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There was low meiotic
pairing in both the crosses (Table
2) with only rod
bivalents and no ring
bivalents or
multivalents except that one trivalent was observed in the cross
WL711 x Ae. triuncialis (Fig.1).
In the previous studies also (Bochev and Ganeva 1981, Abu Bakar and
Kimber 1982, Claesson et al 1990) only rod bivalents were observed
though ring bivalents and multivalents were observed in very low
frequency. In the present study, the average number of bivalents was
1.53 in the cross T. aestivum x Ae. triuncialis.
However, the average frequency of rod bivalents was 5.21 in the study
by Claesson et al (1990) whereas it ranged from 1.87 to 5.06 in the
study by Bochev and Ganeva (1981). According to Claesson et al.
(1990) higher frequency of pairing in some studies may be attributed
to the presence of pairing promotors or genes suppressing the
Ph gene in wrne of the populations of Ae.
triuncialis. The average number of rod bivalents in the cross
T. aestivum x Ae. ovata was 0.51 only. The results are
comparable with that of Abu Bakar and Kimber (1982), McGuire and
Dvorak (1982) and Claesson et al (1990). The low pairing may indicate
that the Ph gene is not suppressed by Ae. ovata
genomes.
The low homoeologous pairing in the two crosses shows that the
chances of transfer of leaf rust resistance to T. aestivum
are low. Since the genes suppressing Ph gene are absent in
the two donor species, there is need to use a system to induce
homoeologous pairing to facilitate transfer of rust resistance from
these accessions. Keeping this in view, monosomic 5B plants of
T. aestivum cv. Chinese Spring have been crossed
with rust resistant accessions of the two Aegilops
species.
Acknowledgement
This research has been financed in part by the United States
Department of Agriculture under US India fund (Grant No. FG-IN-739
Project No. IN-ARS-639)
References
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