Identification of wheat-Secale africanum chromosome 2Rafr introgression lines with novel disease resistance and agronomic characteristics

The wild species, Secale africanum Stapf., serves as a valuable germplasm resource for increasing the diversity of cultivated rye (Secale cereale L.) and providing novel genes for wheat improvement. The objective of this study was to identify new wheat-S. africanum chromosome 2R(afr) derivatives by molecular markers and in situ hybridization, and to test the effects of centric translocations of S. africanum chromosome 2R(afr) on disease resistance and agronomic performance of wheat. The T2R(afr)S.2DL and T2DS.2R(afr)L translocations, and other S. africanum chromosome introgressions such as a 2R(afr) substitution as well as monotelo-2R(afr)S and 2R(afr)L addition lines, were identified by the genomic in situ hybridization and sequential fluorescence in situ hybridization (FISH). Twenty-three molecular markers were localized on chromosome 2R(afr) arms which will facilitate future identification of their introgressions into wheat. A comparison of FISH patterns and the molecular marker distribution between the S. africanum chromosome 2R(afr) and cultivated rye chromosome 2R indicates differentiation between the wild and cultivated Secale genomes. Tests of disease resistance and agronomic performance of wheat-S. africanum chromosome 2R(afr) derivatives indicated that chromosome 2R(afr)L carried gene(s) for dwarfing and stripe rust resistance, while the 2R(afr)S translocation line was the most favorable for agronomic performance when compared with the substitution and 2R(afr)L translocation lines. These results encourage the continued use of novel wheat-S. africanum 2R(afr) derivative lines in wheat improvement.