Molecular markers for the identification and global tracking of whitefly vector-Begomovirus complexes
Molecular markers for the identification and global tracking of whitefly vector-Begomovirus complexes
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DOI：
10.1016/s0168-1702(00)00221-5
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发表时间：
2000-11-01
期刊：
影响因子：
5
通讯作者：
Brown, JK
中科院分区：
文献类型：
--
作者：
Brown, JK
近年来，白蝇烟粉虱（Genn.）种群数量出现了前所未有的激增，这引起了人们对其作为一种害虫和突发性Begomovirus（双病毒科；Begomovirus属）媒介在世界范围内的重要性的极大关注。一些被认为是“新”的begomovirus和其他以前被认为是次要病原体的病毒与最近的流行病有关。尽管认为含dna的病毒不会迅速积累突变，但最近的研究揭示了begomovirus的许多变异。此外，已知某些烟粉虱“变种”更有效或选择性地传播某些begomovirus，并表现出可能影响其传播的生物差异。由于没有标准化的基于分子的追踪方法，人们对由烟粉虱传播的begomovirus的分布和传播模式了解甚少。在新出现的问题背景下，理解病毒/粉虱媒介/寄主植物之间的相互关系只能通过使用分子系统发育方法将预测的进化历史与流行病学联系起来才能实现。信息分子序列的鉴定和验证是这一过程中必不可少的初始步骤。已经开发出全属退化聚合酶链反应（PCR）引物，用于对外壳蛋白开放阅读框（ORF） （V1）的“核心”区域进行扩增和测序，从而通过与所描述的病毒基因型进行比较，实现“通用”检测和临时病毒鉴定。在这里报道的后续研究中，探索了几个潜在的信息病毒orf和一个非编码区。扩大多样性研究的特别用途是群体或病毒特异性序列，可以利用新获得的核心CP序列或其他保守区域，在这些区域周围可以设计广谱引物来靶向关键orf或非编码区域的可变序列。前瞻性标记的选择是基于最高度保守的病毒orf， CP （V1）和部分复制相关蛋白（REP） （LI/CI），以及包含足够变异性和/或病毒特异性序列的关键非编码序列，因此具有潜在的流行病学相关性。由于烟粉虱是一种隐种或物种复合体，具有生物多态性，但形态不变，传统的基于形态的鉴定是不可能的。建立分子标记来鉴定白蝇载体变异的一个最重要的复杂问题是，白蝇的一般序列还没有得到。然而，最近的研究表明，部分线粒体细胞色素氧化酶I （mt COI）序列在地理起源的基础上分离了载体变异，这表明它有助于进一步大规模地探索变异和白蝇的系统发育历史。本文利用白蝇的mt COI核苷酸（nt）序列来推断来自世界主要地区的烟粉虱之间的关系。综合使用这些方法，可首次调查begomovirus-white - fly病媒复合物的分布和传播模式。最终，将有可能更直接地识别外来病毒和白蝇病媒，并及早发现病媒种群的激增和新出现的病毒。(C) 2000 Elsevier Science B.V.版权所有
Recent unprecedented upsurges in populations of the whitefly Bemisia tabaci (Genn.) have drawn much attention to its worldwide importance as an insect pest and as the vector of emergent begomoviruses (Family: Geminiviridae; Genus: Begomovirus). Several begomoviruses that are considered 'new' and others previously regarded as minor pathogens have been linked to recent epidemics. Recent studies have revealed much variation in begomoviruses, despite the view that DNA-containing viruses do not rapidly accumulate mutations. Also, certain B. tabaci 'variants' are known that more effectively or selectively transmit certain begomoviruses and exhibit biotic differences that may influence their spread. Patterns of distribution and dissemination of begomoviruses transmitted by B. tabaci are poorly understood because standardized molecular-based tracking methods have not been available. Understanding virus/whitefly vector/host plant interrelationships in the context of emerging problems can be achieved only by linking predicted evolutionary histories with epidemiology using molecular phylogenetic approaches.Identification and validation of informative molecular sequences are essential initial steps in this process. Genus-wide degenerate polymerase chain reaction (PCR) primers have been developed to amplify and sequence the 'core' region of the coat protein open reading frame (ORF) (V1), permitting 'universal' detection and provisional virus identification by comparisons with described viral genotypes. In subsequent studies reported here, several potentially informative viral ORFs and a non-coding region are explored. Of particular use for expanding diversity studies are group- or virus-specific sequences that can be targeted by utilizing newly available core CP sequences, or additional conserved regions around which broad spectrum primers can be designed to target variable sequences in key ORFs or non-coding regions. Prospective markers under exploration were selected with a basis in the most highly conserved viral ORFs, CP (V1) and a portion of replication-associated protein (REP) (LI/CI), and a key non-coding sequence that contain sufficient variability and/or virus-specific sequences, and are consequently of potential epidemiological relevance. Because B. tabaci occurs as a cryptic species, or species complex, that exhibits biotic polymorphism, yet morphological invariance, traditional morphologically based identification is impossible. An overriding complication to establishing molecular markers for identifying whitefly vector variants is that whitefly sequences in general, have not been available. However, recent work has shown that a partial mitochondria cytochrome oxidase I (mt COI) sequence separates vector variants with a basis in geographical origin, suggesting it is useful for further exploring variability and the phylogenetic history of whiteflies on a large scale. Here, the utility of whitefly mt COI nucleotides (nt) sequences is illustrated for inferring relationships between B. tabaci collected from major world regions. Used collectively, these approaches may permit investigations of the patterns of distribution and dissemination of begomovirus-whitefly vector complexes for the first time. Ultimately, more immediate recognition of exotic viruses and whitefly vectors and early detection of upsurges in vector populations and of emerging viruses will be possible. (C) 2000 Elsevier Science B.V. All rights reserved.