Associação de bioensaios e caracterização molecular para seleção de novos isolados de Bacillus thuringiensis efetivos contra Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

A lagarta de Spodoptera frugiperda (J. E. Smith) é uma das principais pragas do milho e para seu controle o Bacillus thuringiensis se destaca por sua atividade entomopatogênica. Este trabalho objetivou a caracterização molecular de isolados de B. thuringiensis quanto à presença do gene cry1 e a avaliação da sua eficiência no controle de lagartas de S. frugiperda. Nas análises da PCR, foi utilizado o Gral-cry1 para confirmação da presença do gene cry1 nos 115 isolados. Uma suspensão de 3 x 10(8) esporos/ml banhou a dieta utilizada para alimentação de 30 lagartas por isolado, com três repetições. A identificação do tipo de genes cry1 dos diferentes isolados foi realizada para cinco sub-classes de genes e análises de regressão linear foram realizadas para verificar possíveis associações entre a presença de um gene cry individual e altos níveis de toxicidade. Ttodos os DNAs amplificados com os iniciadores Gral-cry1 apresentaram produto de amplificação com tamanho esperado. Quanto aos níveis de eficiência inseticida contra a lagarta-do-cartucho, 41 isolados apresentaram 100% de mortalidade e 16 apresentaram índice entre 75% e 90%. O gene cry1Ab esteve presente em 80 isolados, cryB em 69 isolados, cry1Ac em todos os isolados, cryV e cry1E em 93 e 27 isolados, respectivamente. Os valores referentes ao efeito individual de cada gene na mortalidade de larvas foram significativos a 1% de probabilidade, para os genes cry1Ac e cry1E.The fall armyworm, Spodoptera frugiperda (J. E. Smith), is one of the main corn pests and Bacillus thuringiensis is important in its control because of its entomopathogenic property. The objective of this study was the molecular characterization of B. thuringiensis isolates for cry1 locus presence and the assessment of the efficiency of these isolates in controlling S. frugiperda caterpillars. Gral-cry1 was used in the PCR analyses to confirm the presence of the cry1 locus in 15 isolates. A 3 x 10(8) spore/ml suspension bathed the diet used to feed 30 caterpillars per isolate, with three replications. The cry1 locus type genes of the different isolates were identified for five gene subclasses; linear regression analyses were carried out to ascertain possible associations between the presence of an individual cry1 locus gene and high levels of toxicity. All the DNAs amplified with Gral-cry1 presented an amplification product with the expected size. Regarding the levels of insecticide efficiency against the cob worm, 41 isolates presented 100% mortality and 16 presented an index between 70% and 90%. The cry1Ab gene was present in 80 isolates, cryb in 69 isolates, cry1Ac in all the isolates and cryv and cry1E in 93 and 27 isolates, respectively. The values regarding the individual effect of each gene on caterpillar mortality were significant at 1% probability for the cry1Ac and cry1E genes.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Analysis and Functional Annotation of an Expressed Sequence Tag Collection for Tropical Crop Sugarcane

To contribute to our understanding of the genome complexity of sugarcane, we undertook a large-scale expressed sequence tag (EST) program. More than 260,000 cDNA clones were partially sequenced from 26 standard cDNA libraries generated from different sugarcane tissues. After the processing of the sequences, 237,954 high-quality ESTs were identified. These ESTs were assembled into 43,141 putative transcripts. Of the assembled sequences, 35.6% presented no matches with existing sequences in public databases. A global analysis of the whole SUCEST data set indicated that 14,409 assembled sequences (33% of the total) contained at least one cDNA clone with a full-length insert. Annotation of the 43,141 assembled sequences associated almost 50% of the putative identified sugarcane genes with protein metabolism, cellular communication/signal transduction, bioenergetics, and stress responses. Inspection of the translated assembled sequences for conserved protein domains revealed 40,821 amino acid sequences with 1415 Pfam domains. Reassembling the consensus sequences of the 43,141 transcripts revealed a 22% redundancy in the first assembling. This indicated that possibly 33,620 unique genes had been identified and indicated that >90% of the sugarcane expressed genes were tagged