Abstract

CORTES, SIMÓN  and  LOPEZ, CAMILO. Strategy of Gene Silencing in Cassava for Validation of Resistance Genes. Acta biol.Colomb. [online]. 2010, vol.15, n.2, pp.203-218. ISSN 0120-548X.

Cassava (Manihot esculenta) is a major source of food for more than 1000 million people in the world and constitutes an important staple crop. Cassava bacterial blight, caused by the gram negative bacterium Xanthomonas axonopodis pv. manihotis, is one of the most important constraints for this crop. A candidate resistance gene against cassava bacterial blight, named RXam1, has been identified previously. In this work, we employed the gene silencing approach using the African Cassava Mosaic Virus (ACMV) to validate the function of the RXam1 gene. We used as positive control the su gen, which produce photoblanching in leaves when is silenced. Plants from the SG10735 variety were bombardment with the ACMV-A-SU+ACMV-B y ACMV-A-RXam1+ACMV-B constructions. The silencing efficiency employing the su gene was low, only one of seven plants showed photoblanching. In the putative silenced plants for the RXam1 gene, no presence of siRNAs corresponding to RXam1 was observed; although a low diminution of the RXam1 gene expression was obtained. The growth curves for the Xam strain CIO136 in cassava plants inoculated showing a little but no significance difference in the susceptibility in the silenced plants compared to not silenced.

Keywords : Cassava; VIGS; resistance; cassava bacterial blight.

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