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A Genomic Comparison of Homoeologous Recombinants of the Lr19 (T4) Translocation in Wheat

Mohamed Somo, Shiaoman Chao, Maricelis Acevedo, Jason Zurn, Xiwen Cai, Francois Marais
Crop science 2014 v.54 no.2 pp. 565-575
Puccinia recondita, Triticum aestivum, chromosome translocation, endosperm, fluorescence, genes, in situ hybridization, loci, microsatellite repeats, mutants, pigmentation, single nucleotide polymorphism, wheat
The Lr19 translocation continues to provide broad resistance to Puccinia triticina in many parts of the world and can be particularly useful in resistance gene pyramids. Previously, an associated gene for yellow endosperm pigmentation precluded its use in many countries, and as a result, allosyndetic recombinants and mutants lacking the pigmentation genes have been developed. Such a primary white endosperm recombinant (Lr19-149) and four secondary recombinants (Lr19-149–252, −299, −462, and −478) were obtained in earlier studies. This study characterized the translocations making use of fluorescence genomic in situ hybridization (FGISH), simple sequence repeat (SSR), sequence tagged site (STS), and single nucleotide polymorphism (SNP) markers. The recombined segments were shown to be intercalary inserts of different size and were mapped to the most distal 7BL deletion bin. In addition to a previously reported duplication that involves the Wsp-1 locus, primary recombinant −149 also has a deletion of the PSY-1 containing region. These apparently small aberrations have been retained in three of the secondary recombinants that resulted from single, proximal crossovers. The fourth secondary recombinant (−478) resulted from a distal crossover that apparently restored a normal wheat telomeric region with single copies of the Wsp-B1 and PSY-B1 loci and appears to be the most useful.