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    与烟草抗黑胫病Ph基因紧密连锁的SNP标记开发

    Development of SNP Markers Tightly Linked to the Ph Gene Conferring Resistance to Tobacco Black Shank Disease

    • 摘要: 来源于野生烟草N. plumbaginifoliaPh基因是烟草抗黑胫病育种的一个优质抗源。为开发与该基因连锁的SNP标记以满足当前分子育种的需求,本研究以携带Ph基因的抗黑胫病烤烟品种Coker371-Gold和不携带Ph基因的感黑胫病烤烟品种中烟特香301为材料,利用烟草SSR标记和基于全基因组重测序的33份栽培烟草种质资源的SNP变异,对携带Ph基因的N. plumbaginifolia染色体片段的分子特征进行了描述。通过构建黑胫病抗性分离的回交群体,对已知与Ph基因连锁的8个分子标记进行整合遗传图谱的绘制,在此基础上进行更为紧密连锁的SNP分子标记开发。结果表明:(1)携带Ph基因的N. plumbaginifolia染色体片段很可能是以末端易位的形式转移到栽培烟草中的,且与被替换的栽培烟草染色体片段之间存在较好的同源关系,其易位点位于云烟87 HIC_ASM_14染色体18.54 Mb附近;(2)Ph基因被定位于易位片段末端,很可能接近片段易位点,在其双侧各获得1个紧密连锁的特异SNP标记。上述结果为进一步创制更具育种价值的中间插入小片段易位系提供理论依据,从而为今后更好地利用这一黑胫病抗源提供技术支撑。

       

      Abstract: Originated from the wild tobacco N. plumbaginifolia, the Ph gene is a high-quality resistance source to black shank in tobacco breeding. In order to develop SNP markers linked to this gene to meet the demand of current molecular breeding, this study used black shank-resistant flue-cured tobacco variety Coker371-Gold with the Ph gene and a susceptible variety Zhongyan texiang 301 without the Ph gene as materials. Using tobacco SSR markers and SNP variations of 33 cultivated tobacco germplasm resources based on whole genome resequencing, the molecular characteristics of the chromosomal fragment of N. plumbaginifolia carrying the Ph gene was described. By constructing a backcross population segregating for black shank resistance, an integrated genetic map of 8 known molecular markers linked to the Ph gene was drawn, and on the basis, more closely linked SNP markers to the Ph gene were developed. The results showed that: (1) the N.plumbaginifolia chromosomal fragment carrying the Ph gene was probably transferred into cultivated tobacco in the form of terminal translocation, and had a good homology relationship with the replaced cultivated tobacco chromosomal fragment, and its translocation site was located near 18.54 Mb of Yunyan 87 HIC_ASM_14 chromosome; (2) Ph gene was located at the end of the translocation fragment, which probably being close to the translocation site, and one closely linked specific SNP marker was obtained on each side of the gene. These results provided a theoretical basis for further creating a more valuable intercalary translocation line with small fragment, thereby providing technical support for better utilization of this black shank disease resistance source in the future.

       

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