BAC libraries construction from the ancestral diploid genomes of the allotetraploid cultivated peanut

Patricia M Guimarães,Karina Proite,Christian Chaine,Olivier Garsmeur,Angelique D'Hont,Soraya Cm Leal-Bertioli,David J Bertioli,Guilhermo Seijo

doi:10.1186/1471-2229-8-14

Abstract

BackgroundCultivated 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.ResultsWe 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.ConclusionThese 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.

Highlights

Cultivated peanut, Arachis hypogaea is an allotetraploid of recent origin, with an AABB genome
As a complement to this resource, here we describe the production of Bacterial Artificial Chromosome (BAC) libraries for the two diploid wild species A. duranensis (AA genome) and A. ipaënsis (BB genome) that have been identified as the most probable ancestors of cultivated peanut [8,30]
High levels of carbohydrate and polyphenols are present in both A. duranensis and A. ipaënsis leaves

Summary

Introduction

Cultivated peanut, Arachis hypogaea is an allotetraploid of recent origin, with an AABB genome. Peanut is produced throughout the tropics and warmer regions of the subtropics, but is important in Africa, Asia and in the United States [1] It is an allotetraploid (AABB) of recent origin that arose from hybridization of two wild species and spontaneous chromosome duplication [2,3]. This polyploidization event gave rise to a severe genetic bottle-neck [2,3] which has led to lack of variability in some important traits, limited availability of allelic combinations and restrictions in productivity. In parallel new genetic and genomic tools (see below) for monitoring the introgression of wild genes into a cultivated background are opening the perspectives for the efficient introgression of wild genes into the peanut crop using molecular breeding

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Discussion

Conclusion