Afanasenko O S, Khiutti A V, Mironenko N V, Lashina N M
All-Russian Research Institute of Plant Protection, Pushkin, St. Petersburg, Russia.
Vavilovskii Zhurnal Genet Selektsii. 2022 May;26(3):272-280. doi: 10.18699/VJGB-22-34.
Potato spindle tuber viroid (PSTVd) is a naked, circular, single-stranded RNA (356-363 nucleotides in length) which lacks any protein-coding sequences. It is an economically important pathogen and is classified as a high-risk plant quarantine disease. Moreover, it is known that PSTVd is mechanically transmitted by vegetative plant propagation through infected pollen, and by aphids. The aim of this study is to determine the possibility of viroid transmission by potato pathogen Phytophthora infestans (Mont.) de Bary. PSTVd-infected (strain VP87) potato cultivars Gala, Colomba, and Riviera were inoculated with P. infestans isolate PiVZR18, and in 7 days, after the appearance of symptoms, re-isolation of P. infestans on rye agar was conducted. RT-PCR diagnostics of PSTVd in a mixture of mycelia and sporangia were positive after 14 days of cultivation on rye agar. The PSTVd-infected P. infestans isolate PiVZR18v+ was used to inoculate the healthy, viroid-free plants of potato cv. Gala and tomato cv. Zagadka. After 60 days, an amplification fragment of PSTVd was detected in the tissues of one plant of tomato cv. Zagadka by RT-PCR with the primer set P3/P4, indicating successful transmission of PSTVd by P. infestans isolate PiVZR18v+. This result was confirmed by sequencing of the RT-PCR amplicon with primers P3/P4. The partial sequence of this amplicon was identical (99.5 %) to PSTVd strain VP87. RT-PCR showed the possibility of viroid stability in a pure culture of P. infestans isolate PiVZR18v+ after three consecutive passages on rye agar. PSTVd was not detected after the eighth passage on rye agar in P. infestans subculture. These results are initial evidence of potato viroid PSTVd being bidirectionally transferred between P. infestans and host plants.
马铃薯纺锤块茎类病毒（PSTVd）是一种裸露的、环状的单链RNA（长度为356 - 363个核苷酸），不含任何蛋白质编码序列。它是一种具有重要经济意义的病原体，被列为高风险植物检疫性病害。此外，已知PSTVd可通过受感染花粉的植物营养繁殖以及蚜虫进行机械传播。本研究的目的是确定马铃薯病原菌致病疫霉（Phytophthora infestans (Mont.) de Bary）传播类病毒的可能性。用致病疫霉分离株PiVZR18接种感染了PSTVd（VP87株系）的马铃薯品种嘎啦（Gala）、哥伦巴（Colomba）和里维埃拉（Riviera），7天后，在症状出现后，将致病疫霉在黑麦琼脂上进行再次分离。在黑麦琼脂上培养14天后，对菌丝体和孢子囊混合物中的PSTVd进行RT-PCR诊断呈阳性。用感染了PSTVd的致病疫霉分离株PiVZR18v +接种健康、无类病毒的马铃薯品种嘎啦和番茄品种扎加德卡（Zagadka）。60天后，通过使用引物对P3/P4的RT-PCR在番茄品种扎加德卡的一株植物组织中检测到PSTVd的扩增片段，表明致病疫霉分离株PiVZR18v +成功传播了PSTVd。通过用引物P3/P4对RT-PCR扩增子进行测序证实了这一结果。该扩增子的部分序列与PSTVd株系VP87相同（99.5%）。RT-PCR显示致病疫霉分离株PiVZR18v +在黑麦琼脂上连续传代三次后的纯培养物中类病毒具有稳定性。在致病疫霉继代培养中，在黑麦琼脂上传代八次后未检测到PSTVd。这些结果是马铃薯类病毒PSTVd在致病疫霉和寄主植物之间双向转移的初步证据。
