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Abstract
The supernumerary B chromosome of maize is dispensable, containing no vital genes, and thus is variable in number and presence in lines of maize. In order to be maintained in populations, it has a drive mechanism consisting of nondisjunction at the pollen mitosis that produces the two sperm cells, and then the sperm with the two B chromosomes has a preference for fertilizing the egg as opposed to the central cell in the process of double fertilization. The sequence of the B chromosome coupled with B chromosomal aberrations has localized features involved with nondisjunction and preferential fertilization, which are present at the centromeric region. The predicted genes from the sequence have paralogues dispersed across all A chromosomes and have widely different divergence times suggesting that they have transposed to the B chromosome over evolutionary time followed by degradation or have been co-opted for the selfish functions of the supernumerary chromosome.
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Affiliation(s)
- James A. Birchler
- Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA
| | - Hua Yang
- Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA
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Yao Q, Gao J, Chen F, Li W. Development and application of an optimized drop-slide technique for metaphase chromosome spreads in maize. Biotech Histochem 2019; 95:276-284. [PMID: 31762324 DOI: 10.1080/10520295.2019.1686167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Chromosome spreads are important for complex molecular cytogenetic studies. An adequate chromosome spreading method for identification and isolation of the maize B chromosome, however, has not been reported. We used the maize inbred lines, B73 and Mo17, the hybrid YD08 line and the landrace DP76 to develop an optimized chromosome spreading method. We investigated the effects of four treatment factors on the quality of metaphase chromosome spreads using a factorial analysis of variance. Optimal conditions for metaphase spreading were identified using regression analysis based on multifactor orthogonal design of four treatment factors with five levels for each factor. We developed optimal conditions for metaphase spreading as follows: nitrous oxide treatment for 2 h, glacial acetic acid fixation for 2 h, enzyme hydrolysis for 6.0 h, and a drop height of 35 cm for cell suspension. We obtained high quality metaphase chromosome spreads with large metaphase areas, large numbers of chromosomes, few chromosome overlaps and high frequency of intact metaphases. Our optimized drop-slide procedure was markedly better than the traditional flame smear technique. We identified 487 B chromosomes in three forms from maize landraces from Southwest China. We found no relation between the C-band number and B chromosome. Single B chromosomes also were isolated directly from a metaphase chromosome drop-slide using a micromanipulator. Our optimized method provides a simple, efficient and reproducible procedure for preparing high quality plant chromosome spreads.
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Affiliation(s)
- Qilun Yao
- Department of Life Sciences, Yangtze Normal University, Fuling 408100, P. R. China.,Centre for Green Development and Collaborative Innovation in Wuling Mountain Region, Yangtze Normal University, Fuling, 408100, P. R. China
| | - Jian Gao
- Department of Life Sciences, Yangtze Normal University, Fuling 408100, P. R. China.,Centre for Green Development and Collaborative Innovation in Wuling Mountain Region, Yangtze Normal University, Fuling, 408100, P. R. China
| | - Fabo Chen
- Department of Life Sciences, Yangtze Normal University, Fuling 408100, P. R. China.,Centre for Green Development and Collaborative Innovation in Wuling Mountain Region, Yangtze Normal University, Fuling, 408100, P. R. China
| | - Wenbo Li
- Department of Life Sciences, Yangtze Normal University, Fuling 408100, P. R. China.,Centre for Green Development and Collaborative Innovation in Wuling Mountain Region, Yangtze Normal University, Fuling, 408100, P. R. China
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Udall JA, Long E, Ramaraj T, Conover JL, Yuan D, Grover CE, Gong L, Arick MA, Masonbrink RE, Peterson DG, Wendel JF. The Genome Sequence of Gossypioides kirkii Illustrates a Descending Dysploidy in Plants. FRONTIERS IN PLANT SCIENCE 2019; 10:1541. [PMID: 31827481 PMCID: PMC6890844 DOI: 10.3389/fpls.2019.01541] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 11/05/2019] [Indexed: 05/20/2023]
Abstract
One of the extraordinary aspects of plant genome evolution is variation in chromosome number, particularly that among closely related species. This is exemplified by the cotton genus (Gossypium) and its relatives, where most species and genera have a base chromosome number of 13. The two exceptions are sister genera that have n = 12 (the Hawaiian Kokia and the East African and Madagascan Gossypioides). We generated a high-quality genome sequence of Gossypioides kirkii (n = 12) using PacBio, Bionano, and Hi-C technologies, and compared this assembly to genome sequences of Kokia (n = 12) and Gossypium diploids (n = 13). Previous analysis demonstrated that the directionality of their reduced chromosome number was through large structural rearrangements. A series of structural rearrangements were identified comparing the de novo G. kirkii genome sequence to genome sequences of Gossypium, including chromosome fusions and inversions. Genome comparison between G. kirkii and Gossypium suggests that multiple steps are required to generate the extant structural differences.
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Affiliation(s)
- Joshua A. Udall
- Crop Germplasm Research, USDA, College Station, TX, United States
- *Correspondence: Joshua A. Udall, ; Jonathan F. Wendel,
| | - Evan Long
- Plant Breeding and Genetics, Cornell University, Ithaca, NY, United States
| | - Thiruvarangan Ramaraj
- National Center of Genome Resources, Santa Fe, NM, United States
- School of Computing, DePaul University, Chicago, IL, United States
| | | | - Daojun Yuan
- EEOB Department, Iowa State University, Ames, IA, United States
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | | | - Lei Gong
- Key Laboratory of Molecular Epigenetics of the Ministry of Education, Northeast Normal University, Changchun, China
| | - Mark A. Arick
- Institute for Genomics, Biocomputing & Biotechnology, Mississippi State University, Mississippi State, MS, United States
| | - Rick E. Masonbrink
- Genome Informatics Facility, Iowa State University, Ames, IA, United States
| | - Daniel G. Peterson
- Institute for Genomics, Biocomputing & Biotechnology, Mississippi State University, Mississippi State, MS, United States
| | - Jonathan F. Wendel
- EEOB Department, Iowa State University, Ames, IA, United States
- *Correspondence: Joshua A. Udall, ; Jonathan F. Wendel,
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Singh J, Singhal VK. The Presence and Behavior of B-Chromosomes in Meiocytes in <i>Apluda mutica</i> L. CYTOLOGIA 2018. [DOI: 10.1508/cytologia.83.93] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Houben A. B Chromosomes - A Matter of Chromosome Drive. FRONTIERS IN PLANT SCIENCE 2017; 8:210. [PMID: 28261259 PMCID: PMC5309253 DOI: 10.3389/fpls.2017.00210] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 02/03/2017] [Indexed: 05/23/2023]
Abstract
B chromosomes are supernumerary chromosomes which are often preferentially inherited, deviating from usual Mendelian segregation. The balance between the so-called chromosome drive and the negative effects that the presence of Bs applies on the fitness of their host determines the frequency of Bs in a particular population. Drive is the key for understanding most B chromosomes. Drive occurs in many ways at pre-meiotic, meiotic or post-meiotic divisions, but the molecular mechanism remains unclear. The cellular mechanism of drive is reviewed based on the findings obtained for the B chromosomes of rye, maize and other species. How novel analytical tools will expand our ability to uncover the biology of B chromosome drive is discussed.
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In vivo modification of a maize engineered minichromosome. Chromosoma 2013; 122:221-32. [DOI: 10.1007/s00412-013-0403-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 02/25/2013] [Accepted: 02/27/2013] [Indexed: 10/27/2022]
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Masonbrink RE, Fu S, Han F, Birchler JA. Heritable loss of replication control of a minichromosome derived from the B chromosome of maize. Genetics 2013; 193:77-84. [PMID: 23114381 PMCID: PMC3527256 DOI: 10.1534/genetics.112.146126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2012] [Accepted: 10/29/2012] [Indexed: 01/24/2023] Open
Abstract
During an accumulation regime of a small telomere-truncated B chromosome, a derivative with large variations in size and multiple punctate centromere loci exhibiting amplified copy numbers was discovered. Multiple centromere satellite loci or transgene signals were documented in amplified chromosomes, suggesting over-replication. Immunolocalization studies revealed multiple foci of biochemical markers characteristic of active centromeres such as CENP-C and phosphorylation of histones H3S10 and H2AThr133. The amplified chromosomes exhibit an absence of chromosome disjunction in meiosis I and an infrequent chromosome disjunction in meiosis II. Despite their unusual structure and behavior these chromosomes were observed in the lineage for seven generations during the course of this study. While severely truncated relative to a normal B chromosome, the progenitor minichromosome is estimated to be at least several megabases in size. Given that the centromere and transgene signals at opposite ends of the chromosome generally match in copy number, the replication control is apparently lost over several megabases.
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Affiliation(s)
- Rick E. Masonbrink
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
| | - Shulan Fu
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese National Academy of Sciences, Beijing, China
| | - Fangpu Han
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese National Academy of Sciences, Beijing, China
| | - James A. Birchler
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211
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Masonbrink RE, Gaeta RT, Birchler JA. Multiple maize minichromosomes in meiosis. Chromosome Res 2012; 20:395-402. [DOI: 10.1007/s10577-012-9283-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 04/09/2012] [Accepted: 04/10/2012] [Indexed: 10/28/2022]
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Gaeta RT, Danilova TV, Zhao C, Masonbrink RE, McCaw ME, Birchler JA. Recovery of a telomere-truncated chromosome via a compensating translocation in maize. Genome 2011; 54:184-95. [PMID: 21423281 DOI: 10.1139/g10-108] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Maize-engineered minichromosomes are easily recovered from telomere-truncated B chromosomes but are rarely recovered from A chromosomes. B chromosomes lack known genes, and their truncation products are tolerated and transmitted during meiosis. In contrast, deficiency gametes resulting from truncated A chromosomes prevent their transmission. We report here a de novo compensating translocation that permitted recovery of a large truncation of chromosome 1 in maize. The truncation (trunc-1) and translocation with chromosome 6 (super-6) occurred during telomere-mediated truncation experiments and were characterized using single-gene fluorescent in situ hybridization (FISH) probes. The truncation contained a transgene signal near the end of the broken chromosome and transmitted together with the compensating translocation as a heterozygote to approximately 41%-55% of progeny. Transmission as an addition chromosome occurred in ~15% of progeny. Neither chromosome transmitted through pollen. Transgene expression (Bar) cosegregated with trunc-1 transcriptionally and phenotypically. Meiosis in T1 plants revealed eight bivalents and one tetravalent chain composed of chromosome 1, trunc-1, chromosome 6, and super-6 in diplotene and diakinesis. Our data suggest that de novo compensating translocations allow recovery of truncated A chromosomes by compensating deficiency in female gametes and by affecting chromosome pairing and segregation. The truncated chromosome can be maintained as an extra chromosome or together with the super-6 as a heterozygote.
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Affiliation(s)
- Robert T Gaeta
- Department of Biological Sciences, University of Missouri-Columbia, Columbia, MO 65211, USA
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Similar rye A and B chromosome organization in meristematic and differentiated interphase nuclei. Chromosome Res 2011; 19:645-55. [PMID: 21674259 DOI: 10.1007/s10577-011-9224-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 05/26/2011] [Accepted: 05/26/2011] [Indexed: 12/28/2022]
Abstract
Supernumerary (B) chromosomes of rye are not required for plant development and exhibit a reduced transcription activity. These special features inspired us to analyse whether there are differences between A and B chromatin organization in interphase nuclei. Applying fluorescence in situ hybridization, we found that both rye A and B chromosomes added to hexaploid wheat showed in meristematic nuclei a string-like shape and a clear Rabl orientation. In 4C differentiated leaf nuclei, a more relaxed chromatin structure, round-shaped chromosome territories and a less pronounced Rabl configuration were found. Also, the observed random association of homologues in 2C and 4C nuclei indicated in general a similar behaviour of A and B chromosomes. Whereas in differentiated 4C nuclei A sister centromeres are separated, B sister centromeres align in nearly all nuclei. In short, despite the different transcription activity of A and B chromosomes, both types of chromosomes exhibit a similar organization in meristematic and differentiated interphase nuclei. But the deletion of a B chromosome segment responsible for non-disjunction during gametogenesis induces released sister centromeres also in some interphase nuclei of somatic tissue. Hence, the control of rye B chromosome non-disjunction is also active in sporophytic cells.
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