Most wheat cultivars planted worldwide are susceptible to the stem rust Ug99 race group. To prepare for the potential spread of these races into South America, we aimed to identify genomic regions responsible for resistance to Ug99 race group in germplasm adapted to South America. Two RIL populations from a cross between a stem rust susceptible parent “Baguette 13” and resistant local parents “INIA Tero” and “BR23//CEP19/PF85490” were developed. Phenotypical evaluation was completed at the seedling stage in Uruguay and under field conditions in Uruguay and Kenya. Both RIL populations were genotyped using the GBS approach. Besides Sr24, three other resistance loci in “INIA Tero” were detected on chromosomes 2B, 6A, and 7B. All four QTL were effective to local races, whereas only the QTL on chromosome 2B was effective against the Ug99 race group. Besides Sr31, “BR23//CEP19/PF85490” also carries two other stem rust resistance loci on chromosomes 2B and 6A. All three explained the resistance in Uruguay, while only the QTL on 2B was effective to Ug99 in Kenya. The physical location suggested that the QTL identified on chromosome 2B in both populations may correspond to Sr28, which was confirmed using specific molecular markers. Further studies are needed to determine the relationship between QTL for resistance to local races identified on chromosomes 6A and 7B and previously reported resistance genes and QTL. The results of this study are highly relevant for breeding wheat cultivars with diverse and durable resistance to stem rust.

世界各地种植的大多数小麦品种都容易受到茎锈病Ug99种族的影响。为了准备这些种族向南美洲的潜在传播，我们旨在确定适应于南美的种质对Ug99种族群体具有抗性的基因组区域。从易受茎锈病侵害的亲本“ Baguette 13”与抗性亲本“ INIA Tero”和“ BR23 // CEP19 / PF85490”之间的杂交中开发了两个RIL群体。在乌拉圭的苗期以及在乌拉圭和肯尼亚的田间条件下完成了表型评估。使用GBS方法对两个RIL人群进行基因分型。除了Sr24，在2B，6A和7B号染色体上检测到“ INIA Tero”中的其他三个抗性基因座。所有四个QTL对当地种族有效，而只有2B染色体上的QTL对Ug99种族有效。除Sr31外，“ BR23 // CEP19 / PF85490”在染色体2B和6A上还携带另外两个茎杆抗锈基因座。这三者都解释了乌拉圭的抵抗，而只有2B的QTL对肯尼亚的Ug99有效。物理位置表明两个种群中在染色体2B上鉴定出的QTL可能对应于Sr28，已使用特定的分子标记进行了确认。需要进一步的研究来确定QTL对在6A和7B染色体上鉴定的局部种族的抗性与先前报道的抗性基因和QTL之间的关系。这项研究的结果与具有不同且持久的抗茎锈病能力的小麦品种的育种高度相关。