DNA Metabarcoding as a Complementary Approach to Traditional Surveys for Monitoring the Plant Diversity in the Amazon canga

The canga of the Serra dos Carajás in the Eastern Amazon (Pará, Brazil) has one of the largest iron ore deposits on the planet and is home to a community of endemic and rare plants. However, conservation and monitoring programs in megadiverse areas, as in the case of the region, are often hampered by the lack of knowledge of the species that inhabit these ecosystems. In this scenario, the comprehensive DNA barcoding effort directed to the complete flora of the canga in the Brazilian Amazon has enabled the implementation of DNA metabarcoding approaches for species monitoring. Here, we assessed the potential of implementing DNA metabarcoding with environmental DNA (eDNA) in future surveys of plant species of the ironstone outcrops of the Serra dos Carajás. After extracting eDNA from soil samples, the nuclear ITS2 region was amplified and sequenced using the Illumina MiSeq platform. With the metabarcoding analyses, we detected 95 species from 72 genera and 35 families, revealing a higher overall diversity than the morphology-based approach, including taxa that were not identified in a traditional floristic survey. The fact that DNA metabarcoding results mostly agreed with the data from the floristic survey indicates the robustness of the molecular approach to be used in monitoring studies of plant diversity in the region. Additionally, we discuss the relevance of our results to guide the development of broader applications of eDNA-based biodiversity monitoring in species-rich environments such as the Serra dos Carajás.