Resumen

CONTRERAS, Elízabeth  y  LOPEZ, Camilo. Identification of polymorphisms in RXam2 a cassava bacterial blight resistance gene candidate. Rev. colomb. biotecnol [online]. 2011, vol.13, n.2, pp.63-69. ISSN 0123-3475.

Cassava is a staple food for more than a billion people. One of the major diseases of cassava which could compromise food security is known as cassava bacterial blight, caused by the bacterium Xanthomonas axonopodis pv. manihotis (Xam). The RXam2 resistance gene candidate encodes a protein with Nucleotide Binding Site and Leucine Rich Repeats domains, and colocalizes with a QTL (Quantitative Trait Loci) that accounts for 61.6% of the resistance to the Xam strain CIO151. In this work we sequenced 1816 bp corresponding to a partial sequence of this gene in three cassava varieties with the aim of having a preliminary overview of the degree of Single Nucleotide Polymorphisms (SNPs). The sequenced regions included 507 bp of the promotor and 1309 bp of the coding sequence. It was possible to identify five and 31 intravarietal SNPs in MCOL2246 and TMS60444, respectively. In addition, the number of SNPs between varieties was 44, 34 and 23 for MCOL2246-TMS60444, TMS60444-SG107-35 and MCOL2246-SG107-35, respectively. The largest number of SNPs was located in the promoter region -500 to -300 bp. This study may help to develop alternatives to identify SNPs in a more diverse group of cassava varieties, and possibly associate them with resistance/susceptible phenotypes.

Palabras clave :   Cassava;  resistance;  polymorphisms;  SNP..

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