Mohamed Ibrahim1, Seyedmostafa Mostafa Pirseyedi2, Xiwen Cai3 and G. Francois Marais2, (1)North Dakota State University, Fargo, ND (2)Plant Sciences, North Dakota State University, Fargo, ND (3)department of plant sciences, North Dakota State University, Fargo, ND
Abstract:
Molecular
mapping of three recombined versions of the Lr56/Yr38
translocation in wheat
Mohamed Somo,
Seyed Mostafa Pirseyedi,
Xiwen Cai and Francois Marais
Department of plant
Sciences, North Dakota State University, Fargo, ND 58108.
Leaf
rust (caused by PucciniatriticinaErikss) may inflict significant yield losses in wheat. The
use of resistance genes is the most economical and environmentally friendly way
to combat the disease. A dwindling supply of new and effective resistance genes
from within the primary gene pool of wheat has prompted geneticists to search
for similar genes in the secondary and tertiary gene pools. The linked leaf
rust and stripe rust (caused by PucciniastriiformisWestend) resistance genes Lr56/Yr38 were transferred from Aegilopssharonensis(Hackel) MaireetWeiler to
common wheat chromosome 6A in an earlier study. A fairly big translocation
occurred spontaneously during backcrossing of the primary and secondary hybrids
to wheat. The full length translocation line (0352-4) showed strong
resistance to prevalent isolates of South African, Australian, and Canadian,
leaf and stripe rust races. Due to the size of the alien fragment, the line was
not deployed in breeding programs. Following allosyndetic
pairing induction in the absence of Ph1,
three resistant recombinants with greatly reduced alien chromatin have been
derived (Lr56-39, Lr56-157, and Lr56-175). The alien segments in the three recombinants are thought to be comparatively
small and to occur between Xgwm427
and Xwmc59 on 6AL, yet this has not
been confirmed. The present study employed previously mapped microsatellite
markers and unmapped DArT loci in a continued attempt
to physically map the recombinants and determine which has retained the least
linkage drag. An F2 population for each recombinant is also being
employed to genetically map Lr56 with
the use of single nucleotide polymorphism (SNP) markers. Finally, genomic in
situ hybridization (GISH) is being done in order to confirm and compare the
alien inserts. Eventually, an attempt will be made to construct integrated
linkage and cytogenetic maps for the recombinant chromosomes in order to
determine which will be the most useful for breeding purposes.