Submitted to: Peanut Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/28/2004
Publication Date: 12/29/2004
Citation: Anderson, W.F., Kochert, G., Holbrook Jr, C.C., Stalker, H.T. 2004. Phenotypic and molecular evaluation of interspecific peanut lines. Peanut Science 31:65-70. Interpretive Summary: Approximately 130 peanut lines, originating from crosses of domesticated peanut (Arachis hypogaea) with different diploid wild species of peanut, were evaluated for resistances to various diseases of peanut for use in a commercial peanut breeding program. They were also evaluated via molecular genetic techniques to determine variation that could be used in marker-assisted breeding techniques. A number of new sources of resistance to peanut root-knot nematode and late leafspot caused by Cercosporidium personatum were discovered from these interspecific crosses. Genetic polymorphisms from restriction fragment length polymorphisms (RFLPs) and amplified fragment length polymorphisms (AFLPs) were also observed. The resistance genes should be valuable in improving disease and nematode resistances. With further work, these resistances could be combined into single genotypes through conventional and molecular genetic techniques.
Technical Abstract: Peanut breeders are constantly searching for sources of genes that will improve production and quality. These traits include genes for higher potential yield, improved pod and seed attributes, disease resistance and abiotic stress tolerances. The search for useful genes for peanut improvement begins with available sources within the Arachis hypogaea germplasm that includes private and public breeding programs and plant introductions from repositories in the U. S. and other countries. Often, however, favorable genes for traits conferring disease resistances are only found in related Arachis species. The objective of this study was to evaluate interspecific hybrid peanut lines generated from interspecific crosses for wild species introgression, including resistance to important peanut diseases. A number of diploid Arachis wild species were crossed with allotetraploid peanut breeding lines and through decades of selfing, 130 different tetraploid lines were developed. These lines were evaluated for the amount of introgression using RFLP technology, plant morphology, and disease resistance scores. By using RFLP probes from a diploid map, 41 lines showed measurable introgression and 12 hexaploid-derived lines were polymorphic for at least four probes. Greenhouse and field evaluations indicated that resistant lines were not present in the lines tested for tomato spotted wilt virus, early leafspot, or Cylindrocladium black rot. However, very high levels of resistance were found for peanut root-knot nematode (Meloidogyne arenaria (Neal) Chitwood) among lines derived from crosses with A. diogoi, A. correntina , A. batizocoi, and A. cardenasii. Significant resistance to late leafspot (Cercosporidium personatum Berk. & M.A. Curt.) was found in field evaluations performed in Gainesville, FL over 2 yr, where the greatest resistance was found among lines from crosses with A. batizocoi, A. duranensis, A. stenosperma, A. magma, and A. diogoi. Results indicate that it should be possible to identify molecular markers to tag resistance genes for use in conventional breeding programs, and stack these genes in highly productive peanut cultivars.