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Genetic diversity and structure of an endangered medicinal plant species (Pilocarpus microphyllus) in eastern Amazon: implications for conservation


Few studies have evaluated the genetic status of medicinal plants exposed to commercial harvesting. Here, we examine the genetic variability of Pilocarpus microphyllus, an endemic and threatened medicinal plant species from the eastern Amazon, across its largest remaining wild population. Popularly known as jaborandi, species of Pilocarpus genus are the unique known natural source of pilocarpine, an alkaloid used to treat glaucoma and xerostomia. However, Populations of P. microphyllus has experienced a severe decline in the last decades. Using RAD sequencing, we identified a total of 5,266 neutral and independent SNPs in 277 individuals collected from the Carajás National Forest (CNF). We quantified genetic diversity and gene flow patterns and estimated the minimum number of individuals necessary to establish a germplasm bank. Our results revealed high genetic diversity and four spatially distinct clusters of P. microphyllus with substantial admixture among them. Geographic distance and temperature dissimilarity were the factors that best explained the relatedness patterns among individuals. Additionally, our findings indicate that at least 40 matrices sampled randomly from each population would be required to conserve genetic diversity in the long term. In short, P. microphyllus showed high levels of genetic diversity and an effective population size (NE) sufficient to reduce the likelihood of extinction due to inbreeding depression. Our results indicate that diversity has been maintained despite the continuous harvesting of raw leaf material in the area over recent decades. Finally, the results provide information essential for the design of a germplasm bank to protect the endangered medicinal plant species.

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The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.


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To the Cooperativa de Extrativistas de Carajás (COEX-Carajás) for the support in gathering samples in the study area and to the partners of Vale Meio Ambiente Team.


This study was financially supported by the Instituto Tecnológico Vale: RBRS000603.82.GR.JB.

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All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Waleria Monteiro, Jeronymo Dalapicolla, Carolina S. Carvalho, Jamille Costa and Cecilio F Caldeira. The first draft of the manuscript was written by Waleria Monteiro and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

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Correspondence to Cecílio Frois Caldeira.

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Monteiro, W.P., Dalapicolla, J., Carvalho, C.S. et al. Genetic diversity and structure of an endangered medicinal plant species (Pilocarpus microphyllus) in eastern Amazon: implications for conservation. Conserv Genet 23, 745–758 (2022).

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  • Jaborandi
  • Gene flow
  • Population management
  • SNPs
  • Germplasm bank