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Wheat Information
Service
Number 76: 23-26 (1993)
Rust
resistance and chromosome pairing in Triticum x
Aegilops crosses
Harjit Singh, H.S.Dhaliwal, Jaswinder Kaur and K.S.Gill
Biotechnlogy Centre, Punjab Agricultural University, Ludhiana 141
004, India
The wild relatives of wheat have served as a good source of
resistance to wheat rusts (Sharma and Gill 1983, Knott 1989). It has
been observed that Aegilops species with C, U and M genomes
are a good source of resistance to leaf and stripe rusts (Dhaliwal et
al 1991). Keeping this in view, leaf rust resistant accessions of
Aegilops triuncialis (UC) and Ae. ovata (UM) were crossed
with a hexaploid spring wheat cultivar WL711. The transfer of
desirable characters from the donor species depends upon the extent
of homoeologous chromosome pairing between the genomes of two
species. This article reports the rust resistance and meiotic
chromosome pairing in two intergeneric crosses.
Triticum aestivum cv. WL711 (a widely adapted and
agronomically superior Indian spring wheat cultivar) was crossed as
female with Ae. triuncialis (Acc No. 3549) and Ae.
ovata (Acc No. 3547) during 1990-91. The rust reactions of the
parents are given in Table1.
The F1's of the two crosses were planted at
Ludhiana in October 1991. The spikes of hybrid plants were fixed in
6:3:1, Carnoy's solution, for analysis of meiosis. The spikes were
removed to 70% ethanol and the anthers were dissected and squashed in
acetocarmine. Meiotic metaphase of more than 50 PMC's were scored for
chromosome pairing in each cross.
The number of florets pollinated for the two crosses WL711 x Ae.
triuncialis and WL711
x Ae. ovata
were 40 and 100, respectively, and the per cent seed set 25 and 9,
respectively. Ozgen (1983) found 32% crossability in the cross
T. aestivum
x Ae.
triuncialis and Claesson et al. (1990) obtained 2% seed set in a
T. aestivum x
Ae. ovata
cross. However, Claesson et al. (1990) observed much higher
crossability with Ae. triuncialis (67%) and Ae. ovata
(40%) when T. aestivum was used as male parent rather
than the female parent.
The percentage germination of the crossed seeds for the crosses with
Ae. triuncialis and Ae. ovata was 50.0 and 44.4,
respectively. Ozgen (1983) had obtained 26.8 to 100 percent
germination in the crosses of seven Aegilops species with
T. aestivum. The hybrid plants of both the intergeneric
crosses were free from leaf rust whereas leaf rust score was 90S on
the hexaploid parent WL711 ( Table1).
This indicated that the leaf rust resistance gene(s) from both the
Aegilops species were dominant in the WL711 background. The
accessions of Ae. triuncialis and Ae. ovata used in the
intergeneric crosses were susceptible to the M race of yellow rust (
Table1).
These lines were also susceptible to yellow rust under field
conditions at Gurdaspur. However, F1 hybrid of WL711 x
Ae. ovata (Acc. 3547) was resistant to yellow rust. The hybrid
plants of both the crosses were completely male and highly female
sterile. The pollination of 50 spikes of each cross with pollen from
WL711, however, gave 11 backcross seeds in the cross WL711
x
Ae.
triuncialis and 12 seeds in the cross WL711
x Ae.
ovata.
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