9 Jun 2010
Latest confirmed race analysis results
Confirmed results from race analysis completed in the 2009/10 season are now available. The confirmed spread of Ug99 variants carrying combined Sr31 + Sr24 virulence in Africa continues, along with the continued predominance of these variants in Kenya. The absence of Ug99 from samples collected in Pakistan in 2009 was also confirmed.
In Ethiopia, two isolates collected near Meraro in the Rift Valley during October 2007 were confirmed to have combined virulence to both Sr31 and Sr24. Samples were collected by EIAR scientists and analysis undertaken by the Cereal Research Centre, Winnipeg, AAFC, Canada. The race was postulated to be PTKST. This represents the first confirmed occurrence of a Ug99 variant with virulence to Sr24 in Ethiopia.
In Kenya, a total of 55 samples were collected in 2009 by KARI scientists but race analysis was only possible on 12 viable samples. Race analysis was undertaken by the Cereal Research Centre, Winnipeg, AAFC, Canada. Races identified were; TTKST (Ug99+Sr24) (50%), PTKST (34%), and PTKSK (16%). Despite the low sample size, the results did indicate the continued predominance of Ug99 variants with combined Sr31 + Sr24 virulence in Kenya (Wanyera et al 2010).
In Pakistan, samples were collected during the 2009 season from Sindh and lower Punjab. Isolates were analysed at Murree in Pakistan and at the Cereal Research Centre, Winnipeg, AAFC, Canada. All isolates tested were identified as race RRTTF. This race has also been previously identified in Ethiopia (2007) and in Yemen (2007, 2008). RRTTF has reported virulence on Sr13, Sr36 and SrTmp. It is avirulent on Sr8a, 9e, 22, 24, 25, 26, 27, 31, 32, 39, 40. Preserved urediniospores were also sent to PBI, Uni Sydney, Australia for DNA fingerprinting for Ug99 and negative results were obtained. Combined analyses indicate the absence of Ug99 in the 2009 Pakistan stem rust samples (Mirza et al 2010).