Plant Science Research Unit, USDA-ARS, North Carolina State University, Raleigh, NC, 27695, USA.
Department of Crop and Soil Sciences, Colorado State University, Fort Collins, CO, 80523, USA.
Theor Appl Genet. 2024 Aug 19;137(9):206. doi: 10.1007/s00122-024-04702-0.
The Puccinia graminis f. sp. tritici (Pgt) Ug99-emerging virulent races present a major challenge to global wheat production. To meet present and future needs, new sources of resistance must be found. Identification of markers that allow tracking of resistance genes is needed for deployment strategies to combat highly virulent pathogen races. Field evaluation of a DH population located a QTL for stem rust (Sr) resistance, QSr.nc-6D from the breeding line MD01W28-08-11 to the distal region of chromosome arm 6DS where Sr resistance genes Sr42, SrCad, and SrTmp have been identified. A locus for seedling resistance to Pgt race TTKSK was identified in a DH population and an RIL population derived from the cross AGS2000 × LA95135. The resistant cultivar AGS2000 is in the pedigree of MD01W28-08-11 and our results suggest that it is the source of Sr resistance in this breeding line. We exploited published markers and exome capture data to enrich marker density in a 10 Mb region flanking QSr.nc-6D. Our fine mapping in heterozygous inbred families identified three markers co-segregating with resistance and delimited QSr.nc-6D to a 1.3 Mb region. We further exploited information from other genome assemblies and identified collinear regions of 6DS harboring clusters of NLR genes. Evaluation of KASP assays corresponding to our co-segregating SNP suggests that they can be used to track this Sr resistance in breeding programs. However, our results also underscore the challenges posed in identifying genes underlying resistance in such complex regions in the absence of genome sequence from the resistant genotypes.
禾柄锈菌小麦专化型（Pgt）Ug99 新生毒力小种对全球小麦生产构成重大挑战。为了满足当前和未来的需求，必须找到新的抗性来源。鉴定允许跟踪抗性基因的标记对于部署策略以对抗高度毒力的病原体小种是必要的。DH 群体的田间评价定位到一个位于 6DS 染色体臂远端的抗秆锈病（Sr）基因 QSr.nc-6D，该基因来自于 MD01W28-08-11 系，该基因与 Sr42、SrCad 和 SrTmp 等 Sr 抗性基因有关。在 DH 群体和 AGS2000×LA95135 杂交衍生的 RIL 群体中，鉴定到一个对 Pgt 小种 TTKSK 的幼苗抗性基因。抗性品种 AGS2000 在 MD01W28-08-11 的系谱中，我们的结果表明它是该系中 Sr 抗性的来源。我们利用已发表的标记和外显子捕获数据，在 QSr.nc-6D 侧翼的 10 Mb 区域富集标记密度。我们在杂合自交系家族中的精细作图确定了三个与抗性共分离的标记，并将 QSr.nc-6D 限定在 1.3 Mb 区域内。我们进一步利用来自其他基因组组装的信息，鉴定到含有 NLR 基因簇的 6DS 共线性区域。对与我们共分离 SNP 对应的 KASP 分析的评估表明，它们可用于在育种计划中跟踪这种 Sr 抗性。然而，我们的结果也强调了在缺乏抗性基因型基因组序列的情况下，在如此复杂的区域中鉴定抗性基因所面临的挑战。
