BAC libraries construction from the ancestral diploid genomes of the allotetraploid cultivated peanut
- Equal contributors
1 Biotechnology Unit, Embrapa Genetic Resources and Biotechnology, Brasília, DF, Brazil
2 Centre de Coopération International en Recherche Agronomique pour le Developpement (CIRAD), Montpellier, France
3 Cell Biology Department, IB-University of Brasília (UnB), Brasília, DF, Brazil
4 Plant Cytogenetics and Evolution Laboratory, Instituto de Botánica del Nordeste, Corrientes, Argentina
5 Biotechnology and Genomic Sciences Department, Campus II Catholic University of Brasília, Brasília, DF, Brazil
BMC Plant Biology 2008, 8:14 doi:10.1186/1471-2229-8-14Published: 29 January 2008
Cultivated peanut, Arachis hypogaea is an allotetraploid of recent origin, with an AABB genome. In common with many other polyploids, it seems that a severe genetic bottle-neck was imposed at the species origin, via hybridisation of two wild species and spontaneous chromosome duplication. Therefore, the study of the genome of peanut is hampered both by the crop's low genetic diversity and its polyploidy. In contrast to cultivated peanut, most wild Arachis species are diploid with high genetic diversity. The study of diploid Arachis genomes is therefore attractive, both to simplify the construction of genetic and physical maps, and for the isolation and characterization of wild alleles. The most probable wild ancestors of cultivated peanut are A. duranensis and A. ipaënsis with genome types AA and BB respectively.
We constructed and characterized two large-insert libraries in Bacterial Artificial Chromosome (BAC) vector, one for each of the diploid ancestral species. The libraries (AA and BB) are respectively c. 7.4 and c. 5.3 genome equivalents with low organelle contamination and average insert sizes of 110 and 100 kb. Both libraries were used for the isolation of clones containing genetically mapped legume anchor markers (single copy genes), and resistance gene analogues.
These diploid BAC libraries are important tools for the isolation of wild alleles conferring resistances to biotic stresses, comparisons of orthologous regions of the AA and BB genomes with each other and with other legume species, and will facilitate the construction of a physical map.