Variation of isozyme patterns among Arachis species
1993
Stalker, H.T. (North Carolina State Univ., Raleigh (USA). Dept. of Crop Science) | Phillips, T.D. | Murphy, J.P. | Jones, T.M.
The genus Arachis contains a large number of species and undescribed taxa with patterns of genetic variation that are little understood. The objectives of this investigation were to estimate genetic diversity among species of Arachis by utilizing electrophoretic techniques and to establish the potential for use of isozymes as markers for germplasm introgression. 113 accessions representing six of the seven sections of the genus were analyzed for isozyme variationof 17 enzymes. Section Rhizomatosae species were not included because they produce very few seeds. Seeds were macerated and the crude extract was used for starch-gel electrophoretic analyses. Although thecultivated species has few polymorphic isozymes, the diploid species are highly variable and two-to-six bands were observed for each isozyme among accessions. Because of the large number of isozyme differences between Arachis hypogaea and Arachis batizocoi (the presumed donor of the B genome), this species can no longer be considered as a progenitor of the cultivated peanut. Seed-to-seed polymorphisms within many accessions were also observed which indicatethat germplasm should be maintained as bulk seed lots, representative of many individuals, or as lines from individual plants from original field collections. The area of greatest interspecific genetic diversity was in Mato Grosso, Brazil; however, the probability of finding unique alleles from those observed in A. hypogaea was greatestin north, north-central, south and southeast Brazil. The large number of polymorphic loci should be useful as genetic markers for interspecific hybridization studies.
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