Basidiomycetous endophytes in jungermannialean (leafy) liverworts have novel cytology and species-specific host ranges: a cytological and experimental study
Basidiomycetous endophytes in jungermannialean (leafy) liverworts have novel cytology and species-specific host ranges: a cytological and experimental study
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DOI：
10.1139/b06-073
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发表时间：
2006-07-01
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影响因子：
--
通讯作者：
Ligrone, Roberto
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文献类型：
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作者：
Duckett, Jeffrey G.;Russell, Julia;Ligrone, Roberto
本文回顾了已发表的有关jungermannialean（叶状）地钱中可能存在担子菌内生菌的数据，并根据对新鲜收集的标本的观察，并通过透射电子显微镜确认代表性分类群中的长孔菌隔膜，提出了一个新的概述。这些协会是广泛分布在Lophoziaceae和Arnelliaceae和零星的Jungermanniaceae，Scapaniaceae和Geocalycaceae。它们几乎完全局限于生长在排水良好、富含腐殖质的基质上的类群，不存在于附生植物和裸岩和水淹生境中的物种。无菌培养的苔类（Lophozia，Nardia，Diplophyllum，Southbya和Aneura在Metzgeriales）和它们的mycobiont之间的交叉感染实验显示，该协会是主机特定的，在与广泛的主机范围以前记录在Cephorziaceae和其他家庭的根状子囊菌形成鲜明对比。再合成的担子菌协会与它们的纯对应物相比，生长更旺盛，这表明对苔类植物的营养益处。真菌通过假根的顶端进入寄主，并在苔类植物的茎中形成独特的分布。在金线莲科，这包括一个中央髓股;在Lophoziaceae和Scapaniaceae，腹侧髓质包含一个受感染和未感染细胞的马赛克。在后者中，宿主壁物质的栓状物过度生长穿透菌丝。电子显微镜观察发现，所有的内生菌都具有直的异担子菌典型的无菌外鞘体。真菌形成的菌丝盘卷比宿主细胞质寿命长，并且不存在如在动脉瘤科和紫穗槐科菌根中所见的真菌生物体的消化。在Lophoziaceae和Scapaniaceae中密切相似的镶嵌感染模式加强了基于分子数据的两个家族之间的联系，但目前的交叉感染和超微结构数据表明，Calypogeia内生菌是子囊菌，而不是先前报道的Sebacinaceae的成员。在地钱中的担子菌协会的分布表明，这些可能出现了几次，是最近的起源比协会与glomeromycotean真菌。
This article reviews published data on the likely occurrence of basidiomycetous endophytes in jungermannialean (leafy) liverworts and presents a new overview based on observations on freshly collected specimens supplemented with confirmation, by transmission electron microscopy, of dolipore septa in representative taxa. These associations are widespread in the Lophoziaceae and Arnelliaceae and sporadic in the Jungermanniaceae, Scapaniaceae, and Geocalycaceae. They are almost exclusively confined to taxa growing on well-drained, humus-rich substrata and are absent from epiphytes and species from bare rocks and waterlogged habitats. Cross-infection experiments between axenically cultured liverworts (Lophozia, Nardia, Diplophyllum, Southbya, and Aneura in the Metzgeriales) and their mycobionts revealed the associations to be host specific, in striking contrast with the wide host ranges previously recorded for rhizoidal ascomycetes in the Cephaloziaceae and other families. More vigorous growth of resynthesized basidiomycete associations compared with their axenic counterparts is indicative of nutritional benefits to the liverworts. The fungi enter their hosts via the tips of the rhizoids and develop distinctive distributions within the liverwort stem. In the Arnelliaceae, this comprises a central medullary strand; in the Lophoziaceae and Scapaniaceae, the ventral medulla contains a mosaic of infected and noninfected cells. In the latter, pegs of host wall material overgrow penetrating hyphae. Electron microscopy revealed that all of the endophytes have straight imperforate parenthesomes typical of heterobasidiomycetes. The fungi form hyphal coils that outlive the host cytoplasm, and digestion of the mycobionts, as seen in Aneuraceae and orchidaceous mycorrhizas, are absent. Closely similar mosaic infection patterns in Lophoziaceae and Scapaniaceae strenghten the link between the two families based on molecular data, but the present cross-infection and ultrastructural data indicate that the Calypogeia endophyte is ascomycetous rather than a member of the Sebacinaceae as reported previously. The distribution of basidiomycete associations in liverworts suggests that these probably arose several times and are more recent in origin than associations with glomeromycotean fungi.