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Hybrids between diploid,
tetraploid wheat and D. villosum have been readily achieved in
a range of crossable rates (see review of von Bothmer and Claesson
1990). However, direct hybridization of hexaploid wheat with D.
villosum has been more difficult. Successful crosses have been
obtained, but usually with an extremely low percentage of seed set
(Chen and Liu 1982; Jan et al. 1986; von Bothmer and Claesson 1990).
Despite most of the possible chromosome addition lines of D.
villosum to hexaplold wheat, T. aestivum L.cv. Chinese
Spring, have been produced by a species-bridging method (Sears 1953;
Hyde 1953), the direct cross between hexaploid wheat and
D.
villosum
is beneficial to study the evolutionary and homoeologous
relationships of the genus Dasypyrum with hexaploid
Triticum, because of the Dasypyrum chromosomes in a pure
hexaploid wheat background, while the addition lines achieved by a
species-bridging procedure may contain either the genes or
chromosomes of the bridging species. In this paper we report the
results of an attempt to make cross between hexaploid wheat and
D. villosum.
Materials and
methods
Triticum aestivum L. cv. Chinese Spring, monosomics of
Chinese Spring and Dasypyrum villosum (L.) Candargy from E. R.
Sears were employed in the present study. All materials were grown in
the field at Sichuan Agricultural University, Yaan city, Sicuan
province, China. Dasypyrum villosum was planted normally at
beginning of November in 1993. It is necessary that Chinese Spring
and all its monosomics were sowed after a month to meet the flowering
with D. villosum.
Chinese Spring and its monosomics, except the monosomics of 2D and
7B, were crossed as female with D. villosum. The Chinese
Spring monosomic parents were selected from the selfed progenies of
monosomic plants by means of root-tip mitosis analyses. No special
aids and techniques were adopted in those crosses except to put newly
mature anthers on just maternal stigma in profuse quantities.
Well-developed caryopses were harvested after a month of pollination.
Identifications of hybrid plants were carried out by the mitosis
analyses. In the meanwhile, we examined whether the embryos were
present for the nongerminating seeds or not Thus the crossable
percentage of this cross was estimated as the ratio of number of
seeds with embryo to the number of pollinated florets. A Student's
statistical t-test was applied to detect the crossability difference
between a monosomics of Chinese Spring wheat and the control (normal
Chinese Spring). The results of crossabilities of Chinese Spring
wheat with D. villosum in two years were also used to control
the crossable reliability.
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