Department of Plant Pathology, Stellenbosch University, Matieland, 7600, South Africa.
Phytopathology. 2012 Feb;102(2):204-13. doi: 10.1094/PHYTO-04-11-0107.
Fusarium oxysporum f. sp. cepae, which causes basal rot of onion, consists of seven vegetative compatibility groups (VCGs 0420 to 0426) and several single-member VCGs (SMVs). F. oxysporum f. sp. cepae populations in South Africa and Colorado each consist of one main VCG (namely, VCG 0425 and 0421, respectively). The aim of this study was to develop sequence-characterized amplified region (SCAR) markers for the identification of VCGs 0425 and 0421, using 79 previously characterized F. oxysporum isolates. A second aim was to investigate the prevalence of VCG 0425 among 88 uncharacterized South African onion F. oxysporum isolates using (i) the developed SCAR markers and (ii) inter-retrotransposon (IR)- and random amplified polymorphic DNA (RAPD) fingerprinting. Only two RAPD primers provided informative fingerprints for VCG 0425 isolates but these could not be developed into SCAR markers, although they provided diagnostic fragments for differentiation of VCG 0425 from VCG 0421. IR fingerprinting data were used to develop a multiplex IR-SCAR polymerase chain reaction method for the identification of VCG 0421, VCG 0425, and SMV 4 isolates as a group. Molecular identification of the uncharacterized collection of 88 F. oxysporum isolates (65 F. oxysporum f. sp. cepae and 23 F. oxysporum isolates nonpathogenic to onion) confirmed that VCG 0425 is the main VCG in South Africa, with all but 3 of the 65 F. oxysporum f. sp. cepae isolates having the molecular characteristics of this VCG. Genotyping and VCG testing showed that two of the three aforementioned isolates were new SMVs (SMV 6 and SMV 7), whereas the third (previously known as SMV 3) now belongs to VGC 0247.
尖镰孢菌洋葱专化型（Fusarium oxysporum f. sp. cepae）可引起洋葱基腐病，它由 7 个营养体亲和群（VCGs 0420 至 0426）和几个单成员营养体亲和群（SMVs）组成。南非和科罗拉多的尖镰孢菌洋葱专化型种群各由一个主要 VCG（即 VCG 0425 和 0421）组成。本研究旨在利用 79 个先前已鉴定的尖镰孢菌分离物，为鉴定 VCGs 0425 和 0421 开发序列特征扩增区域（SCAR）标记。第二个目的是利用（i）已开发的 SCAR 标记和（ii）反向转座子（IR）和随机扩增多态性 DNA（RAPD）指纹分析，调查南非 88 个未鉴定洋葱尖镰孢菌分离物中 VCG 0425 的流行情况。只有两个 RAPD 引物为 VCG 0425 分离物提供了信息丰富的指纹，但这些引物不能开发成 SCAR 标记，尽管它们为区分 VCG 0425 和 VCG 0421 提供了诊断片段。IR 指纹数据用于开发一种多重 IR-SCAR 聚合酶链反应方法，用于鉴定 VCG 0421、VCG 0425 和 SMV 4 分离物作为一组。对 88 个未鉴定的尖镰孢菌分离物（65 个尖镰孢菌洋葱专化型和 23 个对洋葱无致病性的尖镰孢菌分离物）的分子鉴定证实，VCG 0425 是南非的主要 VCG，除了 65 个尖镰孢菌洋葱专化型分离物中的 3 个之外，其余 62 个均具有该 VCG 的分子特征。基因分型和 VCG 测试表明，上述三个分离物中的两个是新的 SMV（SMV 6 和 SMV 7），而第三个（以前称为 SMV 3）现在属于 VGC 0247。
