A hexaploid triticale 4D (4B) substitution line confers superior stripe rust resistance

Abstract

Triticale lines tend to become less resistant to stripe rust and other fungal diseases over time and exhibit relatively limited genetic diversity. Therefore, it is important that new triticale varieties with superior agronomic traits are continually produced to enrich the available genetic pool. In this study, a new hexaploid triticale line (K14-827-1), which was derived from the progenies of a wheat–rye–Psathyrostachys huashanica trigeneric hybrid, was identified and analyzed using genomic and fluorescence in situ hybridizations, seed protein profiling, and molecular markers. Meiotic pairing studies suggested that the mean chromosomal configuration of K14-827-1 was 2n = 42 = 0.24 I + 18.23 II (ring) + 2.65 II (rod). The in situ hybridization karyotyping results indicated that K14-827-1 was a 4D (4B) substitution line, consisting of complete R and A genomes and chromosomes 4D, 1B–3B, and 5B–7B. Simple sequence repeat analysis of K14-827-1 confirmed that wheat chromosome 4B had been substituted by chromosome 4D. The seed protein profiling results uncovered polymorphic 75K γ-secalin and low-molecular-weight glutenin subunits between K14 - 827-1 and its recurrent triticale parent (Zhongsi828). Furthermore, the K14-827-1 plants were highly resistant to the stripe rust pathogen (Puccinia striiformis f. sp. tritici) prevalent in China, including race V26/Gui22, than Zhongsi828 plants at the seedling and adult stages. This new hexaploid triticale line may be useful for diversifying triticale germplasms and breeding new varieties with improved forage grass traits.