Abstract
Small farmers have played an important role in maintaining genetic resources of traditional varieties. Collecting and characterizing germplasm, especially landraces and heirloom varieties, are strategic activities that would create a knowledge base describing the traditional varieties of a given region and reduce the risk of genetic erosion. The objectives of this work were as follows: collect sweet potato roots from rural properties and local markets in Rio de Janeiro State, Brazil; characterize the accessions using RAPD and ISSR molecular markers, comparing the efficiency in discrimination of these two types of molecular markers; and estimate the genetic variability of the population. Fifty-nine samples from rural properties and 19 from local markets were studied. A matrix of binary data was developed to analyze the molecular data using the Jaccard index to estimate genetic differences among accessions, and clusters were made using the UPGMA method. The molecular techniques detected genetic variability among the accessions, with cophenetic correlation coefficients (CCC) of 0.80 for RAPDs and 0.89 for ISSRs. The RAPD and ISSR marker results corresponded well, with a correlation of 0.55. All of the accessions were considered distinct, which demonstrates that traditional farmers maintain sweet potato genotypes that have good genetic diversity.
Highlights
Sweet potato (Ipomoea batatas (L.) Lam.) is considered one of the least risky vegetables to grow, due to its rusticity, good production in poor soils, low incidence of pests and diseases, high tolerance to drought, low cost, cultivated mainly by small local farmers, and use as a staple food in many areas of the world (ROESLER et al, 2008)
We observed a high level of polymorphisms with the RAPD-generated markers
The large mean distance that we found is an indication of a high level of genetic diversity
Summary
Sweet potato (Ipomoea batatas (L.) Lam.) is considered one of the least risky vegetables to grow, due to its rusticity, good production in poor soils, low incidence of pests and diseases, high tolerance to drought, low cost, cultivated mainly by small local farmers, and use as a staple food in many areas of the world (ROESLER et al, 2008). They have various uses including human consumption, animal feed, and, recently, for producing ethanol and its derivatives. The tuberous roots are highly nutritive, due to their elevated starch levels, and sweet potatoes are an important source of minerals, especially calcium and iron, and vitamins such as C and B-complex vitamins (FONSECA et al, 2008).
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