The ecology and genetics of a host shift:: Microbotryum as a model system
The ecology and genetics of a host shift:: Microbotryum as a model system
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DOI：
10.1086/342143
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发表时间：
2002-10-01
影响因子：
2.9
通讯作者：
Partain, J
中科院分区：
文献类型：
--
作者：
Antonovics, J;Hood, M;Partain, J
由于需要预防和治愈新出现的疾病，因此往往无法继续在现场进行研究。在石竹科植物Silene上，利用花药黑穗病(Microbotryum Violaceum)模型系统研究了寄主移位引起的病害发生过程。这个系统几乎没有直接的社会影响，而且它很容易受到实验性的操纵。我们的微进化研究集中在弗吉尼亚州的一个种群中，小花叶微孢子菌的寄主从Silene alba(=宽叶；白色Campion)转移到Silene vallgaris(囊状Campion)。核型变异表明，寄主转移是最近的，起源于共面白纹伊蚊的病害。对疾病空间格局的分析表明，寄主转移取决于这两个物种在当地范围内的共存情况。交叉接种研究表明，新寄主的家系对病原菌的敏感性差异很大，这表明了抗性快速进化的潜力。在新寄主上的疾病表达经常是异常的，这表明病原体对新寄主的适应不完全。在实验种群中，旧宿主种群内的疾病传播大于新宿主种群内的疾病传播。然而，疾病从新宿主向旧宿主传回的传播率也很高，这表明反馈效应增加了整个社区的疾病流行。对这些种群的持续研究旨在确定这种新的宿主-病原体系统是否可能自我维持，并量化宿主和病原体的进化变化。
The need to prevent and cure emerging diseases often precludes their continuing study in situ. We present studies on the process of disease emergence by host shifts using the model system of anther-smut disease (Microbotryum violaceum) on the plant genus Silene (Caryophyllaceae). This system has little direct social impact, and it is readily amenable to experimental manipulation. Our microevolutionary studies have focused on the host shift of Microbotryum from Silene alba (= latifolia; white campion) onto Silene vulgaris (bladder campion) in a population in Virginia. Karyotypic variation shows that the host shift is recent and originates from the disease on sympatric S. alba. Analysis of the spatial pattern of disease shows that the host shift has been contingent on the co-occurrence of the two species at a local scale. Cross-inoculation studies show that families of the new host differ greatly in their susceptibility to the pathogen, indicating the potential for rapid evolution of resistance. Disease expression on the new host is frequently abnormal, suggesting that the pathogen is imperfectly adapted to its new host. In experimental populations, disease transmission within populations of the old host is greater than within populations of the new host. However, there is also a high transmission rate of the disease from the new host back to the old host, suggesting a feedback effect that increases disease prevalence in the community as a whole. Continuing studies of these populations are designed to determine whether this new host-pathogen system is likely to be self-sustaining and to quantify evolutionary changes in both the host and the pathogen.