Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network, Budapest, Hungary.
Laboratory of Phytoprotection, Science and Technology, Faculty of Agriculture, Kindai University, Nara, Japan.
PLoS One. 2021 May 11;16(5):e0251444. doi: 10.1371/journal.pone.0251444. eCollection 2021.
A total of 26 Ampelomyces strains were isolated from mycelia of six different powdery mildew species that naturally infected their host plants in Japan. These were characterized based on morphological characteristics and sequences of ribosomal DNA internal transcribed spacer (rDNA-ITS) regions and actin gene (ACT) fragments. Collected strains represented six different genotypes and were accommodated in three different clades of the genus Ampelomyces. Morphology of the strains agreed with that of other Ampelomyces strains, but none of the examined characters were associated with any groups identified in the genetic analysis. Five powdery mildew species were inoculated with eight selected Ampelomyces strains to study their mycoparasitic activity. In the inoculation experiments, all Ampelomyces strains successfully infected all tested powdery mildew species, and showed no significant differences in their mycoparasitic activity as determined by the number of Ampelomyces pycnidia developed in powdery mildew colonies. The mycoparasitic interaction between the eight selected Ampelomyces strains and the tomato powdery mildew fungus (Pseudoidium neolycopersici strain KTP-03) was studied experimentally in the laboratory using digital microscopic technologies. It was documented that the spores of the mycoparasites germinated on tomato leaves and their hyphae penetrated the hyphae of Ps. neolycopersici. Ampelomyces hyphae continued their growth internally, which initiated the atrophy of the powdery mildew conidiophores 5 days post inoculation (dpi); caused atrophy 6 dpi; and complete collapse of the parasitized conidiphores 7 dpi. Ampelomyces strains produced new intracellular pycnidia in Ps. neolycopersici conidiophores ca. 8-10 dpi, when Ps. neolycopersici hyphae were successfully destroyed by the mycoparasitic strain. Mature pycnidia released spores ca. 10-14 dpi, which became the sources of subsequent infections of the intact powdery mildew hyphae. Mature pycnidia contained each ca. 200 to 1,500 spores depending on the mycohost species and Ampelomyces strain. This is the first detailed analysis of Ampelomyces strains isolated in Japan, and the first timing and quantification of mycoparasitism of Ps. neolycopersici on tomato by phylogenetically diverse Ampelomyces strains using digital microscopic technologies. The developed model system is useful for future biocontrol and ecological studies on Ampelomyces mycoparasites.
从自然侵染其宿主植物的 6 种不同白粉病菌株的菌丝体中共分离到 26 株嗜木霉。根据核糖体 DNA 内转录间隔区 (rDNA-ITS) 区和肌动蛋白基因 (ACT) 片段的序列及形态特征对这些菌株进行了表征。收集到的菌株代表了 6 种不同的基因型，并被归入嗜木霉属的 3 个不同的分支中。菌株的形态与其他嗜木霉菌株一致，但在遗传分析中没有发现任何与任何分组相关的特征。用 8 株选定的嗜木霉菌株接种 5 种白粉病菌，研究其生防活性。在接种实验中，所有嗜木霉菌株均成功侵染所有测试的白粉病菌，而且在所形成的嗜木霉分生孢子数量方面，没有观察到其生防活性存在显著差异。使用数字显微镜技术在实验室中对 8 株选定的嗜木霉菌株与番茄白粉病菌（Pseudoidium neolycopersici 菌株 KTP-03）的生防互作进行了实验研究。记录表明，生防菌的孢子在番茄叶片上萌发，其菌丝穿透 Ps. neolycopersici 的菌丝。嗜木霉的菌丝在内部继续生长，这导致接种后 5 天（dpi）白粉病菌的分生孢子梗萎缩；第 6 天 dpi 时导致其萎缩；第 7 天 dpi 时被寄生的分生孢子梗完全崩溃。嗜木霉菌株在 Ps. neolycopersici 的分生孢子梗中大约 8-10 dpi 时产生新的细胞内分生孢子，此时生防菌已成功破坏了 Ps. neolycopersici 的菌丝。成熟的分生孢子大约在 10-14 dpi 时释放，成为完整白粉病菌菌丝再次感染的来源。成熟的分生孢子根据其宿主物种和嗜木霉菌株的不同，每个大约包含 200 至 1500 个孢子。这是首次对日本分离到的嗜木霉菌株进行详细分析，也是首次使用数字显微镜技术对番茄上的 Ps. neolycopersici 进行生防作用的时间和数量的研究。所建立的模型系统对于未来关于嗜木霉生防菌的生物防治和生态研究很有用。
