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Braz GT, Yu F, Zhao H, Deng Z, Birchler JA, Jiang J. Preferential meiotic chromosome pairing among homologous chromosomes with cryptic sequence variation in tetraploid maize. THE NEW PHYTOLOGIST 2021; 229:3294-3302. [PMID: 33222183 DOI: 10.1111/nph.17098] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 11/13/2020] [Indexed: 06/11/2023]
Abstract
Meiotic chromosome pairing between homoeologous chromosomes was reported in many nascent allopolyploids. Homoeologous pairing is gradually eliminated and replaced by exclusive homologous pairing in well-established allopolyploids, an evolutionary process referred to as the diploidization of allopolyploids. A fundamental question of the diploidization of allopolyploids is whether and to what extent the DNA sequence variation among homoeologous chromosomes contribute to the establishment of exclusive homologous chromosome pairing. We developed aneuploid tetraploid maize lines that contain three copies of chromosome 10 derived from inbred lines B73 and H99. We were able to identify the parental origin of each copy of chromosome 10 in the materials using oligonucleotide-based haplotype-specific chromosome painting. We demonstrate that the two identical copies of chromosome 10 from H99 pair preferentially over chromosome 10 from B73 in different stages of prophase I and metaphase I during meiosis. Thus, homologous chromosome pairing is favored to partners with the most similar DNA sequences and can be discriminated based on cryptic sequence variation. We propose that innate preference of homologous chromosome pairing exists in nascent allopolyploids and serves as the first layer that would eventually block all homoeologous chromosome pairing in allopolyploids.
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Affiliation(s)
- Guilherme T Braz
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Fan Yu
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Hainan Zhao
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
| | - Zuhu Deng
- National Engineering Research Center for Sugarcane, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - James A Birchler
- Division of Biological Sciences, University of Missouri, Columbia, MO, 65211, USA
| | - Jiming Jiang
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA
- Department of Horticulture, Michigan State University, East Lansing, MI, 48824, USA
- Michigan State University AgBioResearch, East Lansing, MI, 48824, USA
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Wheat, Rye, and Barley Genomes Can Associate during Meiosis in Newly Synthesized Trigeneric Hybrids. PLANTS 2021; 10:plants10010113. [PMID: 33430522 PMCID: PMC7826760 DOI: 10.3390/plants10010113] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 12/29/2020] [Accepted: 01/05/2021] [Indexed: 11/24/2022]
Abstract
Polyploidization, or whole genome duplication (WGD), has an important role in evolution and speciation. One of the biggest challenges faced by a new polyploid is meiosis, in particular, discriminating between multiple related chromosomes so that only homologs recombine to ensure regular chromosome segregation and fertility. Here, we report the production of two new hybrids formed by the genomes of species from three different genera: a hybrid between Aegilops tauschii (DD), Hordeum chilense (HchHch), and Secale cereale (RR) with the haploid genomic constitution HchDR (n = 7× = 21); and a hybrid between Triticum turgidum spp. durum (AABB), H. chilense, and S. cereale with the constitution ABHchR (n = 7× = 28). We used genomic in situ hybridization and immunolocalization of key meiotic proteins to establish the chromosome composition of the new hybrids and to study their meiotic behavior. Interestingly, there were multiple chromosome associations at metaphase I in both hybrids. A high level of crossover (CO) formation was observed in HchDR, which shows the possibility of meiotic recombination between the different genomes. We succeeded in the duplication of the ABHchR genome, and several amphiploids, AABBHchHchRR, were obtained and characterized. These results indicate that recombination between the genera of three economically important crops is possible.
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Kumar K, Neelam K, Singh G, Mathan J, Ranjan A, Brar DS, Singh K. Production and cytological characterization of a synthetic amphiploid derived from a cross between Oryza sativa and Oryza punctata. Genome 2019; 62:705-714. [PMID: 31330117 DOI: 10.1139/gen-2019-0062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oryza punctata Kotschy ex Steud. (BB, 2n = 24) is a wild species of rice that has many useful agronomic traits. An interspecific hybrid (AB, 2n = 24) was produced by crossing O. punctata and Oryza sativa variety Punjab Rice 122 (PR122, AA, 2n = 24) to broaden the narrow genetic base of cultivated rice. Cytological analysis of the pollen mother cells (PMCs) of the interspecific hybrids confirmed that they have 24 chromosomes. The F1 hybrids showed the presence of 19-20 univalents and 1-3 bivalents. The interspecific hybrid was treated with colchicine to produce a synthetic amphiploid (AABB, 2n = 48). Pollen fertility of the synthetic amphiploid was found to be greater than 50% and partial seed set was observed. Chromosome numbers in the PMCs of the synthetic amphiploid were 24II, showing normal pairing. Flow cytometric analysis also confirmed doubled genomic content in the synthetic amphiploid. Leaf morphological and anatomical studies of the synthetic amphiploid showed higher chlorophyll content and enlarged bundle sheath cells as compared with both of its parents. The synthetic amphiploid was backcrossed with PR122 to develop a series of addition and substitution lines for the transfer of useful genes from O. punctata with least linkage drag.
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Affiliation(s)
- Kishor Kumar
- School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, Punjab, 141004, India.,Faculty Centre on Integrated Rural Development and Management, Ramakrishna Mission Vivekanada Educational and Research Institute, Narendrapur, Kolkata, 700103, India
| | - Kumari Neelam
- School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, Punjab, 141004, India
| | - Gurpreet Singh
- School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, Punjab, 141004, India
| | - Jyotirmaya Mathan
- National Institute of Plant Genome Research, New Delhi, 110067, India
| | - Aashish Ranjan
- National Institute of Plant Genome Research, New Delhi, 110067, India
| | - Darshan Singh Brar
- School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, Punjab, 141004, India
| | - Kuldeep Singh
- School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, Punjab, 141004, India.,ICAR-National Bureau of Plant Genetic Resources, PUSA, New Delhi, 110012, India
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He F, Xing P, Bao Y, Ren M, Liu S, Wang Y, Li X, Wang H. Chromosome Pairing in Hybrid Progeny between Triticum aestivum and Elytrigia elongata. FRONTIERS IN PLANT SCIENCE 2017; 8:2161. [PMID: 29312403 PMCID: PMC5742266 DOI: 10.3389/fpls.2017.02161] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 12/07/2017] [Indexed: 05/29/2023]
Abstract
In this study, the intergeneric hybrids F1, F2, BC1F1, BC1F2, and BC2F1 from Elytrigia elongata and Triticum aestivum crosses were produced to study their chromosome pairing behavior. The average E. elongata chromosome configuration of the two F1 hybrids agreed with the theoretical chromosome configuration of 21I+7II, indicating that the genomic constitution of this F1 hybrid was ABDStStEeEbEx. Compared with the BC1F1 generation, the BC2F1 generation showed a rapid decrease in the number of E. elongata chromosomes and the BC1F2 generation showed a more extensive distribution of E. elongata chromosomes. In addition, pairing between wheat and E. elongata chromosomes was detected in each of the wheat-E. elongata hybrid progenies, albeit rarely. Our results demonstrated that genomic in situ hybridization (GISH) using an E. elongata genomic DNA probe offers a reliable approach for characterizing chromosome pairing in wheat and E. elongata hybrid progenies.
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Affiliation(s)
- Fang He
- Guizhou Subcenter of National Wheat Improvement Center, College of Agronomy, Guizhou University, Guiyang, China
| | - Piyi Xing
- State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Taian, China
| | - Yinguang Bao
- State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Taian, China
| | - Mingjian Ren
- Guizhou Subcenter of National Wheat Improvement Center, College of Agronomy, Guizhou University, Guiyang, China
| | - Shubing Liu
- State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Taian, China
| | - Yuhai Wang
- College of Life Science, Zaozhuang University, Zaozhuang, China
| | - Xingfeng Li
- State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Taian, China
| | - Honggang Wang
- State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Taian, China
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Kang HY, Huang J, Zhu W, Li DY, Diao CD, Tang L, Wang Y, Xu LL, Zeng J, Fan X, Sha LN, Zhang HQ, Zheng YL, Zhou YH. Cytogenetic Behavior of Trigeneric Hybrid Progeny Involving Wheat, Rye and Psathyrostachys huashanica. Cytogenet Genome Res 2016; 148:74-82. [PMID: 27116422 DOI: 10.1159/000445793] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2015] [Indexed: 11/19/2022] Open
Abstract
Trigeneric hybrids are commonly used as bridges to transfer genes from some wild species to cultivated wheat and to measure the genomic interaction between donor species. We previously reported that trigeneric germplasms were produced by crossing wheat-Psathyrostachys huashanica amphiploids (PHW-SA, 2n = 8x = 56, AABBDDNsNs) with hexaploid triticale (Zhongsi 828, 2n = 6x = 42, AABBRR). In the present study, chromosome pairing behavior and the genome constitution of the F4 progenies of wheat-rye-P. huashanica trigeneric hybrids were studied. Cytological analysis showed that the chromosome number of F4 progenies ranged from 39 to 46, and 57.5% of them had 42 chromosomes. The mean meiotic configuration of F4 lines was 1.71 univalents, 20.26 bivalents, 0.04 trivalents, and 0.001 quadrivalents per pollen mother cell. Among the lines with 2n = 42, the average pairing configuration was 1.21 univalents, 16.22 ring bivalents, 4.16 rod bivalents, and 0.01 trivalents. This result indicated that these lines were cytologically stable. Other lines with 2n = 39, 40, 41, 43, 44, 45, and 46, bearing a high number of univalents or multivalents, showed abnormal meiotic behavior. Genomic in situ hybridization (GISH) revealed that all F4 lines had 11-14 rye chromosomes, but no P. huashanica chromosomes. The complete set of 14 rye chromosomes was found in 19 lines. At meiosis, GISH detected 1-6 univalents with hybridization signals of rye in 13 lines. Bivalents with fluorescence signals were identified in each line, ranging from 3 to 7. A quadrivalent with hybridization signals was observed in only 1 line, K13-714-8. Lagging chromosomes, chromosome bridges, micronuclei, and chromosome fragments hybridizing with the probe were not discovered in any of the lines. These results inferred that the behavior of rye chromosomes was normal during meiosis. In addition, 21 lines of 2n = 42 (91.3%) with 12 or 14 rye chromosomes, always contained 6 or 7 bivalents bearing fluorescence signals. This suggested that the rye chromosomes exhibiting complete pairing in these lines were cytologically stable during meiosis and may therefore be considered as new hexaploid triticales. Thus, these lines might be potential materials for further hexaploid triticale improvement.
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Affiliation(s)
- Hou-Yang Kang
- Triticeae Research Institute, Sichuan Agricultural University, Chengdu, China
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Jauhar PP, Peterson TS. Synthesis and characterization of advanced durum wheat hybrids and addition lines with thinopyrum chromosomes. J Hered 2013; 104:428-36. [PMID: 23396879 DOI: 10.1093/jhered/ess143] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Durum wheat (Triticum turgidum L., 2n = 4x = 28; AABB genomes) is a natural hybrid-an allotetraploid between 2 wild species, Triticum urartu Tumanian (AA genome) and Aegilops speltoides Tausch (BB genome). Even at the allotetraploid level, durum wheat can tolerate chromosomal imbalance, for example, addition of alien chromosome 1E of diploid wheatgrass, Lophopyrum elongatum. Therefore, one way to broaden its genetic base is to add a desirable chromosome(s) from diploid wild relatives. We attempted chromosomal engineering with chromosomes of a diploid wheatgrass, Thinopyrum bessarabicum-a source of resistance to some diseases including Fusarium head blight. Several advanced hybrids and alien addition lines were studied using traditional cytology, multicolor fluorescent genomic in situ hybridization, and molecular markers. Hybrid derivatives varied in chromosome number from F1 to F8 generations and in backcross generations. In advanced generations, we exercised selection against 28-chromosome plants and in favor of 30-chromosome plants that helped recover 14 addition lines in the F8 generation, as indicated by the absence of segregation for 29-chromosome plants. Disomic additions showed regular meiosis with 15 bivalents, 14 of durum wheat, and 1 of Th. bessarabicum. The addition lines will facilitate further chromosome engineering work on durum wheat for broadening its genetic base.
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Affiliation(s)
- Prem P Jauhar
- United States Department of Agriculture, Agricultural Research Service, Northern Crop Science Laboratory, Fargo, ND 58102, USA.
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Jauhar PP, Peterson TS. Synthesis and cytological analyses of hybrids between hexaploid wheat, with and without Ph1, and diploid wheatgrass. THE NUCLEUS 2011. [DOI: 10.1007/s13237-011-0037-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
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Arterburn M, Kleinhofs A, Murray T, Jones S. Polymorphic nuclear gene sequences indicate a novel genome donor in the polyploid genus Thinopyrum. Hereditas 2011; 148:8-27. [DOI: 10.1111/j.1601-5223.2010.02084.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Gene conversion in angiosperm genomes with an emphasis on genes duplicated by polyploidization. Genes (Basel) 2011; 2:1-20. [PMID: 24710136 PMCID: PMC3924838 DOI: 10.3390/genes2010001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 12/06/2010] [Accepted: 01/06/2011] [Indexed: 11/16/2022] Open
Abstract
Angiosperm genomes differ from those of mammals by extensive and recursive polyploidizations. The resulting gene duplication provides opportunities both for genetic innovation, and for concerted evolution. Though most genes may escape conversion by their homologs, concerted evolution of duplicated genes can last for millions of years or longer after their origin. Indeed, paralogous genes on two rice chromosomes duplicated an estimated 60–70 million years ago have experienced gene conversion in the past 400,000 years. Gene conversion preserves similarity of paralogous genes, but appears to accelerate their divergence from orthologous genes in other species. The mutagenic nature of recombination coupled with the buffering effect provided by gene redundancy, may facilitate the evolution of novel alleles that confer functional innovations while insulating biological fitness of affected plants. A mixed evolutionary model, characterized by a primary birth-and-death process and occasional homoeologous recombination and gene conversion, may best explain the evolution of multigene families.
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Jauhar PP. Genetic control of chromosome behaviour: Implications in evolution, crop improvement, and human biology. THE NUCLEUS 2010. [DOI: 10.1007/s13237-010-0010-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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11
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Fradkin M, Greizerstein E, Paccapelo H, Ferreira V, Grassi E, Poggio L, Ferrari MR. Cytological analysis of hybrids among triticales and trigopiros. Genet Mol Biol 2009; 32:797-801. [PMID: 21637457 PMCID: PMC3036882 DOI: 10.1590/s1415-47572009005000070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2008] [Accepted: 04/28/2009] [Indexed: 11/22/2022] Open
Abstract
We studied three different tricepiros: (Don Santiago x Don Noé), (Cumé x Horovitz) and (Cumé x Don Noé). The tricepiro (Don Santiago x Don Noé) was obtained by crossing the triticale Don Santiago INTA (AABBRR, 2n = 6x = 42) with the trigopiro Don Noé INTA (AABBDDJJ, 2n = 8x = 56). The number of chromosomes for the F1 was 2n = 49, the most frequent meiotic configuration being 14 bivalents and 21 univalents. The univalents were situated in the periphery of the equatorial plane, whereas the bivalents were located in the central zone. The chromatids in some of the univalents split when bivalents underwent reductional division in anaphase I. There were few laggard chromosomes or chromatids at this phase. The number of chromosomes (2n = 48-58) was high and variable, and the number of bivalents per cell (18-23) also high in F 3 individuals. In all F 8 tricepiros (Don Santiago x Don Noé), F 12 tricepiros (Cumé x Horovitz) and F 12 tricepiros (Cumé x Don Noé), the number of chromosomes (2n = 42) was the same, these retaining the rye genome, as demonstrated by GISH and FISH. These new synthesized allopolyploids constitute interesting models for investigating the evolutionary changes responsible for diploidization, and the chromosomal and genomic re-ordering that cannot be revealed in natural allopolyploids.
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Affiliation(s)
- Maia Fradkin
- Laboratorio de Citogenética y Evolución, Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires Argentina
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Jauhar PP, Peterson TS, Xu SS. Cytogenetic and molecular characterization of a durum alien disomic addition line with enhanced tolerance to Fusarium head blight. Genome 2009; 52:467-83. [PMID: 19448727 DOI: 10.1139/g09-014] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Current durum wheat (Triticum turgidum L. subsp. durum (Desf.)) cultivars have little or no resistance to Fusarium head blight (FHB), a ravaging disease of cereal crops. A diploid wheatgrass, Lophopyrum elongatum (Host) A. Löve (2n = 2x = 14, EE genome), is an excellent source of FHB resistance. Through an extensive intergeneric hybridization using durum cultivar Langdon, we have developed a disomic alien addition line, named DGE-1 (2n = 28 + 2), with a wheatgrass chromosome pair. We used a unique method for isolating the addition line taking advantage of unreduced gametes functioning in Langdon x L. elongatum F1 hybrids in their first backcross to the Langdon parent, resulting in 35-chromosome plants from which we derived DGE-1. The addition line DGE-1 has a plant type similar to its Langdon parent, although it is shorter in height with narrower leaves and shorter spikes. It is meiotically and reproductively stable, generally forming 15 bivalents with two chiasmata each. The alien chromosome pair from the grass confers FHB resistance to the addition line, which has less than 21% infection on the visual scale, mean = 6.5%. Using various biochemical and molecular techniques (Giemsa C-banding, fluorescent genomic in situ hybridization (fl-GISH), chromosome-specific simple sequence repeat (SSR) markers, targeted region amplified polymorphism (TRAP) markers, and sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS-PAGE)), we have shown that the extra chromosome involved is 1E of L. elongatum. This is the first time that FHB resistance has been discovered on chromosome 1E. We have established a chromosome-specific marker for 1E that may be used to screen fertile hybrid derivatives and durum addition lines for this chromosome that confers FHB resistance.
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Affiliation(s)
- Prem P Jauhar
- United States Department of Agriculture, Agricultural Research Service, Northern Crop Science Laboratory, Fargo, ND 58105, USA.
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Benavente E, Cifuentes M, Dusautoir JC, David J. The use of cytogenetic tools for studies in the crop-to-wild gene transfer scenario. Cytogenet Genome Res 2008; 120:384-95. [PMID: 18504367 DOI: 10.1159/000121087] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2007] [Indexed: 11/19/2022] Open
Abstract
Interspecific hybridization in plants is an important evolutionary phenomenon involved in the dynamics of speciation that receives increasing interest in the context of possible gene escapes from transgenic crop varieties. Crops are able to cross-pollinate with a number of wild related species and exchange chromosome segments through homoeologous recombination. In this paper, we review a set of cytogenetic techniques that are appropriate to document the different steps required for the stable introgression of a chromosome segment from a donor species (i.e., the crop) into a recipient species (i.e., the wild). Several examples in hybrids and derivatives are given to illustrate how these approaches may be used to evaluate the potential for gene transfer between crops and wild relatives. Different techniques, from classical chromosome staining methods to recent developments in molecular cytogenetics, can be used to differentiate genomes and identify the chromosome regions eventually involved in genetic exchanges. Some clues are also given for the study of fertility restoration in the interspecific hybrid forms.
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Affiliation(s)
- E Benavente
- Departamento de Biotecnología, ETS Ingenieros Agrónomos, Universidad Politécnica de Madrid, Spain.
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Ge XH, Li ZY. Intra- and intergenomic homology of B-genome chromosomes in trigenomic combinations of the cultivated Brassica species revealed by GISH analysis. Chromosome Res 2007; 15:849-61. [PMID: 17899408 DOI: 10.1007/s10577-007-1168-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 07/18/2007] [Accepted: 07/18/2007] [Indexed: 12/22/2022]
Abstract
Intragenomic chromosome homology in the B genome of Brassica nigra and their homoeology with the chromosomes of the A-genome of B. rapa and C-genome of B. oleracea was investigated in triploids (ABC, n = 27) of different origins obtained following hybridizations between natural B. napus (AACC, 2n = 38) x B. nigra (BB, 2n = 16) [AC.B], synthetic B. napus x B. nigra [A.C.B] and B. carinata (BBCC, 2n = 34) x B. rapa (AA, 2n = 20) [BC.A]. A relatively high percentage of pollen mother cells (PMCs) with at least one B-genome chromosome paired allosyndetically with A/C chromosomes was evident in all three combinations. A maximum of three B-genome chromosomes undergoing allosyndesis per cell was observed in AC.B and A.C.B combinations. A maximum of two autosyndetic bivalents within the B genome appeared at diakinesis in all combinations. The accurate analyses of auto- and allo-syndetic pairing for B genome in trigenomic combinations provided further evidence for the hypothesis that the three basic diploid genomes of the cultivated Brassica species evolved from one common ancestral genome with a lower chromosome number. The results showed that Brassica diploids may not be ancient polyploids but may have undergone chromosomal duplications instead of whole-genome duplication. The relevance of these results along with genetic changes of progenitor genomes which occurred during the evolution of Brassica polyploids is discussed.
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Affiliation(s)
- Xian-Hong Ge
- National Key Laboratory of Crop Genetic Improvement, National Center of Crop Molecular Breeding Technology, National Center of Oil Crop Improvement (Wuhan), Huazhong Agricultural University, Wuhan, 430070, PR China
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Cifuentes M, Blein M, Benavente E. A cytomolecular approach to assess the potential of gene transfer from a crop (Triticum turgidum L.) to a wild relative (Aegilops geniculata Roth.). TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2006; 112:657-64. [PMID: 16333611 DOI: 10.1007/s00122-005-0168-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Accepted: 11/13/2005] [Indexed: 05/05/2023]
Abstract
When a crop hybridizes with a wild relative, the potential for stable transmission to the wild of any crop gene is directly related to the frequency of crop-wild homoeologous pairing for the chromosomal region where it is located within the crop genome. Pairing pattern at metaphase I (MI) has been examined in durum wheat x Aegilops geniculata interspecific hybrids (2n=4x=ABUgMg) by means of a genomic in-situ hybridization procedure that resulted in simultaneous discrimination of A, B and wild genomes. The level of MI pairing in the hybrids varied greatly depending on the crop genotype. However, their pattern of homoeologous association was very similar, with a frequency of wheat-wild association close to 60% in all genotype combinations. A-wild represented 80-85% of wheat-wild associations which supports that, on average, A genome sequences are much more likely to be transferred to this wild relative following interspecific hybridization and backcrossing. Combination of genomic DNA probes and the ribosomal pTa71 probe has allowed to determine the MI pairing behaviour of the major NOR-bearing chromosomes in these hybrids (1 B, 6B, 1 Ug and 5 Ug), in addition to wheat chromosome 4A which could be identified with the sole use of genomic probes. The MI pairing pattern of the wild chromosome arms individually examined has confirmed a higher chance of gene escape from the wheat A genome. However, a wide variation regarding the amount of wheat-wild MI pairing among the specific wheat chromosome regions under analysis suggests that the study should be extended to other homoeologous groups.
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Affiliation(s)
- Marta Cifuentes
- Departamento de Biotecnología (Genética), E. T. S. Ingenieros Agrónomos, Universidad Politécnica, 28040, Madrid, Spain,
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Jauhar P. Cytogenetic Architecture of Cereal Crops and Their Manipulation to Fit Human Needs. GENETIC RESOURCES, CHROMOSOME ENGINEERING, AND CROP IMPROVEMENT 2006. [DOI: 10.1201/9780203489260.ch1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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Ceoloni C, Jauhar P. Chromosome Engineering of the Durum Wheat Genome. GENETIC RESOURCES, CHROMOSOME ENGINEERING, AND CROP IMPROVEMENT 2006. [DOI: 10.1201/9780203489260.ch2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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