Alien Introgression in Wheat Cytogenetics, Molecular Biology, and Genomics

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8.2.2 Disease Resistance

8.2.2.1 Stem Rust Resistance

The fi rst recorded introgression of stem rust resistance from an emmer to hexaploid
wheat took place over 80 years ago (McFadden 1930 ). This source of resistance has
been exploited regularly ever since. Sr2 is a resistance gene that was introgressed
from “Yaroslav” emmer into cultivars Hope and H44-24. It is effective against race
TTKSK. It is carried by cultivars such as Selkirk, Redman, and Renown. Seven
alleles are known for Sr9 , located in chromosome 2B, as shown in Table 8.3. This
gene is not effective against TTKSK. Sr9d and 9e are not effective against race
15B, whereas Sr9g is a useful gene. The genes Sr11 , Sr12 , and Sr17 have been
widely used and deployed, whereas Sr13 and Sr14 are potentially useful and have
not been deployed extensively as yet. 359 accessions of [ T. turgidum l. subsp.
dicoccum (Shrank) Thell] were evaluated for resistance to race TTKSK (Ug99) of
stem rust (Oliver et al. 2011 ). It was found that 31.8 % of accessions were resistant
at the seedling stage. Genetic studies on fi ve accessions indicated that resistance
was controlled by single genes. Resistance to TTTTF was also identifi ed in some

Table 8.3 Sources of stem rust resistance in emmer wheat

Gene Source

Chromosome

location Reference

Sr2 T. turgidum var dicoccoides cv.

Yaroslav

3BS McFadden ( 1930 )

Sr9 T. dicoccum (7 alleles are known) 2B Knott and Anderson

( 1956 )

Sr9a Frontiere Green et al. ( 1960 )

Sr9b Kenyan wheat Green et al. ( 1960 )

Sr9d ( Sr1 ) T. turgidum cv. Yaroslav McFadden ( 1930 )

Sr9e ( SrV ) T. turgidum cv. Bernalemmer McIntosh and Luig

( 1973 )

Sr9f T. turgidum var. durum Loegering ( 1975 )

Sr9g T. turgidum var. durum McIntosh and Luig

( 1973 )

Sr11 ( Kc2 ) T. turgidum var. durum cv. Gaza 6B Knott and Anderson

( 1956 )

Sr12 T. turgidum var. durum cv. Iumillo 3B Sheen and Snyder

( 1964 )

Sr13 T. turgidum var. dicoccum cv.

Khapli

6AL Knott ( 1962 )

Sr14 T. turgidum var. dicoccum cv.

Khapli

1BL Knott ( 1962 )

Sr17 T. turgidum var. dicoccum cv.

Yaroslav

7BL McIntosh ( 1988 )

Srdp2 T. turgidum 6AS Rondon et al. ( 1966 )
Note : of the above genes, only Sr2 and Sr14 are effective against Ug99

8 Alien Introgressions from wild Tr it icu m species, T. monococcum...