الفهرس 
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Abstract
This study was carried out at the Faculty of Agriculture, Ain
shams University and the Environmental Stress Laboratory (ESL) at
Agriculture Genetic Engineering Research Institute (AGERI),
Agriculture Research Center (ARC), Giza, Egypt, during the period
from 2010 to 2016. It aimed to investigate the Egyptian cultivars for the
presence of Sr genes and their effectiveness against stem rust; especially
aganist Ug99 and its variants. Simple Sequence Repeats (SSR) was
used to screen the presence of stem rust resistance genes Sr2, Sr22,
Sr24, Sr26, Sr33, Sr35, Sr36 and Sr40 into Misr1, Misr2, Gemeza 10,
Gemeza 11, Sids 1, Sids 12, Sids 13, Skha 93, CYMITT, Sahel1,
Gemeza9, Gemeza7, and G168.
This goal was achieved by using the specific molecular markers
gwwm533, cfa2019, barc71, Sr26#43, abc156, cfa2193, gwm319,
wmc477 and wmc661.
Further detection for the Sr35 gene was carried out as it is a
highly effective wide-resistance range gene. Using specific primers the
Sr35 was found in three cultivars Misr1, Misr2 and Gemiza10, the last
was not exhibited by the SSR markers.
Artificial infection was performed to evaluate the gene
expression using real-time PCR and the results showed that Gemiza10
has the highest Sr35 expression against infection followed by Misr1.
The main results could be summarized as follows:
1. Sr2 was present in all the studied cultivars except for Misr1,
Misr2 and Giza 168
2. None of the studied cultivars showed the presence of Sr22
3. Sr24 existed in the studied cultivars except for Sakha93,
Gemiza7 and Giza 168.
4. None of the studied cultivars carried the Sr26 gene.5. Only Misr1 indicated the occurrence of Sr33 presence
6. Misr1 and Misr2 showed the presence of the sr35 gene.
7. Sr36 was present in all the studied cultivars.
8. Only the CYMITT line showed the presence of Sr40 gene.
9. The detection of Sr35 in the genomic background of the
studied cultivars showed its occurrence in Misr1, Misr2 and
Gemiza10 which mean that the molecular marker alone may
not be good enough and it may be preferable to use a
functional marker instead
10. The Sr35 expression increased by the infection in Gemiza 10
and Misr1 respectively more than in Misr2.
11. Most Egyptian cultivars have pyramided Sr genes. Misr1
and CYMMITT have four Sr genes, Gemiza7 and Sk93 have
two Sr genes, while the rest have three Sr genes except G168
which has only one Sr gene.
12. The Egyptian cultivars depend mainly on three Sr genes; Sr2
which is a source of broad-spectrum resistance, however, it
is affected by environmental conditions and genetic
background, also it is expressed only in the adult stage
providing insufficient protection, so it must be pyramided
with other Srs. Then, Sr24 gene resistant to the Ug99 race
but it is not effective against more recent races variant
(TTKST). Finally, Sr36 which is common in all Egyptian
cultivars, this gene confers resistance against Ug99 but it is
not effective against the other race variant TTTSK.
13. Sr22 and Sr26 are effective genes for stem rust resistance
against Ug99, but they cause yield penalty, both genes don’t
exist in the Egyptian cultivars.
14. Sr35 is an effective stem rust resistance gene against Ug99
and its variants and the races TRTTF and RKQQC. This
gene exists in three cultivars; Misr1, Misr2 and Gemiza10.
Expression analysis study of this gene in the three cultivarsusing semi-quantitative RT-PCR and real-time PCR showed
that Gemiza10 has the highest expression level in response
to stem rust infection followed by Misr1. Misr2 showed the
lowest expression level of Sr35 although it is a resistant
cultivar.
15. Sr35 gene is recommended to be transferred to Egyptian
cultivars through molecular marker back crossing to provide
protection against Ug99, and this transferring should be
followed by expression study to insure its expression levels
in the recipient cultivars.