Northern Crop Science Laboratory, Cereal Crops Research Unit, USDA-ARS, 1605 Albrecht Blvd. North, Fargo, ND, 58102-2765, USA.
Theor Appl Genet. 2014 Apr;127(4):969-80. doi: 10.1007/s00122-014-2272-4. Epub 2014 Feb 7.
Wheat lines carrying Ug99-effective stem rust resistance gene Sr43 on shortened alien chromosome segments were produced using chromosome engineering, and molecular markers linked to Sr43 were identified for marker-assisted selection. Stem rust resistance gene Sr43, transferred into common wheat (Triticum aestivum) from Thinopyrum ponticum, is an effective gene against stem rust Ug99 races. However, this gene has not been used in wheat breeding because it is located on a large Th. ponticum 7el(2) chromosome segment, which also harbors genes for undesirable traits. The objective of this study was to eliminate excessive Th. ponticum chromatin surrounding Sr43 to make it usable in wheat breeding. The two original translocation lines KS10-2 and KS24-1 carrying Sr43 were first analyzed using simple sequence repeat (SSR) markers and florescent genomic in situ hybridization. Six SSR markers located on wheat chromosome arm 7DL were identified to be associated with the Th. ponticum chromatin in KS10-2 and KS24-1. The results confirmed that KS24-1 is a 7DS·7el(2)L Robertsonian translocation as previously reported. However, KS10-2, which was previously designated as a 7el(2)S·7el(2)L-7DL translocation, was identified as a 7DS-7el(2)S·7el(2)L translocation. To reduce the Th. ponticum chromatin carrying Sr43, a BC(2)F(1) population (Chinese Spring//Chinese Spring ph1bph1b*2/KS10-2) containing ph1b-induced homoeologous recombinants was developed, tested with stem rust, and genotyped with the six SSR markers identified above. Two new wheat lines (RWG33 and RWG34) carrying Sr43 on shortened alien chromosome segments (about 17.5 and 13.7 % of the translocation chromosomes, respectively) were obtained, and two molecular markers linked to Sr43 in these lines were identified. The new wheat lines with Sr43 and the closely linked markers provide new resources for improving resistance to Ug99 and other races of stem rust in wheat.
利用染色体工程创制携带矮腥黑穗病 Ug99 有效抗性基因 Sr43 的小麦品系，并鉴定与 Sr43 紧密连锁的分子标记用于辅助选择。来自中间偃麦草（Thinopyrum ponticum）的 Sr43 是一种抗小麦秆锈病 Ug99 生理小种的有效基因，但由于该基因位于一段较大的 Th. ponticum 7el(2)染色体片段上，该片段还携带有不良性状基因，因此尚未在小麦育种中应用。本研究旨在消除 Sr43 周围过多的 Th. ponticum 染色质，使其可用于小麦育种。首先利用简单重复序列（SSR）标记和荧光基因组原位杂交分析携带 Sr43 的两个原始易位系 KS10-2 和 KS24-1。在 KS10-2 和 KS24-1 中鉴定到与 Th. ponticum 染色质相关的 6 个位于小麦染色体臂 7DL 上的 SSR 标记。结果证实，如先前报道的，KS24-1 是一个 7DS·7el(2)L 罗伯逊易位；而先前被指定为 7el(2)S·7el(2)L-7DL 易位的 KS10-2 则被鉴定为 7DS-7el(2)S·7el(2)L 易位。为了减少携带 Sr43 的 Th. ponticum 染色质，利用含有 ph1b 诱导的同源重组的 BC(2)F(1)群体（Chinese Spring//Chinese Spring ph1bph1b*2/KS10-2），开发、接种秆锈病并利用上述 6 个 SSR 标记进行基因型鉴定。获得了两个携带 Sr43 的新小麦系（RWG33 和 RWG34），它们在易位染色体上的外源片段缩短约 17.5%和 13.7%，并在这些系中鉴定到与 Sr43 紧密连锁的两个分子标记。带有 Sr43 和紧密连锁标记的新小麦系为提高小麦对 Ug99 及其他秆锈病生理小种的抗性提供了新资源。
