Caracterización molecular del germoplasma de ñame colombiano utilizando "dna amplificaron fingerprinting (daf)" en condiciones radiactivas

Abstract

Para la realización de este trabajo se utilizaron muestras de la colección de ñame (Dioscorea spp.) de la Universi­dad de Córdoba y algunas muestras provenientes del IITA (International Institute of Tropical Agriculture, Ibadan, Nigeria), con el fin de caracterizarlas molecularmente y complementar la información que se tiene de ellas. Dada la importancia del cultivo del ñame para los pequeños productores de la costa atlántica, surgió la propuesta de iniciar estudios moleculares en una primera etapa empleando técnicas como los AFLP En este trabajo, utilizan­do DNA amplificación "fingerprinting" (DAF), técnica basada en la PCR que utiliza oligos aleatorios que gene­ran patrones de bandeo característicos de cada individuo, se encontró que la diversidad de la población fue 0.0413 con una media de similaridad de 0.9587, lo cual indica que la colección de ñame existente en el país posee muy poca diversidad genética, y esto puede explicar parcialmente la vulnerabilidad del cultivo a plagas y enfer­medades, como sucedió a finales de la década de 1980 cuando la antracnosis prácticamente acabó con el cultivo en la costa atlántica colombiana. Es recomendable continuar con los estudios de caracterización utilizando una técnica de mayor poder de discriminación.

Samples from the Universidad de Córdoba's yam collection (Dioscorea spp.) and others originating from IITA (International Institute of Tropical Agriculture, Ibadan, Nigeria) were molecularly characterised to complement existing information about them. The yam (Diosocorea spp.) represents a basic crop for small-scale farmers on the Colombian Atlantic Coast who sow around 20,000 hectares per year. Even though they are dioecious species, only one sex is represented in Colombia; it must also be stated that climatic conditions are not propitious for its flowering. This situation has caused difficulty for work in yam breeding. The yam species and varieties used in the Colombian ABP (Agricultural Biotechnology Programme) have been molecularly characterised by AFLPs in a previous publication describing a preliminary study emerging from the need to broaden the characterisation of those accessions kept at the Universidad de Córdoba. Comparisons have also been done with some African accessions donated by IITA. In this article, samples were molecularly characterised by another fingerprinting technique, the DAF technique (DNA Amplification Fingerprinting) based on PCR, using random oligonucleotides for generating characteristic band patterns from each individual. The results showed 0.0413 population diversity with 0.9587 average similarity, indicating that the yam collection studied had very little genetic diversity and, probably, this could be why the crop is vulnerable to plagues and diseases, as happened at the end of the 1980s when anthracnose practically devastated the crop on the Colombian Atlantic coast. Similarity was also found between those Colombian and African samples analysed, agreeing with low diversity and less distance between common ancestors. The molecular results suggest the need for using other molecular techniques having a greater power of discrimination and also the need to broaden the genetic diversity in yam crops for providing greater sustainability for small-scale Colombian yam farmers.