Armstrong Charlotte, Ganasamurthy Syaliny, Wigley Kathryn, Mercier Celine, Wakelin Steve
Scion, Christchurch, 8011, New Zealand.
Scion, Rotorua, 3010, New Zealand.
Environ Microbiome. 2024 Dec 18;19(1):103. doi: 10.1186/s40793-024-00656-4.
Pollen is a crucial source of nutrients and energy for pollinators. It also provides a unique habitat and resource for microbiota. Previous research on the microbiome of pollen has largely focused on angiosperm systems, with limited research into coniferous gymnosperms. This study characterises the pollen microbiome and metabolome associated with one of the world's most widely grown tree species, Pinus radiata. Trees were sampled from locations across Canterbury, New Zealand. Repeated collections were undertaken in 2020 and 2021.
Metabolomic analysis revealed the main compounds present on P. radiata pollen to be amino acids (principally proline), and carbohydrates (fructose, glucose, and sucrose). Although phenolic compounds such as ρ-coumaric acid and catechin, and terpenoids such as dehydroabietic acid, were present at low concentrations, their strong bioactive natures mean they may be important in ecological filtering of microbiome communities on pollen. The P. radiata pollen microbiome was richer in fungal taxa compared with bacteria, which differs from many angiosperm species. Geographic range and annual variation were evaluated as drivers of microbiome assembly. Neither sampling location (geographic range) nor annual variation significantly influenced the fungal community which exhibited remarkable conservation across samples. However, some bacterial taxa exhibited sensitivity to geographic distances and yearly variations, suggesting a secondary role of these factors for some taxa. A core microbiome was identified in P. radiata pollen, characterized by a consistent presence of specific fungal and bacterial taxa across samples. While the dominant phyla, Proteobacteria and Ascomycota, align with findings from other pollen microbiome studies, unique core members were unidentified at genus level.
This tree species-specific microbiome assembly emphasizes the crucial role of the host plant in shaping the pollen microbiome. These findings contribute to a deeper understanding of pollen microbiomes in gymnosperms, shedding light on the need to look further at their ecological and functional roles.
花粉是传粉者重要的营养和能量来源。它还为微生物群提供了独特的栖息地和资源。先前关于花粉微生物组的研究主要集中在被子植物系统，对针叶裸子植物的研究有限。本研究对与世界上种植最广泛的树种之一辐射松相关的花粉微生物组和代谢组进行了表征。树木样本采自新西兰坎特伯雷各地。在2020年和2021年进行了多次采集。
代谢组学分析表明，辐射松花粉中的主要化合物为氨基酸（主要是脯氨酸）和碳水化合物（果糖、葡萄糖和蔗糖）。尽管诸如对香豆酸和儿茶素等酚类化合物以及脱氢枞酸等萜类化合物的浓度较低，但其强大的生物活性意味着它们可能在花粉上微生物群落的生态筛选中发挥重要作用。与许多被子植物物种不同，辐射松花粉微生物组中的真菌类群比细菌更丰富。评估了地理范围和年度变化作为微生物组组装的驱动因素。采样地点（地理范围）和年度变化均未对真菌群落产生显著影响，真菌群落在样本间表现出显著的保守性。然而，一些细菌类群对地理距离和年度变化表现出敏感性，表明这些因素对某些类群起次要作用。在辐射松花粉中鉴定出一个核心微生物组，其特征是在各个样本中始终存在特定的真菌和细菌类群。虽然优势门变形菌门和子囊菌门与其他花粉微生物组研究的结果一致，但在属水平上未鉴定出独特的核心成员。
这种特定树种的微生物组组装强调了宿主植物在塑造花粉微生物组中的关键作用。这些发现有助于更深入地了解裸子植物的花粉微生物组，揭示了进一步研究其生态和功能作用的必要性。
