小麦–中间偃麦草隐形渗入系抗白粉病基因pmCH83分子定位

Molecular Mapping of Powdery Mildew Resistance Gene pmCH83 in a Putative Wheat–Thinopyrum intermedium Cryptic Introgression Line

小麦新种质CH09W83为八倍体小偃麦TAI7047与高感小麦品种晋太170杂交、回交后代衍生而来的高代选系,在苗期免疫或高抗我国白粉病菌株E09、E20、E21、E23、E26、Bg1和Bg2。为定位CH09W83中的抗病基因,将CH09W83与感病亲本杂交和回交,通过对F1、F2、F2:3和BC1代的接种鉴定和遗传分析,证实CH09W83成株期对E09的抗性由1对隐性核基因控制,暂命名为pmCH83。采用分离群体分组分析法(bulked segregant analysis,BSA),以658对SSR标记对台长29(感病)×CH09W83的F2群体分析发现,抗性基因pmCH83与SSR标记Xgpw7272、Xwmc652、Xgwm251、Xgwm193连锁,与两翼邻近标记Xwmc652和Xgwm251的遗传距离分别为3.8 cM和4.3 cM。利用中国春缺体–四体、双端体将pmCH83及其连锁标记定位在4BL染色体上。原位杂交、染色体配对及连锁标记分析结果表明,CH09W83可能是一个小麦与中间偃麦草的隐形异源渗入系。系谱和图谱位置分析表明,pmCH83很可能是来自中间偃麦草一个新的抗白粉病基因。

Wheat introgression line CH09W83 is immune or highly resistant to wheat powdery mildew caused by Blumeria graminis f. sp. tritici （Bgt） pathotypes E09, E20, E21, E23, E26, Bg1, and Bg2 at seedling stage in China. This line was derived from the cross between wheat–Thinopyrum intermedium line TAI7047 （resistant） and wheat cultivar Jintai 170 （susceptible）. To identify the Bgt resistance gene（s） in CH09W83, we developed segregating populations （F2, F2：3, and BC1） by crossing/backcrossing CH09W83 with susceptible wheat parents. The result of genetic analysis showed that the adult resistance to Bgt E09 in CH09W83 was controlled by a single recessive gene, which was tentatively designated as pmCH83. Using the F2 population of Taichang 29 （susceptible） ′ CH09W83 and 658 pairs of SSR primers, four codominant SSR markers, i.e., Xgwm193, Xgwm251, Xwmc652, and Xgpw7272, were identified to be linked with pmCH83 according to bulked segregant analysis, and the genetic distances between the target gene and flanking markers were 4.3 cM to Xgwm251 and 3.8 cM to Xwmc652. Using Chinese Spring nullitetrasomic and ditelosomic lines, pmCH83 was located on chromosomal arm 4BL of wheat. In combination with evidence of bivalent pairing at metaphase I and GISH, CH09W83 is probably a cryptic wheat–Th. intermedium translocation. Based on pedigree analysis and linkage map, we deduced that pmCH83 is a novel Bgt resistance gene originating from Th. intermedium.