Navegando por Autor "Oliveira, Luiz Orlando de"
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Item Análise da estabilidade fenotípica de cultivares de soja por meio da regressão linear simples e da regressão linear segmentada(Revista Ceres, 1990-11) Sediyama, Carlos Shigueyuki; Oliveira, Luiz Orlando de; Cruz, Cosme DamiãoCultivares de soja provenientes de ensaios finais de competição, realizados em 23 épocas de plantio, nos anos agrícolas de 1983/1984 e 1984/1985, em Ponta Porã, MS, foram avaliados, quanto a estabilidade fenotípica da produção de grãos, por meio de regressão linear simples e de regressão linear segmentada. Houve alteração na estabilidade fenotípica dos cultivares Doko, Dourados, IAC-8, IAC-9, IAC-11, IAC 73-5185, Numbaíra e UFV-1, quando avaliados em dois subgrupos de ambientes (desfavoráveis e favoráveis), tendo os cultivares Doko, IAC-8 e IAC-11 sido considerados teoricamente ideais. Não houve alteração na interpretação do desempenho dos cultivares Cristalina, Paranagoiana e Santa Rosa, quando avaliados por meio dos dois métodos de análise de estabilidade.Item Clonal diversity and conservation genetics of the medicinal plant Carapichea ipecacuanha (Rubiaceae)(Genetics and Molecular Biology, 2009-07-01) Oliveira, Luiz Orlando de; Venturini, Bruna Afonso; Rossi, Ana Aparecida Bandini; Hastenreiter, Saulo SantosThe roots of the understorey shrub Carapichea ipecacuanha (ipecac) have medicinal properties, and the uprooting of wild plants has supplied most of the world demand for this species. Although under severe population decline, C. ipecacuanha lacks legal protection. In the wild, the aerial stems of ipecac clump together to form clusters with well-defined borders. Cluster size may range from several to hundreds of aerial stems. To investigate the extent of clonality among aerial stems in ipecac clusters, we sampled 50 wild clusters (a total of 291 aerial stems) and screened them with 89 inter-simple sequence repeat (ISSR) markers. The 291 aerial stems were grouped into 42 putative clones. The clonal groups generally consisted of aerial stems from the same cluster, and there was little or no genetic differentiation among aerial stems at the cluster level. These findings suggest that strategies designed to conserve ipecac in situ should not rely upon census data, which are based on the number of aerial stems per cluster and the number of clusters per population, because such data greatly underestimate the species effective population size and genetic diversity. Our results also indicate that this species needs protection at a federal level.Item Distyly and variation in floral traits in natural populations of Psychotria ipecacuanha (Brot.) Stokes (Rubiaceae)(Brazilian Journal of Botany, 2005-04) Oliveira, Luiz Orlando de; Vieira, Milene F.; Rossi, Ana Aparecida B.Psychotria ipecacuanha is a perennial, medicinal herb that grows in clusters in the understory of humid, shady areas of the Atlantic Rain Forest of southeastern Brazil. The present study characterized the variation in floral traits among 35 clusters from three natural populations of this plant species. Field observations showed that the clusters are isomorphic, that is, a given cluster will either set long-styled or short-styled flowers. Stigmas and anthers are reciprocally placed in each morph, a dimorphism characteristic of distyly. The populations are isoplethic, that is, a given population exhibits an equilibrium 1:1 ratio of floral morphs. Morphometric analyses revealed that anther length, stigma length, corolla diameter, and pollen grain diameter were consistently greater in short-styled flowers, regardless of the population investigated. Significant differences for floral traits in the short-styled morph were found among populations. Floral traits in the long-styled morph also showed some significant differences among populations, but not for stigma height and corolla length. Controlled pollinations carried out in natural populations showed that fruit production was higher after inter-morph pollination. Nevertheless, observations of pollen tube growth in style, and also fruit production after spontaneous self-pollination and intra-morph pollination, indicated partial intramorph compatibility in this plant species.Item Diversidade genética entre acessos de mentrasto avaliada por características botânico-agronômicas, moleculares e fitoquímicas(Revista Ceres, 2004-03) Silva, Derly José Henriques da; Castro, Henrique Guilhon de; Oliveira, Luiz Orlando de; Ferreira, Francisco Affonso; Sakiyama, Ney Sussumu; Barbosa, Luiz Cláudio de Almeida; Ribeiro Júnior, José IvoObjetivou-se avaliar a divergência genética entre cinco acessos de mentrasto por métodos multivariados, utilizando-se características botânico-agronômicas, moleculares (marcadores RAPD) e fitoquímicas (teor e composição do óleo essencial). A análise de agrupamento por meio do método de Tocher, das características botânico-agronômicas, moleculares e fitoquímicas, formou dois grupos. Na análise da divergência genética por marcadores moleculares, 14 primers deram origem a 26 bandas polimórficas. A biomassa fresca e & biomassa seca foram as características botânico- agronômicas que mais contribuíram para a diversidade genética. As características fitoquímicas que mais contribuíram para a diversidade genética foram os compostos precoceno I e precoceno ll. Verificou-se coeficiente de correlação significativo entre biomassa seca e precoceno I. Foram constatados coeficientes de correlação não-significativos entre as características botânico-agronômicas, moleculares e fitoquímicas, com base nas distâncias dos acessos.Item Diversidade genética estimada com marcadores entre sequências simples repetidas em cultivos comerciais de Cupuaçuzeiro(Ciência Rural, 2016-01) Oliveira, Luiz Orlando de; Silva, Bruna Mezzalira da; Rossi, Ana Aparecida Bandini; Dardengo, Juliana de Freitas Encinas; Araujo, Vitor Arreguy Amado Correa de; Rossi, Fernanda Saragosa; Clarindo, Wellington RonildoQuinze primers ISSR (entre sequências simples repetidas) foram utilizados para avaliar a diversidade genética entre e dentro de pomares comerciais de Theobroma grandiflorum (Willd. ex Spreng.) K. Schum. Para isso, foram analisados sessenta indivíduos, distribuídos nos três cultivos. Um total de 102 bandas foi amplificado, com uma porcentagem de 52,0% de polimorfismo em nível de espécie e média de 6,8 alelos por primer ISSR. A média do Índice de Conteúdo Polimórfico (PIC) foi de 0,55. Em relação aos índices de diversidade gênica de Nei (H) e de Shannon (I), os cultivos analisados apresentaram os valores: SAR H = 0,114 e I = 0,177; SSL H = 0,108 e I = 0,162 e SEC H = 0,104 e I = 0,156, considerados valores de moderados a baixos. A AMOVA revelou 34,91% da variância total entre os cultivos e 65,09% dentro deles. Os marcadores moleculares ISSR revelaram que há diversidade genética dentro de cada cultivo comercial estudado, portanto é possível selecionar genótipos superiores que poderão ser utilizados para originar cultivos mais uniformes. Esse resultado tem sido considerado de grande relevância, por fornecer ferramentas para a implementação de programas de melhoramento e delineamento de estratégias de conservação ex situ e in situ.Item Diversidade genética estimada com marcadores ISSR em populações brasileiras de Zabrotes subfasciatus(Pesquisa Agropecuária Brasileira, 2008-07) Souza, Giselle Anselmo de; Carvalho, Márcia Rodrigues de Oliveira; Martins, Ernane Ronie; Guedes, Raul Narciso Carvalho; Oliveira, Luiz Orlando deO objetivo deste trabalho foi estimar a diversidade genética de populações de Zabrotes subfasciatus, por meio de marcadores moleculares ISSR. Foram avaliadas 12 populações, provenientes de oito estados brasileiros, no total de 269 indivíduos. Cinco iniciadores ISSR permitiram a obtenção do total de 51 fragmentos polimórficos. A percentagem média de locos polimórficos, dentro de cada população, foi de 83,8%. A heterozigosidade corrigida de Nei esperada variou de 0,23 a 0,33, com média de 0,29, e o índice de diversidade genética de Shannon e Weaver variou de 0,29 a 0,48, com média de 0,42. No nível de espécie, estes dois índices apresentaram valores de 0,36 e 0,54, respectivamente. A análise de variância molecular mostrou que 66% da variância molecular total pode ser atribuída a diferenças intrapopulacionais e que os 34% restantes podem ser atribuídos a diferenças interpopulacionais. O teste de Mantel mostrou baixa correlação entre: distância geográfica e diferenciação genética, identidade genética e diferenciação genética e, distância genética de Nei e diferenciação genética. As populações brasileiras de Z. subfasciatus possuem baixa diferenciação genética e fraca estruturação geográfica.Item Evolutionary history of Manihot carthagenensis (Euphorbiaceae) and allied species in eastern South America(Molecular Phylogenetics and Evolution, 2019-03) Silveira, Thamyres Cardoso da; Martins, Márcio Lacerda Lopes; Rody, Hugo Vianna Silvapt-BR; Oliveira, Luiz Orlando deIntermittent episodes of climate changes, such as those that occurred during the Pleistocene, likely shaped the diversification of the young genus Manihot Mill. (Euphorbiacheae). One of such recently-derived congeners ─ M. carthagenensis ─ exhibits a widely disjunct distribution across dry environments in Eastern South America. Herein, we used molecular data from four nuclear gene regions (sts, ch_metE, g3pdh, and nia-i3) and seven nuclear microsatellite loci for reconstructing the phylogenetic relationships among M. carthagenensis and allied species and exploring likely phylogeographic scenarios that shaped the diversification and the distribution of gene pools of M. carthagenensis across the Caatinga and Chaco. Our data suggest that M. carthagenensis is not a monophyletic clade, as presently circumscribed. Morphological differences, genealogical relationships, and vegetation associations support three well-differentiated lineages, each of which merits the species rank: M. carthagenensis, M. glaziovii, and M. hahnii. Microsatellite data suggest that the newly circumscribed M. carthagenensis consists of at least three distinct gene pools, which are partly structured according to geography. The three gene pools likely evolved in allopatry, but remained interfertile. Population expansions after climate amelioration contributed to structuring hybrid zones. Moreover, we described two new single-copy gene regions (sts and ch_metE) as sources of molecular variation; they can facilitate the fine-scale probing of other parts of the phylogeny across Manihot.Item Evolutionary history of the cobalamin-independent methionine synthase gene family across the land plants(Molecular Phylogenetics and Evolution, 2017-12-06) Rody, Hugo Vianna Silva; Oliveira, Luiz Orlando dePlants are successful paleopolyploids. The wide diversity of land plants is driven strongly by their gene duplicates undergoing distinct evolutionary fates after duplication. We used genomic resources from 35 model plant species to unravel the evolutionary fate of gene copies (paralogs) of the cobalamin-independent methionine synthase (metE) gene family across the land plants. To explore genealogical relationships and characterize positive selection as a driving force in the evolution of metE paralogs within a single species, we carried out complementary analyses on genomic data of 32 genotypes of soybean. The size of the metE gene family remained small across the land plants; most of the studied species possessed 1–6 paralogs. Gene products were either cytosolic or chloroplastic; this dual subcellular distribution arose early during the divergence of the land plants and reached all extant lineages. Biased gene loss and gene retention events took place multiple times; recurrent evolution remodeled redundant metE paralogs to recover and maintain the dual subcellular distribution of MetE. Shared whole-genome duplication events gave rise to the metE paralogs of both soybean and Medicago truncatula. In soybean, the ancestral paralog pair GlymaPP2A encoded a cytosolic isoform of MetE, was under strong purifying selection, and retained high levels of expression across eight RNA-seq expression libraries. The daughters GlymaPP1 and GlymaPP2B showed accelerated rates of evolution, accumulated many sites predicted to be under positive selection, and possessed low levels of expression. Our results suggest that the metE paralogs of soybean follow Ohno’s neofunctionalization model of gene duplicate evolution.Item Genetic diversity and geographic differentiation of disjunct Atlantic and Amazonian populations of Psychotria ipecacuanha (Rubiaceae)(Genetica, 2008-08-05) Rossi, Ana Aparecida Bandini; Oliveira, Luiz Orlando de; Venturini, Bruna Afonso; Silva, Roberta dos SantosIpecac (Psychotria ipecacuanha) is a perennial, medicinal herb that grows in the understory of semi-deciduous tropical forests in the Neotropics. Ipecacs present a widely disjunct distribution, with two of its three ranges occurring in Brazil. The Amazonian populations are at least 1600 km from the nearest Atlantic populations. This work used ISSR markers to compare the genetic diversity and structure of populations from the two Brazilian ranges. Lower genetic diversity in Amazon populations (P = 60.11%, Hs = 0.18) and higher genetic diversity in Atlantic populations (P = 73.94%, Hs = 0.20) were detected. Differentiation between ranges were high (θ B = 0.6838, GST-B = 0.6665). AMOVA revealed that 65.3% of the total molecular variance can be attributed to regional differences between the two ranges. Principal coordinate analyses and cluster analyses organized ipecacs at either individual or population level into two exclusive groups that correspond each to one of the two disjunct ranges, without exception. The results do not support a scenario that postulates human-mediated, long-distance dispersal events as a plausible origin for the distribution of the Brazilian ipecacs, but indicate geographic isolation as a long-standing barrier to genetic exchange and connectivity among populations from different ranges. Conservation implications are discussed.Item Genetic entanglement between Cercospora species associating soybean purple seed stain(Mycological Progress, 2017-03-23) Oliveira, Luiz Orlando de; Guillin, Eduardo A.; Grijalba, Pablo E.; Gottlieb, Alexandra M.Soybean purple seed stain (S-PSS) is a destructive, worldwide distributed fungal disease caused by several Cercospora species. This work aims to shed light on the nature of the genealogical and genetic relationships amongst S-PSS causal agents. Fungal isolates were obtained from Argentina and Brazil, which belong to the leading countries in soybean production worldwide. DNA sequences were obtained from eight loci across the collection of isolates. Relationships were evaluated through Bayesian phylogenetic inferences, and distance and character-based network analyses and discriminant analyses. The occurrence of reticulate evolutionary events was tested with recombination tests. The high haplotype diversity (H = 1.0) was arranged in four validated haplogroups. Reticulate network topologies were evident, and 11 recombination events were validated through several tests. Five of these events occurred across species boundaries. Comparison with sequences from 70 Cercospora species indicated that at least five monophyletic groups of S-PSS-causing agents are currently present in South America. The provided evidence supports the hypothesis that interspecific genetic exchange plays a significant role in the evolutionary dynamics of Cercospora species in this region. The occurrence of interspecific recombination has implications for understanding epidemiological threats to soybean production that appear to be more serious than previously anticipated.Item Mesoamerican origin and pre- and post-columbian expansions of the ranges of Acanthoscelides obtectus say, a cosmopolitan insect pest of the common bean(PLOS ONE, 2013-07-31) Oliveira, Márcia Rodrigues Carvalho; Corrêa, Alberto Soares; Souza, Giselle Anselmo de; Guedes, Raul Narciso Carvalho; Oliveira, Luiz Orlando deAn unprecedented global transfer of agricultural resources followed the discovery of the New World; one consequence of this process was that staple food plants of Neotropical origin, such as the common bean (Phaseolus vulgaris), soon expanded their ranges overseas. Yet many pests and diseases were also transported. Acanthoscelides obtectus is a cosmopolitan seed predator associated with P. vulgaris. Codispersal within the host seed seems to be an important determinant of the ability of A. obtectus to expand its range over long distances. We examined the phylogeographic structure of A. obtectus by (a) sampling three mitochondrial gene sequences (12s rRNA, 16s rRNA, and the gene that encodes cytochrome c oxidase subunit I (COI)) throughout most of the species’ range and (b) exploring its late evolutionary history. Our findings indicate a Mesoamerican origin for the current genealogical lineages of A. obtectus. Each of the two major centers of genetic diversity of P. vulgaris (the Andes and Mesoamerica) contains a highly differentiated lineage of the bean beetle. Brazil has two additional, closely related lineages, both of which predate the Andean lineage and have the Mesoamerican lineage as their ancestor. The cosmopolitan distribution of A. obtectus has resulted from recent expansions of the two Brazilian lineages. We present additional evidence for both pre-Columbian and post-Columbian range expansions as likely events that shaped the current distribution of A. obtectus worldwide.Item Molecular characterization of beta-tubulin from Phakopsora pachyrhizi, the causal agent of Asian soybean rust(Genetics and Molecular Biology, 2010-06-01) Maciel, Talles Eduardo Ferreira; Freire, Maíra Cristina Menezes; Almeida, Álvaro M.R. de; Oliveira, Luiz Orlando deβ-tubulins are structural components of microtubules and the targets of benzimidazole fungicides used to control many diseases of agricultural importance. Intron polymorphisms in the intron-rich genes of these proteins have been used in phylogeographic investigations of phytopathogenic fungi. In this work, we sequenced 2764 nucleotides of the β-tubulin gene (Pp tubB) in samples of Phakopsora pachyrhizi collected from seven soybean fields in Brazil. Pp tubB contained an open reading frame of 1341 nucleotides, including nine exons and eight introns. Exon length varied from 14 to 880 nucleotides, whereas intron length varied from 76 to 102 nucleotides. The presence of only four polymorphic sites limited the usefulness of Pp tubB for phylogeographic studies in P. pachyrhizi. The gene structures of Pp tubB and orthologous β-tubulin genes of Melampsora lini and Uromyces viciae-fabae were highly conserved. The amino acid substitutions in β-tubulin proteins associated with the onset of benzimidazole resistance in model organisms, especially at His 6 , Glu 198 and Phe 200 , were absent from the predicted sequence of the P. pachyrhizi β-tubulin protein.Item Molecular evidence of cryptic speciation, historical range expansion, and recent intraspecific hybridization in the Neotropical seasonal forest tree Cedrela fissilis (Meliaceae)(Elsevier Molecular Phylogenetics and Evolution, 2011-09-10) Garcia, Magali Gonçalves; Silva, Roberta Santos; Carniello, Maria Antonia; Veldman, Joseph William; Rossi, Ana Aparecida Bandini; Oliveira, Luiz Orlando deMolecular phylogeography can lead to a better understanding of the interaction between past climate events, large-scale vegetation shifts, and the evolutionary history of Neotropical seasonal forests. The endangered timber tree species Cedrela fissilis is associated with seasonal forests and occurs throughout South America. We sampled C. fissilis from 56 sites across the species’ range in Brazil and Bolivia and obtained sequence data for nuclear and chloroplast DNA. Most specimens (149 out of 169) exhibited intraindividual polymorphism for the nuclear internal transcribed spacer (ITS). Cloning and an array of complementary sequence analyses indicated that the multiple copies of ITS were functional paralogs – concerted evolution in C. fissilis appeared to be incomplete. Independent Bayesian analyses using either ITS or cpDNA data revealed two separate phylogenetic lineages within C. fissilis that corresponded to populations located in separate geographic regions. The divergence occurred in the Early Pliocene and Late Miocene. We argue that climate-mediated events triggered dispersal events and split ancestral populations into at least two large refugial areas of seasonal forest that were located to the east and west of the present day Cerrado. Upon recent climate amelioration, formerly isolated lineages reconnected and intraspecific hybridization gave rise to intraindividual polymorphism and incomplete concerted evolution in C. fissilis.Item Molecular evidence of hybrid zones of Cedrela (Meliaceae) in the Yungas of Northwestern Argentina(Molecular Phylogenetics and Evolution, 2016-05-19) Zelener, Noga; Tosto, Daniela; Oliveira, Luiz Orlando de; Soldati, María Cristina; Inza, María Virginia; Fornes, Luis FernandoIn the Yungas of Northwestern Argentina, three endangered species of Cedrela (C. angustifolia, C. saltensis, and C. balansae) follow altitudinal gradients of distribution with contact zones between them. We sampled 210 individuals from 20 populations that spanned most of Cedrela’s geographical range in the Yungas, and used Amplified Fragment Length Polymorphism (AFLP) markers and DNA sequences of the nuclear Internal Transcribed Spacer (ITS) to investigate hybrid zones. Data analyses employed an array of complementary methods, including principal coordinate analyses, Bayesian clustering analyses, maximum likelihood tree-building, and network techniques. Both nuclear molecular systems – AFLP and ITS – provided insights into the evolutionary history of Cedrela in the Yungas in a congruent manner. We uncovered strong support for the occurrence of natural hybridization between C. balansae and C. saltensis. Additionally, we identified hybrid zones in areas of sympatry (at both the Calilegua National Park and the San Andrés farm) and in transition zones from 820 to 1100 meters above sea level (localities of Pintascayo and Acambuco). There was no evidence for hybridization of either C. balansae or C. saltensis with C. angustifolia. The role of hybrid populations in conservation and use of genetic resources in the Yungas were discussed.Item Molecular phylogeography of Carapichea ipecacuanha, an amphitropical shrub that occurs in the understory of both semideciduous and evergreen forests(Molecular Ecology, 2010-01-24) Oliveira, Luiz Orlando de; Rossi, Ana Aparecida Bandini; Martins, Ernane Ronie; Batista, Flávia Reis de Carvalho; Silva, Roberta SantosThe medicinal shrub Carapichea ipecacuanha (ipecac) is an amphitropic species with three disjunct areas of distribution. In the Brazilian Atlantic and Amazonian ranges, the species was associated mostly with the understory of seasonal semideciduous forests, whereas in the Central American–Colombian range, the species occurred in the understory of moist evergreen forests. We examined the phylogeographic structure of ipecac using chloroplast trnT-trnL and nuclear internal transcribed spacer (ITS) sequences from 120 and 46 specimens, respectively. To complement existing data on root alkaloid profiles, we used high-performance liquid chromatography to assess the levels of emetine and cephaeline in 33 specimens from the two Brazilian ranges. The three ranges shared neither nuclear nor chloroplast haplotypes. The phylogeographic structures showed an uneven distribution of genetic diversity, sharp breaks and high levels of genetic differentiation among ranges. Our results suggest that the extant populations are descendents of at least four distinct ancestral lineages. The Atlantic ipecacs showed higher levels of genetic diversity than ipecacs from the other two ranges; it is likely that they derive from two ancestral lineages, with long-term persistence in that region. The Amazonian ipecacs were monomorphic with respect to the ITS and cpDNA sequences, which supports the view that there was a recent expansion from a single parental source after a strong genetic bottleneck. The existence of a fourth distinct lineage is apparent from the high levels of genetic and chemical differentiation that we identified in the Central American–Columbian ipecacs.Item More Cercospora species infect soybeans across the Americas than meets the eye(Plos One, 2015-08-07) Soares, Ana Paula Gomes; Guillin, Eduardo A.; Borges, Leandro Luiz; Silva, Amanda C. T. da; Almeida, Álvaro M. R. de; Grijalba, Pablo E.; Gottlieb, Alexandra M.; Bluhm, Burton H.; Oliveira, Luiz Orlando deDiseases of soybean caused by Cercospora spp. are endemic throughout the world’s soybean production regions. Species diversity in the genus Cercospora has been underestimated due to overdependence on morphological characteristics, symptoms, and host associations. Currently, only two species (Cercospora kikuchii and C. sojina) are recognized to infect soybean; C. kikuchii causes Cercospora leaf blight (CLB) and purple seed stain (PSS), whereas C. sojina causes frogeye leaf spot. To assess cryptic speciation among pathogens causing CLB and PSS, phylogenetic and phylogeographic analyses were performed with isolates from the top three soybean producing countries (USA, Brazil, and Argentina; collectively accounting for ~80% of global production). Eight nuclear genes and one mitochondrial gene were partially sequenced and analyzed. Additionally, amino acid substitutions conferring fungicide resistance were surveyed, and the production of cercosporin (a polyketide toxin produced by many Cercospora spp.) was assessed. From these analyses, the long-held assumption of C. kikuchii as the single causal agent of CLB and PSS was rejected experimentally. Four cercosporin-producing lineages were uncovered with origins (about 1 Mya) predicted to predate agriculture. Some of the Cercospora spp. newly associated with CLB and PSS appear to represent undescribed species; others were not previously reported to infect soybeans. Lineage 1, which contained the ex-type strain of C. kikuchii, was monophyletic and occurred in Argentina and Brazil. In contrast, lineages 2 and 3 were polyphyletic and contained wide-host range species complexes. Lineage 4 was monophyletic, thrived in Argentina and the USA, and included the generalist Cercospora cf. flagellaris. Interlineage recombination was detected, along with a high frequency of mutations linked to fungicide resistance in lineages 2 and 3. These findings point to cryptic Cercospora species as underappreciated global considerations for soybean production and phytosanitary vigilance, and urge a reassessment of host-specificity as a diagnostic tool for Cercospora.Item Pleiotropic impact of endosymbiont load and co-occurrence in the Maize Weevil Sitophilus zeamais(Public Library of Science One, 2014-10-27) Carvalho, Gislaine A.; Vieira, Juliana L.; Haro, Marcelo M.; Corrêa, Alberto S.; Ribon, Andrea Oliveira B.; Oliveira, Luiz Orlando de; Guedes, Raul Narciso C.Individual traits vary among and within populations, and the co-occurrence of different endosymbiont species within a host may take place under varying endosymbiont loads in each individual host. This makes the recognition of the potential impact of such endosymbiont associations in insect species difficult, particularly in insect pest species. The maize weevil, Sitophilus zeamais Motsch. (Coleoptera: Curculionidae), a key pest species of stored cereal grains, exhibits associations with two endosymbiotic bacteria: the obligatory endosymbiont SZPE (“Sitophilus zeamais Primary Endosymbiont”) and the facultative endosymbiont Wolbachia. The impact of the lack of SZPE in maize weevil physiology is the impairment of nutrient acquisition and energy metabolism, while Wolbachia is an important factor in reproductive incompatibility. However, the role of endosymbiont load and co-occurrence in insect behavior, grain consumption, body mass and subsequent reproductive factors has not yet been explored. Here we report on the impacts of co-occurrence and varying endosymbiont loads achieved via thermal treatment and antibiotic provision via ingested water in the maize weevil. SZPE exhibited strong effects on respiration rate, grain consumption and weevil body mass, with observed effects on weevil behavior, particularly flight activity, and potential consequences for the management of this pest species. Wolbachia directly favored weevil fertility and exhibited only mild indirect effects, usually enhancing the SZPE effect. SZPE suppression delayed weevil emergence, which reduced the insect population growth rate, and the thermal inactivation of both symbionts prevented insect reproduction. Such findings are likely important for strain divergences reported in the maize weevil and their control, aspects still deserving future attention.Item Reproductive studies in ipecac (Psychotria ipecacuanha (Brot.) stockes; Rubiaceae): pollen development and morphology(Brazilian Archives of Biology and Technology, 2008-09) Oliveira, Luiz Orlando de; Souza, Margarete Magalhães; Martins, Ernane Ronie; Pereira, Telma Nair SantanaThe aim of this work was to carry out the reproductive studies on Brazilian accessions of ipecac, Psychotria ipecacuanha. It presented heterostyly, with brevistylous and longistylous flowers. The pollen development was observed from the sections of the anthers embedded in resin. Anther development was normal as usually observed in dicotyledones, displaying four layers: outer epidermis, endothecium, middle layer and inner tapetum. The pollen was bicellular and filled with starch at the microspore stage. Pollen morphology was studied using SEM, which showed pollen polymorphism within and between the two floral morphs. Five types of pollen with reticulate or perforate exine were identified. The characteristics showed that the sexual process was as important as the vegetative propagation for the reproduction of this species.Item Specific boundaries between the causal agents of the soybean stem canker(Tropical Plant Pathology, 2014-07) Oliveira, Luiz Orlando de; Guillin, Eduardo A.; Grijalba, Pablo E.; Gottlieb, Alexandra M.Pathogens within the Diaporthe complex cause seed decay, stem blight and stem canker on soybean, representing a serious threat for this crop species. We herein utilize worldwide sequence data retrieved from Genbank in order to assess the species boundaries between the soybean stem canker causal agents, and define whether or not they should be regarded as members of the same biological species. These studies were complemented with compatibility tests, in order to validate our findings from a biological standpoint. Species delimitation assays supported the occurrence of a speciation event between D. caulivora and D. phaseolourm var. meridionalis. A speciation hypothesis between D. aspalathi and D. phaseolourm var. meridionalis was also supported, based on three reciprocally monophyletic substitutions at locus EF1-α. Compatibility tests further validated species delimitation assays indicating that D. caulivora has developed barriers to gene exchange with D. phaseolorum var. meridionalis. Clarification of the specific boundaries of the SSC pathogens and related entities will be an important asset to future research in soybean pathology, epidemiology and breeding.Item Specific boundaries between the causal agents of the soybean stem canker(Tropical Plant Pathology, 2014-07) Oliveira, Luiz Orlando de; Guillin, Eduardo A.; Grijalba, Pablo E.; Gottlieb, Alexandra M.Pathogens within the Diaporthe complex cause seed decay, stem blight and stem canker on soybean, representing a serious threat for this crop species. We herein utilize worldwide sequence data retrieved from Genbank in order to assess the species boundaries between the soybean stem canker causal agents, and define whether or not they should be regarded as members of the same biological species. These studies were complemented with compatibility tests, in order to validate our findings from a biological standpoint. Species delimitation assays supported the occurrence of a speciation event between D. caulivora and D. phaseolourm var. meridionalis. A speciation hypothesis between D. aspalathi and D. phaseolourm var. meridionalis was also supported, based on three reciprocally monophyletic substitutions at locus EF1-α. Compatibility tests further validated species delimitation assays indicating that D. caulivora has developed barriers to gene exchange with D. phaseolorum var. meridionalis. Clarification of the specific boundaries of the SSC pathogens and related entities will be an important asset to future research in soybean pathology, epidemiology and breeding.