Time filter

Source Type

Brasília, Brazil

Ramiro D.,CIRAD - Agricultural Research for Development | Jalloul A.,Damascus University | Petitot A.-S.,CIRAD - Agricultural Research for Development | Grossi de Sa M.F.,Embrapa Cenargen | And 2 more authors.
Tree Genetics and Genomes

In plants, WRKY proteins are a group of transcription factors existing as a gene superfamily that play important roles in regulation of defense response pathways. To assess the diversity of this protein family in coffee (Coffea spp.), data mining methods were used on a set of around 200,000 coffee expressed sequence tags. A total of 53 different putative WRKY genes were obtained, but only 22 unigenes encoding a protein with a WRKY domain were identified, eight of which are supported by full-length cDNA sequences. Alignment of WRKY domain sequences of the coffee unigenes and 72 Arabidopsis thaliana WRKY genes showed that the 22 coffee WRKY members were distributed among the main A. thaliana WRKY subgroups and shared conserved peptide domains. To assess the involvement of WRKY genes in coffee defense response pathways, their expression was analyzed under biotic (nematode and rust fungus infection), hormonal (salicylic acid, methyl-jasmonate), and wounding treatments, leaf senescence, and fruit development. Five members of WRKY groups IId and III were regulated only by pathogens and hormone treatments. Although a significant correlation of WRKY genes expression after MeJA and rust treatments was observed, expression of coffee genes involved in JA biosynthesis and lipoxygenase (EC activity assays did not support the involvement of JA in the early coffee resistance responses to the rust pathogen. The five WRKY transcription factor members identified might play important roles as regulators of pathogen resistance responses and could be useful for improving coffee tolerance to various biotic stresses. © 2010 Springer-Verlag. Source

Pozzobon M.T.,Embrapa Cenargen | de Souza K.R.R.,Embrapa Hortalicas | de Carvalho S.I.C.,Embrapa Hortalicas | Reifschneider F.J.B.,Embrapa Hortalicas
Horticultura Brasileira

Twelve lines of pepper, from different groups {Jalapeño (CNPH 2862, CNPH 2864), Dedo-de-Moça (CNPH 1397, CNPH 0039, CNPH 0053), Cambuci (CNPH 0283), Peixe-Boi (CNPH 0434), Falsa Cumari (CNPH 3761), Bode Vermelha (CNPH 3773), Biquinho Doce (CNPH 3870), Tabasco (CNPH 3000) and Malagueta (CNPH 2869) had their meiotic behavior and the estimation of pollen viability analyzed with the aim of indicating potentially fertile material for the Capsicum breeding program. Conventional analysis by staining revealed a slightly irregular behavior during microsporogenesis for the majority of lines: the meiotic index (MI) and pollen viability were over 90%, therefore considered meiotically stable. The main abnormalities observed were chromosome stickiness, unoriente chromosomes, laggards, bridges, micronuclei, microcytes and cytomixis. Three lines (CNPH 0283, CNPH 3000 and CNPH 3773) showed lower pollen viability, 77, 66 and 58% respectively. The lower pollen viability in CNPH 0283 was associated with higher frequency of irregularities and consequently the low MI (77%). The findings of the present manuscript confirm the importance of the cytological analyzes as a useful tool in selecting of lines meiotically stable and potentially fertile enabling a better planning of seed production of promising cultivars. Source

Morais H.C.,University of Brasilia | Sujii E.R.,Embrapa Cenargen | Almeida-Neto M.,University of Brasilia | De-Carvalho P.S.,University of Brasilia | And 2 more authors.

Decrease in the species composition similarity of herbivore assemblages with increasing phylogenetic distance between host plants is a widespread pattern. Here we used data for caterpillars in the Brazilian Cerrado to investigate how the similarity in caterpillar species composition decreases as the taxonomic level and genetic distance (GD) of their host plants increases. In addition, we elucidate the plant taxonomic level that provides the greatest contribution to turnover in the caterpillar species composition among host taxa. Adult Lepidoptera were reared from caterpillars collected from 52 plants over 13yr in the same area, with each host plant sampled for 1yr. Most species were specialists, with 66 percent of genus specialists among the nonsingleton species. The similarity in caterpillar species composition across plant taxa decreased from host species to genera, and from host genera to orders. Above this level, the similarity was consistently low. The GD between plants explained 82 percent of the variation in the similarity of caterpillar species composition. The contribution of caterpillar species turnover among host orders from the same superorder and among host superorders from the same subclass explained 70 percent of the caterpillar species richness as a whole. Our results lend support to the view that most tropical caterpillars are host specialists. Our findings further indicate that the number of orders and superorders of plants provide the greatest contribution to the total caterpillar richness compared with all of the other host taxonomic levels combined. © 2011 The Author(s). Journal compilation © 2011 by The Association for Tropical Biology and Conservation. Source

Valencia J.W.A.,University of the Atlantic | De Sa M.F.G.,Embrapa Cenargen | Jimenez A.V.,University of Caldas
Protein and Peptide Letters

The enzymatic activity of leucine aminopeptidase (EC from the intestinal tract of sugarcane giant borer (Telchin licus licus) was assayed by using a simple and sensitive spectrophotometric assay that uses L-leucyl-2-naphthylamide as substrate. In this assay, L-leucyl-2-naphthylamide is hydrolyzed to produce 2-naphthylamine and Lleucine. The product 2-naphthylamine reacts with Fast Black K and can be monitored using a continuous spectrophotometric measurement at 590 nm. The data on the kinetic parameters indicates that the Km for the L-leucyl-2-naphthylamide at pH 7.0 was found to be lower than those found for other LAP substrates. The Km and Vmax for the LAP were determined to be 84.03 βM and 357.14 enzymatic units mg-1, respectively. A noticeable difference of LAP activity between the two insect orders tested was observed. This method could be used to screen for natural LAP inhibitors. © 2014 Bentham Science Publishers. Source

Bontemps C.,University of York | Elliott G.N.,Macaulay Institute | Simon M.F.,Embrapa Cenargen | Dos Reis Junior F.B.,Embrapa Cerrados | And 8 more authors.
Molecular Ecology

Burkholderia has only recently been recognized as a potential nitrogen-fixing symbiont of legumes, but we find that the origins of symbiosis in Burkholderia are much deeper than previously suspected. We sampled 143 symbionts from 47 native species of Mimosa across 1800 km in central Brazil and found that 98% were Burkholderia. Gene sequences defined seven distinct and divergent species complexes within the genus Burkholderia. The symbiosis-related genes formed deep Burkholderia-specific clades, each specific to a species complex, implying that these genes diverged over a long period within Burkholderia without substantial horizontal gene transfer between species complexes. © 2009 Blackwell Publishing Ltd. Source

Discover hidden collaborations