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1.
By using the isoschizomers Hpa II and Msp I which display differential sensitivity to cytosine methylation, a modified amplified fragment length polymorphism (AFLP)
technique has been developed to investigate DNA methylation profiles in eukaryotic organims. Genomic DNA was digested with
a mixture of EcoR I and one of the isoschizomers, and ligated to oligonucleotide adapters. After two rounds of selective PCR amplification,
followed by DNA separation on a Long Ranger gel electrophoresis, a subset of restriction fragments can be displayed on an
X-ray film. Comparison of AFLP banding patterns between Hpa II and Msp I revealed the extent of DNA methylation. The technique has been successfully applied in this study to investigate DNA methylation
profiles of apple ( Malus domestica cv. Gala) genomic DNA extracted from leaves of field-grown adult trees and in vitro-grown shoot cultures. The results showed that up to 25 percent of AFLP bands were derived from methylated sequences, and
among those, a few bands unique to either adult trees or in vitro shoots were observed. These results demonstrated that this protocol is effective in identifying methylated DNA profiles.
Both first authors have contributed equally to this work. 相似文献
2.
Sweet orange is an important group of citrus cultivars, which includes a number of bud sport cultivars. Little is known about
the CpG methylation status of the CCGG sequences in the orange genome. In this study, methylation-sensitive amplification
polymorphism (MSAP), based on the application of isoschizomers ( Hpa II and Msp I), was first used to analyze cytosine methylation patterns in 57 orange cultivars that were not fully differentiated by
regular DNA molecular markers. Three types of bands were generated from ten primer pairs. Type I bands were present following
restriction with Eco RI + Hpa II and Eco RI + Msp I; type II or type III were present only following restriction with either Eco RI + Hpa II or with Eco RI + Msp I. The total number of these three types of bands was 802, 72, and 157, respectively. Among these, the number of polymorphic
bands were 244 (30.2%), 23 (31.9%), and 32 (20.4%), in type I, II and III, respectively. The methylation patterns of these
57 cultivars are discussed and assessed by dendrograms derived from the analysis of polymorphic MSAP bands. The distribution
of polymorphic bands of the above three types demonstrate the methylation patterns and frequency at the cytosine loci. We
suggest that methylation events could be more frequent than demethylation events, and that the methylation patterns maybe
associated with phenotypic traits. 相似文献
3.
DNA-methylation profiles of leaf tissues of Rosa hybrida cv. Carefree Beauty collected from in vivo-grown greenhouse plants, in vitro-grown proliferating shoots at different passages, regenerants of embryogenic callus, regenerants of organogenic callus, as well as calli from undifferentiated callus (UC), embryogenic callus, and organogenic callus were investigated using an amplified fragment-length polymorphism (AFLP)-based detection technique. Three types of AFLP bands were recovered. Type I bands were observed with both isoschizomers Msp and HpaII, while type II and type III bands were observed only with MspI and HpaII, respectively. Sequence analysis of the three types of AFLP bands revealed that a nonmethylated MspI/ HpaII-recognition site 5-CCGG-3 resulted in a type I band, while an inner 5-methylcytosine generated most type II and type III bands. About 40% of inner and 20% of outer cytosines in 5-CCGG-3 sequences were fully methylated, and only a few hemimethylated outer cytosines were observed. Changes in types of AFLP bands among different tissues were frequently observed, including appearance and disappearance of type I, II, and III AFLP bands, as well as exchanges between either type I and type II or type I and type III AFLP bands. Methylation alterations of outer cytosines in 5-CCGG-3 sequences triggered appearance and disappearance of type I and II AFLP bands. Methylation changes of both outer and inner cytosines resulted in either removal or generation of type III AFLP bands. Methylation alteration of an inner cytosine was responsible for exchange between type I and type II, while hemimethylation of an outer cytosine accounted for exchange between type I and type III AFLP bands. During UC induction, a significant DNA-methylation alteration was detected in both inner and outer cytosines. Variations in methylation profiles significantly differed between somatic embryogenesis and in vitro organogenesis. Demethylation of outer cytosines occurred at a high frequency during somatic embryogenesis, and most altered AFLP bands in embryogenic callus were passed on to its regenerants. However, most methylation-altered AFLP bands during organogenesis were recovered in shoot regenerants derived via organogenic callus. Seven tissue-specific bands were isolated, cloned, and sequenced. Blast search revealed that two of these might be derived from functional genes.Mingliang Xu and Xiangqian Li contributed equally to this paper 相似文献
4.
Salinity is an important limiting environmental factor for rapeseed production worldwide. In this study, we assessed the extent and pattern of DNA damages caused by salt stress in rapeseed plants. Amplified fragment length polymorphism (AFLP) analysis revealed dose-related increases in sequence alterations in plantlets exposed to 10-1000 mmol/L sodium chloride. In addition, individual plantlets exposed to the same salt concentration showed different AFLP and selected region amplified polymorphism banding patterns. These observations suggested that DNA mutation in response to salt stress was random in the genome and the effect was dose-dependant. DNA methylation changes in response to salt stress were also evaluated by methylation sensitive amplified polymorphism (MSAP). Three types of MSAP bands were recovered. Type Ⅰ bands were observed with both isoschizomers Hpa Ⅱ and Msp Ⅰ, while type Ⅱ and type Ⅲ bands were observed only with Hpa Ⅱ and Msp Ⅰ, respectively. Extensive changes in types of MSAP bands after NaCI treatments were observed, including appearance and disappearance of type Ⅰ, Ⅱ and Ⅲ bands, as well as exchanges between either type Ⅰand type Ⅱ or type Ⅰ and type Ⅲ bands. An increase of 0.2-17.6% cytosine methylated CCGG sites were detected in plantlets exposed to 10- 200 mmol/L salt compared to the control, and these changes included both de novo methylation and demethylation events. Nine methylation related fragments were also recovered and sequenced, and one sharing a high sequence homology with the ethylene responsive element binding factor was identified. These results demonstrated clear DNA genetic and epigenetic alterations in planUets as a response to salt stress, and these changes may suggest a mechanism for plants adaptation under salt stress. 相似文献
5.
We have reported recently that tissue culture induced a high level of genetic variation at the primary nucleotide sequence
in regenerants of medicinal plant Codonopsis lanceolata. It is not known, however, whether epigenetic variation in the form of alteration in DNA methylation also occurred in these
plants. Here, we investigated possible alterations in level and pattern of cytosine methylation at the CCGG sites in the same
set of regenerants relative to the donor plant, by the MSAP method employing a pair of isoschizomers, HpaII and MspI, which recognize the same restriction site but are differentially sensitive to cytosine methylation at the CCGG sites. A
total of 1,674 MSAP profiles were resolved using 39 primer combinations. Of these, 177 (10.5%) profiles were polymorphic among
the regenerants and/or between the regenerant(s) and the donor plant, in EcoRI + HpaII or EcoRI + MspI digest but not in both, indicating alteration in cytosine methylation patterns of specific loci, though their estimated
total level of methylation remained more or less the same as the donor plant. Gel blot analysis validated most of the variant
MSAP profiles as bona fide alteration in methylation patterns. Correlation analysis between the MSAP data and the previously
reported ISSR and RAPD data revealed significant correlations, suggesting their possible intrinsic interrelatedness. Thirty-seven
typical variant MSAP profiles were isolated and sequenced, of which 5 showed significant homology to known-function genes,
2 to chloroplast sequences, whilst the rest 30 did not find a match in the database.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
W. L. Guo and R. Wu contributed equally to this work. 相似文献
6.
The restriction endonucleases Hpa II and Msp I were used to examine cytosine methylation in the ribosomal RNA genes (rDNA) of inbred lines of maize and species of teosinte. In all of the rDNAs examined, Msp I (not sensitive to mCpG) digestion yielded a distribution of lower molecular weight fragments indicative of multiple recognition sites. The majority of the rDNA arrays in an individual were inaccessible to Hpa II (sensitive to mCpG) cleavage, but a significant fraction (10–25%) was cleaved at least once by Hpa II into repeat unit length fragments (9.1 kbp). In some maize inbred lines, one or two additional fragment populations (less than 9.1 kbp in length) were also produced by Hpa II digestion. All of the unmethylated Hpa II sites mapped to the intergenic spacer (IGS), and the major unmethylated site was located approximately 800 bp 5 to the start of the 18S RNA coding sequence. An Eco RI polymorphism, present in the 26S gene of certain inbred lines and hybrids, was utilized to investigate the organization of unmethylated repeat units in the rDNA array. In double digest experiments with Hpa II/ Eco RI, the fragments from repeat units with two Eco RI sites were sensitive to Hpa II digestion, whereas, the fragments from repeat units with a single Eco RI site were almost completely resistant to Hpa II digestion. Similar digestion patterns were also observed in Eco RII (sensitive to mCNG)/ Eco RI digests. These results suggest that unmethylated and Eco RI polymorphic sites occur in the same repeat units. 相似文献
7.
The methylation status of carrot ( Daucus carota L.) mitochondrial DNA (mtDNA) was studied using isoschizomeric restriction enzymes MspI/ HpaII (CCGG) and MvaI/ EcoRII [CC(A/T)GG]. Southern hybridisations with probes for mitochondrial genes coxII and atpA were performed. MtDNAs isolated from non-embryogenic cell suspensions and roots were analysed. No differences were found
using MspI/ HpaII but after digesting the mtDNA with MvaI and EcoRII, some qualitative and quantitative differences between the restriction patterns appeared. Distinction was also revealed
after Southern hybridisation with the coxII probe. These data indicate that the mtDNA of carrot is methylated in CNG trinucleotides and unmethylated in CG dinucleotides
in CCGG sequences. The results were reproducible for cell suspensions of various genotypes and even cultivars but the extent
of methylation was different in the root. The possible role of methylation in the mitochondrial genome of higher plants is
discussed.
Received: 16 April 1997 / Revision received: 4 July 1997 / Accepted: 30 July 1997 相似文献
8.
The tomato nuclear genome was determined to have a G+C content of 37% which is among the lowest reported for any plant species. Non-coding regions have a G+C content even lower (32% average) whereas coding regions are considerably richer in G+C (46%).5-methyl cytosine was the only modified base detected and on average 23% of the cytosine residues are methylated. Immature tissues and protoplasts have significantly lower levels of cytosine methylation (average 20%) than mature tissues (average 25%). Mature pollen has an intermediate level of methylation (22%). Seeds gave the highest value (27%), suggesting de novo methylation after pollination and during seed development.Based on isoschizomer studies we estimate 55% of the CpG target sites (detected by Msp I/ Hpa II) and 85% of the CpNpG target sites (detected by Bst NI/ Eco RI)are methylated. Unmethylated target sites (both CpG and CpNpG) are not randomly distributed throughout the genome, but frequently occur in clusters. These clusters resemble CpG islands recently reported in maize and tobacco.The low G+C content and high levels of cytosine methylation in tomato may be due to previous transitions of 5mCT. This is supported by the fact that G+C levels are lowest in non-coding portions of the genome in which selection is relaxed and thus transitions are more likely to be tolerated. This hypothesis is also supported by the general deficiency of methylation target sites in the tomato genome, especially in non-coding regions.Using methylation isoschizomers and RFLP analysis we have also determined that polymorphism between plants, for cytosine methylation at allelic sites, is common in tomato. Comparing DNA from two tomato species, 20% of the polymorphisms detected by Bst NI/ Eco RII could be attributed to differential methylation at the CpNpG target sites. With Msp I/ Hpa II, 50% of the polymorphisms were attributable to methylation (CpG and CpNpG sites). Moreover, these polymorphisms were demonstrated to be inherited in a mendelian fashion and to co-segregate with the methylation target site and thus do not represent variation for transacting factors that might be involved in methylation of DNA. The potential role of heritable methylation polymorphism in evolution of gene regulation and in RFLP studies is discussed. 相似文献
9.
Cytosine methylation changes (hyper- or hypomethylation) in centromeric and telomeric sequences were observed in all three studied rice introgression lines containing DNA from wild rice, Zizania latifolia Griseb. The changed genomic Southern hybridization patterns were complex and non-concordant between a pair of isoschizomers ( HpaII/ MspI) digests, indicating methylation modifications at both the inner and outer cytosines of the CCGG sites. The changed patterns were inherited through generations. Possible mechanism for the methylation changes and their potential implications for the phenotypic variation and genome organization are discussed. 相似文献
10.
We have examined transgene methylation in the DNA from the livers of a pedigree of mice carrying three copies of an integrated MToGH1 transgene. Utilizing the methylation-sensitive isoschizomers Msp I and Hpa II, Southern blot analysis revealed that all second generation animals derived from a transgenic female had hypermethylated DNA, whereas first generation animals sired by a transgenic male displayed a range of methylation phenotypes ranging from no methylation to hypermethylation of the transgene sequences. Of the mice that exhibited hypermethylation of the transgene in CpG dinucleotides (CmCGG), a minority of these animals also exhibited apparent CpC methylation (i.e. inhibition of Msp I cutting, presumably blocked by methylation of the outer C of CCGG). Methylation was also examined in the inner C of CC(A/T)GG sequences in the MToGH1 transgene using the isoschizomer pair BstN I and EcoR II. A minority of MToGH1 animals in the F 1 generation showed clear evidence of methylation in these sites as well as in the inner and outer Cs of CCGG sites. An examination of MToGH1 expression in terms of oGH levels in serum revealed that there was a high degree of variation in the levels of circulating oGH between animals of this pedigree. There was a weak inverse relationship between the serum level of oGH and the extent of methylation of the transgene. In particular, mice exhibiting CpC together with CpG methylation were found to have very low levels of circulating oGH. Our results highlight the nature and complexity of epigenetic factors associated with transgene sequences which may ultimately influence expression of introduced genes in the mammalian genome. 相似文献
11.
Plant DNA is distinguished from the DNA of all other organisms by its high content of 5-methylcytosine (5mC). 5mC levels may amount to 30% of total cytosines, distributed between the sequences CG and CXG. The results presented here show that the methylation status of CXG sequences could be influenced by culturing tobacco tissues on subtoxic concentrations of ethionine. The hypomethylating effect of ethionine, evaluated as the capability of MspI or HpaII to cleave the DNA, proved to be rather specific for CCG and differed from that or 5-azacytidine which did not discriminate between CG and CXG sequences. 相似文献
12.
We have studied the distribution and methylation of CpG islands on human chromosomes, using the novel technique of self-primed
in situ labeling (SPRINS). The SPRINS technique is a hybrid of the two techniques primed in situ labeling (PRINS) and nick
translation in situ. SPRINS detects chromosomal DNA breaks, as in nick translation in situ, and not annealed primers, as is
the case in PRINS. We analyzed in situ-generated DNA breaks induced by the restriction enzymes HpaII and MspI. These restriction enzymes enable the detection of chromosomal CpG islands. Both HpaII- and MspI-SPRINS produce a banding pattern resembling R-banding, indicating a higher level of CpG islands in R-positive bands than
in R-negative bands. Our SPRINS banding observations also indicate differences in sequence copy number in the satellites of
homologous acrocentric chromosomes. Furthermore, a comparison of homologous HpaII-SPRINS-banded X chromosomes of females from lymphocyte cultures grown without methotrexate or bromodeoxyuridine revealed
methylation difference between them. The same comparison of homologous X chromosomes from the cell line GM01202D, which has
four X chromosomes, one active and three inactive, revealed the active X chromosome to be hypermethylated.
Received: 5 February 1998; in revised form: 8 May 1998 / Accepted: 11 May 1998 相似文献
13.
The best known and most thoroughly studied epigenetic phenomenon is DNA methylation, which plays an important role in regulating
gene expression during plant regeneration and development. In this study, the methylation-sensitive amplified polymorphism
(MSAP) technique was carried out to determine differences in methylation profiles between two forms of protocorm-like bodies
(PLBs), continuously proliferating PLBs (cPLBs) and spontaneously-differenting PLBs (sdPLBs), derived from cultures of Cymbidium hybridium. A total of 72 selective primer combinations were used to assess the status of cytosine methylation of DNA in these tissues.
Of 4,440 fragments obtained 911 fragments, each representing a recognition site cleaved by one or both of the isoschizomers
( Hpa II and Msp I), were amplified and were significantly different between the two forms of PLBs. Frequency of total and full-methylation
of cPLBs and sdPLBs were 26.7/12.2%, 24.1/11.1%, respectively. In addition, 14 types of MSAP patterns detected in the two
forms of PLBs belonged to two classes, type I and II. Sequencing of 14 differentially methylated fragments and their subsequent
blast search revealed that cytosine methylated 5′-CCGG-3′ sequences were equally distributed in the coding and non-coding
regions. Southern blotting was conducted to verify the methylation polymorphism. 相似文献
14.
We have analyzed DNA methylation of plastid DNA from fully ripened red fruits, green mature fruits, and green leaves of tomato ( Lycopersicon esculentum var. Firstmore). Essentially identical restriction profiles were obtained between chromoplast and chloroplast DNAs by EcoRI digestion. BstNI/ EcoRII and HpaII/ MspI are pairs of isoschizomers that can discriminate between methylated and unmethylated DNAs. These endonucleases produced different restriction patterns of plastid DNAs from tomato fruits compared to tomato leaves. Moreover, we have found from Southern blots that methylation was not detected in DNA fragments containing certain genes that are actively expressed in chromoplasts, whereas DNA fragments bearing genes that are barely transcribed in chromoplasts are methylated. 相似文献
15.
Chromochloris zofingiensis (Dönz) Fucíková & L.A.Lewis, due to its production of highly valuable carotenoids such as astaxanthin, is a model organism in biotechnology. Since the recognition of this physiological property, many biotechnological applications have only used a single strain (SAG 211-14 = CCAP 211/14 = UTEX 32 = ATCC 30412) to produce biomass and carotenoids. However, multiple acquisitions of strains putatively belonging to the same species raised the question of the conspecificity of those strains and their properties. In this study, the conspecificity of the available strains, which are deposited axenically in SAG, was tested using SSU and ITS rDNA sequencing and AFLP (EcoRI/PstI) analyses. The comparison of SSU and ITS rDNA sequences as well as the AFLP patterns revealed that the investigated strains formed two very similar groups, (1) SAG 211-14, SAG 4.80, SAG 31.80, and SAG 34.80 and (2) SAG 221-2. All strains belonged to one species, C. zofingiensis, and represented one monophyletic lineage within the so-called DO-group of the Chlorophyceae. The robustness to cryopreservation and the subsequent epigenetic variability was detected using the methylation-sensitive AFLP (EcoRI/MspI and EcoRI/HpaII) among the five Chromochloris strains. All strains showed a high rate of survival (54.4–98.1%) during cryopreservation. The methylation patterns varied between precryo and postcryo in all strains detected among three time points (before, shortly after, and 8 weeks after cryopreservation), showing that the MS-AFLP technique has the potential to detect epigenetic effects occurring in response to cryopreservation and other stresses. Finally, the potential of these five strains for usage in biotechnological applications was proven by growing them in aerated cultures with and without additional carbon dioxide supply. The comparison showed that all strains produced high amounts of biomass and carotenoids under aeration with additional CO2 and were therefore suitable in biotechnology. 相似文献
16.
While it has become clear that X-inactivation in the female soma is complete in mouse (in contrast to being “patchy” in man), the degree of X-inactivation in the testes has not been ascertained. We have compared autosomal and X-linked zinc finger homolog expression and X-linked and Y-linked zinc finger homolog methylation in an attempt to elucidate this question. Using RTPCR, we have extended earlier studies of Zfx and Zfa expression in developing testes and find that Zfa expression starts at the time of X-inactivation while Zfx expression is continuous. Cell separation studies did not preclude continued expression of Zfx in adult germ cells. The methylation status of four CCGG residues in the Zfx promoter was studied using PCR bridging this region before and after DNA digestion with the isoschizomers Msp I and Hpa II, the latter being methylation sensitive. Hpa II resistant Zfx promoter DNA was found in all female tissues, but not in male tissues, including the testes. Previous studies have shown that Zfy is expressed at meiosis (like Zfa and unlike Zfx). Despite its expression, the Zfy gene is adjacent to, or contains, highly methylated CCGG sites since hybridization after Msp I digestion detected multiple small fragments that were not released after DNA digestion with Hpa II. Thus, Zfx is not methylated in sperm, while Zfy is, in contrast to their apparent patterns of expression. © 1993 Wiley-Liss, Inc. 相似文献
17.
Genetic diversity among 37 isolates of the sorghum anthracnose pathogen Colletotrichum graminicola, from four geographically distinct regions of Brazil, was evaluated by RAPD and RFLP-PCR markers and virulence characters on a set of 10 differential sorghum genotypes. Twenty-two races were identified and race 13B was the most frequent, but present in only two regions. RAPD analysis revealed 143 polymorphic bands that grouped the isolates according to their geographic origin, but not by their virulence phenotypes. RFLP with HaeIII, MspI, HinfI, HhaI, HpaII, EcoRI, HindIII, PstI, RsaI, Taq I, and AluI enzymes over ITS domains and 5.8 rDNA genes of C. graminicola did not show differences among the isolates, indicating high conservation of these restriction sites. Molecular polymorphism was observed among isolates belonging to the same race. No association between virulence phenotypes and molecular profiles was observed. 相似文献
18.
Shoot bud regeneration from Petunia leaf disks was inhibited when they were cultured with the demethylating agents, 5-azacytidine (AzaC) and 5-aza-2′-deoxycytidine
(AzadC), in shoot induction (SI) medium. Explants induced shoot primordia if they were transferred after 1 week from the medium
containing the drugs to medium without drugs. The fresh weight of leaf disks cultured on SI medium for 2 weeks in the presence
of the drugs was 60–80% lower when compared to control shoot-forming cultures. Internode length was reduced when shoots were
transferred to phytohormone-free Murashige and Skoog medium containing the drugs. However, no other morphological abnormalities
were seen in these shoots, even at 20 μ m AzaC or 5 μ m AzadC. Coupled restriction enzyme digestion (with HpaII and MspI) and random amplification of genomic DNA was performed to detect the level of methylation of CCGG sites in the DNA of the
explants exposed to AzaC and AzadC. Over 15 amplified bands were detectable in the control. Five of these bands were absent
in the amplified products when digested DNA from the drug-treated explants was used as the template, showing that hypomethylation
of DNA had occurred. This suggests that inhibition of shoot bud formation in the presence of the drugs AzaC and AzadC may
be due to the altered methylation status.
Received: 7 January 1997 / Revision received: 17 February 1997 / Accepted: 1 March 1997 相似文献
19.
A modification of the amplified fragment length polymorphism technique was developed for the determination of DNA methylation
in dimorphic fungi representative of three of the major fungal taxa: Mucor rouxii, a zygomycete; Yarrowia lipolytica, an ascomycete; and Ustilago maydis, a basidiomycete. DNA obtained from the yeast or mycelial stages of the fungi was digested with a mixture of EcoRI, and one of the isoschizomers MspI and HpaII, whose ability to cleave at the sequence CpCpGpG is affected by the methylation state. The resulting fragments were ligated
to primers and subjected to a double round of amplification by the polymerase chain reaction, radiolabeled in the second round,
and separated by polyacrylamide gel electrophoresis. Comparison of patterns revealed differences indicative of fragments whose
methylation state did or did not change during the dimorphic transition. These results indicate the usefulness of the method
for the study of DNA methylation, demonstrate the universality of DNA methylation in fungi, and confirm that differential
DNA methylation occurs during fungal morphogenesis.
Received: 3 May 1996 / Accepted: 19 September 1996 相似文献
20.
Amplified fragment length polymorphisms (AFLPs) have become important markers for genetic mapping because of their ability
to reliably detect variation at a large number of loci. We report here the dissimilar distribution of two types of AFLP markers
generated using restriction enzymes with varying sensitivities to cytosine methylation in the soybean genome. Initially, AFLP
markers were placed on a scaffold map of 165 RFLP markers mapped in 42 recombinant inbred (F 6:7) lines. These markers were selected from a map of over 500 RFLPs analyzed in 300 recombinant inbred (F 6:7) lines generated by crossing BSR101×PI437.654. The randomness of AFLP marker map position was tested using a Poisson-model
distribution. We found that AFLP markers generated using EcoRI/ MseI deviated significantly from a random distribution, with 34% of the markers displaying dense clustering. In contrast to the
EcoRI/ MseI AFLP markers, PstI/ MseI-generated AFLP markers did not cluster and were under represented in the EcoRI/ MseI marker clusters. The restriction enzyme PstI is notably sensitive to cytosine methylation, and these results suggest that this sensitivity affected the distribution
of the AFLP markers generated using this enzyme in the soybean genome. The common presence of one EcoRI/ MseI AFLP cluster per linkage group and the infrequent presence of markers sensitive to methylation in these clusters are consistent
with the low recombination frequency and the high level of cytosine methylation observed in the heterochromatic regions surrounding
centromeres. Thus, the dense EcoRI/ MseI AFLP marker clusters may be revealing structural features of the soybean genome, including the genetic locations of centromeres.
Received: 5 November 1998 / Accepted: 20 February 1999 相似文献
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