Arbuscular Mycorrhizal Fungal Community Composition in Carludovica palmata, Costus scaber and Euterpe precatoria from Weathered Oil Ponds in the Ecuadorian Amazon

Abstract

Arbuscular mycorrhizal fungi (AMF) are ubiquitous to most natural and anthropized ecosystems, and are often found in polluted environments. However, their occurrence and community composition in highly weathered petroleum-polluted soils has been infrequently reported. In the present study, two ponds of weathered crude oil and their surrounding soil from the Charapa field in the Amazon region of Ecuador were selected and root colonization by AMF of their native plants investigated. The AMF community was further analyzed in three selected plant species (i.e., Carludovica palmata, Costus scaber and Euterpe precatoria) present in the two ponds and the surrounding soil. A fragment covering partial SSU, the whole ITS and partial LSU rDNA region was amplified (i.e., 1.5 kb), cloned and sequenced from the roots of each host species. AMF root colonization exceeded 56% in all plant species examined and no significant difference was observed between sites or plants. For AMF community analysis, a total of 138 AMF sequences were obtained and sorted into 32 OTUs based on clustering (threshold ≥97%) by OPTSIL. The found OTUs belonged to the genera Rhizophagus (22%), Glomus (31%), Acaulospora (25%) and Archaeospora (22%). Glomus and Archaeospora were always present regardless of the plant species or the site. Acaulospora was found in the three plant species and in the two ponds while Rhizophagus was revealed only in the surrounding soil in one plant species (Euterpe precatoria). Our study contributed to the molecular community composition of AMF and revealed an unexpected high presence of four AMF genera which have established a symbiosis with roots of native plants from the Amazon forest under high polluted soil conditions.

Community composition of arbuscular mycorrhizal fungi associated with native plants growing in a petroleum‐polluted soil of the Amazon region of Ecuador

“…Root colonization by AMF was observed in all the plants. Total root colonization was above 40% and was very similar to a previous study (Garcés‐Ruiz et al., ). High colonization was also reported by Huang, Tang, Niu, and Zhang () in 13 plant species growing in a petroleum‐contaminated soil at the Sichuan Province in China.…”

“…Interestingly, only the four‐first genera ( Glomus, Rhizophagus , Acaulospora and Archaeospora ) were detected by Sanger sequencing in Garcés‐Ruiz et al. () in the same study site. However, in the study of Garcés‐Ruiz et al.…”

“…Conversely, in the study of Garcés‐Ruiz et al. (), this genus was less abundant (13%) with the presence of A. longula associated with Carludovica palmata and one unindentified species associated with Costus scaber inside the Pond, while A. ketinensis was revealed outside the Pond colonizing C. palmata (Garcés‐Ruiz et al., ). The study performed by Iffis, St‐Arnaud, and Hijri () also identified Acaulospora as a dominant genus in hydrocarbon‐polluted soils.…”

“…However, in the study of Garcés‐Ruiz et al. (), only three plant species (representing 9 samples) were analyzed. The higher number of genera/species detected in this study could thus be attributed, at least partly, to the greater number of sequences generated from the 25 plants species (40 samples) analyzed.…”

“…More details and description of this site can be found in Garcés‐Ruiz et al. (). The Pond has an irregular shape; the west, north, and south sides measured around ~23 m while the east side was only ~15 m. The perimeter of the Pond was marked every ~ 7.3 m (11 points in total).…”