Abstract: Main quantitative trait locus (QTL) PA7-2 controls low hydrocyanic acid content trait of sorghum-sudangrass hybrid, and fine mapping of this gene can provide the basis of further research on candidate genes related to low-cyanide trait, function analysis, and molecular marker-assisted breeding. Based on our previous research work, a total of 121 quantitative trait loci isogenic recombinants (QIRs) were selected from the F₂ segregation population containing 1 200 individual plants of sorghum-sudangrass hybrid (Scattered ear Sorghum bicolor×Red shell Sorghum sudanense) in this study. Plants with very low or high cyanide traits were bagged and self-crossed to obtain an F₃ segregation population, and from which 130 QIRs individual strains were screened. A genetic linkage map was constructed using bulk segregate analysis and simple sequence repeat markers (BSA-SSR), which covered a total length of 230.7 cM, with an average marker distance of 4.81 cM. The QTL PA7-2 was located at 38 cM, and between SSR markers Sobic.8 g1-600 and XM00242-400. Comparing with the sorghum genome, the low-cyanide QTL PA7-2 was finely mapped at the physical interval of 3.77 Mb (51.415 Mb-55.182 Mb) of chromosome 8 in the sorghum genome for the first time, and an SSR marker SORBI4G3-600 was closely linked with it.

Key words: Sorghum-sudangrass hybrid, Low hydrocyanic acid content trait, Major QTL PA7-2, BSA-SSR technology, Fine mapping

摘要： 为了精细定位高丹草低氢氰酸含量性状主效数量性状基因座QTL PA7-2，对进一步开展低氰性状相关候选基因挖掘、功能解析及分子标记辅助育种等研究提供理论依据。本试验在前期研究工作基础上，从高丹草（散穗高粱Scattered ear Sorghum bicolor×红壳苏丹草Red shell Sorghum sudanense）F₂代1 200个分离群体单株中筛选出121个QIRs（Quantitative trait locus（QTL）isogenic recombinants）植株，选出低氰和高氰极端株套袋自交获得F₃代分离群体，选出QIRs群体植株130个，利用BSA-SSR（Bulked segregation analysis（BSA）and simple sequence repeats）技术构建了长度为230.7 cM、密度为4.81 cM的遗传连锁图谱，通过定位分析明确了QTL PA7-2的位置在38 cM处，位于SSR标记Sobic.8 g1-600和XM00242-400之间。经与高粱基因组比对分析，首次将低氰QTL PA7-2精细定位至高粱8号染色体3.77 Mb（51.415 Mb~55.182 Mb）的物理区间，并发现SSR标记SORBI4G3-600与其紧密连锁。

关键词: 高丹草, 低氢氰酸含量性状, 主效QTL PA7-2, BSA-SSR技术, 精细定位