School of Agriculture and Environment and University of Western Australia (UWA) Institute of Agriculture, Faculty of Science, UWA, Crawley, WA 6009, Australia; and Cooperative Research Centre for Plant Biosecurity, Canberra, ACT 2617, Australia.
School of Agriculture and Environment and UWA Institute of Agriculture, Faculty of Science, UWA; and Cooperative Research Center for Plant Biosecurity, Canberra, Australia.
Plant Dis. 2018 Mar;102(3):589-599. doi: 10.1094/PDIS-08-17-1156-RE. Epub 2018 Jan 17.
Sweet potato feathery mottle virus (SPFMV) and Sweet potato virus C (SPVC) isolates from sweetpotato were studied to examine genetic connectivity between viruses from Australia and Southeast Asia. East Timorese samples from sweetpotato were sent to Australia on FTA cards. Shoot and tuberous root samples were collected in Australia and planted in the glasshouse, and scions were graft inoculated to Ipomoea setosa plants. Symptoms in infected sweetpotato and I. setosa plants were recorded. RNA extracts from FTA cards and I. setosa leaf samples were subjected to high-throughput sequencing (HTS). Complete genomic sequences (CS) of SPFMV and SPVC (11 each) were obtained by HTS, and coat protein (CP) genes from them were compared with others from GenBank. SPFMV sequences clustered into two major phylogroups (A and B = RC) and two minor phylogroups (EA[I] and O[II]) within A; East Timorese sequences were in EA(I) and O(II), whereas Australian sequences were in O(II) and B(RC). With SPVC, CP trees provided sufficient diversity to distinguish major phylogroups A and B and six minor phylogroups within A (I to VI); East Timorese sequences were in minor phylogroup I, whereas Australian sequences were in minor phylogroups II and VI and in major phylogroup B. With SPFMV, Aus13B grouped with East Timorese sequence TM64B within minor phylogroup O, giving nucleotide sequence identities of 97.4% (CS) and 98.3% (CP). However, the closest match with an Australian sequence was the 97.6% (CS) and 98.7% (CP) nucleotide identity between Aus13B and an Argentinian sequence. With SPVC, closest nucleotide identity matches between Australian and East Timorese sequences were 94.1% with Aus6a and TM68A (CS) and 96.3% with Aus55-4C and TM64A (CP); however neither pair member belonged to the same minor phylogroup. Also, the closest Australian match was 99.1% (CP) nucleotide identity between Aus4C and New Zealand isolate NZ4-4. These first complete genome sequences of SPFMV and SPVC from sweetpotato plantings in the Australian continent and neighboring Southeast Asia suggest at least two (SPFMV) and three (SPVC) separate introductions to Australia since agriculture commenced more than two centuries ago. These findings have major implications for both healthy stock programs and biosecurity management in relation to pathogen entry into Australia and elsewhere.
甘薯羽状斑驳病毒（SPFMV）和甘薯脉斑驳病毒（SPVC）分离物来自甘薯，研究其遗传连接性，以考察来自澳大利亚和东南亚的病毒之间的关系。东帝汶的甘薯样本通过 FTA 卡被送往澳大利亚。在澳大利亚收集了地上茎和块根样本，并在温室中种植，然后将接穗嫁接到蕹菜上。记录了感染甘薯和蕹菜的植株的症状。从 FTA 卡和蕹菜叶片样本中提取 RNA 进行高通量测序（HTS）。通过 HTS 获得了 11 个 SPFMV 和 SPVC 的完整基因组序列（CS），并比较了它们的外壳蛋白（CP）基因与 GenBank 中的其他基因。SPFMV 序列聚类为两个主要的进化枝（A 和 B = RC）和 A 内的两个次要进化枝（EA[I]和 O[II]）；东帝汶序列在 EA（I）和 O（II），而澳大利亚序列在 O（II）和 B（RC）。对于 SPVC，CP 树提供了足够的多样性，可以区分主要进化枝 A 和 B 以及 A 内的六个次要进化枝（I 至 VI）；东帝汶序列在次要进化枝 I，而澳大利亚序列在次要进化枝 II 和 VI 以及主要进化枝 B。SPFMV 中，Aus13B 与东帝汶 TM64B 序列在 O 亚组内聚类，CS 核苷酸序列同一性为 97.4%，CP 核苷酸序列同一性为 98.3%。然而，与澳大利亚序列最接近的匹配是 Aus13B 与阿根廷序列的 97.6%（CS）和 98.7%（CP）核苷酸同一性。SPVC 中，澳大利亚和东帝汶序列之间最接近的核苷酸同一性匹配是 Aus6a 和 TM68A（CS）之间的 94.1%和 Aus55-4C 和 TM64A（CP）之间的 96.3%；然而，这两个配对成员不属于同一亚组。此外，澳大利亚最接近的匹配是 Aus4C 与新西兰分离株 NZ4-4 之间的 99.1%（CP）核苷酸同一性。这些来自澳大利亚大陆和邻近东南亚的甘薯种植中的 SPFMV 和 SPVC 的第一个完整基因组序列表明，自两个多世纪前农业开始以来，至少有两次（SPFMV）和三次（SPVC）独立的引入澳大利亚。这些发现对病原体进入澳大利亚和其他地区的健康库存计划和生物安全管理都具有重大意义。
