Evidence of Genomic Exchanges between Homeologous Chromosomes in a Cross of Peanut with Newly Synthetized Allotetraploid Hybrids

Nguepjop, J R and Tossim, H A and Bell, J M and Rami, J F and Sharma, S and Courtois, B and Mallikarjuna, N and Sane, D and Fonceka, D (2016) Evidence of Genomic Exchanges between Homeologous Chromosomes in a Cross of Peanut with Newly Synthetized Allotetraploid Hybrids. Frontiers in Plant Science, 7 (1635). 01-12. ISSN 1664-462X

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Abstract

Cultivated peanut and synthetics are allotetraploids (2n = 4x = 40) with two homeologous sets of chromosomes. Meiosis in allotetraploid peanut is generally thought to show diploid-like behavior. However, a recent study pointed out the occurrence of recombination between homeologous chromosomes, especially when synthetic allotetraploids are used, challenging the view of disomic inheritance in peanut. In this study, we investigated the meiotic behavior of allotetraploid peanut using 380 SSR markers and 90 F2 progeny derived from the cross between Arachis hypogaea cv Fleur 11 (AABB) and ISATGR278-18 (AAKK), a synthetic allotetraploid that harbors a K-genome that was reported to pair with the cultivated B-genome during meiosis. Segregation analysis of SSR markers showed 42 codominant SSRs with unexpected null bands among some progeny. Chi-square tests for these loci deviate from the expected 1:2:1 Mendelian ratio under disomic inheritance. A linkage map of 357 codominant loci aligned on 20 linkage groups (LGs) with a total length of 1728 cM, averaging 5.1 cM between markers, was developed. Among the 10 homeologous sets of LGs, one set consisted of markers that all segregated in a polysomic-like pattern, six in a likely disomic pattern and the three remaining in a mixed pattern with disomic and polysomic loci clustered on the same LG. Moreover, we reported a substitution of homeologous chromosomes in some progeny. Our results suggest that the homeologous recombination events occurred between the A and K genomes in the newly synthesized allotetraploid and have been highlighted in the progeny. Homeologous exchanges are rarely observed in tetraploid peanut and have not yet been reported for AAKK and AABB genomes. The implications of these results on peanut breeding are discussed.

Item Type: Article
Divisions: Research Program : Genetic Gains
CRP: CGIAR Research Program on Grain Legumes
Uncontrolled Keywords: Genetic map, Disomic, Polysomic, Breeding, Inheritance, Peanut, Allotetraploid, Genomic Exchanges
Subjects: Mandate crops > Groundnut
Others > Genetics and Genomics
Depositing User: Mr Ramesh K
Date Deposited: 10 Nov 2016 04:11
Last Modified: 10 Nov 2016 04:11
URI: http://oar.icrisat.org/id/eprint/9769
Official URL: http://dx.doi.org/10.3389/fpls.2016.01635
Projects: UNSPECIFIED
Funders: UNSPECIFIED
Acknowledgement: The authors thank the German Academic Exchange Service (DAAD) for providing the Ph.D. scholarship and, Dr. Pamela Soltis and Dr. Annaliese Mason for their valuable comments and suggestions to improve the manuscript. This article was submitted to Plant Genetics and Genomics, a section of the journal Frontiers in Plant Science
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