Fang D Q, Federici C T, Roose M L
Department of Botany and Plant Sciences, University of California, Riverside, California 92521, USA.
Genetics. 1998 Oct;150(2):883-90. doi: 10.1093/genetics/150.2.883.
Resistance to citrus tristeza virus (CTV) was evaluated in 554 progeny of 10 populations derived from Poncirus trifoliata. A dominant gene (Ctv) controlled CTV resistance in P. trifoliata. Twenty-one dominant PCR-based DNA markers were identified as linked to Ctv by bulked segregant analysis. Of the 11 closest markers to Ctv, only 2 segregated in all populations. Ten of these markers were cloned and sequenced, and codominant RFLP markers were developed. Seven RFLP markers were then evaluated in 10 populations. Marker orders were consistent in all linkage maps based on data of single populations or on combined data of populations with similar segregation patterns. In a consensus map, the six closest marker loci spanned 5.3 cM of the Ctv region. Z16 cosegregated with Ctv. C19 and AD08 flanked Ctv at distances of 0.5 and 0.8 cM, respectively. These 3 markers were present as single copies in the Poncirus genome, and could be used directly for bacterial artificial chromosome library screening to initiate a walk toward Ctv. BLAST searches of the GenBank database revealed high sequence similarities between 2 markers and known plant disease resistance genes, indicating that a resistance gene cluster exists in the Ctv region in P. trifoliata.
对源自枳壳的10个群体的554个后代进行了柑橘衰退病毒（CTV）抗性评估。一个显性基因（Ctv）控制着枳壳对CTV的抗性。通过混合分组分析法确定了21个基于PCR的显性DNA标记与Ctv连锁。在与Ctv最接近的11个标记中，只有2个在所有群体中分离。对其中10个标记进行了克隆和测序，并开发了共显性RFLP标记。然后在10个群体中评估了7个RFLP标记。基于单个群体的数据或具有相似分离模式的群体的合并数据，所有连锁图谱中的标记顺序都是一致的。在一个共识图谱中，与Ctv最接近的6个标记位点跨越了Ctv区域的5.3厘摩。Z16与Ctv共分离。C19和AD08分别在距离Ctv 0.5厘摩和0.8厘摩处侧翼。这3个标记在枳壳基因组中以单拷贝形式存在，可直接用于细菌人工染色体文库筛选，以启动向Ctv的步移。对GenBank数据库的BLAST搜索显示，2个标记与已知植物抗病基因之间具有高度的序列相似性，表明在枳壳的Ctv区域存在一个抗病基因簇。
