الفهرس 
Stem rust pathogen and disease cycleOnly 14 pages are availabe for public view
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Abstract
This study was carried out in the research farm and the laboratory
of the Wheat Research Department, Field Crops Research Institute,
Agricultural Research Center, Giza, Egypt and laboratories of (INRA)
Rabat, Morocco during the period from 2010 to 2014.
The main findings can be summarized as follows:
1. Three bread wheat (Triticum aestivum L.) varieties namely; Misr1
(stem rust resistant parent) as well as Line37 and Line92 (stem rust
susceptible parents) were chosen from a stem rust resistance screening
trial comprising twelve bread wheat varieties according to their
performances under stem rust condition.
2. The grains of the three selected varieties (Misr1, Line 37 and Line 92)
were grown in the field and crossed (Misr1 x line 37, Misr1 x Line 92
and line 37 x line 92) to obtain the F
1
grains for these three crosses.
Some of the F1
grains for each cross were sown in the field and selfed
to obtain the F
2 grains. The three parents and the F
1
grains for the
three crosses were grown in three replicates in a completely
randomized design experiment under the optimum planting date
(normal condition) and late planting date (infected condition). A 200
F2
grains were also grown under only the late planting date (infection
condition). The data were recorded for all plants (parents, F
1 and F
2
plants) after harvest for the following traits which related to stem rust
resistance: Plant height (cm), spike length (cm), number of
spikelets/spike, number of spikes/plant and grain yield/plant (g), rust
reaction, days to heading and days to maturity for the three parents
and their F
1
plants.
3. The F
2
plants which represented by 200 plants for each cross were
classified according to their behavior under infected condition.
According to their performances under rust infection and grain yield
traits for each F
2 individual plants, eight resistant F
2
individual plants and eight susceptible F
2
individual plants for Misr1 X Line37 hybrid,
seven resistant F
2
individual plants and five susceptible F
2
individual
plants for Misr1 X Line92 hybrid and seven resistant F
2
individual
plants and eight susceptible F
2
individual plants for Line37 X Line92
hybrid were chosen for further molecular analysis with their three
parents and F
1
plants.
4. SSR & STS-PCR technique for the F2
resistant and susceptible plants
for each cross as individual plants, the three contrasting parents and
their F
1
plants were used to obtain molecular markers associated with
stem rust.
5. Two primers (Sr2 and Sr25) only detected positive markers for stem
rust with the studied genotypes in (crosses 1 and 2). Sr2 primer
exhibited two positive molecular markers with molecular size of 120
bp which were found only in the resistant parent (Misr1), the F1
plants
and the most resistant F
2
individual plants, while they were absent in
Line37 for cross 1 and Line92 for cross 2 (susceptible parent) and the
most susceptible F2
individual plants (five plants for cross 1 and three
plants for cross 2). and Sr25 primer showed two positive molecular
markers with molecular size of 130 bp which were found only in the
resistant parent (Misr1), the F
1 plants and the most resistant F
2
individual plants, while they were absent in the Line37 for cross 1 and
Line92 for cross 2 (susceptible parent) and the most susceptible F
2
individual plants (six plants for cross 1 and three plants for cross 2).
Sr 36 and Sr 39 genes were absent in all genotypes for the three
crosses under study, however Sr24 was found in all genotypes for the
three crosses.
These four positive markers could be considered as reliable
markers for stem rust resistance in bread wheat. These results agreed with
many reports detected molecular markers for biotic stresses resistance.