Detection of Wheat Stem Rust Races TTHSK and PTKTK in the Ug99 Race Group in Kenya in 2014

Identification and characterization of Sr13 , a tetraploid wheat gene that confers resistance to the Ug99 stem rust race group

“…We tested the efficacy of Sr13 resistance against Pgt races that caused epidemics in Kenya and/or Ethiopia [TTKSK (Ug99), TKTTF] in addition to other virulent races that were previously reported as virulent to Sr13 (TRTTF, JRCQC). Race TKTTF, originally detected in Turkey in the 1990s, is currently distributed throughout Europe, West Asia, North Africa, and East Africa ( 8 , 10 ). TRTTF and the closely related RRTTF race were first detected in Iran in 1997 and have been found later in Ethiopia, Yemen, and Pakistan ( 8 , 39 ).…”

“…As TTKSK spread through Africa and the Middle East, it gained new virulences to wheat cultivars carrying resistance genes Sr24 ( 2 ), Sr36 ( 3 ), Sr9h ( 4 , 5 ), and SrTmp ( 6 ). The expansion of the Ug99 race group to 10 countries in Africa, Egypt, Yemen, and Iran ( 7 , 8 ) has prompted the search for new sources of resistance. This search has been broadened to other virulent races outside the Ug99 race group, such as TKTTF that caused severe stem rust epidemics in southern Ethiopia since 2013 ( 9 ).…”

Progress in breeding for resistance to Ug99 and other races of the stem rust fungus in CIMMYT wheat germplasm

“…New races have continued to emerge and, by 2019, 13 had been identified (Table 1), all within the same 13 countries. Similarly, in 2014, five new variants of Ug99 were detected in Kenya [23,26,27] . Two of these, TTKTK and TTKTT, were highly significant because they had acquired virulence to stem rust gene SrTmp, a key resistance gene in popular eastern African bread wheat cultivars such as cv.…”

“…However, the additive nature of the gene interactions has enabled breeders at CIMMYT to select transgressive progenies that combine multiple minor genes, resulting in enhanced levels of resistance. High levels of APR to the Ug99 race group identified in some semi-dwarf lines was largely due to the selection environments at the phenotyping platforms in Kenya and Ethiopia, and this has allowed targeted breeding effort to build such genetically complex resistance within CIMMYT germplasm [27,40,72] .…”

Wheat Stem Rust Race Ug99: A Shifting Enemy

“…The latest variants are: TTKSF+ which was detected in South Africa and Zimbabwe (Pretorius et al, 2012), TTHST which was collected in Kenya in 2013; TTKTT, TTKTK. PTKTK and TTHSK (Patpour et al, 2015;Fetch and Zegeye, 2016) -all were collected from Kenya in 2014…”