title: Identification of peanut (Arachis hypogaea) chromosomes using a fluorescence in situ hybridization system reveals multiple hybridization events during tetraploid peanut formation.
abstract: The cultivated peanut Arachis hypogaea (AABB) is thought to have originated from the hybridization of Arachis duranensis (AA) and Arachis ipaënsis (BB) followed by spontaneous chromosome doubling. In this study, we cloned and analyzed chromosome markers from cultivated peanut and its wild relatives. A fluorescence in situ hybridization (FISH)-based karyotyping cocktail was developed with which to study the karyotypes and chromosome evolution of peanut and its wild relatives. Karyotypes were constructed in cultivated peanut and its two putative progenitors using our FISH-based karyotyping system. Comparative karyotyping analysis revealed that chromosome organization was highly conserved in cultivated peanut and its two putative progenitors, especially in the B genome chromosomes. However, variations existed between A. duranensis and the A genome chromosomes in cultivated peanut, especially for the distribution of the interstitial telomere repeats (ITRs). A search of additional A. duranensis varieties from different geographic regions revealed both numeric and positional variations of ITRs, which were similar to the variations in tetraploid peanut varieties. The results provide evidence for the origin of cultivated peanut from the two diploid ancestors, and also suggest that multiple hybridization events of A. ipaënsis with different varieties of A. duranensis may have occurred during the origination of peanut.
authors.affiliation: School of Life Sciences, Institute of Plant Molecular Biology and Agricultural Biotechnology, State (China) Key Laboratory for Agrobiotechnology, The Chinese University of Hong Kong, Sha Tin, Hong Kong.
authors.forename: Laining
authors.initials: L
authors.lastname: Zhang
authors.affiliation: School of Life Sciences, Institute of Plant Molecular Biology and Agricultural Biotechnology, State (China) Key Laboratory for Agrobiotechnology, The Chinese University of Hong Kong, Sha Tin, Hong Kong.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Yang
authors.affiliation: Institute of Biological Chemistry, Washington State University, Pullman, WA, 99164-6340, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Tian
authors.affiliation: Shenzhen Research Institute, the Chinese University of Hong Kong, Shenzhen, 518000, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Shenzhen Research Institute, the Chinese University of Hong Kong, Shenzhen, 518000, China.
authors.forename: Weichang
authors.initials: W
authors.lastname: Yu
mesh_terms: D010367:Arachis / Q000235:genetics*; D001483:Base Sequence; D002503:Centromere / Q000235:genetics; D032461:Chromosomes, Plant / Q000235:genetics*; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D005819:Genetic Markers; D018745:Genome, Plant; D006570:Heterochromatin / Q000378:metabolism; D006824:Hybridization, Genetic; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007621:Karyotyping; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D013045:Species Specificity; D016615:Telomere / Q000235:genetics; D057891:Tetraploidy
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers; D006570:Heterochromatin
keywords: chromosome evolution; chromosome marker; cultivated peanut (Arachis hypogaea); fluorescence in situ hybridization (FISH); interstitial telomere repeat (ITR); karyotyping; repetitive DNA