Study on vicariance of obligate biotrophs between East Asia and South America

本研究的目的是(1)通过分子系统发育分析，阐明植物特有的生物营养物质--白粉菌在东亚和南美洲的变异原因；(2)从生物地理学的角度研究白粉菌的演化史。主要研究结果如下：1)白粉组一新种。描述和插图来自阿根廷的巴塔哥尼亚。白蜡虫Erysihe patogiaca sp.Nov.与nothofagi和E.kenjiana相似，但不同之处在于其附属物全长扭曲，附属物、子囊壁和子囊孢子的数量。白蜡梅学派的两个特有种。Uncinula、E.mellanica和E.nothofagi与白粉虫共存于同一叶片上。2)根据5.8S、18S和28S rDNA序列推测了Uncinula在白粉目中的系统发育地位。虽然子囊的附属物是钩状的…与最近引入的基生属Parauncinula ex Uncinula更相似且明显分开。Uncinula prestalles在形态上与白蜡梅学派不同。钩状，有顶生、束状(如三指)、隔开的肉芽附属物和一真孢子状的无性型(分生孢子)。在Parauncinula中，附属物也是顶生的，但不是束状的，子囊孢子弯曲，缺乏无性型。森林钩端菌是一种根基、寄生在树上的白粉病，具有一些附加的祖先特征，包括钩状附属物和6-8个孢子的ASCI。3)黄曲霉是白蜡梅科严格的草本植物寄生属。近年来，从分子系统发育的角度研究了黄曲霉属和菊科真菌之间的寄主-寄生虫共种关系。菊科植物起源于南美洲，后来将其地理分布扩展到北半球。如果黄曲霉与菊科的共生物种起源于南美洲，则黄曲霉的地理起源可推定为南美洲。为了解决这个问题，从南美洲特有的星族Mutisieae的宿主中收集了Golovinmyces物种并进行了测序。结果表明，从木霉亚科中分离到的Odium mutisiae和Golovinmyces leuceriae不属于Golovinmyces树的底部。相反，它们分别位于北半球分离的两个不同的Golovinmyces分支中。因此，Mutisieae族不是戈洛文霉菌最早的寄主。目前的结果表明，戈洛维诺霉菌起源于北半球，而不是南美洲较少

The aims of this study were (1) to clarify the causal factors of vicariance of powdery mildew fungi, obligate biotrophs of plants, between East Asia and South America using molecular phylogenetic analyses, and (2) to study evolutional history of the powdery mildew fungi from the view of biogeography. The main results are described below,1) A new species of Erysiphe sect. Uncinula is described and illustrated from Patagonia, Argentina. Erysiphe patagoniaca sp. nov., found on leaves of Nothofagus x antarctica, is similar to E. nothofagi and E. kenjiana, but differs in its appendages twisted throughout the length, and number of appendages, asci and ascospores. The two endemic species of Erysiphe sect. Uncinula, E. magellanica and E. nothofagi, coexisted on the same leaves together with Erysiphe patagoniaca.2) The phylogenetic position of Uncinula forestalls within the Erysiphales has been inferred from 5.8S, 18S, and 28S rDNA sequences. Although the appendages of the ascomata are Uncinula … More -like and clearly separate from the recently introduced basal genus Parauncinula ex Uncinula. Uncinula forestalls differs morphologically from the species of Erysiphe sect. Uncinula (= Uncinula) in having terminal, fasciculate (as in Podosphaera tridactyla), septate ascoma appendages and a Euoidium-like anamorph (conidia catenate). In Parauncinula, the appendages are also terminal but not fasciculate, the ascospores are curved, and the anamorph is lacking. Uncinula forestalis is a basal, tree-inhabiting powdery mildew with some additional ancestral characteristics, including Uncinula-like appendages and 6-8-spored asci. The new genus Caespitotheca is proposed, with C. forestalis as the type species.3) Golovinomyces is a strictly herb-parasitic genus in the Erysiphaceae. Host-parasite co-speciation was reported recently between the genus Golovinomyces and Asteraceae from molecular phylogenetic analyses. The Asteraceae originated in South America and latterly expanded their geographic distribution into the Northern Hemisphere. If the co-speciation between Golovinomyces and Asteraceae originated in South America, the geographic origin of Golovinomyces could be assumed to be South America. To address this question, Golovinomyces species from hosts of the tribe Mutisieae, an asteraceous tribe endemic to South America, were collected and sequenced. Results indicate that Oidium mutisiae and Golovinomyces leuceriae isolated from the Mutisieae do not belong at the base of the Golovinomyces tree. Instead, they are situated separately within two different clades of Golovinomyces isolates from the Northern Hemisphere. Therefore, the tribe Mutisieae is not the most early host of Golovinomyces. Present results suggest that Golovinomyces originated in the Northern Hemisphere, and not in South America Less