AFLP-based Genetic Diversity Assessment of Global Sweetpotato (Ipomoea batatas (L.) Lam.) Germplasm Resources: Progress Toward The Development of a Sweetpotato Core Collection.

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Date

2004-11-15

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Abstract

Sweetpotato (Ipomoea batatas (L.) Lam) is an extremely diverse and important crop ranking seventh in terms of global production. It is grown throughout the world as a staple crop, and is particularly important in tropical developing countries due to its wide adaptability as well as its enormous potential for preventing malnutrition. The International Potato Center (CIP) in Lima, Peru and the USDA-ARS Plant Genetic Resources Conservation unit (PGRCU) in Griffin, Georgia are the most important sweetpotato gene banks worldwide. Roughly 7,000 and 750 accessions are present in each, respectively. Both collections have been characterized for many phenotypic traits of economic importance, and they are very important in terms of germplasm conservation, as they represent a vital resource for breeders seeking future genetic improvement of sweetpotato. The molecular genetic diversity present in each collection, however, is poorly understood. In this study, 775 accessions from the PGRCU collected from various countries were sampled and fingerprinted using AFLP markers derived from 10 primer pair combinations. A total of 183 polymorphic and clearly scorable bands were generated. Using polymorphisms and phylogenetic software (PAUP and NTSysPC), we were able to clearly distinguish a different banding pattern for each of the 775 accessions. A Neighbor-Joining phylogram was constructed and revealed 6 base clades with no region specificity. Analysis of molecular variance (AMOVA) was carried out using the software program Arlequin. The within-region variation at 97.94% was the major source of molecular variance. Pairwise genetic distances between regions were calculated and the smallest distance was between the Caribbean and Central America and the greatest distance was between the Pacific Islands and South America. Principle coordinate analysis (PCO) was performed by NTSysPC and several clusters of germplasm were noted. This research indicates that there is an abundance of genetic diversity present in sweetpotato.

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Keywords

Genetic Diversity, Sweetpotato, Core Collection, AFLP

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Degree

MS

Discipline

Horticultural Science

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