Plant Genome II Conference
Town & Country Conference Center, San Diego, CA, January, 1994.
PG-II: THE ORIGIN OF THE MIDGET CHROMOSOME FROM WITHIN THE RYE GENOME
USING RFLP MARKERS
THE ORIGIN OF THE MIDGET CHROMOSOME FROM WITHIN THE RYE GENOME
USING RFLP MARKERS
Michael Francki, Peter Langridge and Ken Shepherd, Centre for
Cereal Biotechnology, Waite Agricultural Research Institute,
University of Adelaide, Glen Osmond, South Australia, 5062
The diminutive "midget" chromosome is found in lines
containing a wheat genome with a substituted rye cytoplasm. This
cytoplasmic substituted line was the result of successively
backcrossing a wheat/rye amphiploid using wheat as the recurrent
male parent. This small chromosome behaves at meiosis and
mitosis like a normal cereal chromosome and it is assumed to have
all the structural features needed for chromosome function. In
addition, it appears to carry genes that permit compatibility
between the wheat nuclear genome and a rye cytoplasm. Southern
and in situ hybridization data using the rye specific dispersed
repeat, R173 as a probe, indicates that this chromosome
originates from the rye genome. Various group 1 DNA markers were
used to show the origin of the midget chromosome from within the
rye genome. A total of 10 short arm and 36 long arm probes were
used and one matter was identified which hybridizes to the midget
chromosome and maps to the proximal region of the long arm of
chromosome 1R. An additional marker was generated from a
genomic library of the line containing the midget chromosome,
this also maps to the long arm of 1R. Therefore, it appears that
the midget chromosome was generated from the long arm of
chromosome 1R of rye.
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