Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/16/1995
Publication Date: N/A
Technical Abstract: Bread wheat cultivar 'Thatcher' has been documented to carry only one of the designated genes for leaf rust resistance, namely, Lr22b. The latter is expressed only in the adult plants and 'Thatcher' is considered as "universal suscept" in the seedling stage to leaf rust of wheat. However, 'Thatcher' was recently shown to be seedling resistant to many isolates from durum wheat leaf rust collections from Ethiopia. It may be noted that 'Thatcher' was developed from an interspecific double cross involving one between two bread wheats 'Marquis' and 'Kanred', and the other between 'Marquis' and 'Iumillo' durum wheat. It was not clear if this seedling resistance in 'Thatcher' was derived from its durum parent or from one of the bread wheats involved in its parentage. Our seedling tests with a number of isolates indicate that the source of above seedling resistance in 'Thatcher' is probably 'Kanred'. The low infection types (ITs) on 'Thatcher' and 'Kanred' were identical while significantly higher ITs were produced on 'Marquis' and 'Iumillo' when tested with the same isolates. Conversely, isolates giving high ITs on 'Thatcher' and 'Kanred' produced lower ITs on 'Marquis' and 'Iumillo'. Genetic studies are in progress to confirm these observations.