Zhou Xueping, Xie Yan, Tao Xiaorong, Zhang Zhongkai, Li Zhenghe, Fauquet Claude M
Institute of Biotechnology, Zhejiang University, Hangzhou 310029, P.R. China.
Yunnan Biotechnology Research Institute, Yunnan Academy of Agricultural Sciences, Kunming 650223, P.R. China.
J Gen Virol. 2003 Jan;84(Pt 1):237-247. doi: 10.1099/vir.0.18608-0.
Eighteen samples of begomoviruses isolated from tobacco, tomato and weed species in Yunnan, China were found to be associated with DNAbeta molecules, for which the complete nucleotide sequences were found to contain 1333-1355 nt. The 18 DNAbeta molecules identified consist of three main types, each associated with a different begomovirus species: 72-99 % nucleotide identity was found within one type, but only 39-57 % identity was found between types. All the DNAbeta molecules reported here and elsewhere contain a 115 nt conserved region that has 93-100 % identity with a consensus sequence, and have a common ORF encoding 118 amino acids on the complementary strand (designated C1). Co-agroinoculation of the DNA-A component of Tomato yellow leaf curl China virus tobacco isolate Y10, with its associated DNAbeta (Y10beta), shows this DNAbeta to be involved in symptom induction in tobacco and tomato. The in-frame ATG mutation of C1 of Y10beta caused much milder symptoms as compared with wild Y10beta, indicating a functional role for this ORF. Pairwise nucleotide sequence identity comparisons of DNAbeta molecules and their cognate viral DNA-A molecules indicate that DNAbeta molecules have co-evolved with their cognate helper viruses. Recombination between DNAbeta molecules is documented and a DNAbeta species concept is proposed and discussed.
在中国云南，从烟草、番茄和杂草中分离出的18个双生病毒样本被发现与DNAβ分子有关，其完整核苷酸序列为1333 - 1355 nt。鉴定出的18个DNAβ分子由三种主要类型组成，每种类型与不同的双生病毒种类相关：同一类型内核苷酸同一性为72 - 99%，但不同类型之间仅为39 - 57%。本文及其他地方报道的所有DNAβ分子都包含一个115 nt的保守区域，与一个共有序列的同一性为93 - 100%，并且在互补链上有一个共同的开放阅读框，编码118个氨基酸（命名为C1）。中国番茄黄化曲叶病毒烟草分离株Y10的DNA - A组分与其相关的DNAβ（Y10β）共同农杆菌接种，结果表明该DNAβ参与了烟草和番茄的症状诱导。与野生型Y10β相比，Y10β的C1框内ATG突变导致的症状要轻得多，这表明该开放阅读框具有功能作用。DNAβ分子与其同源病毒DNA - A分子的成对核苷酸序列同一性比较表明，DNAβ分子与其同源辅助病毒共同进化。记录了DNAβ分子之间的重组，并提出和讨论了DNAβ物种概念。
