A stable, highly fertile wheat Secale africanum substitution line LF24, derived from the F₇ generation of a cross between Mianyang11 (MY11) and Triticum durum, S. africanum amphiploid (YF) was identified through molecular cytogenetic analysis. Application of C-banding, in situ hybridization and molecular markers analysis showed that LF24 was a wheat S. africanum 2R^a(2D) substitution line. When inoculated with stripe rust isolates, T. durum and MY11 were highly susceptible, while S. africanum, YF and LF24 were immune. It is confirmed through molecular cytogenetic analysis that the stripe rust resistance of LF24 was derived from S. africanum chromosome 2R^a. We compared the banding patterns and disease resistance of reported chromosomes 2R from different S. cereale introduced into wheat background, and found that there was new stripe rust resistance gene(s) on S. africanum 2R^a. LF24 is a new substitution line which can be used as stripe rust resistant source in wheat improvement.

Although the unique properties of wheat 𝛼-gliadin gene family are well characterized, little is known about the evolution and genomic divergence of 𝛼-gliadin gene family within the Triticeae. We isolated a total of 203 𝛼-gliadin gene sequences from 11 representative diploid and polyploid Triticeae species, and found 108 sequences putatively functional. Our results indicate that 𝛼-gliadin genes may have possibly originated from wild Secale species, where the sequences contain the shortest repetitive domains and display minimum variation. A miniature inverted-repeat transposable element insertion is reported for the first time in 𝛼-gliadin gene sequence of Thinopyrum intermedium in this study, indicating that the transposable element might have contributed to the diversification of 𝛼-gliadin genes family among Triticeae genomes. The phylogenetic analyses revealed that the 𝛼-gliadin gene sequences of Dasypyrum, Australopyrum, Lophopyrum, Eremopyrum and Pseudoroengeria species have amplified several times. A search for four typical toxic epitopes for celiac disease within the Triticeae 𝛼-gliadin gene sequences showed that the 𝛼-gliadins of wild Secale, Australopyrum and Agropyron genomes lack all four epitopes, while other Triticeae species have accumulated these epitopes, suggesting that the evolution of these toxic epitopes sequences occurred during the course of speciation, domestication or polyploidization of Triticeae.