None of the Sr genes provide resistance to all races of stem rust. For instance many of them are ineffective against the Ug99 lineage. Notably Ug99 has virulence against "Sr31", which was effective against all previous stem rust races. Recently, a new stem rust resistance gene "Sr59" from "Secale cereale" was introgressed into wheat, which provides an additional asset for wheat improvement to mitigate yield losses caused by stem rust. Singh et al. (2011) provide a list of known Sr genes and their effectiveness against Ug99.