Análisis de expresión génica durante la respuesta de defensa de la yuca a la bacteriosis vascular (añublo bacteriano)
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EspañolPublication Date
2006Metadata
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La bacteriosis vascular de la yuca es una destructiva enfermedad en Sur AmØrica y África, causada por la bacteria Xanthomonas axonopodis pv. manihotis (Xam). Produce pérdidas entre el 12% y 100% de los cultivos. Algunos estudios se han realizado a nivel bioquímico y citoquímico para conocer las respuestas de defensa de la yuca a Xam; sin embargo, las bases moleculares de los mecanismos de defensa no han sido aún caracterizadas. Con el propósito de identificar genes diferencialmente expresados durante la respuesta de la planta al patógeno, se ha construido una librería sustractiva, usando el método de Sustracción Diferencial en Cadena (DSC), con 1536 clones de dos variedades resistentes (MBRA 685 y SG 107-35). De esta librería fueron seleccionados al azar 110 clones para ser secuenciados y realizar búsquedas de similitud en bases de datos públicas. El análisis de secuencia mostró 14 clones con similitud a genes previamente reportados como involucrados en procesos de defensa en plantas, 70 clones con similitud a genes de plantas sin función conocida o que no presentaron similitud, representando nuevos genes potencialmente involucrados en las respuestas de defensa de la yuca. Finalmente fueron construidos microarreglos de ADNc, usando los clones seleccionados de las librerías sustractivas para confirmar su expresión diferencial durante el desarrollo de la infección. Palabras clave: yuca, añublo bacteriano, identificación de genes, librerías sustractivas, microarreglos.Summary
Cassava bacterial blight (CBB) caused by Xanthomonas axonopodis pv. manihotis (Xam) is a destructive disease in the South América and África and yield losses range between 12 and 100%. Cytochemistry and biochemistry of defense response to CBB have been well studied. However, the response of the plant to pathogen attack at the molecular and cellular level remains uncharacterized. Identification of genes associated with defense responses is one of most critical steps leading to the elucidation of disease resistance mechanisms in cassava. In this study, we identified differentially expressed genes during pathogen attack by subtractive hybridization, using the Differential Subtraction Chain method (DSC). A population of cDNA obtained from infected plants was used as "treatment" and a population of cDNA obtained from healthy plants was used as "control". 1536 clones were isolated from the resistant varieties (MBRA 685 and SG 107-35). Of these, 110 randomly selected clones were sequenced and a homology search was conducted. The sequence analysis showed that 14 cDNA clones shared homology with plant genes involved in defense responses, 70 clones were either homologous to plant genes of unknown function or showed no homology, representing new genes potentially involved in cassava defense responses. A cDNA microarray was constructed by spotting the clones identified from our subtractive libraries. Other clones potentially involved in cassava defense responses were also included. The cassava defense cDNA microarray was used to confirm the differential expression of the clones. Keywords: cassava, bacterial blight, gene expression, subtractive library, microarrays.Keywords
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