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91.
92.
Inferences on the genome structure of progenitor maize through comparative analysis of rice, maize and the domesticated panicoids. 总被引:26,自引:0,他引:26
Corn and rice genetic linkage map alignments were extended and refined by the addition of 262 new, reciprocally mapped maize cDNA loci. Twenty chromosomal rearrangements were identified in maize relative to rice and these included telomeric fusions between rice linkage groups, nested insertion of rice linkage groups, intrachromosomal inversions, and a nonreciprocal translocation. Maize genome evolution was inferred relative to other species within the Panicoideae and a progenitor maize genome with eight linkage groups was proposed. Conservation of composite linkage groups indicates that the tetrasomic state arose during maize evolution either from duplication of one progenitor corn genome (autoploidy) or from a cross between species that shared the composite linkages observed in modern maize (alloploidy). New evidence of a quadruplicated homeologous segment on maize chromosomes 2 and 10, and 3 and 4, corresponded to the internally duplicated region on rice chromosomes 11 and 12 and suggested that this duplication in the rice genome predated the divergence of the Panicoideae and Oryzoideae subfamilies. Charting of the macroevolutionary steps leading to the modern maize genome clarifies the interpretation of intercladal comparative maps and facilitates alignments and genomic cross-referencing of genes and phenotypes among grass family members. 相似文献
93.
Positive selection and sequence rearrangements generate extensive polymorphism in the gamete recognition protein bindin 总被引:27,自引:12,他引:15
Bindin is a gamete recognition protein of sea urchins that mediates
species-specific attachment of sperm to an egg-surface receptor during
fertilization. Sequences of bindin from closely related urchins show fixed
species-specific differences. Within species, highly polymorphic bindin
alleles result from point substitution, insertion/deletion, and
recombination. Since speciation, positive selection favoring allelic
variants has generated diversity in bindin polypeptides. Intraspecific
bindin variation can be tolerated by the egg receptor, which suggests
functional parallels between this system and other flexible recognition
systems, including immune recognition. These results show that polymorphism
in mate recognition loci required for rapid evolution of sexual isolation
can arise within natural populations.
相似文献
94.
RFLP mapping of isozymes,RAPD and QTLs for grain shape,brown planthopper resistance in a doubled haploid rice population 总被引:17,自引:0,他引:17
Huang Ning Parco Arnold Mew Teresita Magpantay Gerard McCouch Susan Guiderdoni Emmanuel Xu Jichen Subudhi Prasanta Angeles Enrique R. Khush Gurdev S. 《Molecular breeding : new strategies in plant improvement》1997,3(2):105-113
We have developed an RFLP framework map with 146 RFLP markers based on a doubled haploid population derived from a cross between an indica variety IR64 and a japonica variety Azucena. The population carries 50.2% of IR64 loci and 49.8% of Azucena loci, indicating an equal amount of genetic materials from each parent has been transmitted to the progenies through anther culture. However, some markers show segregation distortion. These distorted marker loci are located on 10 chromosomal segments. Using this map we were able to place 8 isozymes, 14 RAPDs, 12 cloned genes, 1 gene for brown planthopper (BPH) resistance, and 12 QTLs for grain length, grain width and length/width ratio onto rice chromosomes. The major gene for BPH resistance was mapped on chromosome 12 near RG463 and isozyme Sdh-1. Most of the QTLs identified for the three grain characters were closely linked on chromosomes 1, 2, 3 and 10. We concluded that the RFLP framework map presented here will be useful for mapping other genes segregating in this doubled haploid population. Thus rapid generation of doubled haploid lines and their unbiased segregation make it very attractive for gene mapping. 相似文献
95.
S. E. Harrington H. F. J. Bligh W. D. Park C. A. Jones S. R. McCouch 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1997,94(5):564-568
The chromosomal position of Starch Branching Enzyme III (SBEIII) was determined via linkage to RFLP markers on an existing
molecular map of rice (Oryza sativa L.). A cDNA of 890 bp was generated using specific PCR primers designed from available SBEIII sequence data and used as a
probe in Southern analysis. The SBEIII cDNA hybridized to multiple restriction fragments, but these fragments mapped to a
single locus on rice chromosome 2, flanked by CDO718 and RG157. The detection of a multiple-copy hybridization pattern suggested the possibility of a tandemly duplicated gene at this
locus. The map location of orthologous SBE genes in maize, wheat, and oat were predicted based on previously published genetic
studies and comparative maps of the grass family.
Received : 5 August 1996 / Accepted : 13 September 1996 相似文献
96.
The partition matrix: exploring variable phylogenetic signals along nucleotide sequence alignments 总被引:6,自引:2,他引:4
The partition matrix is a graphical tool for comparative analysis of
nucleotide sequences following alignment. It is particularly useful for
investigating the divergent phylogenies of sequence regions undergoing
reticulate evolution. A partition matrix is generated by determining the
consistency of the parsimoniously informative sites in a set of aligned
sequences with the binary partitions inferred from the sequences. Since the
linear order of sites is maintained, the matrix can be used to assess
whether the distribution of sites either supporting or conflicting with
particular partitions changes along the length of the alignment. The
usefulness of the matrix in allowing visual identification of differences
in evolutionary history among regions depends on the order in which
partitions are shown; several suitable ordering schemes are proposed. We
demonstrate the use of the partition matrix in interpreting the evolution
of the pseudoautosomal boundary region on the sex chromosome of catarrhine
primates. Its routine use should help to avoid attempts to derive single
phylogenies from sequences whose evolution has been reticulate and to
identify the gene conversion or recombination events underlying the
reticulation. The method is relatively fast. It is exploratory, and it can
form the basis for more formal analysis, which we discuss.
相似文献
97.
An improved protocol for non-radioactive labelling and detection of rice and tomato DNA is described. The procedure includes
the use of polymerase chain reaction for the incorporation of digoxigenin-dUTP in the DNA molecule and the use of a chemiluminescent
compound (AMPPD) for the signal detection. 相似文献
98.
Mapping and genome organization of microsatellite sequences in rice (Oryza sativa L.) 总被引:38,自引:15,他引:23
S. Temnykh William D. Park Nicola Ayres Sam Cartinhour N. Hauck L. Lipovich Y. G. Cho T. Ishii S. R. McCouch 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,100(5):697-712
In order to enhance the resolution of an existing genetic map of rice, and to obtain a comprehensive picture of marker utility
and genomic distribution of microsatellites in this important grain species, rice DNA sequences containing simple sequence
repeats (SSRs) were extracted from several small-insert genomic libraries and from the database. One hundred and eighty eight
new microsatellite markers were developed and evaluated for allelic diversity. The new simple sequence length polymorphisms
(SSLPs) were incorporated into the existing map previously containing 124 SSR loci. The 312 microsatellite markers reported
here provide whole-genome coverage with an average density of one SSLP per 6 cM. In this study, 26 SSLP markers were identified
in published sequences of known genes, 65 were developed based on partial cDNA sequences available in GenBank, and 97 were
isolated from genomic libraries. Microsatellite markers with different SSR motifs are relatively uniformly distributed along
rice chromosomes regardless of whether they were derived from genomic clones or cDNA sequences. However, the distribution
of polymorphism detected by these markers varies between different regions of the genome.
Received: 5 May 1999 / Accepted: 16 August 1999 相似文献
99.
100.
Simple sequence length polymorphism analysis was carried out to reveal microsatellite variation and to clarify the phylogenetic relationships among A-genome species of rice. Total DNA from 29 cultivars (23 Oryza sativa and 6 O. glaberrima) and 30 accessions of wild A-genome species (12 O. rufipogon, 5 O. glumaepatula, 2 O. longistaminata, 6 O. meridionalis, and 5 O. barthii) was used as a template for PCR to detect 24 nuclear and 10 chloroplast microsatellite loci. Microsatellite allelic diversity was examined based on amplified banding patterns. Microsatellites amplified clearly in all 59 accessions, with an average of 18.4 alleles per locus. The polymorphism information content (PIC) value ranged from 0.85 to 0.94, with an average of 0.89. At the species level, high average PIC values were observed in O. sativa (0.79) and O. rufipogon (0.80). For chloroplast microsatellites, the average number of alleles per locus and the average PIC value were 2.9 and 0.38, respectively. While the magnitude of diversity was much greater for nuclear microsatellites than for chloroplast microsatellites, they showed parallel patterns of differentiation for each taxonomic group. Using the ratio of common alleles (estimated as size of amplified fragments) as a similarity index, the average percentages of common microsatellite alleles were calculated between taxa. For both nuclear and chloroplast microsatellites, O. sativa showed the highest similarity values to O. rufipogon, and O. glaberrima was most similar to O. barthii. These data support previous evidence that these cultivars originated from the corresponding wild ancestral species. 相似文献