G3 (Bethesda). 2011 Sep;1(4):283-91. doi: 10.1534/g3.111.000513. Epub 2011 Sep 1.
The complex inheritance of resistance to Cercospora leaf spot (CLS), the most severe fungal foliar disease in sugar beet, was investigated by means of quantitative trait loci (QTL) analysis. Over a three year period, recombinant inbred lines (RILs) of sugar beet (Beta vulgaris L.), generated through a cross between lines resistant ('NK-310mm-O') and susceptible ('NK-184mm-O') to CLS, were field-tested for their resistance to the pathogen. Composite interval mapping (CIM) showed four QTL involved in CLS resistance to be consistently detected. Two resistant QTL (qcr1 on chromosome III, qcr4 on chromosome IX) bearing 'NK-310mm-O' derived alleles promoted resistance. Across 11 investigations, the qcr1 and qcr4 QTL explained approximately 10% and over 20%, respectively, of the variance in the resistance index. Two further QTL (qcr2 on chromosome IV, qcr3 on chromosome VI) bearing 'NK-184mm-O' derived alleles each explained about 10% of the variance. To identify the monogenic effect of the resistance, two QTL derived from 'NK-310mm-O' against the genetic background of 'NK-184mm-O', using molecular markers. The qcr1 and qcr4 were precisely mapped as single QTL, using progenies BC(5)F(1) and BC(2)F(1), respectively. The qcr1 that was located near e11m36-8 had CLS disease severity indices (DSI) about 15% lower than plants homozygous for the 'NK-184mm-O' genotype. As with qcr1, heterozygosis of the qcr4 that was located near e17m47-81 reduced DSI by about 45% compared to homozygosis. These two resistant QTL might be of particular value in marker-assisted selection (MAS) programs in CLS resistance progression.
利用数量性状位点（QTL）分析研究了甜菜褐斑病（CLS）抗性的复杂遗传，CLS 是甜菜最严重的真菌叶病。在三年的时间里，通过对 CLS 抗性（'NK-310mm-O'）和敏感性（'NK-184mm-O'）品系的杂交产生的甜菜重组自交系（RIL）进行田间试验，以测试其对病原体的抗性。复合区间作图（CIM）显示，有四个与 CLS 抗性相关的 QTL 被一致检测到。两个抗性 QTL（位于第 III 染色体上的 qcr1 和位于第 IX 染色体上的 qcr4）带有 'NK-310mm-O' 衍生的等位基因，促进了抗性。在 11 项研究中，qcr1 和 qcr4 QTL 分别解释了抗性指数变异的约 10%和 20%以上。另外两个 QTL（位于第 IV 染色体上的 qcr2 和位于第 VI 染色体上的 qcr3）带有 'NK-184mm-O' 衍生的等位基因，每个都解释了约 10%的变异。为了确定抗性的单基因效应，利用分子标记从 'NK-310mm-O' 中获得了两个针对 'NK-184mm-O' 遗传背景的 QTL。使用 BC(5)F(1)和 BC(2)F(1)后代，qcr1 和 qcr4 分别被精确地映射为单个 QTL。位于 e11m36-8 附近的 qcr1 使 CLS 疾病严重指数（DSI）比纯合 'NK-184mm-O' 基因型的植物低约 15%。与 qcr1 一样，位于 e17m47-81 附近的 qcr4 的杂合性使 DSI 降低了约 45%，与纯合性相比。这两个抗性 QTL 在 CLS 抗性进展的标记辅助选择（MAS）计划中可能具有特别的价值。
