Plant Genome I Conference
Town & Country Conference Center, San Diego, CA, November, 1992.
PG-I: 31pg1
DEVELOPMENT OF GENOME REGION-SPECIFIC LIBRARIES FOR MAPPING IN
CEREALS.
D.E. Delaney, S.H. Hulbert and B.S. Gill, Department of Plant
Pathology, Kansas State University, Manhattan, KS 66506.
The development of techniques to generate high density maps
in specific areas of the genome will make the construction of
localized maps feasible for individual investigators, and is a
necessary first step for map-based cloning efforts. The
polyploid nature of the wheat genome and its ability to tolerate
varying amounts of alien chromatin make it an excellent organism
for use in construction of specialized libraries. Our particular
interest is in developing an RFLP map for chromosome arm 6RL of
rye which carries a gene for resistance to Hessian fly larvae.
The approach we have taken is to screen a cosmid library of a
wheat ditelo-6RL addition line (insert size 20-40kb) with several
rye specific repetitive sequences, to isolate those clones
carrying rye chromatin. Cosmids having inserts from 6RL are then
evaluated further for the presence of low copy fragments which
can be used in mapping experiments. The rye repetitive sequences
were selected for high specificity to rye and for lack of
homology to any telomeric sequences which would be less likely to
be in close association with genes. We are currently evaluating
which of our rye-specific repetitive sequences is most frequently
interspersed with low copy sequences, and is thus most useful for
identifying mapping clones. To date we have isolated two low
copy sequences with one of our repetitive clones, both of which
map to 6RL. By using these low copy sequences as probes on
Southern blots containing DNA from a series of wheat-6RL
translocation lines we can obtain a rough estimate of the
physical location of each RFLP marker and its proximity to the
Hessian fly resistance locus. These data will later be confirmed
by recombinational data from mapping populations.
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