Cereal Research Centre, Agriculture & Agri-Food Canada, 195 Dafoe Road, Winnipeg, MB, R3T 2M9, Canada.
Theor Appl Genet. 2012 Aug;125(4):817-24. doi: 10.1007/s00122-012-1874-y. Epub 2012 May 12.
Stem rust, caused by Puccinia graminis f. sp. tritici, is a devastating disease of wheat. The emergence of race TTKSK (Ug99) and new variants in Africa threatens wheat production worldwide. The best method of controlling stem rust is to deploy effective resistance genes in wheat cultivars. Few stem rust resistance (Sr) genes derived from the primary gene pool of wheat confer resistance to TTKSK. Norin 40, which carries Sr42, is resistant to TTKSK and variants TTKST and TTTSK. The goal of this study was to elucidate the inheritance of resistance to Ug99 in Norin 40 and map the Sr gene(s). A doubled haploid (DH) population of LMPG-6/Norin 40 was evaluated for resistance to the race TTKST. Segregation of 248 DH lines fitted a 1:1 ratio (χ (2) 1:1= 0.58, p = 0.45), indicating a single gene in Norin 40 conditioned resistance to Ug99. This was confirmed by an independent F(2:3) population also derived from the cross LMPG-6/Norin 40 where a 1:2:1 ratio (χ (2)1:2:1 = 0.69, p = 0.71) was observed following the inoculation with race TTKSK. Mapping with DNA markers located this gene to chromosome 6DS, the known location of Sr42. PCR marker FSD_RSA co-segregated with Sr42, and simple sequence repeat (SSR) marker BARC183 was closely linked (0.5 cM) to Sr42. A previous study found close linkage between FSD_RSA and SrCad, a temporarily designated gene that also confers resistance to Ug99, thus Sr42 may be the same gene or allelic. Marker FSD_RSA is suitable for marker-assisted selection (MAS) in wheat breeding programs to improve stem rust resistance, including Ug99.
茎锈病由禾柄锈菌引起，是小麦的一种毁灭性疾病。在非洲，TTKSK（Ug99）和新变体的出现威胁着全球的小麦生产。控制茎锈病的最佳方法是在小麦品种中部署有效的抗性基因。少数来自小麦初级基因库的茎锈病抗性（Sr）基因赋予对 TTKSK 的抗性。携带 Sr42 的 Norin 40 对 TTKSK 及其变体 TTKST 和 TTTSK 具有抗性。本研究的目的是阐明 Norin 40 对 Ug99 的抗性遗传，并对 Sr 基因进行作图。使用 LMPG-6/Norin 40 的加倍单倍体（DH）群体评估对 TTKST 菌株的抗性。248 条 DH 系的分离符合 1:1 比例（χ（2）1:1=0.58，p=0.45），表明 Norin 40 中的单个基因决定了对 Ug99 的抗性。这一点也通过另一个独立的 F（2:3）群体得到了证实，该群体也来自 LMPG-6/Norin 40 的杂交，在接种 TTKSK 后观察到 1:2:1 的比例（χ（2）1:2:1=0.69，p=0.71）。利用位于 6DS 染色体上的 DNA 标记进行基因作图，该位置已知存在 Sr42。PCR 标记 FSD_RSA 与 Sr42 共分离，简单重复序列（SSR）标记 BARC183 与 Sr42 紧密连锁（0.5 cM）。先前的研究发现 FSD_RSA 与 SrCad 之间的紧密连锁，SrCad 是一个暂时指定的基因，也赋予对 Ug99 的抗性，因此 Sr42 可能是相同的基因或等位基因。标记 FSD_RSA 适合于小麦育种计划中的标记辅助选择（MAS），以提高包括 Ug99 在内的茎锈病抗性。
