Vohník Martin, Pánek Matěj, Fehrer Judith, Selosse Marc-André
Department of Mycorrhizal Symbioses, Institute of Botany ASCR, Průhonice, 25243, Czech Republic.
Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Prague, 12844, Czech Republic.
Mycorrhiza. 2016 Nov;26(8):831-846. doi: 10.1007/s00572-016-0717-0. Epub 2016 Jun 21.
The Sebacinales are a monophyletic group of ubiquitous hymenomycetous mycobionts which form ericoid and orchid mycorrhizae, ecto- and ectendomycorrhizae, and nonspecific root endophytic associations with a wide spectrum of plants. However, due to the complete lack of fungal isolates derived from Ericaceae roots, the Sebacinales ericoid mycorrhizal (ErM) potential has not yet been tested experimentally. Here, we report for the first time isolation of a serendipitoid (formerly Sebacinales Group B) mycobiont from Ericaceae which survived in pure culture for several years. This allowed us to test its ability to form ericoid mycorrhizae with an Ericaceae host in vitro, to describe its development and colonization pattern in host roots over time, and to compare its performance with typical ErM fungi and other serendipitoids derived from non-Ericaceae hosts. Out of ten serendipitoid isolates tested, eight intracellularly colonized Vaccinium hair roots, but only the Ericaceae-derived isolate repeatedly formed typical ericoid mycorrhiza morphologically identical to ericoid mycorrhiza commonly found in naturally colonized Ericaceae, but yet different from ericoid mycorrhiza formed in vitro by the prominent ascomycetous ErM fungus Rhizoscyphus ericae. One Orchidaceae-derived isolate repeatedly formed abundant hyaline intracellular microsclerotia morphologically identical to those occasionally found in naturally colonized Ericaceae, and an isolate of Serendipita (= Piriformospora) indica produced abundant intracellular chlamydospores typical of this species. Our results confirm for the first time experimentally that some Sebacinales can form ericoid mycorrhiza, point to their broad endophytic potential in Ericaceae hosts, and suggest possible ericoid mycorrhizal specificity in Serendipitaceae.
座担菌目是一类单系的、广泛存在的膜菌纲菌根真菌，它们能与多种植物形成石楠状菌根和兰花菌根、外生菌根和内外生菌根，以及非特异性的根内生菌关联。然而，由于完全缺乏源自杜鹃花科植物根系的真菌分离物，座担菌目的石楠状菌根（ErM）潜力尚未经过实验验证。在此，我们首次报告从杜鹃花科植物中分离出一种类偶然菌（原座担菌目B组）菌根真菌，该真菌在纯培养中存活了数年。这使我们能够测试其在体外与杜鹃花科宿主形成石楠状菌根的能力，描述其随时间在宿主根中的发育和定殖模式，并将其表现与典型的ErM真菌以及源自非杜鹃花科宿主的其他类偶然菌进行比较。在所测试的10种类偶然菌分离物中，有8种在细胞内定殖于越橘属植物的毛根，但只有源自杜鹃花科的分离物反复形成形态上与自然定殖的杜鹃花科植物中常见的石楠状菌根相同的典型石楠状菌根，不过与著名的子囊菌ErM真菌刺盾炱菌在体外形成的石楠状菌根不同。一种源自兰科植物的分离物反复形成大量形态上与自然定殖的杜鹃花科植物中偶尔发现的相同的透明细胞内微菌核，而印度类偶然菌（=梨形孢属）的一个分离物产生了该物种典型的大量细胞内厚垣孢子。我们的结果首次通过实验证实了一些座担菌目真菌能够形成石楠状菌根，指出了它们在杜鹃花科宿主中的广泛内生潜力，并暗示了类偶然菌科可能存在的石楠状菌根特异性。
