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Spetsov et al. (1997) implied that two of the three HMW subunits of
Ae. variabilis were expressed in the wheat- Ae.
variabilis disomic addition and substitution lines. However, in
the wheat-Ae. kotschyi substitution lines, Spetsov et al.
(1998) found that only one of the three HMW subunits were expressed
and a new band from Ae. kotschyiwas produced. The present
study also showed that a HMW subunit gene modified its expression in
the amphiploid background. Therefore, it is supposed that the
variation of genetic expression of HMW subunits of Aegilops in
wheat background may be caused by gene recombination between the
closely homologous chromatins between wheat and Aegilops.
Recently, Wan et al. (2000) stated that some HMW-GS of several
Aegilops species exhibit subunits closely or distantly related
to wheat. It is possible that we can use the wheat- Aegilops
amphiploid to create new glutenin gene recombination between wheat
and Aegilops. Moreover, gliadin structural genes from Ae.
variabilis were also quite different from those of wheat. The
relationship of the gliadin and glutenin introduced from
Aegilops to wheat background for improving wheat quality is
worth exploring further.
Disease resistance survey: Resistance investigation of the amphiploid
were conducted with references to its parents when inoculated by
powdery mildew isolates and stripe rust races. Ae. variabilis
showed high resistance to these tested isolates in seedling and
adults plant, respectively. Whereas the wheat parent J-11ph1b
was highly susceptible, the amphiploid plant with 2n=70
displayed high resistance to powdery mildew and intermediate
resistance to stripe rust. These results indicated that powdery
mildew resistance from Ae. variabilis was expressed easier
than stripe rust resistance in the amphiploid.
The present study suggested that the amphiploid can serve as a donor
to transfer the disease resistance from Ae. variabilis to
wheat breeding. When examining the hybrids of wheat and other
Aegilops species, we found that about half of them did not
express the stripe rust resistance from Aegilops accession
(Yang and Liu in press). It seems that the expression of resistance
from Ae. variabilis in the wheat background was independent of
the specific wheat genotype or genomic interaction of both
parents.
Several plants were recovered from wheat-Ae. variabilis
amphiploid backcrossed with common wheat. It is expected that some of
the spontaneous translocation between wheat and Aegilops would
be produced following the effects of ph1b gene
existed in the amphiploid and the resulting generation. On the basis
of present data, the morphological, cytological and biochemical
results are beneficial to trace the Ae. variabilis chromatin
for transferring the novel resistance to powdery mildew and stripe
rust to wheat background.
Acknowledgments
The authors are thankful to the National Natural Science
Foundation of China, and the Science and Technology Committee of
Sichuan Province, China for their financial support. We particularly
thank Dr. D. C. Liu and Mr. M, W. Wiggs for reviewing the
manuscript.
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