Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2007
Publication Date: 8/1/2007
Citation: Jin, Y., Pretorius, Z., Singh, R. 2007. New virulence within race TTKS (Ug99) of the stem rust pathogen and effective resistance gene [abstract]. Phytopathology. 97:S137.
Technical Abstract: Stem rust resistance gene Sr24 in wheat is a valuable gene, effective against most races of the stem rust pathogen (Puccinia graminis f. sp. tritici) worldwide. It is highly effective against race TTKS (or Ug99), a recently emerged race in Eastern Africa that is considered to be a serious threat to wheat production worldwide. In 2006, moderately susceptible to susceptible infection responses were observed on wheat lines and cultivars carrying Sr24 in a field stem rust screening nursery planted in Njoro, Kenyan. Pure cultures derived by single-pustule isolation were tested on seedling plants of the stem rust differentials and tester stocks carrying various stem rust resistance genes. Isolates were identified to be race TTKS with virulence on Sr24, indicating the occurrence of a new variant within race TTKS. Genes effective against this new variant include: Sr13, 22, 25, 26, 27, 28, 29, 32, 35, 36, 37, 39, 40, 44, Tmp, and stem rust resistance present on the 1A.1R translocation. The combination of virulence on Sr2 and Sr31 has substantially increased the vulnerability of wheat to stem rust worldwide.