Cytological Studies an the Peanut, &lt;i&gt;Arachis&lt;/i&gt;. II

Husted, Ladley

doi:10.1508/cytologia.7.396

Cited by 113 publications

(24 citation statements)

References 13 publications

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“…Cultivated peanuts were domesticated from the wild tetraploid A. monticola, which was formed between two diploid species A. duranensis and A. ipaensis. [3][4][5][6][7][8] While genome sequences of wild diploids, wild tetraploid, and cultivated tetraploid species of peanuts are available, little is known about subgenome evolution and trait domestication in tetraploid peanuts. [2,15,16] Sequencing and comparative analyses of the wild tetraploid species have filled the genomic and evolutionary gap between the wild diploids and cultivated tetraploids.…”

Section: Discussionmentioning

confidence: 99%

“…Notably, genomic organization including these structural variations is highly maintained from the wild A. monticola to cultivated A. hypogaea tetraploid species and is more conservative than that comparing to their progenitor-like diploids (Figures S2a and S3a, Supporting Information), supporting origin of the domesticated peanut from A. monticola. [3][4][5][6][7][8] Besides, there are several large inversions in A03, A07, A09, B05, and B10 of A. monticola, which are not observed in A. hypogaea, suggesting the possible introgression events occurred from wild diploids to cultivated A. hypogaea (Figures S2a and S3a, Supporting Information). These large inversions are present with discrete chromatin interactions around breakpoints by mapping Hi-C links between species (Figures S2b and S3b, Supporting Information), and similar Hi-C interaction maps have been used to identify large-scale chromosomal rearrangements in tetraploid cotton.…”

Section: Comparative Analyses Of the A Monticola Genome And Cultivatmentioning

confidence: 99%

“…[2] Hybridization between two diploid species like Arachis duranensis (A. duranensis) (AA, 2n = 2x = 20) and Arachis ipaensis (A. ipaensis) (BB, 2n = 2x = 20) gave rise to a wild tetraploid species, A. monticola (AABB, 2n = 4x = 40), which was domesticated into the cultivated tetraploid crop. [3][4][5][6][7][8] Thus, A. monticola is an Like many important crops, peanut is a polyploid that underwent polyploidization, evolution, and domestication. The wild allotetraploid peanut species Arachis monticola (A. monticola) is an important and unique link from the wild diploid species to cultivated tetraploid species in the Arachis lineage.…”

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Comparison ofArachis monticolawith Diploid and Cultivated Tetraploid Genomes Reveals Asymmetric Subgenome Evolution and Improvement of Peanut

Yin

Song

et al. 2019

Advanced Science

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Like many important crops, peanut is a polyploid that underwent polyploidization, evolution, and domestication. The wild allotetraploid peanut species Arachis monticola (A. monticola) is an important and unique link from the wild diploid species to cultivated tetraploid species in the Arachis lineage. However, little is known about A. monticola and its role in the evolution and domestication of this important crop. A fully annotated sequence of ≈2.6 Gb A. monticola genome and comparative genomics of the Arachis species is reported. Genomic reconstruction of 17 wild diploids from AA, BB, EE, KK, and CC groups and 30 tetraploids demonstrates a monophyletic origin of A and B subgenomes in allotetraploid peanuts. The wild and cultivated tetraploids undergo asymmetric subgenome evolution, including homoeologous exchanges, homoeolog expression bias, and structural variation (SV), leading to subgenome functional divergence during peanut domestication. Significantly, SV‐associated homoeologs tend to show expression bias and correlation with pod size increase from diploids to wild and cultivated tetraploids. Moreover, genomic analysis of disease resistance genes shows the unique alleles present in the wild peanut can be introduced into breeding programs to improve some resistance traits in the cultivated peanuts. These genomic resources are valuable for studying polyploid genome evolution, domestication, and improvement of peanut production and resistance.

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Section: Discussionmentioning

confidence: 99%

Section: Comparative Analyses Of the A Monticola Genome And Cultivatmentioning

confidence: 99%

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confidence: 99%

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Comparison ofArachis monticolawith Diploid and Cultivated Tetraploid Genomes Reveals Asymmetric Subgenome Evolution and Improvement of Peanut

Yin

Song

et al. 2019

Advanced Science

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“…Early cytological research identified one pair of significantly smaller chromosomes (termed "A" chromosomes) in species of section Arachis and a unique chromosome pair that had a large secondary constriction (termed "B" chromosomes) in the species A. batizocoi Krapov. & W. C. Gregory (Husted, 1936). Hybrids between species with the small chromosome pair are partially to fully fertile, and most will produce F 2 seeds; however, hybrids between the species with the small chromosome pair and those with a B chromosome are sterile (Stalker and Simpson, 1995).…”

Section: Section Classificationmentioning

confidence: 99%

Utilizing Wild Species for Peanut Improvement

2017

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The cultivated peanut (Arachis hypogaea L.) is an allotetraploid species with a very large and complex genome. This species is susceptible to numerous foliar and soil‐borne diseases for which only moderate levels of resistance have been identified in the germplasm collection, but several of the 81 wild species are extremely resistant to many destructive peanut diseases. Peanut species were grouped into nine sections, but only taxa in section Arachis will hybridize with A. hypogaea. Most of these species are diploid, but two aneuploids and two tetraploids also exist in the section. The first peanut cultivars released after interspecific hybridization were ‘Spancross’ and ‘Tamnut 74’ during the 1970s from a cross between A. hypogaea and its tetraploid progenitor. However, introgression of useful genes from diploids has been difficult due to sterility barriers resulting from genomic and ploidy differences. To utilize diploids in section Arachis, direct hybrids have been made between A. hypogaea and diploid species, the chromosome number doubled to the hexaploid level, and then tetraploids recovered with resistances to nematodes, leaf spots, rust, and numerous insect pests. ‘Bailey’, a widely grown Virginia‐type peanut, was released from these materials, and other cultivars are gown in Asia and South America. Alternatively, hybrids between diploid A and B genome species have been made, the chromosome number doubled, and cultivars released with nematode resistance derived from Arachis species. Introgression from Arachis species to A. hypogaea appears to be in large blocks rather than as single genes, and new genotyping strategies should enhance utilization of wild peanut genetic resources.

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“…This species is autogamous and allotetraploid (2 n = 4 x = 40), harboring homeologous A and B genomes (Husted, 1936; Smartt et al, 1978). It is assumed that it originated from a single hybridization event between two wild diploid taxa (Simpson et al, 2001), most likely Arachis duranensis (A genome) and Arachis ipaensis (B genome), followed by a spontaneous chromosome duplication (Seijo et al, 2004, 2007; Bertioli et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2016

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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.

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Cytological Studies an the Peanut, <i>Arachis</i>. II

Cited by 113 publications

References 13 publications

Comparison ofArachis monticolawith Diploid and Cultivated Tetraploid Genomes Reveals Asymmetric Subgenome Evolution and Improvement of Peanut

Comparison ofArachis monticolawith Diploid and Cultivated Tetraploid Genomes Reveals Asymmetric Subgenome Evolution and Improvement of Peanut

Utilizing Wild Species for Peanut Improvement

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

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