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Detection and molecular identification of viruses are fundamental to define control strategies against viral diseases, particularly for whitefly-transmitted viruses. Cotton (Gossypium) plants showing leaf mosaic symptoms and yield reduction were observed in commercial cultivars (G. hirsutum) and in plants of the cotton germplasm collection of Embrapa maintained in the field (G. hirsutum, G. barbadense, G. mustelinum). DNA was extracted from cotton plants with symptoms of mosaic and interveinal chlorosis, and a begomovirus-specific genome was amplified with degenerated universal primers, which indicated their association with a begomovirus. This virus was identified as an isolate of sida micrantha mosaic virus (SiMMV) after the amplicon sequencing. The virus could not be transmitted by whiteflies (Bemisia tabaci MEAM1) to cotton plants when the latter were used as inoculum source under protected cultivation house, suggesting a complex interaction among viruses, plants and vectors. RESUMO A detecção e identificação molecular de vírus são fundamentais para se definir estratégias de controle de viroses, tendo uma importancia crucial para vírus transmitidos por moscas-brancas. Plantas de algodoeiro (Gossypium) com sintomas de mosaico e redução de produtividade foram observadas em cultivares comerciais (G. hirsutum) e em acessos do banco de germoplasma de algodão da Embrapa mantidos em campo (G. hirsutum, G. barbadense, G. mustelinum). A extração de DNA a partir de plantas com sintomas de mosaico e clorose internerval e amplificação do genoma de begomovírus com primers degenerados e universais mostrou a associação com um begomovírus. Este vírus foi identificado como um isolado de sida micrantha mosaic virus (SiMMV) por sequenciamento do amplicon. O vírus não pode ser transmitido para algodão por mosca-branca (Bemisia tabaci MEAM1) quando plantas de algodão foram usadas como fonte de inóculo, em casa de cultivo protegido, sugerindo uma complexa interação entre vírus, plantas e vetores. more...

Oilseed plants such as cotton (Gossypium sp.) generate abundant biomass residues which contain significant levels of edible oil, crude proteins and other desirable biomolecules for the animal nutrition industry. The application of cottonseed cake in animal feed, a by-product of the cotton industry, is limited due to the natural presence of toxic free gossypol (FG), wherein efficient and cost-effective methods for FG detoxification are necessary. Herein, pretreatment methods for reducing FG in crushed whole cottonseed (CWCS) were compared, with residual FG quantified using a sensitive Ultra High-Performance Liquid Chromatography method for detection at trace levels in cottonseed materials. Physical treatment by autoclaving resulted in up to 96% detoxification of FG, without reduction in crude protein (CP) content. Chemical treatment with 1% and 2% Ca(OH)2 eliminated FG to as low as 0.04%, although a reduction in CP content was observed. Similarly, native fermentation, whilst reducing FG content by 99.66% after 6 days incubation, also reduced CP content. In combined physical and biological solid-state fermentation (SSF), basidiomycete fungi Ganoderma lucidum CC351, Panus lecomtei CC40, Pleurotus ostreatus CC389, Pleurotus sapidus CC28 and Pycnoporus sanguineus CC400 all degraded FG in autoclaved CWCS to trace levels often lower than obtained by individual treatments. A reduction in total lipids and increase in CP were also observed, improving nutritional quality. The most efficient fungi, P. ostreatus CC389 and P. lecomtei CC40, secreted considerable laccase and manganese peroxidase enzymes during SSF, potentially involved in FG detoxification. Cost effective, non-polluting, value-adding approaches for FG detoxification offer potential in animal feed industries. more...

Cultivar BRS 433FL B2RF is a high-quality fiber upland cotton with high lint yield potential and resistance to several diseases. The introgressed trans-genic events Bollgard II® and Roundup Ready Flex® confer enhanced resistance to lepidopteran pests and tolerance to the herbicide glyphosate, respectively. Fiber length exceeds 32.5 mm and fiber strength 33 gf tex-1. Made available in DSpace on 2020-12-03T09:02:10Z (GMT). No. of bitstreams: 1 Cultivar-BRS-433FL.pdf: 327178 bytes, checksum: ffd2f388d62c98a6c847c4a0a900b0ff (MD5) Previous issue date: 2020 more...

Transgenic cotton cultivars BRS 430 B2RF and BRS 432 B2RF, medium and late season respectively, were developed by EMBRAPA in partnership with Bahia Foundation, aiming to create a high-yielding germplasm. The Bt toxins Cry1Ac and Cry2Ab target lepidopteran pests and the CP4-EPSPS gene confers tolerance to the herbicide glyphosate. more...

O objetivo deste trabalho foi identificar marcadores polimorficos de sequencias simples repetidas (SSR) para identificacao varietal de algodao e avaliacao da distância genetica entre as variedades. Inicialmente, 92 marcadores SSR foram genotipados em 20 cultivares de algodao do Brasil. Desse total, 38 locos foram polimorficos, dos quais dois deles foram amplificados por um unico par de iniciadores; o numero medio de alelos por loco foi 2,2. Os conteudos de informacao polimorfica (PIC) e de poder de discriminacao (DP) foram, em media, 0,374 e 0,433, respectivamente. A distância genetica media foi de 0,397 (minima de 0,092 e maxima de 0,641). Um painel de 96 variedades originarias de diversas regioes do mundo foi avaliado por 21 locos polimorficos derivados a partir de 17 pares de iniciadores selecionados. Entre essas variedades, a distância genetica media foi de 0,387 (minima de 0 e maxima de 0,786). Os dendrogramas elaborados a partir de media aritmetica nao ponderada (UPGMA) nao refletiram as regioes do Brasil (20 genotipos) ou do mundo (96 genotipos), onde as variedades ou linhagens foram selecionadas. O procedimento de reamostragem bootstrap mostra que a identificacao dos genotipos e viavel com 19 locos. Os marcadores polimorficos avaliados sao uteis na identificacao varietal de um painel amplo de variedades de algodao e podem ser aplicados em estudos de diversidade da especie. more...

Cotton has been collected in Brazil for decades for its conservation, evaluation, and the use of its genetic resources. Gossypium mustelinum is an allotetraploid cotton species that only occurs in Brazil, and little is known about its genetic potential for improvement. However, the species is threatened by habitat fragmentation and interspecific hybridization with exotic species of cotton. In this study, we investigated the rate of natural hybridization in two populations of G. mustelinum in Bahia, Brazil, with G. hirsutum and G. barbadense using a set of microsatellite markers. more...

BRS 369RF and BRS 370RF were developed by the EMBRAPA as a part of efforts to create high-yielding germplasm with combinations of transgenic traits. BRS 369RF and BRS 370RF are midseason cultivars and have yield stability, adaptation to the central Brazilian savanna, good fiber quality and tolerance to glyphosate herbicide. more...

Cotton cultivar BRS 335 is a midseason high-yield cultivar and has adaptation to the Northeast Brazilian savanna, yield stability, desirable resistance to main cotton diseases and good fiber quality. The cultivar BRS 335 meets growers? demands for competitive lint yield as well as fulfilling industrial textile requirements. Made available in DSpace on 2021-11-12T12:00:45Z (GMT). No. of bitstreams: 1 BRS-335.pdf: 288519 bytes, checksum: 9deb571e7e679b3288a49028a7a0cc19 (MD5) Previous issue date: 2012 more...

Moco cotton belong to the same species as the cultivated species, Gossypium hirsutum, and cultivated forms were mainly landraces but also developed as cultivars, bearing good fiber quality and drought tolerant when cropped as a perennial species. The northeast Brazil crop system based on this cotton type is finished, with a few small area planted in the three main States, where it was previously cultivated (Ceara, Paraiba, and Rio Grande do Norte), but in others, maintenance is accomplished by single dooryard plants. Plants were found in all visited Northeast Brazil municipalities, sometimes in the North of the country, and were collected for ex situ preservation and evaluation. Most of seeds had no fuzz (62.2%) and 94.6% of the genotypes presented spot in flowers. Seventy-one alleles were revealed in 12 loci. The genetic structure of the population evaluated by microsatellite markers shows two main groups, one comprising the Serido region where landraces were originated and other comprising the state of Ceara, where a specific breeding program was developed. Genotypes collected in North Brazil States as well as those collected in Bahia, Alagoas, and Sergipe grouped with those collected in Ceara. The Mantel correlogram indicates a significant (P < 0.05) correlation between genetic and geographical distances up to 77 km. The ex situ maintenance and agronomical evaluation are the main concerns for moco, as the use of the agricultural interesting traits, possibly introgressed to other genotypes, is predicted. The in situ preservation is still of interest since there is more diversity there than in the collected plants and some should be continued due to use as medicinal plant. more...

a b s t r a c t Two major cultivated cotton species, Gossypium hirsutum (Gh) and G. barbadense (Gb) contribute to the bulk of cotton fiber production worldwide (95%). These species are largely inter-fertile and each displays a series of distinctive characteristics in terms of numerous botanical features and, more importantly, in their agronomic performance, adaptability and overall fiber quality. A recombinant inbred line (RIL) pop- ulation derived from an inter-specific cross between Gh and Gb, used previously for QTL mapping of fiber quality characteristics, has also been evaluated over 6 sites and 2 years for various plant morphological, phenological and yield component traits. A total of 27 traits were assessed across a varying number of locations (up to 6 locations, in Australia, USA, Brazil, Cameroon, Belgium and France) and years, represent- ing up to 10 different combinations. Variability in many of these traits was observed among the RILs and they frequently showed transgression. One hundred and sixty six significant QTLs, covering the 27 traits, were detected by composite interval mapping when using individual datasets. Cases of confirmation of localizations of individual QTLs from different data sets were detected in 27 instances, indicating that the 166 individual QTLs in this study could be represented by a maximum of 121 chromosome positions. QTL were shared between traits related to hairiness (22 individual QTLs), plant morphology of vegetative (29 QTLs) and reproductive (37 QTLs) parts, phenology (17 QTLs), and yield-related traits (61 QTLs). This is the first report of QTL mapping in cotton for various within-boll yield-related traits assessed on a per-seed basis, including fiber mass per unit of seed surface area (5 QTLs), calculated number of fibers per seed (2 QTLs) or per unit of seed surface area (1 QTL). This report confirms the importance of considering such basic yield components in selection for better yielding cotton varieties. more...

Gossypium mustelinum is the only cotton species native to Brazil; it is endemic to the semi-arid region of the northeast. The populations are found near perennial and semi-perennial sources of water, such as ponds or pools in intermittent streams. Problems with in situ conservation derive from human interference in its habitat, mainly because of excessive cattle grazing and deforestation. Establishing efficient strategies for in situ conservation requires knowledge of the genetic structure of the populations. We evaluated the structure and genetic variability of populations of G. mustelinum in the Tocó and Capivara Rivers (State of Bahia). Two hundred and eighteen mature G. mustelinum plants were genotyped with SSR markers. The molecular data were used to estimate the allelic frequencies, the heterozygosity, the F statistics, and the genetic distance among the populations and among individuals. We found high genetic diversity among the populations. The FST indexes for each population were also high and strongly correlated with physical distance. The high estimated level of endogamy and the low observed heterozygosity are indicative that the populations reproduce mainly by self-fertilization and crosses between related individuals. Consequently, strategies for in situ preservation should include at least three occurrence sites of G. mustelinum from each population. For ex situ conservation, the collections should include as many sites as possible. more...

Accessions of Gossypium spp., some of them never previously tested, were evaluated for resistance to a local isolate of Meloidogyne incognita race 3 in greenhouse experiments. Nematode infection was characterized based on the galling and egg mass indexes and the reproduction factors (RF). Root-knot nematode reproduction among the newly tested accessions varied from highly susceptible (AS0188, AS0189) to moderately resistant (MT123 no. 3), and some accessions showed highly reduced nematode reproduction (CIR1343, CIR1348, Fai Mui). Histological observations of two resistant accessions (G. barbadense CIR1348 and G. hirsutum TX-25, respectively) showed that resistance occurs through a two-stage mechanism in the first accession and through a single-stage mechanism in the second. Parasitism is blocked early after second-stage juvenile (J2) penetration or during its initial tissue migration (CIR1348) and the development of later-stage juveniles into female adults is suppressed at a later stage (TX-25 and CIR1348). Fluorescence and bright light microscopy showed that root cells surrounding nematodes exhibit a hypersensitivity-like reaction, with the accumulation of presumably phenolic compounds and the presence of necrotic cells that limit the development of nematodes and the formation of giant cells. Underdeveloped giant cells with degenerated cytoplasmic content were found in small numbers in CIR1348 and in large numbers in TX-25, along with deformed nematodes. The full characterization of the defence mechanisms of novel sources of resistance to the root-knot nematode in cotton constitutes a first step towards their use in crop improvement. (Resume d'auteur) more...

The genus Gossypium is composed of both diploid and allotetraploid species. The five allotetraploid species of Gossypium are sexually compatible, and only partial sexual barriers have been described. Natural hybrids among them do not occur or occur in situ with very low frequency in Brazil in the rare places where cultivated upland cotton ( Gossypium hirsutum L.) occurs in a sympatric range with Gossypium barbadense L. or Gossypium mustelinum Miers. We evaluated the presence of pollen competition as a prezygotic barrier in crosses between upland cotton and G. barbadense and G. mustelinum. We found that G. barbadense pollinated with a mixture of 50% upland cotton and 50% G. barbadense pollen resulted in 17.4%–31.1% interspecific hybrids, depending upon the upland cotton genotype used as pollen donor. Mixtures containing pollen from G. mustelinum and upland cotton, used to pollinate G. mustelinum in proportions of 25%:75%, 50%:50%, and 75%:25%, produced 61.3%, 22.5%, and 3.6% interspecific hybrids, respectively. These low rates of hybrid production demonstrate that pollen competition is present with G. mustelinum and G. barbadense and confirms this mechanism as a sexual barrier. more...

Gossypium mustelinum Miers ex Watt is a native from Northeastern Brazil and belongs to the primary gene pool of the cultivated cotton. The unique places where the species was known to occur were visited to plan ex situ and in situ preservation. Two populations at Caico became extinct, and only eleven individuals were found. At Jaguarari, although one population became extinct, a new one was localized with approximately 500 adult plants, where a fence avoided cattle feeding. The population from Macurure consisted of 28 plants protected from animals by thorns of Bromelia laciniosa Mart. ex Schult. f. Thirteen SSR primer pairs amplified 40 alleles, among which 30% were exclusive of one of the populations. The genetic differences between populations represented 58.3% of the total genetic variation observed. The high genetic distances are likely to be caused by geographical isolation as well as by the small number of individuals which contribute to new generations, and consequential genetic drift. more...

Neste trabalho foi avaliado o cultivo in vitro de somaclones de abacaxizeiro, na presença de elevadas concentrações de NaCl. Propágulos de abacaxizeiro foram submetidos a um período de cultivo in vitro em diferentes concentrações de NaCl (0, 12,5, 25 e 50 mM). Em seguida, foram cultivados na ausência do sal e, por fim, foram submetidos a um outro período de cultivo in vitro em 0 e 100 mM de NaCl. Não se observou interação entre as concentrações empregadas nos dois períodos de exposição ao NaCl, de modo que propágulos provenientes de tratamentos com concentrações mais elevadas não apresentaram melhor desempenho durante o segundo período de exposição; no entanto, constatou-se alteração negativa para os valores referentes à maioria das variáveis avaliadas em propágulos cultivados na presença de 100 mM de NaCl, na segunda exposição. Ao final do experimento foram selecionadas famílias cultivadas na presença de 100 mM de NaCl, com base na semelhança fenotípica ao controle. As famílias selecionadas eram originárias, igualmente, das quatro concentrações do primeiro período de tratamento com NaCl. Desse modo, as concentrações empregadas no primeiro período de exposição ao NaCl não influenciaram significativamente o crescimento dos propágulos durante o segundo período de cultivo in vitro na presença de NaCl. more...

3 Depto. de GenOtica e Biologia Celular, UFRN 4 Embrapa Semi-`rido Resumo: A cultura de tecidos tem sido utilizada como ferramenta para gerar e selecionar variabilidade genOtica que confira maior toler‚ncia das espOcies cultivadas ‡ salinidade. Plantas de abacaxi das variedades POrola e Smooth Cayenne foram micropropagadas em meio de cultura contendo zero, 12,5 e 25 mM de NaCl e avaliadas durante a fase de aclimataAao quanto ‡s alteraAies induzidas pelo NaCl durante o cultivo in vitro e para determinar o melhor par‚metro para quantificar estas alteraAies. Foram avaliados os caracteres altura das plantas, di‚metro da roseta foliar, nœmero de folhas, comprimento e largura da folha eDi aos 0, 15, 45, 75 e 105 dias apUs a instalaAao do experimento. Observou-se que as plantas micropropagadas em meio com NaCl e sem NaCl apresentaram mOdias e taxas de crescimento semelhantes, mas diferiram quanto ‡s correlaAies entre os caracteres e ‡s vari‚ncias fenotIpicas. Os resultados indicaram que a vari‚ncia fenotIpica foi o par‚metro mais adequado para avaliar o impacto da seleAao in vitro sobre caracteres aparentemente nao relacionados com a salinidade em plantas de abacaxi. Palavras-chave: Ananas comosus, cultura de tecidos, salinidade Effects of in vitro culture in the presence of NaCl in pineapple plants during the acclimatization phase Abstract: Plant tissue culture has been used to induce and select genetic variability in order to increase the level of salinity tolerance in several species. Pineapple plants from POrola and Smooth Cayenne varieties were micropropagated for six months in a medium with 0, 12.5 and 25 mM of NaCl and evaluated during the acclimatization phase to verify the changes induced by NaCl during in vitro cultivation and to determine the best parameter to quantify these changes. The traits evaluated for plant height, plant diameter, leaf number, length and width of the D leaf at 0, 15, 45, 75 and 105 days after the installation of the experiment. There was no effect of different levels of NaCl during the micropropagation on the traits and mean growing rates. Differences were found in the correlation coefficients between the characters and mainly, in the phenotypic variances. The results indicated that the phenotypic variances were more adequate to evaluate the impact of in vitro selection for NaCl tolerance on traits apparently not related to salinity in pineapple plants. more...

The objective of this study was to estimate genetic diversity of cotton mocó planted in Paraíba and Rio Grande do Norte using microsatellite markers, since mocó landraces are a valuable source of genetic diversity. A set of 38 accessions - 21 plants from Rio Grande do Norte and 17 from Paraiba - was analyzed using 24 pairs of cotton microsatellite primers, which amplified 20 polymorphic loci. The average inbreeding was 0.432, and was slightly higher in individuals from Paraíba than from Rio Grande do Norte. Genetic diversity (Nei´s unbiased estimator) between individuals from each state's populations had similar values (HT = 0.327 and 0.302 in Paraíba and Rio Grande do Norte, respectively), indicating that comparable variability has been maintained. Moreover, the proportion of diversity between populations was extremely low (DST = 0.007), but expressive between mesoregions (DST = 0.069). These data led us to conclude that the genetic similarities between populations are high. more...

Fungi and bacteria were isolated from surface disinfected leaf tissues of several citrus rootstocks. The principal bacterial species isolated were Alcaligenes sp., Bacillus spp. (including B. cereus, B. lentus, B. megaterium, B. pumilus, and B. subtilis), Burkholderia cepacia, Curtobacterium flaccumfaciens, Enterobacter cloacae, Methylobacterium extorquens, and Pantoea agglomerans, with P. agglomerans and B. pumilus being the most frequently isolated species. The most abundant fungal species were Colletotrichum gloeosporioides, Guignardia citricarpa, and Cladosporium sp. Genetic variability between 36 endophytic bacterial isolates was analysed by the random amplified polymorphic DNA (RAPD) technique, which indicated that B. pumilus isolates were more diverse than P. agglomerans isolates, although genetic diversity was not related to the host plants. In vitro interaction studies between G. citricarpa isolates and the most frequently isolated endophytic bacteria showed that metabolites secreted by G. citricarpa have an inhibitory growth effect on some Bacillus species, and a stimulatory growth effect on P. agglomerans.Key words: endophytes, citrus, fungal-bacterial interaction, RAPD, diversity, Pantoea agglomerans, Bacillus pumilus, Guignardia citricarpa. more...

The present study was conducted in five Gossypium mustelinum populations that were phenotyped and genotyped to quantify their resistance to the major diseases that affect cultivated cotton (G. hirsutum) in Brazil. Four G. mustelinum populations, in addition to genotypes of G. hirsutum and G. barbadense (resistant or susceptible controls), were phenotyped for resistance to cotton blue disease, angular leaf spot, common mosaic and ramulose. Artificial inoculation of cotton plants with causative agents of cotton blue disease, angular leaf spot and ramulose, as well as those naturally infested with common mosaic virus, showed that all G. mustelinum accessions were susceptible to every disease studied. Four microsatellite markers linked to disease resistance genes for cotton blue disease, angular leaf spot and root-knot nematodes (Meloidogyne spp.) in G. hirsutum were used for genotyping of the five populations. The markers amplified different alleles from those associated with resistance genes in cultivated cotton, revealing polymorphisms different from reported cases of G. hirsutum resistance. The susceptibility to all diseases studied may represent a phytosanitary risk for the in situ conservation of natural G. mustelinum populations. more...

The SSR marker CIR246, which is linked to the B 12 gene that confers resistance to race 18 of Xanthomonas axonopodis pv. malvacearum (Xam), was used to evaluate a series of cotton germplasms that were also tested for their response to inoculation with race 18 of Xam (S-295, Delta Opal, 101-102B, Guazuncho-2, Acala 44, Mebane B1, and Stoneville 2B-S9). The allele associated with resistance was amplified in genotypes that carry the B 12 gene (S-295 and Delta Opal) as well as in those that carry B 2 B 3 (101-102B) and B 9L B 10L (Guazuncho-2), indicating that the molecular marker is able to identify genotypes resistant to the Xam races up to race 18, with resistance genes other than B 12 . more...

International audience; The root-knot nematode Meloidogyne incognita is widely distributed and a major pathogen of cotton (Gossypium spp.) worldwide. The objectives of this study were to assess the genetic variability and aggressiveness of Brazilian populations of M. incognita in cotton. Five populations of M. incognita and one isolate of M. enterolobii (outgroup) were used in the molecular analysis. Our results showed that only 2.7 % of the RAPD and AFLP fragments were polymorphic. Despite the existence of two races (races 3 and 4) and two esterase phenotypes (I1 and I2), a low genetic variability among populations was observed, which might be due to the mitotic parthenogenetic mode of reproduction of this pathogen. The aggressiveness/virulence among populations towards different cotton genotypes was also studied. None of the populations was virulent to the resistant cotton genotypes M-315 RNR, TX-25, CIR1343, Wild Mexican Jack Jones and CIR1348 (reproduction factor < 1). Two populations of M. incognita from the states of Mato Grosso do Sul and Parana (Umuarama) (races 4 and 3, respectively) were highly aggressive to the susceptible control FM966 and virulent to the accessions LA-887 and Clevewilt-6 that showed moderate resistance to other populations tested. more...

Begomoviruses are plant viruses responsible for severe losses in important crops, such as beans, cassavas, tomatoes, and cotton, around the world. Here, we report the first full-genome sequence of a bipartite begomovirus species collected from cotton plants in Brazil. more...

Gossypium mustelinum is a wild cotton relative found only in the semiarid region of Bahia state in Brazil, and changes caused by humans in the natural habitat of this species have endangered the existence of several natural populations. Information about the occurrence and genetic composition of these populations is necessary to design effective conservation measures. The aim of this study was to characterize the in situ maintenance mode and assess the genetic diversity of G. mustelinum populations in the basin of the De Contas River. A sample of 205 G. mustelinum specimens was collected from the margins of the Jacaré, Riacho Quixaba, Riacho Serra Azul, and Riacho Riachão rivers and genotyped using 13 SSR primer pairs. In general, all G. mustelinum populations exhibit inadequate in situ maintenance, predominantly due to the deforestation of riparian vegetation and herbivory. The observed total genetic diversity of G. mustelinum was significant (H E = 0.489), highly structured (F ST = 0.534), and organized in homozygous genotypes (F IS = 0.873). The high observed inbreeding level is consistent with the predominance of self-fertilization and geitonogamy (t m = 0.234). In addition, the pattern of genetic structure tended to form groups that coincided with the collection sites, i.e., first clustering within subpopulations, then within populations, and finally within the closest populations. Thus, the observed genetic diversity is likely to be rapidly lost, and conservation measures should therefore be undertaken. more...

How to measure biodiversity? One of the possibilities is to use DNA. The mention of DNA can hint evolution, but this question is much more complicated and beyond the proposition of a biodiversity measure. The reasons stated for use DNA instead of other possible molecules could be that it is stable and responsible for the transmission of traits to future generations. But another reason is simple that it is suitable for measures. First, due to universality among all living things. Second, because it is a big molecule, constituted by variations of just four bases, making it easy to make a great number of sequence comparisons and used it on biodiversity measures. When individuals to be compared are similar, a greater number of comparisons have to be made to obtain a quantification of the differences among them. Conservation biology is not concerned only with the extinction of species, but also with diversity within species or subspecies, where accurate measures of diversity may be required. A third reason is that a good amount of methodologies is already developed to study its nature. DNA markers when used to study biodiversity are frequently designed for a great number of comparisons of similarities or differences among individuals, groups of individuals, or populations. DNA is the code for protein synthesis, but in most of the studies DNA markers are considered exclusively for comparison, which may not to be linked or recognized to be linked with any trait or adaptability of the individual. There are lots of kinds of markers, and one important thought to have in mind is that there is not a best one among them, but the choice should consider the species to be studied and the objective of the diversity analysis. more...

Le moco cotton (Gossypium hirsutum L. race Marie-Galante (Watt) Hutch.) constitue une source potentielle d'allè les intéressants pour les programmes d'amélioration génétique, compte tenu surtout de sa grande adaptabilité aux conditions semi-arides. Dans le but de quantifier la variabilité du cotton moco, les auteurs ont récolté 187 plantes dans le nordest du Brésil et en ont fait l'évaluation à l'aide de marqueurs satellites. Ils ont amplifié un total de 62 allèles allant de trois à huit allèles polymorphes par lieu. La diversité génétique s'avère élevée (0,52) et lorsque mesurée sur la base par état, elle atteint 0,37 en moyenne. La population montre un faible degré d'hétérozygocité (HO = 16), reflétant un haut degré d'endogamie (FIS = 0,67). L'analyse phylogénétique à l'aide de la méthode d'union des voisins révèle que les plantes échantillonne´es dans diffe´rents e´tats tendent a` se regrouper selon leur origine géographique, sauf pour celles récoltées dans les états de Pariba et Rio Grande do Norte, qui se regroupent ensemble. Les plantes provenant de l'e´tat de Piaui frment deux groupes, l'un portant apparemment une contribution allélique du G. barbadense, alors que le second groupe de plantes s'apparente plus à celles de Pariba et Rio Grande do Norte. En dépit de la forte diversité génétique observée dans les populations résiduelles, des efforts urgents de conservation devront êre déployés compte tenu du fort degré d'endogamie et de l'accélération du processus d'extinction caractérisant ces populations. De tels efforts doivent être axés sur la récolte et le maintien ex situ d'une diversité génétique représentative. more...

The objective of this work was to determine the inheritance of cotton blue disease resistance by cotton plants. Populations derived from the CD 401 and Delta Opal resistant varieties were evaluated, through a greenhouse test with artificial inoculation by viruliferous aphids. Cotton blue disease resistance is conditioned by one dominant gene, both in CD 401 and Delta Opal varieties. O objetivo deste trabalho foi determinar a herança da resistência do algodoeiro à doença-azul. Populações derivadas das variedades resistentes CD 401 e Delta Opal foram avaliadas em casa de vegetação, por meio da inoculação de pulgões virulíferos. A resistência à doença-azul do algodoeiro é condicionada por um gene dominante, tanto em 'DC 401' quanto em 'Delta Opal'. more...

Cotton blue disease is an aphid-transmitted cotton disease described in Brazil in 1962 as Vein Mosaic “var. Ribeirao Bonito”. At present it causes economically important losses in cotton crops if control measures are not implemented. The observed symptoms and mode of transmission have prompted researchers to speculate that cotton blue disease could be attributed to a member of the family Luteoviridae, but there was no molecular evidence supporting this hypothesis. We have amplified part of the genome of a virus associated with this disease using degenerate primers for members of the family Luteoviridae. Sequence analysis of the entire capsid and a partial RdRp revealed a virus probably belonging to the genus Polerovirus. Based on our results we propose that cotton blue disease is associated with a virus with the putative name Cotton leafroll dwarf virus (CLRDV). more...

O efeito de diferentes concentrações de ANA e BAP na micropropagação do abacaxizeiro, bem como no cultivo em hidroponia das plântulas obtidas in vitro, foram estudados em brotos de abacaxizeiro da variedade Pérola, inoculados em meio de cultura básico MS, suplementado com os fitorreguladores BAP e ANA em diferentes concentrações. Caracteres morfológicos quantitativos relacionados ao crescimento dos brotos e das plântulas de abacaxizeiro foram avaliados respectivamente durante os cultivos in vitro e em hidroponia e mostraram que, o tratamento T1 (BAP = 1,0 mg L-1e ANA = 0,5 mg L-1) proporcionou a maior taxa média de regeneração de brotos e conseqüentemente uma maior produção de matéria fresca. Entretanto, a altura dos brotos e a formação de suas raízes foram maiores nos tratamentos T2 (BAP = 0,5 mg L-1 e ANA = 0,25 mg L-1 ) e T3 (BAP = 0,25 mg L-1 e ANA = 0,12 mg L-1 ). Após sessenta dias de cultivo em hidroponia, todas as plântulas oriundas do tratamento T1 apresentaram um bom desenvolvimento, expresso pela maioria dos caracteres morfológicos avaliados. O sistema de micropropagação utilizado neste trabalho possibilitou a obtenção de brotos de abacaxizeiro Pérola, em quantidade suficiente e ao mesmo tempo de fácil individualização, seguida da regeneração de plântulas que foram cultivadas em hidroponia. The effect of different ANA and BAP concentrations on in vitro and hydroponic cultures were studied. Pineapple shoots derived from Pérola explants variety were inoculated in MS media containing BAP and ANA in different concentrations. Growth parameters of shoots and plantlets were measured for in vitro and hydroponic cultures. Showed a highest multiplication rates of shoots and consequently highest fresh matter production were obtained with BAP and ANA at the concentrations of 1,0 and 0,5 mg L-1 respectively. However, the shoot length as well as the root number formed were higher in the T2 (0,5 de BAP + 0,25 de ANA) and T3 (0,25 de BAP + 0,12 de ANA) treatments. The results showed that after sixty days of hydroponic culture and in the presence of T1 treatment, all plantlets had good developing that was observed in the majority of morphological growth parameters evaluated. The results showed that it is possible to obtain high quantities of shoots and then plantlets which could be cultivated in hydroponic culture using the pineapple micropropagation procedures methods. more...