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Wheat Information
Service
Number 82: 33-35 (1996)
Research Information
Development
of rust resistant wheat lines using Sr31, Lr26 and Yr9
genes
R.N. Brahma, M.Sivasamy and Aloka Saikia
Indian Agricultural Research Institute, Regional Station,
Wellington 643231, Tamil Nadu, India
Presently no wheat varieties released in India is resistant to all
the three rusts of wheat viz, stem (Puccinia graminis f.
sp. tritici. ), leaf (Puccinia recondita f. sp.
tritici.) and stripe (Puccinia striiformis)
under Wellington conditions. Efforts were made to develop wheat
lines with durable resistance suitable for southern hills of India
comprising Nilgiri and Palani hills. Development of a resistant line
to all the three rusts is a hard task particularly in the absence of
durable resistance genes for different rusts and the difficulties in
while incorporating all these components in a single line without
having any adverse effect on yield and quality. Hence, an effort was
made to develop such varieties by crossing wheat cultivars HD 2380
and VL 616 susceptible to all the three rusts with MACS 2496
resistant to stem and stripe rusts.
The cultivars HD 2380 and VL 616 were individually crossed with MACS
2496. The resistant F1
hybrids were
backcrossed to recurrent parents and lines showing resistance to
stem, leaf and stripe rusts were selected and constituted after 3rd
successive backcrosses followed by repeated selfing. The resultant
lines were extensively tested, for five generations, for possession
of resistance to all the three rusts under natural epiphytotic
conditions at Wellington.
The resultant lines showed resistance to stem and stripe rust and
moderately resistance to brown rust (Table
1). The donor
parent MACS 2496 carrying Lr1, Lr23, Lr26, unknown Lr
genes and Sr31 and Yr9 showed high degree of resistance
to stem and stripe rust. The genes, Sr31
and Yr9
offer high degree of resistance against the prevailing races of rusts
in India (Sawhney 1985 ; Gupta 1985). Tomar et al. (1985) reported
the effectiveness of Yr9 against the prevailing races at
Wellington. The variety HD 2380 carries specific genes Lr13,
Lr14a, Lr23 and Sr30 and VL 616 carries Lr14a
and YrA (Sawhney 1994). The resistance to stem and stripe rust
in MACS 2496 is controlled by dominant genes Sr31 and Yr9,
respectively and since all the F1 hybrids showed
resistance to both stem and stripe rusts, it confirms that the
transfer of these genes has occurred. However, the varieties HD 2380,
VL 616 and MACS 2496 were susceptible to leaf rust (Table
1). Surprisingly,
the constituted lines showed the susceptible reaction at seedling
stage while it showed moderately resistance to leaf rust at adult
stage. This may be due to the presence of Lr13, Lr14a and
some unknown genes in HD 2380 and Lr14a
in VL 616 which are known to be associated with adult plant
resistance. Browder (1981) observed that Lr12,
Lr13, Lr14a and Lr22a
are only adult plant resistance genes. Moreover Lr13 is known
to be highly interactive with other genes, and this might have
resulted in the adult plant resistance in the new lines constituted.
Gupta (1985) reported that the gene Lr13 is highly interactive
and it appears that some other unknown gene either alone or in
combination with Lr13 confers adult plant resistance.
Similarly Samborski and Dyck (1982) also observed that Lr13 is
a highly interactive gene and its resistance can be enhanced by
Lr16 in
cultivar Neepawa and Lr30 in cultivar Columbus.
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