Development and characterisation of novel durum wheat 4H chromosome lines as a source for resistance to Septoria tritici blotch.

The use of wild species as a source of genetic variability is a valued tool in the framework of crop breeding. Roem. Schult is a wild barley species that can be a useful genetic donor for sustainable wheat breeding which carries genes conferring resistance to some diseases or increasing grain quality, among others. Septoria tritici blotch (STB), caused by the fungus, is one of the most important wheat diseases worldwide, affecting both bread and durum wheat and having a high economic impact. Resistance to STB has been previously described in chromosome 4H. In this study, we have developed introgression lines for chromosome 4H in durum wheat using interspecific crosses, advanced backcrosses, and consecutive selfing strategies. Alien chromosome segments have been reduced in size by genetic crosses between disomic substitution lines in durum wheat and durum wheat lines carrying the deletion. genetic introgressions were identified in the wheat background through several plant generations by fluorescence hybridisation (FISH) and simple sequence repeat (SSR) markers. An STB infection analysis has also been developed to assess STB resistance to a specific chromosome region. The development of these introgression lines with moderate to high resistance to STB represents an important advance in the framework of durum breeding and can be a valuable tool for plant breeders.