Singh R P, Lakshman D K, Boucher A, Tavantzis S M
Agriculture Canada Research Branch, Fredericton, New Brunswick.
J Gen Virol. 1992 Nov;73 ( Pt 11):2769-74. doi: 10.1099/0022-1317-73-11-2769.
A viroid was isolated from symptomless Nematanthus wettsteinii plants using the return-PAGE method for analysis of low M(r) nucleic acids. The RNA was transmitted to tomato, three cultivars of potato, and Scopolia sinensis plants by mechanical inoculation or by grafting. Infected solanaceous plants developed symptoms similar to those caused by potato spindle tuber viroid (PSTVd). The Nematanthus viroid consists of 372 nucleotides, 214 G+C, 158 A+U, with a G+C/A+U ratio of 1.35. One of seven cDNA clones showed a sequence heterogeneity (G to A) at position 73. The most stable secondary structure of this viroid has 78 G:C, 37 A:U and 11 G:U base pairs with a minimum free energy of -456.9 kJ. The viroid is closely related to the 370 nucleotide Columnea latent viroid. The Nematanthus viroid possesses regions of 100% sequence identity with six viroids belonging to the PSTVd and apple scar skin viroid groups. The viroid also replicated in tomato plants when mixed with PSTVd. Tomato plants were cross-protected against PSTVd when preinfected with the viroid from N. wettsteinii.
利用用于分析低分子量核酸的往返聚丙烯酰胺凝胶电泳法，从无症状的腺叶苣苔属植物中分离出一种类病毒。通过机械接种或嫁接，将该RNA传播给番茄、三个马铃薯品种和华洋参植株。受感染的茄科植物出现了与马铃薯纺锤块茎类病毒（PSTVd）引起的症状相似的症状。腺叶苣苔类病毒由372个核苷酸组成，其中214个为G+C，158个为A+U，G+C/A+U比值为1.35。七个cDNA克隆中的一个在第73位显示出序列异质性（G到A）。该类病毒最稳定的二级结构有78个G:C、37个A:U和11个G:U碱基对，最小自由能为-456.9 kJ。该类病毒与370个核苷酸的锦叶苣苔潜伏类病毒密切相关。腺叶苣苔类病毒与属于PSTVd和苹果锈果类病毒组的六种类病毒具有100%的序列同源区域。当与PSTVd混合时，该类病毒也能在番茄植株中复制。用来自腺叶苣苔的类病毒预先感染番茄植株后，番茄植株对PSTVd具有交叉保护作用。
