Genetic and chemical diversity of Uncaria tomentosa (Willd. ex. Schult.) DC. in the Brazilian Amazon
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2017-05
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Uncaria tomentosa (Willd. ex Schult.) DC., a plant native to the Amazon region, is used
widely in popular medicine and by the pharmaceutical industry because of its anti-inflammatory
activity. However, the survival of this species is endangered by deforestation and
indiscriminate collection, and a preservation plan is urgently required. The objectives of
this study were to determine the genetic and chemical variability between and within eight
populations of U. tomentosa from the Brazilian states of Acre, Para and Amapa , and to
investigate possible correlations between genetic and geographical distances, and
between geographical distances or altitude and the accumulation of bioactive oxindole
alkaloids. Three sequence-related amplified polymorphism (SRAP) markers were
employed to fingerprint genomic DNA, and the amounts of mitraphylline and isomitraphylline
in leaf samples were established by high-performance liquid chromatography.
Although significant divergence existed between the tested populations (FST = 0.246), the
largest genetic diversity and the highest percentage of polymorphism (95.68%) was found
within the population from MaÃncio Lima, Acre. Gene flow was considered rather limited
(Nm = 1.57), and no correlations between genetic and geographical distances were
detected, suggesting that population structure followed an island model. Accumulations of
mitraphylline and isomitraphylline varied in the range 32.94 to 0.57 and 3.75 to 0.36 mg g-1
dry weight, respectively. The concentration of isomitraphylline was positively influenced by
altitude, such that the population collected at the site with the highest elevation (Tarauaca ,
Acre) exhibited the greatest alkaloid content. SRAP markers were very efficient in fingerprinting
genomic DNA from U. tomentosa populations and clearly showed that genetic variability
within populations was greater than between populations. A conservation and
management plan should prioritize the creation of germplasm banks to prevent the loss of existing genetic variability, particularly within alkaloid-rich populations such as those of
Tarauaca .
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HONÓRIO, Isabela Cristina G. et al. Genetic structure and chemical diversity in natural populations of Uncaria guianensis (Aubl.) J.F.Gmel. (Rubiaceae). PLoS One, San Francico, v. 13, n. 10, e0205667, May 2017.