An analysis of the B genome speciesArachis batizocoi (Fabaceae)

Stalker, H. T.; Dhesi, J. S.; Parry, D. C.

doi:10.1007/bf00940337

Cited by 15 publications

(13 citation statements)

References 13 publications

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“…It is, therefore, unlikely that the marker location discrepancy was due to mapping of multiple loci and perhaps could reflect a small chromosomal rearrangement. Chromosomal rearrangements are not unexpected based on previous cytological observations in the genus [24,37]. …”

Section: Resultsmentioning

confidence: 82%

A high-density genetic map of Arachis duranensis, a diploid ancestor of cultivated peanut

et al. 2012

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BackgroundCultivated peanut (Arachis hypogaea) is an allotetraploid species whose ancestral genomes are most likely derived from the A-genome species, A. duranensis, and the B-genome species, A. ipaensis. The very recent (several millennia) evolutionary origin of A. hypogaea has imposed a bottleneck for allelic and phenotypic diversity within the cultigen. However, wild diploid relatives are a rich source of alleles that could be used for crop improvement and their simpler genomes can be more easily analyzed while providing insight into the structure of the allotetraploid peanut genome. The objective of this research was to establish a high-density genetic map of the diploid species A. duranensis based on de novo generated EST databases. Arachis duranensis was chosen for mapping because it is the A-genome progenitor of cultivated peanut and also in order to circumvent the confounding effects of gene duplication associated with allopolyploidy in A. hypogaea.ResultsMore than one million expressed sequence tag (EST) sequences generated from normalized cDNA libraries of A. duranensis were assembled into 81,116 unique transcripts. Mining this dataset, 1236 EST-SNP markers were developed between two A. duranensis accessions, PI 475887 and Grif 15036. An additional 300 SNP markers also were developed from genomic sequences representing conserved legume orthologs. Of the 1536 SNP markers, 1054 were placed on a genetic map. In addition, 598 EST-SSR markers identified in A. hypogaea assemblies were included in the map along with 37 disease resistance gene candidate (RGC) and 35 other previously published markers. In total, 1724 markers spanning 1081.3 cM over 10 linkage groups were mapped. Gene sequences that provided mapped markers were annotated using similarity searches in three different databases, and gene ontology descriptions were determined using the Medicago Gene Atlas and TAIR databases. Synteny analysis between A. duranensis, Medicago and Glycine revealed significant stretches of conserved gene clusters spread across the peanut genome. A higher level of colinearity was detected between A. duranensis and Glycine than with Medicago.ConclusionsThe first high-density, gene-based linkage map for A. duranensis was generated that can serve as a reference map for both wild and cultivated Arachis species. The markers developed here are valuable resources for the peanut, and more broadly, to the legume research community. The A-genome map will have utility for fine mapping in other peanut species and has already had application for mapping a nematode resistance gene that was introgressed into A. hypogaea from A. cardenasii.

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Section: Resultsmentioning

confidence: 82%

A high-density genetic map of Arachis duranensis, a diploid ancestor of cultivated peanut

et al. 2012

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“…batizocoi using five accessions [66], hybrids between accessions 30081 and 9484 had reduced pollen stainability (88.6%). Moreover, cytogenetic analyses of F 1 s from the same cross showed a low frequency of quadrivalents [11,66], indicating a reciprocal translocation that would cause pairing between two non-homologous chromosomes during meiosis. The similarity between the two chromosomes involved in reciprocal translocation could explain the integrated linkage group 4/9B in our study.…”

Section: Resultsmentioning

confidence: 99%

“…For example, in an analysis to determine the intraspecific variability within the B-genome species A . batizocoi [66], quadrivalents, hexavalents and octavalents were observed during meiosis in F 1 hybrids of different accessions, indicating one to three reciprocal translocations that differentiate these accessions. Thus, karyotypic evolution via translocations was considered to be an important mechanism for species differentiation [66].…”

Section: Resultsmentioning

confidence: 99%

Comparative mapping in intraspecific populations uncovers a high degree of macrosynteny between A- and B-genome diploid species of peanut

et al. 2012

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BackgroundCultivated peanut or groundnut (Arachis hypogaea L.) is an important oilseed crop with an allotetraploid genome (AABB, 2n = 4x = 40). Both the low level of genetic variation within the cultivated gene pool and its polyploid nature limit the utilization of molecular markers to explore genome structure and facilitate genetic improvement. Nevertheless, a wealth of genetic diversity exists in diploid Arachis species (2n = 2x = 20), which represent a valuable gene pool for cultivated peanut improvement. Interspecific populations have been used widely for genetic mapping in diploid species of Arachis. However, an intraspecific mapping strategy was essential to detect chromosomal rearrangements among species that could be obscured by mapping in interspecific populations. To develop intraspecific reference linkage maps and gain insights into karyotypic evolution within the genus, we comparatively mapped the A- and B-genome diploid species using intraspecific F2 populations. Exploring genome organization among diploid peanut species by comparative mapping will enhance our understanding of the cultivated tetraploid peanut genome. Moreover, new sources of molecular markers that are highly transferable between species and developed from expressed genes will be required to construct saturated genetic maps for peanut.ResultsA total of 2,138 EST-SSR (expressed sequence tag-simple sequence repeat) markers were developed by mining a tetraploid peanut EST assembly including 101,132 unigenes (37,916 contigs and 63,216 singletons) derived from 70,771 long-read (Sanger) and 270,957 short-read (454) sequences. A set of 97 SSR markers were also developed by mining 9,517 genomic survey sequences of Arachis. An SSR-based intraspecific linkage map was constructed using an F2 population derived from a cross between K 9484 (PI 298639) and GKBSPSc 30081 (PI 468327) in the B-genome species A. batizocoi. A high degree of macrosynteny was observed when comparing the homoeologous linkage groups between A (A. duranensis) and B (A. batizocoi) genomes. Comparison of the A- and B-genome genetic linkage maps also showed a total of five inversions and one major reciprocal translocation between two pairs of chromosomes under our current mapping resolution.ConclusionsOur findings will contribute to understanding tetraploid peanut genome origin and evolution and eventually promote its genetic improvement. The newly developed EST-SSR markers will enrich current molecular marker resources in peanut.

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“…Simpson, and A. correntina (Burkart) Krapov. Multiple translocations have been observed in A. duranensis and A. batizocoi (Stalker et al, 1991aGuo et al, 2012), which indicates that species are continuing to evolve. The chromosomes of B-genome species are karyologically more diverse than those with an A genome (Fernandez and Krapovickas, 1994;Seijo et al, 2004).…”

Section: Section Classificationmentioning

confidence: 99%

“…The D genome species A. glandulifera is more distantly related to A. hypogaea than other species of section Arachis. Multiple translocations have been observed in A. duranensis and A. batizocoi (Stalker et al, 1991aGuo et al, 2012), which indicates that species are continuing to evolve. In addition, five different secondary constriction types were observed in A. hypogaea, which were most likely from translocation events (Stalker and Dalmacio, 1986).…”

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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An analysis of the B genome speciesArachis batizocoi (Fabaceae)

Cited by 15 publications

References 13 publications

A high-density genetic map of Arachis duranensis, a diploid ancestor of cultivated peanut

A high-density genetic map of Arachis duranensis, a diploid ancestor of cultivated peanut

Comparative mapping in intraspecific populations uncovers a high degree of macrosynteny between A- and B-genome diploid species of peanut

Utilizing Wild Species for Peanut Improvement

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