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1.
Development of AFLP markers in barley 总被引:36,自引:0,他引:36
To investigate the application of amplified fragment length polymorphism (AFLP) markers in barley, 96 primer combinations
were used to generate AFLP patterns with two barley lines, L94 and Vada. With seven primer combinations, only a few intense
bands were obtained, probably derived from repeated sequences. With the majority of the remaining 89 primer combinations,
on average about 120 amplification products were generated, and the polymorphism rate between the two lines was generally
over 18%. Based on the number of amplified products and the polymorphism rate, the 48 best primer combinations were selected
and tested on 16 barley lines, again including L94 and Vada. Using a subset of 24 primer combinations 2188 clearly visible
bands within the range from 80 to 510 bp were generated; 55% of these showed some degree of polymorphism among the 16 lines.
L94 versus Vada showed the highest polymorphism rate (29%) and Proctor versus Nudinka yielded the lowest (12%). The polymorphism
rates per primer combination showed little dependence on the barley lines used. Hence the most efficient and informative primer
combinations identified for a given pair of lines turned out to be highly efficient when applied to others. Generally, more
than 100 common markers (possibly locus specific) among populations or crosses were easily identified by comparing 48 AFLP
profiles of the parent lines. The existence of such a large number of markers common to populations will facilitate the merging
of molecular marker data and other genetic data into one integrated genetic map of barley.
Received: 28 October 1996 / Accepted: 27 November 1996 相似文献
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Polymorphism, distribution, and segregation of AFLP markers in a doubled haploid rice population 总被引:18,自引:0,他引:18
M. Maheswaran P. K. Subudhi S. Nandi J. C. Xu A. Parco D. C. Yang N. Huang 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(1):39-45
We exploited the newly developed amplified fragment length polymorphism (AFLP) technique to study the polymorphism, distribution
and inheritance of AFLP markers with a doubled haploid rice population derived from ‘IR64’/‘Azucena’. Using only 20 pairs
of primer combinations, we detected 945 AFLP bands of which 208 were polymorphic. All 208 AFLP markers were mapped and distributed
over all 12 chromosomes. When these were compared with RFLP markers already mapped in the population, we found the AFLP markers
to be highly polymorphic in rice and to follow Mendelian segregation. As linkage map of rice can be generated rapidly with
AFLP markers they will be very useful for marker-assisted backcrossing.
Received: 11 April 1996 / Accepted: 14 June 1996 相似文献
5.
R. Waugh K. McLean A. J. Flavell S. R. Pearce A. Kumar B. B. T. Thomas W. Powell 《Molecular genetics and genomics : MGG》1997,253(6):687-694
Retrotransposons are present in high copy number in many plant genomes. They show a considerable degree of sequence heterogeneity and insertional polymorphism, both within and between species. We describe here a polymerase chain reaction (PCR)-based method which exploits this polymorphism for the generation of molecular markers in barley. The method produces amplified fragments containing a Bare–1-like retrotransposon long terminal repeat (LTR) sequence at one end and a flanking host restriction site at the other. The level of polymorphism is higher than that revealed by amplified fragment length polymorphism (AFLP) in barley. Segregation data for 55 fragments, which were polymorphic in a doubled haploid barley population, were analysed alongside an existing framework of some 400 other markers. The markers showed a widespread distribution over the seven linkage groups, which is consistent with the distribution of the Bare–1 class of retrotransposons in the barley genome based on in situ hybridisation data. The potential applicability of this method to the mapping of other multicopy sequences in plants is discussed. 相似文献
6.
Wheat telomere-associated sequences (TASs) were cloned using a Vectorette approach and sequenced. Reverse primers specific
to the TASs were combined with labelled degenerate telomere primers in PCR reactions containing total genomic DNA as template.
Amplification products were separated on sequencing gels. In total, seventeen primer combinations provided 47 polymorphic
fragments. Nine of these mapped beyond the most distal RFLP markers and defined the ends of seven chromosome arms. Seven of
the nine terminal fragments were derived from a 118-bp tandem repeat, indicating that subtelomeric tandem repeat sequences
provide an efficient means to target chromosome ends. A telomere cloning strategy and the terminal and interstitial location
of TASs are discussed.
Received: 13 September 1996 / Accepted: 22 January 1997 相似文献
7.
Polymerase chain reaction (PCR) ribotyping of many bacterial species has shown that polymorphism of the ribosomal RNA (rRNA)
operons, within and between strains, is common. Restriction fragment length polymorphism (RFLP) analysis of the rRNA operons
of thirty-two genetically and geographically distinct strains of group A streptococci (GAS) revealed that there are only two
major HaeIII PCR-ribotypes. This variation is due to a single nucleotide change within the 16S–23S intergenic spacer regions of these
operons. As in many other bacterial species, this spacer region in streptococci also contains the gene for tRNAala. Within each GAS isolate, hybridization results are consistent with the presence of six rRNA operons. Interestingly, for
a given strain, irrespective of its origin, all six rRNA operons have the same RFLP pattern. This contrasts with the findings
in many other bacterial species, where heterogeneity of the rRNA operons within a genome is a common feature. This lack of
heterogeneity of rRNA operons in an organism that is known to acquire genetic sequences through horizontal transfer is intriguing.
Received: 22 November 1996 / Accepted: 30 January 1997 相似文献
8.
F. Kevei B. Tóth A. Coenen Z. Hamari J. Varga J. H. Croft 《Molecular & general genetics : MGG》1997,254(4):379-388
Successful intra- and interspecific mitochondrial transfers were performed by polyethylene glycol (PEG)-induced protoplast
fusion among incompatible strains belonging to the Aspergillus niger species aggregate. The mitochondrial DNAs (mtDNAs) of the strains examined were of three main types based on their restriction
fragment length polymorphism (RFLP) profiles. mtDNA types 1 and 2 correspond to A. niger and A. tubingensis species, respectively, while type 3 is represented by some Brazilian wild-type isolates (possibly a distinct species or subspecies).
mtDNA types 1 and 2 could be further divided into several subgroups (1a–1e and 2a–2f ). All these strains, representing different
RFLP groups or subgroups, were fully incompatible with respect to nuclear complementation. The transfer experiments were carried
out under selection pressure, using a mitochondrial oligomycin-resistant mutant of mtDNA type 1a as donor. Following fusion
mitochondrial oligomycin-resistant progenies were recovered in the presence of oligomycin by selecting for the nuclear phenotypes
of the oligomycin-sensitive recipient strains. All attempted transfers were successful, and resulted in different varieties
of resistant recombinant mitochondrial progenies at various frequencies. Within the group of strains of mtDNA type 1, the
transfer of oligomycin-resistant mitochondria resulted in the appearance of a single recombinant type of RFLP profile in each
case. The recombination events were more complex when the transfer of oligomycin resistance occurred between strains representing
different species (mtDNA groups 1a→2 and 1a→3). A great variety of recombinant mtDNA RFLP profiles appeared. Explanation for
this phenomenon are discussed on the basis of preliminary physical mapping data.
Received: 16 July 1996 / Accepted: 2 December 1996 相似文献
9.
The unstable linear chromosome of Streptomyces lividans was circularized by homologous recombination and its terminal inverted repeats deleted. Strains with circularized chromosomes
showed no obvious phenotypic disadvantages compared to the wild type. However, they segregated about 20 times more chloramphenicol-sensitive
mutants than the wild type (24.3% vs. 1.4%), due to a higher incidence of large deletions. In addition, in all circularized
chromosomes amplification of 30–60 kb fragments was observed at the new chromosomal junction, to levels of approximately 10
copies per chromosome. Arginine auxotrophs that arose spontaneously among the progeny of strains with a circularized chromosome
showed high-copy-number amplification of the DNA element AUD1, as also seen in mutants of the wild type. These observations
demonstrate that the circular form of the Streptomyces chromosome is more unstable than the linear one.
Received: 28 July 1996 / Accepted: 18 November 1996 相似文献
10.
C. Gamini Kannangara Ute C. Vothknecht Mats Hansson Diter von Wettstein 《Molecular & general genetics : MGG》1997,254(1):85-92
Magnesium chelatase catalyses the insertion of Mg2+ into protoporphyrin and is found exclusively in organisms which synthesise chlorophyll or bacteriochlorophyll. Soluble protein
preparations containing >10 mg protein/ml, obtained by gentle lysis of barley plastids and Rhodobacter sphaeroplasts, inserted Mg2+ into deuteroporphyrin IX in the presence of ATP at rates of 40 and 8 pmoles/mg protein per min, respectively. With barley
extracts optimal activity was observed with 40 mM Mg2+. The activity was inhibited by micromolar concentrations of chloramphenicol. Mutations in each of three genetic loci, Xantha-f, -g and -h, in barley destroyed the activity. However, Mg-chelatase activity was reconstituted in vitro by combining pairwise the plastid
stroma protein preparations from non-leaky xantha-f, -g and -h mutants. This establishes that, as in Rhodobacter, three proteins are required for the insertion of magnesium into protoporphyrin IX in barley. These three proteins, Xantha-F,
-G and -H, are referred to as Mg-chelatase subunits and they appear to exist separate from each other in vivo. Active preparations
from barley and Rhodobacter yielded pellet and supernatant fractions upon centrifugation for 90 min at 272 000 × g. The pellet and the supernatant were inactive when assayed separately, but when they were combined activity was restored.
Differential distribution of the Mg-chelatase subunits in the fractions was established by in vitro complementation assays
using stroma protein from the xantha-f, -g, and -h mutants. Xantha-G protein was confined to the pellet fraction, while Xantha-H was confined to the supernatant. Reconstitution
assays using purified recombinant BchH, BchI and partially purified BchD revealed that the pellet fraction from Rhodobacter contained the BchD subunit. The pellet fractions from both barley and Rhodobacter contained ribosomes and had an A260:A280 ratio of 1.8. On sucrose density gradients both Xantha-G and BchD subunits migrated with the plastid and bacterial ribosomal
RNA, respectively.
Received: 9 September 1996 / Accepted: 22 October 1996 相似文献