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Wheat Information
Service
Number 72: 67-69 (1991)
RFLP
analysis of common wheat and its ancestors
Koichiro Tsunewaki
Laboratory of Genetics, Faculty of Agriculture, Kyoto
University
This paper reviews the results of the works on restriction fragment
length polymorphism (RFLP) analysis of common wheat and its
ancestors, which have been carried out last few years in our
laboratory.
(1) Genomic DNA library construction and characterization of the
clones (Liu et al 1990):
We constructed the EcoRI, HindIII and PstI
fragment libraries of the genomic DNA of Chinese Spring wheat (CS).
In all cases, fragments of 0.5 - 2.0 kbp in size were cloned using a
vector pUC119. Numbers of the clones obtained were 143, 180 and 323
for the EcoRI, HindIII and PstI fragments,
respectively. Copy number per haploid nucleus was estimated for the
EcoRI and HindIII fragment clones, of which 49%,
31%,14% and 6% were estimated to be ca. 101,
102, 103 and 104 copies,
respectively. The fragments of the first class were considered the
unique sequence, and used in the foregoing RFLP analysis.
(2) Genetic mapping of the RFLP sites by linkage analysis and
nullitetrasomic analysis (Liu 199l):
As is described in the next section, CS showed the largest RFLP to
Triticum spelta var. duhamelianum (Spelta) among other
seven common wheats tested. Based on this,F2 hybrids were
produced from a cross between these two wheats, and the nuclear DNAs
extracted from the bulked F3 seedlings from each of 66
F2 Plants were subjected to the linkage analysis of RFLP
sites, using the unique sequence clones as probes. In total 197 RFLP
loci were detected between the two parents, and their linkage
relationships were analyzed. These loci and the Q locus were
grouped into 31 linkage groups, with 10 solitary loci.
All but 20 loci showed normal Mendelian segregation. Of the 20
exceptional loci, seven showed preferential transmission of the
Spelta alleles, and another seven showed preferential transmission of
the CS alleles, the remaining six showed abundance (four loci) or
shortage (two loci) of the heterozygote. A few representative loci of
each linkage group and all solitary loci were subjected to the
nullitetrasomic analysis, and they were successfully assigned to
either of the 21 wheat chromosomes. In addition, 226 non-RFLP loci
were located to the individual chromosomes. Thus, 424 loci in total
were allocated to the 21 chromosomes. The present tatal map size
amounts to 1835 cM. Number of RFLP loci located in the D genome was
28, that was much smaller than those allocated in the A and B
genomes, which were 71 and 97, respectively. On the contrary, number
of non-RFLP loci located in the A, B and D genomes was 61, 78 and 85,
respectively, which did not differ significantly among the three
genomes. Apparently, the degree of RFLP between the D genomes of CS
and Spelta was extremely low, comparing to those between their A or B
genomes.
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