Wylie S J, Coutts B A, Jones M G K, Jones R A C
State Agricultural Biotechnology Centre, Murdoch University, Perth, WA 6150, Australia, and Centre for Legumes in Mediterranean Agriculture, University of Western Australia, Perth, WA 6009, Australia.
Agricultural Research Western Australia, Locked Bag No. 4, Bentley Delivery Centre, Perth, WA 6983, Australia.
Plant Dis. 2008 Dec;92(12):1596-1603. doi: 10.1094/PDIS-92-12-1596.
Genetic diversity of Bean yellow mosaic virus (BYMV) was studied by comparing sequences from the coat protein (CP) and genome-linked viral protein (VPg) genes of isolates from four continents. CP sequences compared were those of 17 new isolates and 47 others already on the database, while the VPg sequences used were from four new isolates and 10 from the database. Phylogenetic analysis of the CP sequences revealed seven distinct groups, six polytypic and one monotypic. The largest and most genetically diverse polytypic group, which had intragroup diversity of 0.061 nucleotide substitutions per site, contained isolates from natural infections in eight host species. These original isolation hosts included both wild (four) and domesticated (four) species and were from monocotyledonous and dicotyledonous plant families, indicating a generalized natural host range strategy. Only one of the other five polytypic groups spanned both monocotyledons and dicotyledons, and all contained isolates from fewer species (one to four), all of which were domesticated and had lower intragroup diversity (0.019 to 0.045 nucleotide substitutions per site), indicating host specialization. Phylogenetic analysis of the fewer VPg sequences revealed three polytypic and two monotypic groupings. These groups also correlated with original natural isolation hosts, but the branch topologies were sometimes incongruous with those formed by CPs. Also, intragroup diversity was generally higher for VPgs than for CPs. A plausible explanation for the groups found when the 64 different CP sequences were compared is that the generalized group represents the original ancestral type from which the specialist host groups evolved in response to domestication of plants after the advent of agriculture. Data on the geographical origins of the isolates within each group did not reveal whether the specialized groups might have coevolved with their principal natural hosts where these were first domesticated, but this seems plausible.
通过比较来自四大洲的菜豆黄花叶病毒（BYMV）分离株的外壳蛋白（CP）和基因组连接病毒蛋白（VPg）基因序列，对其遗传多样性进行了研究。所比较的CP序列包括17个新分离株和数据库中已有的47个分离株，而所用的VPg序列来自4个新分离株和数据库中的10个分离株。对CP序列的系统发育分析揭示了7个不同的组，其中6个是多型的，1个是单型的。最大且遗传多样性最高的多型组，其组内每个位点的核苷酸替换多样性为0.061，包含来自8种寄主植物自然感染的分离株。这些最初的分离寄主包括野生植物（4种）和驯化植物（4种），来自单子叶植物和双子叶植物科，表明其具有广泛的自然寄主范围策略。其他5个多型组中只有1个跨越单子叶植物和双子叶植物，且所有组都包含来自较少物种（1至4种）的分离株，所有这些物种都是驯化的，且组内多样性较低（每个位点0.019至0.045个核苷酸替换），表明寄主专一化。对较少的VPg序列进行系统发育分析，揭示了3个多型组和2个单型组。这些组也与最初的自然分离寄主相关，但分支拓扑结构有时与CP形成的拓扑结构不一致。此外，VPg的组内多样性通常高于CP。当比较64个不同的CP序列时发现这些组，一个合理的解释是，广泛的组代表了原始的祖先类型，在农业出现后，随着植物的驯化，专门的寄主组从该类型进化而来。每组内分离株的地理起源数据并未揭示专门的组是否可能与其最初驯化的主要自然寄主共同进化，但这似乎是合理的。
