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

Abstract

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.

Inoculation with rhizospheric microorganisms in tropical dry forests restoration increased microbial diversity but had no effect on seedling growth

“…It is remarkable that we found an extremely low abundance of AMF, which might be explained in two ways: (1) Inga , in general, is associated with very low abundances of AMF. This was reported by Arévalo‐Granda et al (2023) in an extensive study, who found only 1.42% Glomeromycotina (specifically Glomeraceae and Acaulosporaceae) in Ecuadorian Amazon Inga rhizosphere. Also, edaphic factors such as pH, water content, and density, among others, may determine AMF richness (Arévalo‐Granda et al 2023), which may explain the general trend of our seedlings forming lower associations with AMF in these specific field conditions.…”

“…This was reported by Arévalo‐Granda et al (2023) in an extensive study, who found only 1.42% Glomeromycotina (specifically Glomeraceae and Acaulosporaceae) in Ecuadorian Amazon Inga rhizosphere. Also, edaphic factors such as pH, water content, and density, among others, may determine AMF richness (Arévalo‐Granda et al 2023), which may explain the general trend of our seedlings forming lower associations with AMF in these specific field conditions. (2) We may not have detected some of the AMF diversity given that our main goal was focused on microbial diversity in general, not only AMF.…”

Análise fitossociologia e valor de importância em carbono de áreas em restauração florestal na Serra da Mantiqueira, Minas Gerais, Brasil

“…( gênero Inga são reconhecidas por sua eficácia na fixação de nitrogênio devido à sua simbiose com bactérias que colonizam nódulos radiculares, denominadas rizóbios (Rhem et al, 2021;Arévalo-Granda et al, 2023;Velasco-Trejo et al, 2023). I. vera e P. dubium são consideradas espécies-chave em processos de recuperação de áreas degradadas, pois apresentam crescimento rápido, adaptabilidade às diferentes condições de solo e potencial para estocagem de carbono na biomassa, contribuindo para a mitigação das mudanças climáticas (Balestrin et al, 2021, Albuquerque et al 2022Silva et al, 2023).…”