Yu Guotai, Zhang Qijun, Friesen Timothy L, Rouse Matthew N, Jin Yue, Zhong Shaobin, Rasmussen Jack B, Lagudah Evans S, Xu Steven S
Department of Plant Pathology, North Dakota State University, Fargo, ND, 58108, USA.
Theor Appl Genet. 2015 Mar;128(3):431-43. doi: 10.1007/s00122-014-2442-4. Epub 2014 Dec 19.
Mapping studies confirm that resistance to Ug99 race of stem rust pathogen in Aegilops tauschii accession Clae 25 is conditioned by Sr46 and markers linked to the gene were developed for marker-assisted selection. The race TTKSK (Ug99) of Puccinia graminis f. sp. tritici, the causal pathogen for wheat stem rust, is considered as a major threat to global wheat production. To address this threat, researchers across the world have been devoted to identifying TTKSK-resistant genes. Here, we report the identification and mapping of a stem rust resistance gene in Aegilops tauschii accession CIae 25 that confers resistance to TTKSK and the development of molecular markers for the gene. An F2 population of 710 plants from an Ae. tauschii cross CIae 25 × AL8/78 were first evaluated against race TPMKC. A set of 14 resistant and 116 susceptible F2:3 families from the F2 plants were then evaluated for their reactions to TTKSK. Based on the tests, 179 homozygous susceptible F2 plants were selected as the mapping population to identify the simple sequence repeat (SSR) and sequence tagged site (STS) markers linked to the gene by bulk segregant analysis. A dominant stem rust resistance gene was identified and mapped with 16 SSR and five new STS markers to the deletion bin 2DS5-0.47-1.00 of chromosome arm 2DS in which Sr46 was located. Molecular marker and stem rust tests on CIae 25 and two Ae. tauschii accessions carrying Sr46 confirmed that the gene in CIae 25 is Sr46. This study also demonstrated that Sr46 is temperature-sensitive being less effective at low temperatures. The marker validation indicated that two closely linked markers Xgwm210 and Xwmc111 can be used for marker-assisted selection of Sr46 in wheat breeding programs.
定位研究证实，节节麦材料Clae 25对秆锈病菌Ug99小种的抗性由Sr46基因控制，并开发了与该基因连锁的分子标记用于标记辅助选择。小麦秆锈病的病原菌——小麦秆锈菌的TTKSK（Ug99）小种被认为是全球小麦生产的主要威胁。为应对这一威胁，世界各地的研究人员一直致力于鉴定抗TTKSK的基因。在此，我们报道了在节节麦材料CIae 25中鉴定和定位的一个秆锈病抗性基因，该基因赋予对TTKSK的抗性，并开发了该基因的分子标记。首先对来自节节麦杂交组合CIae 25×AL8/78的710株F2群体进行了对TPMKC小种的抗性评价。然后从这些F2植株中选取14个抗性和116个感病的F2:3家系，评价它们对TTKSK的反应。基于这些测试，选择179株纯合感病的F2植株作为定位群体，通过混合分组分析法鉴定与该基因连锁的简单序列重复（SSR）和序列标签位点（STS）标记。鉴定出一个显性秆锈病抗性基因，并用16个SSR标记和5个新的STS标记将其定位到2DS染色体臂的2DS5-0.47-1.00缺失区间，Sr46基因也位于该区间。对CIae 25和两个携带Sr46的节节麦材料进行分子标记和秆锈病测试，证实CIae 25中的基因就是Sr46。本研究还表明，Sr46对温度敏感，在低温下效果较差。标记验证表明，两个紧密连锁的标记Xgwm210和Xwmc111可用于小麦育种计划中Sr46的标记辅助选择。
