CIMMYT小麦种质C615抗叶锈病QTL分析

Mapping QTLs against Leaf Rust in CIMMYT Wheat C615

由Puccinia triticina引起的叶锈病是小麦主要病害之一,引进种质C615具有叶锈病成株期抗性,但其抗病性遗传机制尚不清楚。本研究以抗病亲本C615与高感叶锈病亲本宁麦18构建的F_(2:7)代重组自交系群体为材料,利用337对多态性SSR标记构建遗传连锁图谱,结合2016、2017连续两年的叶锈病鉴定结果进行复合区间作图,结果在1BL、2DS、3BS、4DL和6BS染色体上共发现了5个抗性QTL,暂命名为QLr.njau-1BL、QLr.njau-2DS、QLr.njau-3BS、QLr.njau-4DL和QLr.njau-6BS。其中,QLr.njau-1BL、QLr.njau-3BS和QLr.njau-4DL在两年均被检测到,分别解释10.1%~15.7%、10.9%~13.5%和8.2%~9.0%的表型变异;另2个QTL只在一年被检测到,解释6.2%和9.2%的表型变异。除QLr.njau-2DS外的4个抗性QTL均来源于抗病亲本C615。QLr.njau-1BL和QLr.njau-4DL分别与已报道的慢病性基因Lr46、Lr67在同一区域,QLr.njau-3B可能为一个新的抗叶锈病QTL。此外,本研究在C615/扬麦13(轮回亲本)BC4F5回交群体中选出了15个农艺性状优良且抗叶锈病的株系,利用与C615所含抗性QTL紧密连锁的7个SSR标记对其进行基因型检测,结果显示所有这15个株系均含有来自C615的抗性QTL,且有3个株系聚合了全部抗性位点,表明C615可作为抗源亲本用于高产、抗病育种。本研究结果将为分子标记选育抗叶锈品种提供材料和技术支撑。

Leaf rust, caused by Puccinia triticina, is an important wheat disease. The introduced wheat line C615 shows adult resistance to leaf rust, but its mechanism is not clear. In this study, the quantitative trait loci（QTLs） for leaf rust resistance were identified and located in a linkage map constructed with 337 SSR markers using a recombinant inbred line（RIL） population（112 lines of the F_（2：7） generation） derived from CIMMYT wheat C615（resistant） and Ningmai 18（highly susceptible）. Final disease severity（FDS） of leaf rust was evaluated in 2016 and 2017. Five QTLs were detected on chromosomes 1 BL, 2 DS, 3 BS, 4 DL, and 6 BS, designated QLr.njau-1 BL, QLr.njau-2 DS, QLr.njau-3 BS, QLr.njau-4 DL, and QLr.njau-6 BS, respectively. All the resistance alleles were contributed by the resistant parent C615, except for QLr.njau-2 DS. Three QTLs, QLr.njau-1 BL, QLr.njau-3 BS, and QLr.njau-4 DL, were detected in both years, which explained phenotypic variance by 10.1%–15.7%, 10.9%–13.5%, and 8.2%–9.0%, respectively. The remaining two QTLs were detected in one year with smaller contributions（6.2% and 9.2%, respectively）. QLr.njau-1 BL and QLr.njau-4 DL were located in the same regions of the known resistance genes Lr46 and Lr67, respectively. QLr.njau-3 BS in the marker interval Xbarc102–Xwmc623 is probably a novel QTL for leaf rust resistance. Fifteen BC4 F5 lines derived from the cross of C615/Yangmai 13（recurrent parent） were genotyped for leaf rust resistance using seven SSR markers closely linked to the QTLs from C615. All the 15 lines had QTLs donated by C615 and three of them pyramided four QTLs, indicating that C615 can serve as an elite donor parent in wheat breeding aiming at high-yield and high-resistance to leaf rust. These results provide a basis of marker-assisted selection and providing breeding materials.