The diversity and community structure of arbuscular mycorrhizal fungi (AMF) associated with coconut (Cocos nucifera) roots was evaluated by next generation sequencing (NGS) using partial sequences of the 18S rDNA gene and by spore isolation and morphological identification from rhizosphere soil. Root samples from six different Green Dwarf coconut plantations and from one organic plantation surrounded by tropical dry forest along the coastal sand dunes in Yucatan, Mexico, were collected during the rainy and dry seasons. In total, 14 root samples were sequenced with the Illumina MiSeq platform. Additionally, soil samples from the dry season were collected to identify AMF glomerospores. Based on a 95–97% similarity, a total of 36 virtual taxa (VT) belonging to nine genera were identified including one new genus-like clade. Glomus was the most abundant genus, both in number of VT and sequences. The comparison of dry and rainy season samples revealed differences in the richness and composition of AMF communities colonizing coconut roots. Our study shows that the main AMF genera associated with coconut tree roots in all samples were Glomus, Sclerocystis, Rhizophagus, Redeckera, and Diversispora. Based on glomerospore morphology, 22 morphospecies were recorded among which 14 were identified to species. Sclerocystis sinuosa, Sclerocystis rubiformis, Glomus microaggregatum, and Acaulospora scrobiculata were dominant in field rhizosphere samples. This is the first assessment of the composition of AMF communities colonizing coconut roots in rainy and dry seasons. It is of importance for selection of AMF species to investigate for their potential application in sustainable agriculture of coconut.

中文翻译：

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墨西哥尤卡坦州椰子树根中的丛枝菌根真菌的季节性变化。

椰子丛枝菌根真菌（AMF）的多样性及群落结构（椰子通过使用18S rDNA基因的部分序列的下一代测序（NGS）以及根际土壤中的孢子分离和形态鉴定来评估根。在雨季和干旱季节，从墨西哥尤卡坦州沿海沙丘沿岸的六个热带矮林椰子种植园和热带干旱森林包围的一个有机种植园收集了根样品。总共使用Illumina MiSeq平台对14个根样品进行了测序。另外，收集了干燥季节的土壤样品以鉴定AMF肾小球孢子。基于95％到97％的相似性，总共鉴定出属于9个属的36个虚拟类群（VT），包括一个新的类属进化枝。Glomus无论是VT的数量还是序列，它都是最丰富的属。干燥季节和雨季样品的比较显示，殖民椰子根的AMF群落的丰富度和组成存在差异。我们的研究表明，椰子树的根在所有样品中相关的主要AMF属有球囊，Sclerocystis，Rhizophagus，Redeckera和Diversispora呈现。根据肾小球孢子的形态学，记录了22个形态种，其中有14个为物种。Sclerocystis sinuosa在，Sclerocystis rubiformis，球囊microaggregatum和Acaulospora scrobiculata在野外根际样品中占主导地位。这是对雨季和旱季殖民椰子根的AMF群落组成的首次评估。选择AMF物种对于研究其在椰子可持续农业中的潜在应用至关重要。