Introgression of disease resistance genes from Arachis kempff‐mercadoi into cultivated groundnut

International Crops Research Institute for the Semi-Arid Tropics, 502 324, Patancheru; Andhra Pradesh, India
Plant Breeding (Impact Factor: 1.18). 11/2004; 123(6):573 - 576. DOI:10.1111/j.1439-0523.2004.01036.x

ABSTRACT Arachis kempff-mercadoi is a wild species from the section Arachis. All kempff-mercadoi accessions originate from the Santa Cruz province of Bolivia and they represent Arachis species with the A genome. From molecular analysis it was found that although cultivated A. hypogaea is made up of A and B genomes, A. kempff-mercadoi may not be as closely related to it as are some of the other A genome species. Arachis kempff-mercadoi is of interest because it has multiple disease resistance. It was crossed with a Spanish A. hypogaea cultivar which is susceptible to foliar diseases and to the insect pest Spodoptera litura. The success rate of the cross A. hypogaea (2n = 40) ×A. kempff-mercadoi (2n = 20) was very low, but it could be increased by culturing immature seeds in vitro. Although the hybrids were triploids, a few fertile pollen grains were obtained due to the formation of restitution nuclei in the F1 plants. Interspecific derivatives at the BC2F2 generation were scored for early leaf spot, late leaf spot and to Spodoptera damage. Screening results showed that 29% of the derivatives had both early and late leaf spot resistance and that less than 5% of the derivatives had resistance to both the foliar diseases and to Spodoptera.

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    ABSTRACT: Arachis hypogaea is an allotetraploid species with low genetic variability. Its closest relatives, all of the genus Arachis, are important sources of alleles for peanut breeding. However, a better understanding of the genome constitution of the species and of the relationships among taxa is needed for the effective use of the secondary gene pool of Arachis. In the present work, we focused on all 11 non-A genome (or B genome sensu lato) species of Arachis recognized so far. Detailed karyotypes were developed by heterochromatin detection and mapping of the 5S and the 18S-25S rRNA using FISH. On the basis of outstanding differences observed in the karyotype structures, we propose segregating the non-A genome taxa into three genomes: B sensu stricto (s.s.), F and K. The B genome s.s. is deprived of centromeric heterochromatin and is homologous to one of the A. hypogaea complements. The other two genomes have centromeric bands on most of the chromosomes, but differ in the amount and distribution of heterochromatin. This organization is supported by previously published data on molecular markers, cross compatibility assays and bivalent formation at meiosis in interspecific hybrids. The geographic structure of the karyotype variability observed also reflects that each genome group may constitute lineages that have evolved through independent evolutionary pathways. In the present study, we confirmed that Arachis ipaensis was the most probable B genome donor for A. hypogaea, and we identified a group of other closely related species. The data provided here will facilitate the identification of the most suitable species for the development of prebreeding materials for further improvement of cultivated peanut.
    Theoretical and Applied Genetics 10/2010; 121(6):1033-46. · 3.66 Impact Factor
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    ABSTRACT: Fourteen wild species of different sections in the genus Arachis and 24 accessions of the AABB allotetraploid A. hypogaea (cultivated peanut) from several countries which belong to different botanical varieties, were analyzed by SSR and AFLP marker systems. The assay-units per system needed to distinguish among all the tested accessions were at least five for SSR or two for AFLP. The genetic distance detected by the SSR markers ranged from 0.09 to 0.95, and the mean was 0.73; and the genetic distance detected by the AFLP markers ranged from 0.01 to 0.79 with an average of 0.42. All the tested peanut SSR primer pairs were multilocus ones, and the amplified fragments per SSR marker in each peanut genome ranged from 2 to 15 with the mean of 4.77. The peanut cultivars were closely related to each other, and shared a large numbers of SSR and AFLP fragments. In contrast, the species in the genus Arachis shared few fragments. The results indicated that the cultivated peanut (A. hypogaea L.) varieties could be partitioned into two main groups and tour subgroups at the molecular level, and that A. duranensis is one of the wild ancestors of A. hypogaea. The lowest genetic variation was detected between A. cardenasii and A. batizocoi, and the highest was detected between A. pintoi and the species in the section Arachis. The relationships among the botanical varieties in the cultivated peanut (A. hypogaea L.) and among wild species accessions in section Arachis and those in other sections in the genus Arachis were discussed.
    Agricultural Sciences in China - AGRIC SCI CHINA. 01/2008; 7(4):405-414.
  • 04/2008: pages 179 - 230; , ISBN: 9780470380130


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