Table_1_Exploring the mycobiome and arbuscular mycorrhizal fungi associated with the rizosphere of the genus Inga in the pristine Ecuadorian Amazon.docx

This study explored the composition of the mycobiome in the rhizosphere of Inga seedlings in two different but neighboring forest ecosystems in the undisturbed tropical Amazon rainforest at the Tiputini Biodiversity Station in Ecuador. In terra firme plots, which were situated higher up and therefore typically outside of the influence of river floods, and in várzea plots, the lower part of the forest located near the riverbanks and therefore seasonally flooded, tree seedlings of the genus Inga were randomly collected and measured, and the rhizosphere soils surrounding the root systems was collected. Members of the Fabaceae family and the genus Inga were highly abundant in both forest ecosystems. Inga sp. seedlings collected in terra firme showed a lower shoot to root ratio compared to seedlings that were collected in várzea, suggesting that Inga seedlings which germinated in várzea soils could invest more resources in vegetative growth with shorter roots. Results of the physical-chemical properties of soil samples indicated higher proportions of N, Mo, and V in terra firme soils, whereas várzea soils present higher concentrations of all other macro- and micronutrients, which confirmed the nutrient deposition effect of seasonal flooding by the nearby river. ITS metabarcoding was used to explore the mycobiome associated with roots of the genus Inga. Bioinformatic analysis was performed using Qiime 2 to calculate the alpha and beta diversity, species taxonomy and the differential abundance of fungi and arbuscular mycorrhizal fungi. The fungal community represented 75% of the total ITS ASVs, and although present in all samples, the subphylum Glomeromycotina represented 1.42% of all ITS ASVs with annotations to 13 distinct families, including Glomeraceae (72,23%), Gigasporaceae (0,57%), Acaulosporaceae (0,49%). AMF spores of these three AMF families were morphologically identified by microscopy. Results of this study indicate that AMF surround the rhizosphere of Inga seedlings in relatively low proportions compared to other fungal groups but present in both terra firme and várzea Neotropical ecosystems.

本研究以厄瓜多尔蒂普蒂尼生物多样性站（Tiputini Biodiversity Station）未受干扰的亚马逊热带原始雨林为研究区域，选取两处毗邻但生境迥异的森林生态系统，探究印加树属（Inga）幼苗根际真菌群落（mycobiome）的组成。研究分别在高滩地（terra firme）样地——该样地地势较高，通常不受河流洪水影响——与洪泛林（várzea）样地——该样地坐落于河岸附近的森林低海拔区域，会遭受季节性洪水淹没——中，随机采集印加树属幼苗并测定相关生长指标，同时收集根系周边的根际土壤。豆科（Fabaceae）植物与印加树属在两类森林生态系统中均为优势类群。从高滩地样地采集的印加树属（Inga sp.）幼苗，其地上地下生物量比（shoot to root ratio）低于洪泛林样地的幼苗，这表明在洪泛林土壤中萌发的印加树幼苗可将更多资源投入营养生长，且根系更短。土壤样品理化性质分析结果显示，高滩地土壤中氮（N）、钼（Mo）与钒（V）的占比更高；而洪泛林土壤中其余所有大量元素与微量元素的浓度均更高，这证实了邻近河流季节性洪水带来的养分沉积效应。本研究采用ITS元条形码测序（ITS metabarcoding）技术，探究与印加树属根系相关的真菌群落。使用Qiime 2进行生物信息学分析，以计算真菌与丛枝菌根真菌（arbuscular mycorrhizal fungi, AMF）的α多样性、β多样性、物种分类学信息及差异丰度。真菌类群的ITS扩增子序列变异（ASVs）占总ITS ASVs的75%；尽管球囊菌亚门（Glomeromycotina）在所有样品中均有检出，但其仅占所有注释过的ITS ASVs的1.42%，可归类至13个不同的科，其中包括球囊霉科（Glomeraceae，占比72.23%）、巨孢囊霉科（Gigasporaceae，占比0.57%）及无梗囊霉科（Acaulosporaceae，占比0.49%）。研究人员通过显微镜对这3个丛枝菌根真菌科的孢子进行了形态学鉴定。本研究结果表明，与其他真菌类群相比，丛枝菌根真菌在印加树幼苗根际的占比相对较低，但在高滩地与洪泛林两类新热带生态系统中均有分布。