Verification of the identity of the Chinese Spring ditelosomic
stocks Dt7DS and Dt7DL.1
B.R. Friehe*, E.N. Jellen and B.S. Gill
Wheat Genetics Resource Center and Department of Plant Pathology,
Throckmorton Hall, Manhattan, Kansas 66506- 5502, U.S.A.
The 'Chinese Spring'(CS) aneuploid series produced by Dr. E.R. Sears
(1954) is an invaluable tool for allocating genes and markers to
specific chromosomes and chromosome arms. The identity of most of
these lines has been verified by chromosome banding analysis. This
process exposed a discrepancy in the ditelosomic stocks Dt7DS and
Dt7DL.
All lines designated as either Dt7DS or Dt7DL obtained from different
institutions (University of Columbia, Missouri, USA; University of
Riverside, California, USA; Kyoto University, Japan; Plant Breeding
Institute, Cambridge, UK, and Technical University of Munich,
Germany) were identified as Dt7DS. The 7DS arm is homoeologous to 7AS
and 7BS arms, although it is the physically longer arm (Werner et al.
1991). 7DS has two diagnostic C-bands at a telomeric and a
subtelomeric location (Fig. 1, upper arm in
complete chromosome 7D and telosome shown second from left) (Gill et
al. 199 1). In addition, this arm also has an in situ hybridization
(ISH) site with the NOR rDNA probe pTa71, which contains the 18S,
5.8S, and 26S rRNA genes (Fig. 2, telosome on
the right) (Mukai et al. 1991). The C-banding pattern of the 7DL arm
homoeologous to 7AL and 7BL, which is the physically shorter arm, is
different in having one proximal, one interstitial, and one telomeric
C-band (lower arm in complete chromosome 7D and telosome shown third
from left) and also lacks the pTa71 ISH site.
Sears and Sears (1978) sampled 2.000 gametes, but failed to recover
the Dt7DL. The stock labeled Dt7DL was originally isolated by Kerber
in 'Canthach' wheat (see Sears and Sears, 1978) and the 7DS
telosome was transfered to Chinese Spring (Sears, unpublished data).
However, all the CS ditelosomic stocks analyzed by C banding and ISH
analyses had the genetically short arm of chromosome 7D in the form
of a pair of telosomes.
Evidently, the 7DS telosomes are present in the CS double ditelosomic
stock dDt7D, but information on the production of this line is not
available. We are now attempting to isolate the Dt7DL line from the
dDt7D stock.