Seagrass wasting disease (SWD), an infection believed to be caused by Labyrinthula zosterae, has been linked to seagrass declines in several places around the world. However, there is uncertainty about the mechanisms of disease and the potential involvement of opportunistic colonising microorganisms. Using 16S rRNA gene amplicon sequencing, we compared the microbiome of SWD lesions in leaves of Zostera muelleri with communities in adjacent asymptomatic tissues and healthy leaves. The microbiome of healthy leaf tissues was dominated by Pseudomonas and Burkholderia, whereas the most predominant taxa within adjacent tissues were Pseudomonas and Rubidimonas. Members of the Saprospiraceae, potential macroalgal pathogens, were over-represented within SWD lesions. These pronounced changes in microbiome structure were also apparent when we examined the core microbiome of different tissue types. Although the core microbiome associated with healthy leaves included three operational taxonomic units (OTUs) classified as Burkholderia, Cryomorphaceae and the SAR11 clade, a single core OTU from the Arenicella was found within adjacent tissues. Burkholderia are diazotrophic microorganisms and may play an important role in seagrass nitrogen acquisition. In contrast, some members of the Arenicella have been implicated in necrotic disease in other benthic animals. Moreover, microbiome structure was maintained across sites within healthy tissues, but not within SWD lesions or the tissues immediately adjacent to lesions. Predicted functional profiles revealed increased photoautotrophic functions in SWD tissues relative to healthy leaves, but no increase in pathogenicity or virulence. Notably, we demonstrated the presence of L. zosterae in SWD lesions by polymerase chain reaction, but only in one of the two sampled locations, which indicates that other microbiological factors may be involved in the initiation or development of SWD-like symptoms. This study suggests that the dynamics of the seagrass microbiome should be considered within the diagnosis and management of SWD.

海草浪费病（SWD），一种被认为是由迷宫带状疱疹引起的感染，已与世界各地一些地方的海草数量减少有关。但是，关于疾病的机制和机会性定殖微生物的潜在参与尚不确定。使用16S rRNA基因扩增子测序，我们比较了Zostera muelleri叶片与邻近无症状组织和健康叶片中的群落中SWD病变的微生物组。健康叶组织的微生物组主要是假单胞菌和伯克霍尔德菌，而相邻组织中最主要的类群是假单胞菌和红花单胞菌。。潜在的大型藻类病原体-腐螺菌科的成员在社署病损中占了过多的席位。当我们检查不同组织类型的核心微生物组时，微生物组结构的这些明显变化也很明显。尽管与健康叶片相关的核心微生物组包括三个操作分类单位（OTU），分别归类为Burkholderia，Cryomorphaceae和SAR11进化枝，但在邻近组织中发现了来自Arenicella的单个核心OTU 。伯克霍尔德氏菌是重氮营养微生物，可能在海草氮的吸收中起重要作用。相比之下，槟榔的一些成员曾与其他底栖动物的坏死病有关。此外，微生物组结构在健康组织内的各个部位得以维持，但在SWD病变或紧邻病变的组织内却不存在。预测的功能概况显示，相对于健康的叶子，SWD组织中的光养养功能增加，但致病性或毒力没有增加。值得注意的是，我们证明了通过聚合酶链反应在SWD病变中存在带状杆菌，但仅在两个采样位置之一中存在，这表明其他微生物因素可能与SWD样症状的发生或发展有关。这项研究表明，在SWD的诊断和管理中应考虑海草微生物组的动力学。