Department of Plant Protection, University of Tuscia, Via S. Camillo de Lellis, Viterbo, Italy.
Fungal Biol. 2011 Mar;115(3):275-87. doi: 10.1016/j.funbio.2010.12.013. Epub 2010 Dec 31.
The Himalaya have received little investigation for Phytophthora species. In a remote forest in Western Nepal ten isolates of an unknown Phytophthora were recovered from the rhizosphere of Quercus, Castanopsis, Carpinus and Cupressus spp. The Phytophthora, formally named here as a P. himalsilva sp. nov., is homothallic with either amphigynous or paragynous antheridia and papillate, highly variable sporangia which may also be facultatively caducous. Based on ITS, β-tubulin, and cox I sequences Phytophthora himalsilva falls within Phytophthora Clade 2c together with Phytophthora citrophthora, Phytophthora meadii, Phytophthora colocasiae, and Phytophthora botryosa. It is suggested that Clade 2c has radiated within Asia. Molecular and sporangial characters indicate that P. himalsilva and P. citrophthora may share a recent common ancestor although they have diverged in their breeding systems. Although highly local the P. himalsilva isolates exhibited significant variation in growth rates and optimum temperatures for growth. This may reflect adaptation to different niches within a heterogeneous sub-tropical to temperate forest environment. Their cox I polymorphisms were also rather variable, including possible clustering for subsite. The occurrence of a previously unknown Phytophthora in a remote forest in Nepal highlights once again the plant health risk associated with moving rooted plants and soil between different bio-geographical regions of the world and the need for rapid pathological screening of potential risk organisms.
喜马拉雅山脉的 Phytophthora 物种研究甚少。在尼泊尔西部的一个偏远森林中，从栎属、栲属、山核桃属和柏属植物的根际中分离出了十株未知的 Phytophthora 分离株。这种 Phytophthora，在这里正式命名为新种 P. himalsilva，是同宗配合的，具有两性或雌雄同体的藏卵器和乳突状、高度变异的游动孢子囊，也可能是 facultatively caducous。基于 ITS、β-微管蛋白和 cox I 序列，Phytophthora himalsilva 与 Phytophthora citrophthora、Phytophthora meadii、Phytophthora colocasiae 和 Phytophthora botryosa 一起属于 Phytophthora Clade 2c。表明 Clade 2c 在亚洲范围内发生了辐射。分子和游动孢子囊特征表明，P. himalsilva 和 P. citrophthora 可能有一个最近的共同祖先，尽管它们在繁殖系统上已经分化。尽管高度局限，P. himalsilva 分离株在生长速率和最适生长温度方面表现出显著的变异。这可能反映了它们在异质亚热带到温带森林环境中不同小生境的适应。它们的 cox I 多态性也相当多样，包括可能的亚位点聚类。在尼泊尔偏远森林中发现了一种以前未知的 Phytophthora，再次强调了在世界不同生物地理区域之间移动有根植物和土壤所带来的植物健康风险，以及对潜在风险生物进行快速病理筛选的必要性。
