleya (Hadrolaelia purpurata x Cattleya intermedia), comparando su respuesta con fitorreguladores de auxinas y citoquininas. Para ello se realizaron los siguientes cuatro experimentos: 1. Suplementos orgánicos comparados con diferentes concentraciones de kinetina (N6-furfuril amino purina; KIN) y ácido naftalenacético (ANA), 2. Suplementos orgánicos comparados con diferentes concentraciones de ácido 3-indolbutírico (IBA) y N6-benzyladenine (6BA), 3. Suplementos orgánicos comparados con diferentes concentraciones de IBA y KIN, y 4. Suplementos orgánicos comparados con diferentes concentraciones de ANA y 6BA. El suplemento orgánico de agua de coco fue estadísticamente superior al resto (P<0,01), para la variable número de hojas, en todos los experimentos realizados, con 7,3 hojas por plántula cultivada in vitro. En tanto que la adición de pulpa de banana mostró los mejores resultados en el número de raíces (P<0,01), para todos los experimentos en estudio, con un valor medio de 7,4 raíces. Se concluye que la adición de pulpa de banana o de agua de coco es conveniente para la producción de orquídeas híbridas por presentar un efecto positivo en el desarrollo de las plántulas, y por su costo reducido en relación con el uso de reguladores de crecimiento.

Information on genetic diversity is essential to the characterization and utilization of germplasm. The genetic diversity of twenty-two sweet corn cultivars (seventeen open-pollinated varieties, OPV, and five hybrids, H) was investigated by applying simple sequence repeat markers. A total of 257 primers were tested, of which 160 were found to be usable in terms of high reproducibility for all the samples tested; 45 were polymorphic loci, of which 30 were used to assess the genetic diversity of sweet corn cultivars. We detected a total of 86 alleles using 30 microsatellite primers. The mean polymorphism was 82 %. The highest heterozygosity values (Ho = 0.20) were found in the PR030-Doce Flor da Serra and BR427 III OPVs, whereas the lowest values (0.14) were recorded in the MG161-Branco Doce and Doce Cubano OPVs. The polymorphism information content ranged from 0.19 (Umc2319) to 0.71 (Umc2205). The analysis of molecular variance revealed that most of the genetic variability was concentrated within the cultivars of sweet corn (75 %), with less variability between them (25 %). The consensus tree derived from the neighbor-joining (NJ) algorithm using 1,000 bootstrapping replicates revealed seven genetically different groups. Nei’s diversity values varied between 0.103 (Doce do Hawai × CNPH-1 cultivars) and 0.645 (Amarelo Doce × Lili cultivars), indicating a narrow genetic basis. The Lili hybrid was the most distant cultivar, as revealed by Principal Coordinates Analysis and the NJ tree. This study on genetic diversity will be useful for planning future studies on sweet corn genetic resources and can complement the breeding programs for this crop.

A cross-sectional and descriptive study about the use of laboratory animals in teaching in the Faculty of Pharmacy of the University of Costa Rica was performed. The study included Pharmacy students, specifically those in the Introduction to Pharmacy and Toxicology course. We found that students in both levels had favorable perceptions about the existence of rules governing the use of animals in education and in general the importance of using them for their learning process. We found differences between the groups regarding knowledge about the origin of the animals.

Se realizó un estudio transversal descriptivo del conocimiento del uso de animales de laboratorio en docencia, en la Facultad de Farmacia de la Universidad de Costa Rica. Se tomaron en cuenta estudiantes de la carrera de Licenciatura en Farmacia, de los cursos de Introducción a la Farmacia y Toxicología. Se encontró que los estudiantes de ambos niveles tienen una percepción favorable respecto a la existencia de una normativa que regulA el uso de animales en docencia y en general, de la importancia del uso de animales para su proceso de aprendizaje. Se encontraron diferencias entre los grupos respecto al origen de los animales.

Eucalyptus cladocalyx F. Muell é distribuída em quatro regiões isoladas do sul da Austrália: Kangaroo Island, Flinders Ranges e em duas zonas da Eyre Peninsula. A espécie tem a capacidade de crescer em condições ambientais extremas como ambientes secos e solos salinos. O objetivo do presente estudo foi examinar a diversidade genética em 45 famílias de meio-irmãos cultivadas no norte do Chile, as quais são originarias de cinco localidades diferentes (procedências). A variabilidade genética foi avaliada usando marcadores moleculares ISSR (Inter Simple Sequence Repeat). Os resultados mostraram baixo nível de diversidade genética dentro de populações (He = 0,113 a 0,268) em contraste com outras espécies de Eucalyptus. Adicionalmente, houve uma significativa diferenciação genética entre procedências (Φst = 0.14), coincidindo com a reportada em estudos anteriores. Kangaroo Island é a procedência mais diferenciada. O presente estudo evidenciou que os recursos existentes no Chile são uma amostra representativa das populações Australianas e, portanto, o germoplasma cultivado no norte do Chile seria suficiente para os programas de melhoramento. A tecnologia de marcadores ISSR poderia ser uma alternativa para identificar genótipos de interesse no processo de seleção.

Eucalyptus cladocalyx F. Muell is a tree endemic to southern Australia and is distributed across four isolated regions: Kangaroo Island, southern Flinders Ranges, and two geographical zones in Eyre Peninsula. E. cladocalyx is capable of growing under extreme environmental conditions, including dry and saline soils. The objective of this study was to analyze genetic diversity in 45 half-sib families planted in northern Chile that are distributed across five different zones (provenances). Genetic variability was assessed using ISSR (Inter Simple Sequence Repeat) molecular markers. The results showed low levels of genetic diversity within populations (He = 0.113 to 0.268) in contrast with other Eucalyptus species. In addition, there was a significant genetic differentiation among provenances (Φst = 0.14); populations from the Kangaroo Island provenance showed more differentiation than any other population. These results are in agreement with previous studies of the species. Our study revealed that Chilean resources are a representative sample of Australian populations; therefore, the germplasm planted in northern Chile would be sufficient for the development of improvement programs. ISSR-Marker technology could be an alternative to identify genotypes of interest in material selection.