1 Department of Plant Pathology, Southwest Florida Research and Education Center, University of Florida-IFAS, Immokalee, FL 34142, U.S.A.
2 Molecular Biology, Genetics and Bioengineering, Sabancı University, Istanbul, Turkey.
Plant Dis. 2019 Jul;103(7):1525-1535. doi: 10.1094/PDIS-10-18-1751-RE. Epub 2019 Apr 22.
Rasta is a virus-like disease of unknown etiology affecting tomato () plants in Ghana. Symptoms include stunting; epinasty, crumpling, and chlorosis of leaves; and necrosis of leaf veins, petioles, and stems. Leaf samples with rasta symptoms were collected from commercial tomato fields in Ghana in October 2012 and applied to FTA cards, and RNA extracts were prepared. Reverse-transcription polymerase chain reaction (RT-PCR) tests with primers for , which causes rasta-like symptoms in tomato plants in Mali, were negative, whereas tests with degenerate viroid primer pairs were inconclusive. However, tomato seedlings (Early Pak 7) mechanically inoculated with RNA extracts of 10 of 13 samples developed rasta-like symptoms. In RT-PCR tests with RNA from leaves of the 10 symptomatic seedlings and primers for (PSTVd) or (TASVd), the expected size (approximately 360 bp) of DNA fragment was amplified from eight and two seedlings, respectively. Sequence analyses confirmed that these fragments were from PSTVd and TASVd isolates, and revealed a single PSTVd haplotype and two TASVd haplotypes. The PSTVd and TASVd isolates from Ghana had high nucleotide identities (>94%) with isolates from other geographic regions. In a host range study, PSTVd and TASVd isolates from Ghana induced rasta symptoms in the highly susceptible tomato cultivar Early Pak 7 and mild or no symptoms in Glamour, and symptomless infections in a number of other solanaceous species. PSTVd and TASVd isolates were seed associated and possibly seed transmitted.
拉斯特是一种病因不明的病毒样病害，影响加纳的番茄（）植物。症状包括生长迟缓；叶片的内卷、皱缩和黄化；以及叶脉、叶柄和茎的坏死。2012 年 10 月，从加纳商业番茄田采集具有拉斯特症状的叶片样本并应用于 FTA 卡，制备 RNA 提取物。用引起马里番茄植物拉斯特样症状的引物进行逆转录聚合酶链反应（RT-PCR）测试为阴性，而用简并类病毒引物对进行的测试结果不确定。然而，用 13 个样本中的 10 个的 RNA 提取物机械接种的番茄幼苗（Early Pak 7）表现出拉斯特样症状。在对 10 个症状性幼苗叶片的 RT-PCR 测试中，用 PSTVd 或 TASVd 的引物进行测试，从 8 个和 2 个幼苗中分别扩增出预期大小（约 360 bp）的 DNA 片段。序列分析证实这些片段来自 PSTVd 和 TASVd 分离物，并且揭示了单个 PSTVd 单倍型和两个 TASVd 单倍型。来自加纳的 PSTVd 和 TASVd 分离物与来自其他地理区域的分离物具有高核苷酸同一性（>94%）。在宿主范围研究中，来自加纳的 PSTVd 和 TASVd 分离物在高度敏感的番茄品种 Early Pak 7 中引起拉斯特症状，在 Glamour 中引起轻度或无症状感染，并在一些其他茄科物种中引起无症状感染。PSTVd 和 TASVd 分离物与种子相关，可能通过种子传播。
