Molecular cytogenetic characterization of four partial wheat-Thinopyrum ponticum amphiploids and their reactions to Fusarium head blight, tan spot, and Stagonospora nodorum blotch

Four wheat (Triticum aestivum L.)-Thinopyrum ponticum derivatives SS5 (PI604926), SS156 (PI604947), SS363 (PI604970), and SS660 (PI604879), were identified as resistant to Fusarium head blight (FHB), a serious fungal disease of wheat worldwide. Seedling reactions to tan spot and Stagonospora nodorum blotch (SNB), two important foliar diseases of wheat, suggest that these four derivatives are resistant to tan spot and two of them (SS5 and SS156) are resistant to SNB. Fluorescent genomic in situ hybridization (FGISH) patterns of mitotic chromosomes indicate that these four derivatives are partial wheat-Th. ponticum amphiploids, each with a total of 56 chromosomes, though with different amounts of Th. ponticum chromatin. These four amphiploids were hybridized with each other to determine homology between the Th. ponticum genomes in each of the amphiploids. Analysis of chromosome pairing in the F₁ hybrids using FGISH suggests that each amphiploid carries a similar set of Th. ponticum chromosomes. These wheat-Th. ponticum amphiploids represent a potential novel source of resistance to FHB, tan spot, and SNB for wheat breeding.