Phytopathology. 2002 Mar;92(3):314-20. doi: 10.1094/PHYTO.2002.92.3.314.
ABSTRACT Genetic relationships, mating crosses, and host specificity of Venturia inaequalis isolates from Malus spp. and of Spilocaea pyracanthae isolates from Pyracantha spp. were evaluated. Sequence analysis of the complete internal transcribed spacer (ITS) region (ITS1-5.8S to ITS2) revealed a total similarity between these two putative species. ITS restriction fragment length polymorphism carried out with five restriction enzymes on a collection of 28 isolates confirmed a lack of diversity in this region between and within these two populations. Additional isolates from three related species (V. pirina, V. nashicola, and S. eriobotryae) were divided into two distinct monophyletic groups in a phylogenetic tree using ITS sequence comparison. These groups were related to their anamorph (i.e., Spilocaea or Fusicladium). When inoculated on their host of origin, fields isolates caused typical symptoms of scab disease, and a host specificity was demonstrated by cross pathogenicity of isolates from Malus x domestica and Pyracantha spp. Mating on dried leaves in vitro between one isolate of each putative species led to production of numerous perithecia. Ninety-six sporulating monoascosporic progenies were isolated from this cross. Based on these genetic and pathogenic data, we proposed that pathogens responsible for scab on Malus spp. and Pyracantha spp. are considered as two formae speciales belonging to V. inaequalis.
摘要 本研究评估了苹果属（Malus spp.）上梨形孢（Venturia inaequalis）分离株和火棘属（Pyracantha spp.）上棘盘孢（Spilocaea pyracanthae）分离株的遗传关系、交配杂交和宿主特异性。对完整的内部转录间隔区（ITS）序列（ITS1-5.8S 到 ITS2）的序列分析表明，这两个假定物种之间存在完全相似性。对来自 28 个分离株的集合进行的 5 种限制酶的 ITS 限制片段长度多态性分析证实，在这两个种群之间和内部，该区域缺乏多样性。使用 ITS 序列比较，从三个相关物种（梨形孢属的 V. pirina、V. nashicola 和火棘盘孢属的 S. eriobotryae）的额外分离株在系统发育树中分为两个不同的单系群。这些群与它们的无性型（即 Spilocaea 或 Fusicladium）有关。当在其原始宿主上接种时，田间分离株引起典型的黑星病症状，并通过来自 Malus x domestica 和火棘属的分离物的交叉致病性证明了宿主特异性。在体外干燥叶片上进行的一对每个假定物种的交配导致产生了许多子囊壳。从这次杂交中分离出了 96 个产孢单性生殖后代。基于这些遗传和致病性数据，我们提出，引起苹果属和火棘属黑星病的病原菌被认为是两种特殊形式，属于梨形孢。
