Genetics and molecular mapping of stem rust resistance in bread wheat line WR95

Abstract

The bread wheat line WR95 showed seedling resistance to several Indian stem rust (Puccinia graminis Pers. f. sp. tritici) isolates. Genetic analysis of stem rust resistance in WR95 was undertaken in populations derived from crosses NI5439/WR95 and Agra Local/WR95. The F1, F2, and F3 generations derived from the cross NI5439/WR95 were tested against stem rust isolate 40A and genetic analysis showed a recessive gene for resistance. The results were confirmed in another F2 population derived from the cross Agra Local/WR95. Interestingly, genetic analysis in F2 population from the later cross i.e. Agra Local/WR95 identified a dominant gene against isolates 11 and 11A. The recessive gene against isolate 40A was mapped to the long arm of 5D chromosome. WR95 showed resistance to virulent isolates of Sr30 which is also located on 5DL chromosome. The dominant gene in WR95 that conferred the resistance to isolate 11 and 11A was mapped towards telomeric region of the long arm of 2B chromosome. The long arm of chromosome 2B also carries stem rust resistance genes Sr9, Sr16 and Sr28. WR95 showed resistance to virulent isolates to Sr9b (11, 11A, 21A-2 and 40A), Sr9e (15-1 and 40A) and Sr28 (11, 11A, 15-1, 21A-2 and 40A). The map position of dominant gene identified in WR95 is different from Sr9 and Sr28 while Sr16 is towards telomeric region and not mapped so far. Therefore, the dominant gene in WR95 may be either Sr16 or a new gene.