Abstract
The Arachis section is the most important of the nine sections of the genus Arachis because it includes the cultivated peanut, Arachis hypogaea. The genetic improvement of A. hypogaea using wild relatives is at an early stage of development in spite of their potential as sources of genes, including those for disease and pests resistance, that are not found in the A. hypogaea primary gene pool. Section Arachis species germplasm has been collected and maintained in gene banks and its use and effective conservation depends on our knowledge of the genetic variability contained in this material. Microsatellites are routinely used for the analysis of genetic variability because they are highly polymorphic and codominant. The objective of this study was to evaluate the transferability of microsatellite primers and the assay of genetic variability between and within the germplasm of some species of the Arachis section. Fourteen microsatellite loci developed for three different species of Arachis were analyzed and 11 (78%) were found to be polymorphic. All loci had transferability to all the species analyzed. The polymorphic loci were very informative, with expected heterozygosity per locus ranging from 0.70 to 0.94. In general, the germplasm analyzed showed wide genetic variation.
Highlights
The genus Arachis L. is composed of 69 described species distributed into nine taxonomic sections (Krapovickas and Gregory, 1994)
Independent of the Arachis species (A. hypogaea, A. glabrata or A. pintoi) from which they were originally developed, all the primers tested allowed the amplification of loci in all the Arachis species analyzed
Primer transferability between the Arachis section species demonstrated that the regions flanking these microsatellites are conserved enough to allow locus amplification, agreeing with previous work by other authors who have shown that microsatellite flanking regions are conserved, being even used to phylogenetic inferences in a number of species (Matsuoka et al, 2002; Rosseto et al, 2002)
Summary
The genus Arachis L. is composed of 69 described species distributed into nine taxonomic sections (Krapovickas and Gregory, 1994). The most studied section of the genus is the Arachis section containing 27 species (Krapovickas and Gregory, 1994) including the cultivated peanut (Arachis hypogaea L.), a South America native species which the evidence suggests has its center of origin in Bolivia, where the wild diploid species which are its putative progenitors are found (Gregory et al, 1980; Kochert et al, 1996). Three Arachis species genomes (A, B and D) are known based on chromosomal morphology and crossing relationships, the cultivated peanut being an allotetraploid (AABB) that arose through a single event involving hybridization between two wild diploid section Arachis species, A. duranensis (the A genome) and A. Microsatellites allow easier data integration because they are amplified by using very stringent polymerase chain reaction (PCR) conditions and, generally speaking, only single loci are amplified
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