超级稻沈农265苗期耐冷性QTL定位

QTLs Mapping for Cold Tolerance at Seedling Stage in Super Rice Variety Shennong 265

为挖掘和利用超级稻沈农265(SN265)中的优异耐冷基因,找到不同遗传背景下均能稳定表达且贡献率较大的苗期耐冷数量性状基因(QTL),以SN265分别与2个籼稻品种七山占、IR30杂交衍生的2套重组自交系(RIL)群体(S1和S2)为试验材料,以低温处理下幼苗死苗率作为苗期耐冷性评价指标,同时构建2套群体的遗传连锁图谱,采用完备区间作图法进行耐冷性QTL检测及其遗传效应分析。结果表明,在2套RIL群体中共检测到4个苗期耐冷主效QTL,且苗期耐冷加性效应均来自SN265。S1群体定位到2个QTL位点,位于第5号染色体的qCTS-5.1和第6号染色体的qCTS-6,贡献率分别为47.59%、22.47%,LOD值分别为6.54、4.88;S2群体定位到2个QTL位点,分别位于第5号染色体的qCTS-5.2和第7号染色体的qCTS-7,贡献率分别为22.62%、38.48%,LOD值分别为10.00、9.81。2套群体定位的qCTS-5.1和qCTS-5.2区间基本重合,证明其可在不同的遗传背景中稳定表达。本研究结果为进一步精细定位并克隆水稻苗期耐冷主效QTL奠定了一定的理论基础。

In order to mine and utilize excellent cold tolerance genes from the super rice Shennong 265（SN265） and find out cold tolerance QTLs with stably expression and great contribution at seedling stage under different genetic backgrounds,two sets of recombinant inbred lines（RILs） derived from a cross of the SN265（japonica）/Qishanzhan（indica） and SN265/IR30（indica）,were applied to evaluate cold tolerance at the seedling stage with the ratio of dead seedlings under low-temperature treatment. Using genetic linkage map of two sets of populations and complete interval mapping method,we identified 4 main effect quantitative trait loci（QTL） for cold tolerance at seedling stage and the additive effect were contributed by SN265. There were two QTLs q CTS-5. 1 and q CTS-6 on chromosome 5 and chromosome 6,detected in S1 populations with contribution rate 47. 59% and 22. 47%,respectively. And LOD value is6. 54 and 4. 88,respectively. In S2 populations,two QTLs for cold tolerance（q CTS-5. 2 and q CTS-7） were detected on chromosome 5 and Chromosome 6,explaining 22. 62% and 38. 48% of phenotypic variances,respectively. The LOD value is 10. 00 and 9. 81,respectively. Two sites q CTS-5. 1 and q CTS-5. 2 on chromosome 5 detected in S1 and S2 populations,respectively,coincided with each other the result suggested that it can express steadily under different genetic backgrounds. The results are significant for further fine mapping and cloning the main effect QTLs for cold tolerance at seedling stage.