Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Detection of wheat stem rust races TTHSK and PTKTK in the Ug99 race group in Kenya in 2014.

Abstract

Wheat stem rust, caused by Puccinia graminis f.sp. tritici [P. graminis], causes severe losses in wheat production under epidemic conditions. The detection of isolate Ug99 in east Africa has raised global concerns of the vulnerability of wheat to stem rust. Since initial detection, 10 variants of Ug99 have been reported across 13 countries. Wheat stem rust infection was widespread in Kenya in 2014. Fifty-two samples from common wheat were collected from the Mount Kenya and North, South, and Central Rift regions and analysed for race identity in a level-3 biocontainment laboratory in Canada. Of these samples, 41 yielded viable spores for race pathotyping. Virulence analysis using the letter-code nomenclature system identified two new races in the Ug99 race group from repeated experiments. Race TTHSK was identified from samples collected at Ngorengore (South Rift) and Njoro (field 13), which differs from the original Ug99 isolate (race TTKSK) by avirulence on gene Sr30. Race PTKTK was identified from samples collected at Rotian and Eor-Enkitok in the South Rift region, Cheplasgei and Kaplogoi in the North Rift region, and at the technology farm in Njoro in the Central Rift region. Race PTKTK differs from race PTKSK (first identified in 2007) by additional virulence to gene SrTmp, or alternatively differs from race TTKTK by avirulence to gene Sr21. This report now brings the total number of variants in the Ug99 race group to 13.