The true myrtle, Myrtus communis, is a small perennial evergreen tree that occurs in Europe, Africa, and Asia with a circum-Mediterranean geographic distribution. Unfortunately, the Mediterranean Forests, where M. communis occurs, are critically endangered and are currently restricted to small fragmented areas in protected conservation units. In the present work, we performed, for the first time, a metabarcoding study on the spatial variation of fungal community structure in the foliar endophytome of this endemic plant of the Mediterranean biome, using bipartite network analysis as a model. The local bipartite network of Myrtus communis individuals and their foliar endophytic fungi is very low connected, with low nestedness, and moderately high specialization and modularity. Similar network patterns were also retrieved in both culture-dependent and amplicon metagenomics of foliar endophytes in distinct arboreal hosts in varied biomes. Furthermore, the majority of putative fungal endophytes species were basidiomycete woody saprotrophs of the orders Polyporales, Agaricales, and Hymenochaetales. Altogether, these findings suggest a possible adaptation of these wood-decaying fungi to cope with moisture limitation and spatial scarcity of their primary substrate (dead wood), which are totally consistent with the predictions of the viaphytism hypothesis that wood-decomposing fungi inhabit the internal leaf tissue of forest trees in order to enhance dispersal to substrates on the forest floor, by using leaves as vectors and as refugia, during periods of environmental stress.

中文翻译：

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地中海生物群落特有植物（桃金娘）的叶内生菌群揭示担子菌木本腐生菌的优势

真正的桃金娘，桃金娘，是一种多年生常绿小乔木，生长在欧洲、非洲和亚洲，地理分布在地中海沿岸。不幸的是，M.communis 出现的地中海森林极度濒危，目前仅限于受保护的保护单位中的小块碎片区域。在目前的工作中，我们首次使用二分网络分析作为模型，对地中海生物群落特有植物的叶内植物群中真菌群落结构的空间变异进行了元条形码研究。桃金娘个体及其叶内生真菌的局部二分网络连通性非常低，嵌套性低，并且具有中等高度的专业化和模块化。在不同生物群落中不同树栖宿主的叶内生菌的培养依赖性和扩增子宏基因组学中也检索到了类似的网络模式。此外，大多数假定的真菌内生菌物种是多孔菌目、伞菌目和膜原菌目的担子菌木本腐生菌。总而言之，这些发现表明这些木材腐烂真菌可能会适应其主要基质（死木）的水分限制和空间稀缺性，这与木材腐烂真菌栖息在内部的腐生植物假说的预测完全一致。在环境压力期间，通过使用叶子作为载体和避难所，森林树木的叶子组织以增强向森林地面基质的扩散。