Michel Jennifer, Lehnert Marcus, Nebel Martin, Quandt Dietmar
Department of Plant Biodiversity, Bonn Institute of Organismic Biology (BIOB), University of Bonn, Bonn, North Rhine-Westfalia, Germany.
Plant Sciences, TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liège, Gembloux, Wallonia, Belgium.
PLoS One. 2025 Jul 8;20(7):e0326712. doi: 10.1371/journal.pone.0326712. eCollection 2025.
Arbuscular mycorrhizal fungi (AMF) are amongst the most studied obligate plant symbionts and regularly found in terrestrial plants. However, global estimates of AMF abundance amongst all land plants are difficult because i) the mycorrhizal status of many non-commercial, wild plant species is still unknown, ii) numerous plant species engage in facultative symbiosis, meaning that they can, but do not always do, associate with mycorrhiza, and iii) mycorrhizal status can vary within families, genera, and species. To gain deeper insights to the distribution of the plant-AMF symbiosis we investigated the mycorrhizal status in some of the oldest lineages of extant vascular plants, Polypodiophytina (ferns) and lycophytes, in one of the hotspots of natural plant diversification, the tropical rainforest. Providing a new data set of AMF abundance for 82 fern species representing 19 families, we hypothesized that (1) AMF would be found in 60-80% of the studied plants and (2) plant species with AMF symbionts would be more abundant than non-mycorrhizal species. Both hypotheses were rejected while the following observations were made: (1) AMF occurred in 30.5% of studied species, representing 63% of the studied fern families, (2) AMF colonisation was not correlated with species abundance, (3) a small proportion of AMF-hosting ferns was epiphytic (6%) and (4) mycorrhization was inconsistent among different populations of the same species (facultative mycorrhization). While these observations align with previous studies on ferns, they emphasise that mycorrhization is not a taxonomic trait and underscore the challenges in estimating the global abundance of AMF. In addition, the occurrence of AMF in epiphytic plants and no net benefits of AMF for plant abundance indicate that the mycorrhization observed in this study likely comprises the commensalism to parasitism range of the symbiosis spectrum.
丛枝菌根真菌（AMF）是研究最多的专性植物共生体之一，常见于陆生植物中。然而，要全面估算所有陆地植物中AMF的丰度很困难，原因如下：其一，许多非商业性野生植物物种的菌根状态仍不明确；其二，众多植物物种存在兼性共生现象，即它们能够与菌根共生，但并非总是如此；其三，菌根状态在科、属和物种内部也会有所不同。为了更深入了解植物与AMF共生关系的分布情况，我们在天然植物多样化热点地区之一的热带雨林中，对现存维管植物中一些最古老的谱系，即蕨类植物纲（蕨类植物）和石松类植物的菌根状态进行了调查。我们提供了一个包含19个科82种蕨类植物的AMF丰度新数据集，并假设：（1）在所研究植物中60% - 80%会发现AMF；（2）具有AMF共生体的植物物种比非菌根植物物种更为丰富。但这两个假设均被否定，同时有以下观察结果：（1）AMF出现在30.5%的研究物种中，占所研究蕨类植物科的63%；（2）AMF定殖与物种丰度无关；（3）一小部分有AMF的蕨类植物是附生植物（6%）；（4）同一物种的不同种群之间菌根形成情况不一致（兼性菌根形成）。虽然这些观察结果与之前关于蕨类植物的研究一致，但它们强调菌根形成并非分类学特征，并突出了估算全球AMF丰度的挑战。此外，附生植物中AMF的出现以及AMF对植物丰度没有净益处，表明本研究中观察到的菌根形成可能涵盖了共生光谱中从共栖到寄生的范围。
