Ant handling changes myrmecochore seed coat microbiomes and alters diversity of seed-borne plant pathogenic fungi

The putative benefits to seeds in myrmecochory (ant-mediated seed dispersal) are often cast in a reward context. However, microbes have been mostly overlooked as seed mortality agents in myrmecochory, as have potential treatments provided by ant-handling. We investigated the effects of ant handling on the diversity of seed coat fungal communities of three myrmecochorous plant species. Ant-handling altered measures of both alpha and beta diversity of fungal communities. Ant-handled seeds harbored different overall fungal communities and plant pathogen communities than non-ant-handled seeds. The myrmecochore pathogenic fungal community showed high dissimilarity (high pairwise community turnover) between ant-handled and control seeds, while beta diversity measures for ant-handled seeds and seeds with manually-removed elaiosomes were less dissimilar. Ant handling may offer an additional benefit to myrmecochorous seeds via the reduction of the seed coat pathogenic community, which may be driven by elaiosome removal or as a byproduct of ant cleaning behaviors and chemical secretions.在蚁播（myrmecochory，蚂蚁介导的种子传播）中，种子的潜在益处常被置于奖励框架下探讨。然而，在蚁播研究领域，微生物作为导致种子死亡的因子，以及蚂蚁处理种子所带来的潜在保护作用，长期以来均被极大地忽视。本研究针对3种蚁播植物，探究了蚂蚁处理对其种皮真菌群落多样性的影响。结果显示，蚂蚁处理显著改变了真菌群落的α多样性与β多样性各项指标；经蚂蚁处理的种子，其整体真菌群落与植物病原真菌群落组成均与未处理对照组存在显著差异。蚁播植物种子的病原真菌群落在蚂蚁处理组与对照组之间呈现出极高的群落差异（即群落周转度高）；而经人工去除油质体的种子与蚂蚁处理组种子的β多样性指标差异则相对较小。本研究表明，蚂蚁处理或可通过降低种子种皮的病原真菌群落丰度，为蚁播植物种子提供额外的生存益处，这一效应可能源于油质体的去除，或是蚂蚁清洁行为与化学分泌物共同作用的副产物。