| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
3 Investigen Inc., 851 West Midway Ave., Alameda, California 94501 USA; 4 Department of Soil & Crop Sciences, Texas A&M University, College Station, Texas 77843 USA; and 5 Cabo Canaberal 3904, Colonia Rincon de la Primavera, Guadalupe, Nuevo, Leon, Mexico
Received for publication September 2, 1999. Accepted for publication February 17, 2000.
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Key Words: centromere • FISH • Poaceae • polyploidy • sorghum • sugarcane • tandem repeat
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Centromere-specific repetitive DNA sequences have been isolated from several plant species, including Brassica napus (Xia, Selvaraj, and Bertrand, 1993
; Harrison and Heslop-Harrison, 1995
), Lycopersicon esculentum (Ganal, Lapitan, and Tanksley, 1988
), Arabidopsis thaliana (Martinez-Zapater, Estelle, and Somerville, 1986
; Richards, Goodman, and Ausubel, 1991
), Oryza sativa (Wang et al., 1995
), and Beta procumbens (Schmidt and Heslop-Harrison, 1996
). Alfenito and Birchler (1993)
isolated a centromere-specific 1.4 kb repeat from a Zea mays B chromosome consisting of clustered tandem repeats encompassing 9 Mb of the B chromosome (Kaszas and Birchler, 1996
). The repeat is located at the centromere of B chromosomes and is highly homologous to sequences of maize chromosome knobs (Kaszas and Birchler, 1996
), which can have centromeric properties during meiosis in the presence of a chromosome 10 variant (Rhoades, 1978
; Peacock et al., 1981
).
Jiang et al. (1996)
isolated a 745-bp centromere-specific repeat (pSau3A9) from a sorghum bacterial artificial chromosome (BAC) that is conserved in all cereals tested and may have a role in centromere function. In contrast, a second highly repetitive centromere-specific DNA element from sorghum, pSau3A10, has very limited taxonomic distribution (Miller et al., 1998
). It occurs in several species of section Sorghum, but not in S. versicolor (section Parasorghum), or other grass genera, including Saccharum and Zea (Miller et al., 1998
). FISH of pSau3A10 yielded differentially strong signal in centromeric regions of ten out of the 20 sorghum mitotic chromosomes (Miller et al., 1998
). This pattern is similar to that previously reported for BAC 22B2 (Gomez et al., 1998
). The FISH pattern of BAC 22B2 on mitotic chromosomes of S. bicolor strongly indicated its tetraploid nature and led Gomez et al. (1998)
to designate the two subgenomes as Ab and Bb, where the subscript "b" alludes to "bicolor." Nucleotide sequencing showed that the pSau3A10 element consists of six monomers of 
137 bp organized into three dimers (Miller et al., 1998
). The monomers within dimers shared less homology (62–72%) than the dimers shared with each other (79–82%). The dimer has a copy number of 105 and is tandemly arranged in uninterrupted stretches of up to 81 kb of DNA. Miller et al. (1998)
suggested that the Sau3A10 family is an important part of sorghum centromeres.
Nagaki, Tsujimoto, and Sasakuma (1998)
cloned sequences of a tandemly arranged highly repetitive (2.6 x 105 copies per genome) 140-bp DNA sequence family (SCEN) from sugarcane. High-stringency FISH yielded signal at centromeres of several sugarcane chromosomes, whereas low-stringency FISH of variable PCR-derived probe yielded signal on nearly all sugarcane chromosomes. SCEN elements have an average of 75% homology with each other. The consensus sequence contained three regions similar to the CENP-B box (centromere protein B box) of mammalian chromosomes and, therefore, Nagaki, Tsujimoto, and Sasakuma (1998)
suggested that the SCEN family may function as a centromere.
We herein report the molecular and molecular cytogenetic characteristics of a subgenome-enriched repeat from sorghum BAC 22B2 and its relationship to the sorghum Sau3A10 and sugarcane SCEN repetitive DNA families. The results of this study raise important questions. First, should the revelation of sorghum's polyploid nature modify existing perceptions and approaches for grass genome research? Second, what is the significance of the trimodal distribution of pCEN38 signal in centromeric regions? Third, how are pCEN38 sequences related to genome (subgenome) evolution?
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
. The filter was Southern hybridized (Woo et al., 1994
) using 32P-CTP labeled total genomic sorghum DNA and incubated overnight at -80°C on Kodak X-OMAT AR film with a single intensifying screen. Clones showing intense signals presumably include repetitive sequences and were selected for further analysis.
Clone isolation and analysis
One hundred and twenty clones were selected, replated onto a fresh LB/Amp plate, and incubated overnight at 37°C. Forty clones were used to inoculate 5-mL LB/Amp cultures for plasmid isolation. Fresh overnight cultures were prepared by the miniprep procedure as described by Silhary, Berman, and Enquist (1984)
. Plasmid samples were digested with HindIII for 4 h, run on a 1%, 0.5x TBE (1 mmol/L EDTA, 45 mmol/L TRIS base, 45 mmol/L boric acid) agarose gel, stained with ethidium bromide and photographed. Clones containing various inserts ranging from 0.5 to 2 kb were selected for potential fluorescent in situ hybridization (FISH) analysis.
Fluorescent in situ hybridization (FISH)
Six clones (1–5 kb) determined to contain repetitive sequences by Southern hybridization with total genomic sorghum DNA were selected for FISH. Whole plasmid DNA was labeled with digoxigenin-11-dUTP using nick translation kit 976–776 (Boehringer Mannheim, Indianapolis, Indiana, USA) and with biotin-14-dATP using a BioNick labeling kit (GibcoBRL, Grand Island, New York, New York, USA).
Somatic chromosomes were prepared from roots of Sorghum bicolor BTx623 and a sugarcane line CP72–1210 (derived from hybridization between Saccharum officinarum and S. spontaneum), as described by Jewell and Islam-Faridi (1994)
. Microscopic slides of sorghum meiotic chromosomes were prepared using the technique of Jewell and Islam-Faridi (1994)
, except that squashes were made in 45% acetic acid.
Procedures for FISH followed Islam-Faridi and Mujeeb-Kazi (1994)
, except that no unlabeled Cot-1 DNA was used for blocking (competitive hybridization). Hybridization sites were detected by Cy3-conjugated streptavidin (Jackson ImmunoResearch Laboratories, Inc., West Grove, Pennsylvania, USA) or mouse anti-digoxygenin (Jackson ImmunoResearch Laboratories, Inc., West Grove, Pennsylvania, USA) followed by Cy3-conjugated antimouse antibody (Jackson ImmunoResearch Laboratories, Inc., West Grove, Pennsylvania, USA) Photographic prints were scanned using a standard desktop RGB flatbed scanner and digital images assembled into plates.
To assess relative strengths of FISH signals and their distributions, blue (4',6-diaminodino-2-2-phenylindole [DAPI] signal from chromosomal DNA) and red (Cy3 signal from probe) signals were measured from digital images using Optimas v6.0. Lines for sampling luminance values spanned the lengths of somatic chromosomes or meiotic bivalents, whereas line sampling width was set equal to maximum chromosome width, with 256 (sorghum) or 100 (sugarcane) segments per linear sample. Data were extracted for the Optimas "linear morphology default data collection set," exported to a spreadsheet (Microsoft Excel), and examined graphically in native and ranked orders.
Taxonomic distribution of pCEN38
To assess the distribution of pCEN38 sequences among higher plants, pCEN38 was Southern hybridized to a filter containing DNA from 21 various crop plants. DNA from five varieties of Lycopersicon esculentum, Solanum tuberosum, Capsicum annuum, Solanum melongena, Citrullis lanatus, Cucumis melo, Cucurbita pepo, Cucurbita sp., Arabidopsis thaliana, Brassica oleraceae ssp. botrytis, Phaseolus vulgaris, Glycine max, Oryza sativa cv. Lemont, Oryza sativa cv. Teqing, Zea mays, Triticum aestivum cv. Chinese Spring, Gossypium hirsutum, Rosa sp., Prunus persica, Malus domestica, Juglans regia, and Pinus taeda was isolated as described by Zhang et al. (1995)
. DNA samples were digested with arbitrarily selected EcoRI and HindIII, run on a 1% agarose gel, and blotted onto Hybond N+ filters. Filters were Southern hybridized with 100 ng of radioactively labeled pCEN38, as described above, and exposed to X-ray film for 12 h at -80°C.
Sequencing
Inserted clone pCEN38 was selected for sequencing due to its small size and distinct FISH pattern. A universal primer was used to initiate dye-terminator PCR (polymerase chain reaction) for sequencing using an ABI Prism fluorescent sequencer, as described by its manufacturer (Applied Biosystems Inc., Foster City, California, USA). For complete sequencing of the insert, a 19-nucleotide internal primer was synthesized that was identical to bases 418–436 (GACGCACCCAATGGAACTC) of the sequence in Table 1. Sequence data were analyzed and edited using Sequencher for MacIntosh (Gene Codes Corporation, Ann Arbor, Michigan, USA) and registered at GenBank (BankIt260544 AF137608).
|
) and the sugarcane SCEN family (Nagaki, Tsujimoto, and Sasakuma, 1998
). The consensus sequence of the pSau3A10 family was aligned with that of pCEN38. The 69 sequenced members of the sugarcane SCEN family in the sequence data bank were also compared and aligned by computer analysis to the sequence of pCEN38. Sequences were compared using BCM Search Launcher: Multiple Sequence Alignment (Clustal V1.7). |
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
|
Subgenomic distribution of pCEN38 and relative subgenome sizes
Mitotic FISH of pCEN38 yielded much stronger signals on ten chromosomes, revealing a differential affinity for Ab subgenome centromere regions (Figs. 1–3). Plots of red luminance values along the chromosome lengths confirmed one major red peak for each of the ten Ab subgenome chromosomes and a relatively minor peak on the other ten Bb subgenome chromosomes (Fig. 10). Excluding the NOR-bearing Ab chromosome 1 (largest), the Ab subgenome chromosomes are 15–20% larger than the Bb subgenome chromosomes. However, the lengths of individual members of the two subgenomes overlap.
|
|
. The pSau3A10 sequence aligns with bases number 62–889 of pCEN38 and shows nine single-nucleotide gaps (Table 1).
Dimer repeats in pCEN38
The pCEN38 fragment consists of four tandemly arranged repetitive sequences (A) 45–304 [218 bp]; (B) 305–578 [274 bp]; (C) 579–849 [271 bp] and (D) 850–1047 [190 bp] (Table 2). Repeat A is missing 17 bases at its beginning. D is a repeat that apparently extends beyond the fragment cloned in pCEN38. The A, B, C, and D repeats show 76–82% homology with repeats B, C, and D being more similar to each other (81–83% homology) than to A (76–79% homology) (Table 3). The monomers at the first positions of the dimers A1, B1, C1, and D1 show relatively high homology, as do the monomers at the second position of the dimers A2, B2, C2, and D2 (Table 3). Homology between monomers of the first and second positions of the dimers is much lower (Table 3).
|
|
). The pCEN38 clone fragment showed homology (62–86%) to 68 of the 69 sugarcane SCEN sequences. This homology indicates that the A repeat starts at basepair 45 of the pCEN38 fragment and that each repeat consists of two divergent monomers, A1 (45–166) and A2 (167–304), B1 (305–441) and B2 (442–578), C1 (579–712) and C2 (713–849), and D1 (850–985). Table 2 shows the alignment of five selected SCEN sequences to that of the pCEN38 fragment. These alignments with the sugarcane sequences define the sorghum monomers as variants of a 140-bp repeat.
FISH of pCEN38 to sugarcane chromosomes
Chromosomes in seven somatic metaphase spreads of sugarcane (2n 
112) were grouped by visual evaluation of FISH signal intensity into four classes of 20–40 chromosomes each. But plots of ranked red luminance values (Fig. 12) revealed a distribution of Cy3 signal among signal-bearing chromosomes that was too closely graded to substantiate the visual classification. Similar results were obtained with area sampling methods (not discussed). We thus infer that any qualitative classification scheme of pCEN38 FISH signal strength in sugarcane would involve subjectivity. Nevertheless, it was visually and quantitatively clear that Cy3 signal occurred on three quarters or more but probably not all of the sugarcane chromosomes.
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Properly standardized experiments place the 1C genome size of Sorghum bicolor at 840 megabase (Mb) (Michaelson et al., 1991
) and that of rice at 482 Mb (Bennett and Leitch, 1995
). Given roughly equal contraction among non-NOR-bearing chromosomes of both sorghum subgenomes, the differences in chromosome length (20%) indicate that the Ab subgenome is 460 Mb and that the Bb subgenome 380 Mb. Thus, the basic genome of sorghum is no larger than that of rice (Oryza sativa), which is putatively diploid (Bennetzen and Freeling, 1997
; Ahn and Tanksley, 1993
; Moore et al., 1995
) and an important model for grass genome research. This and other evidence of sorghum's tetraploid architecture seem at odds with the grass genome relationships depicted by Moore et al. (1995)
, especially the one-to-one relationship depicted between rice and sorghum genomes.
FISH of pCEN38 to meiotic metaphase I spreads led to a signal at the attenuated regions of bivalents, i.e., segments collectively spanning biologically active centromeres. Delimitation of the signal on Bb pachytene bivalents to specific subregions of pericentric heterochromatin suggests that pericentric heterochromatin subregions could feature considerable element specificity. Trimodality of the FISH signal distribution on several Bb chromosomes suggests that the arrangement is functionally and/or evolutionarily significant. The distribution requires two intervening regions with little or no pCEN38 homology. The two intervening areas could represent a bimodal component flanking the kinetochore region. Moreover, the collective penta-regional arrangement is dissimilar to the dogmatic view of the localized centromere. In the latter, there are three regions, i.e., a central site of kinetochore activity, flanked on both sides by a larger, centromere-enhancing region that is enriched in repetitive element (Pluta et al., 1995
). Interestingly, Lima-de-Faria (1955)
reported long ago that each centromere of rye is compound and has three chromomeres.
The idea that the sorghum centromere region might be compositionally multipartite is congruent with evidence from the Drosophila where duplication Dp(3f) Th causes instability within the centromere region that allows for subregional analysis (Sunkel and Coelho, 1995
). The data manifest a multipartite centromere system that includes islands of complex composition (Tahiti, Moorea, and Bora Bora) and distinct stretches of different satellite elements. The genomic regions of sorghum that yield the highest pCEN38 FISH signal are perhaps most likely to be involved in centromere function, but they could affect any of a very wide range of possible traits including chromosome condensation structure at any time(s) during the cell or reproductive cycles and intranuclear spatial positioning. However, the limited taxonomic distribution of pCEN38 sequences suggests that they have little to do with any kinetochore function that has been highly conserved at the sequence level.
The family of repetitive sequences represented within pCEN38 consists of a tandemly repeated dimer (<280 bp) consisting of two divergent monomers (<140 bp). The similarity of pCEN38 and pSau3A10 sequences repeat lengths indicate that they contain representatives of the same repetitive family. Miller et al. (1998)
interpreted their 277-bp repeat as consisting of two 137-bp monomers. Our results support their interpretation, and further show that the monomers are related to the 140-bp sugarcane SCEN tandem repeat family. Members of the CEN38/Sau3A10 sequence family in sorghum have diverged relative to each other and to the sugarcane sequences by base pair substitutions, deletions, and/or additions.
The current results coupled with those of Miller et al. (1998)
indicate that pCEN38 and pSau3A10 sequences appear to be present in sorghum and sugarcane, but they are apparently absent in other grasses including Zea mays. Miller et al. (1998)
used Southern blots to show that pSau3A10-like sequences occur in the section Sorghum, but not in S. versicolor of section Parasorghum, or species of other grass genera, including Saccharum. The data of Miller et al. (1998)
regarding lack of affinity of pSau3A10 to Saccharum need clarification, as they are discordant with our findings and those of Nagaki, Tsujimoto, and Sasakuma (1998)
. We found that CEN38 hybridizes well in situ to most Saccharum chromosomes, and Nagaki, Tsujimoto, and Sasakuma (1998)
found SCEN (pSG1–2) hybridizes ex situ to DNA and in situ to chromosomes of sugarcane. Sequence comparisons show high homologies among and within these respective families of elements. Our findings are in agreement with systematic (Clayton and Renvoize, 1986
) and molecular systematic studies (Hamby and Zimmer, 1988
; Springer, Zimmer, and Bennetzen, 1989
; Al-Janabi et al., 1994
), which indicate that Sorghum and Saccharum are more closely related to each other than either is to maize. They also indicate that the CEN38 element is absent or very low in copy number in one or more subgenomes of sugarcane CP72–1210
The data suggest that at least one member of the SCEN family resided in the genomes of an ancestor common to sorghum and sugarcane. The SCEN family of sequences was amplified in at least some species of the Saccharum complex and the pCEN38/pSau3A10 family in at least some genomes of Sorghum. The simplest hypothesis on the origin of the Sorghum CEN38/Sau3A10 family should necessarily involve the amplification of a dimer consisting of two divergent SCEN sequences.
FISH patterns suggest that one subgenome (Ab) of contemporary S. bicolor is differentially enriched for the CEN38/Sau3A10 family, but that the other subgenome is not totally devoid of it. Sexual polyploidization involving parental genomes that differed in their relative abundance of SCEN or CEN38/Sau3A10 sequences could have resulted in the currently observed pattern of half of the chromosome set possessing differential enrichment of the repetitive sequence. It is also possible that one ancestral genome was originally devoid of the element, but was "branded" subsequent to polyploidization, i.e., by trans-subgenomic infection (Hanson et al., 1998
). A third possibility is that one of the genome sets has differentially lost CEN38/Sau3A10 sequences. Sequence analysis will be needed to further study the relatedness of the elements in the two sorghum subgenomes.
|
FOOTNOTES |
|---|
|
LITERATURE CITED |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Alfenito, M. R., and J. A. Birchler. 1993 Molecular characterization of a maize B chromosome centric sequence. Genetics 135: 589–597[Abstract]
Al-Janabi, S. M., M. McClelland, C. Petersen, and B. W. S. Sobral. 1994 Phylogenetic analysis of organellar DNA sequences in the Andropogoneae: Saccharinae. Theoretical and Applied Genetics 88: 933–944[ISI]
Bennett, M. D., and I. J. Leitch. 1995 Nuclear DNA amounts in angiosperms. Annals of Botany 76: 113–176
Bennetzen, J. L., and M. Freeling. 1997 The unified grass genome: synergy and synteny. Genome Research 7: 301–306
Clayton, W. D., and S. A. Renvoize. 1986 Genera graminum, grasses of the world. Her Majesty's Stationary Office, London, UK
Hamby, R. K., and E. A. Zimmer. 1988 Ribosomal RNA sequences for inferring phylogeny within the grass family (Poaceae). Plant Systematics and Evolution 160: 29–37[CrossRef][ISI]
Hanson, R. E., X. Zhao, M. N. Islam-Faridi, A. H. Paterson, M. S. Zwick, C. F. Crane, T. D. McKnight, D. M. Stelly, and H. J. Price. 1998 Evolution of interspersed repetitive elements in Gossypium (Malvaceae). American Journal of Botany 85: 1364–1368
Harrison, G. E., and J. S. Heslop-Harrison. 1995 Centromeric repetitive DNA sequences in the genus Brassica. Theoretical and Applied Genetics 90: 157–165
Ganal, M. W., N. L. Lapitan, and S. D. Tanksley. 1988 A molecular and cytogenetic survey of major repeated DNA sequences in tomato (Lycopersicon esculentum). Molecular and General Genetics 213: 262–268[CrossRef]
Gomez, M., M. N. Islam-Faridi, M. Zwick, D. G. Czeschin Jr., G. E. Hart, R. A. Wing, D. M. Stelly, and H. J. Price. 1998 Tetraploid nature of Sorghum bicolor (L.). Journal of Heredity 89: 188–190
Islam-Faridi, M. N., and A. Mujeeb-Kazi. 1994 Visualization of Secale cereale DNA in wheat germ plasm by fluorescent in situ hybridization. Theoretical and Applied Genetics 90: 595–600[ISI]
Jewell, D. C., and M. N. Islam-Faridi. 1994 A technique for somatic chromosome preparation and C-banding of maize. In M. Freeling and V. Walbot [eds.], The maize handbook, 484–493. Springer-Verlag, New York, New York, USA
Jiang, J., S. Nasuda, F. Dong, C. W. Scherrer, S.-S. Woo, R. A. Wing, B. S. Gill, and D. C. Ward. 1996 A conserved repetitive DNA element located in the centromeres of cereal chromosomes. Proceedings of the National Academy of Sciences, USA 93: 14210–14213
Kaszas, E., and J. A. Birchler. 1996 Misdivision analysis of centromere structure in maize. European Molecular Biology Organization Journal 15: 5246–5255
Lima-de-Faria, A. 1955 Structural differentiation of the kinetochore in rye and agapanthus. Chromosoma 7: 78–89[CrossRef][ISI]
Martinez-Zapater, J. M., M. A. Estelle, and C. R. Somerville. 1986 A highly repeated DNA sequence in Arabidopsis thaliana. Molecular and General Genetics 204: 417–423
Michaelson, M. J., H. J. Price, J. R. Ellison, and J. S. Johnston. 1991 Comparison of plant DNA contents determined by feulgen microspectrophotometry and laser flow cytometry. American Journal of Botany 78: 183–188[CrossRef][ISI]
Miller, J. T., S. A. Jackson, S. Nasuda, B. S. Gill, R. A. Wing, and J. Jiang. 1998 Cloning and characterization of a centromere specific DNA element from Sorghum bicolor. Theoretical and Applied Genetics 96: 832–839
Moore, G., K. M. Devos, Z. Wang, and M. D. Gale. 1995 Cereal genome evolution—grasses, line up and form a circle. Current Biology 5: 737–739[CrossRef][ISI][Medline]
Nagaki, K., H. Tsujimoto, and T. Sasakuma. 1998 A novel repetitve sequence of sugarcane, SCEN family, locating on centromeric regions. Chromosome Research 6: 295–302[CrossRef][ISI][Medline]
Peacock, W. J., E. S. Dennis, M. M. Rhoades, and A. J. Pryor. 1981 Highly repeated DNA sequence limited to knob heterochromatin in maize. Proceedings of the National Academy of Sciences, USA 78: 4490–4494
Pluta, A. F., A. M. Mackkay, A. M. Ainzstein, I. G. Goldberg, and W. C. Earnshaw. 1995 The centromere: hub of chromosomal activities. Science 270: 1591–1594
Rhoades, M. M. 1978 Genetic effect of heterochromatin in maize. In D. B. Walden [ed.], Maize breeding and genetics, 641–671. Wiley, New York, New York, USA
Richards, E. J., H. M. Goodman, and F. M. Ausubel. 1991 The centromere region of Arabidopsis thaliana chromosome 1 contains telomere-similar sequences. Nucleic Acids Research 19: 3351–3357
Schmidt, T., and J. S. Heslop-Harrison. 1996 High-resolution mapping of repetitive DNA by in situ hybridization: molecular and chromosomal features of prominent dispersed and discretely localized DNA families from the wild beet species Beta procumbens. Plant Molecular Biology 30: 1099–1114
Silhary, T. J., M. L. Berman, and L. W. Enquist. 1984 Experiments with gene fusions. Cold Spring Harbor Laboratory Press, Plainview, New York, USA
Springer, P. S., E. A. Zimmer, and J. L. Bennetzen. 1989 Genomic organization of the ribosomal DNA of sorghum and its close relatives. Theoretical and Applied Genetics 77: 844–850[CrossRef][ISI]
Sunkel, C. E., and P. A. Coelho. 1995 The elusive centromere-sequence divergence and functional conservation. Current Opinions in Genetics and Development 5: 756–767[CrossRef]
Wang, Z. X., N. Kurata, S. Saji, Y. Katayose, and Y. Minobe. 1995 A chromosome 5-specific repetitive DNA sequence in rice (Oryza sativa L.). Theoretical and Applied Genetics 90: 907–913[ISI]
Woo, S.-S., J. Jiang, B. S. Gill, A. H. Paterson, and R. A. Wing. 1994 Construction and characterization of a bacterial artificial chromosome library of Sorghum bicolor. Nucleic Acids Research 22: 4922–4931
Zhang, H. B., X. Zhao, D. Ding, A. H. Paterson, and R. A. Wing. 1995 Preparation of megabase-size DNA from plant nuclei. Plant Journal 7: 175–184[CrossRef][ISI]
Xia, X., G. Selvaraj, and H. Bertrand. 1993 Structure and evolution of a highly repetitive DNA sequence from Brassica napus. Plant Molecular Biology 21: 213–224
This article has been cited by other articles:
|
|
 |
|
  J.-S. Kim, M. N. Islam-Faridi, P. E. Klein, D. M. Stelly, H. J. Price, R. R. Klein, and J. E. Mullet Comprehensive Molecular Cytogenetic Analysis of Sorghum Genome Architecture: Distribution of Euchromatin, Heterochromatin, Genes and Recombination in Comparison to Rice Genetics, December 1, 2005; 171(4): 1963 - 1976. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. E. Bowers, M. A. Arias, R. Asher, J. A. Avise, R. T. Ball, G. A. Brewer, R. W. Buss, A. H. Chen, T. M. Edwards, J. C. Estill, et al. Comparative physical mapping links conservation of microsynteny to chromosome structure and recombination in grasses PNAS, September 13, 2005; 102(37): 13206 - 13211. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J.-S. Kim, P. E. Klein, R. R. Klein, H. J. Price, J. E. Mullet, and D. M. Stelly Chromosome Identification and Nomenclature of Sorghum bicolor Genetics, February 1, 2005; 169(2): 1169 - 1173. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. J. PRICE, S. L. DILLON, G. HODNETT, W. L. ROONEY, L. ROSS, and J. S. JOHNSTON Genome Evolution in the Genus Sorghum (Poaceae) Ann. Bot., January 1, 2005; 95(1): 219 - 227. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. E. Bowers, C. Abbey, S. Anderson, C. Chang, X. Draye, A. H. Hoppe, R. Jessup, C. Lemke, J. Lennington, Z. Li, et al. A High-Density Genetic Recombination Map of Sequence-Tagged Sites for Sorghum, as a Framework for Comparative Structural and Evolutionary Genomics of Tropical Grains and Grasses Genetics, September 1, 2003; 165(1): 367 - 386. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. X. Zhong, J. B. Marshall, C. Topp, R. Mroczek, A. Kato, K. Nagaki, J. A. Birchler, J. Jiang, and R. K. Dawe Centromeric Retroelements and Satellites Interact with Maize Kinetochore Protein CENH3 PLANT CELL, November 1, 2002; 14(11): 2825 - 2836. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. N. Islam-Faridi, K. L. Childs, P. E. Klein, G. Hodnett, M. A. Menz, R. R. Klein, W. L. Rooney, J. E. Mullet, D. M. Stelly, and H. J. Price A Molecular Cytogenetic Map of Sorghum Chromosome 1: Fluorescence in Situ Hybridization Analysis With Mapped Bacterial Artificial Chromosomes Genetics, May 1, 2002; 161(1): 345 - 353. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. B. Talbert, R. Masuelli, A. P. Tyagi, L. Comai, and S. Henikoff Centromeric Localization and Adaptive Evolution of an Arabidopsis Histone H3 Variant PLANT CELL, May 1, 2002; 14(5): 1053 - 1066. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. G. Peterson, S. R. Schulze, E. B. Sciara, S. A. Lee, J. E. Bowers, A. Nagel, N. Jiang, D. C. Tibbitts, S. R. Wessler, and A. H. Paterson Integration of Cot Analysis, DNA Cloning, and High-Throughput Sequencing Facilitates Genome Characterization and Gene Discovery Genome Res., May 1, 2002; 12(5): 795 - 807. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
