Uncaria tomentosa Willd. ex Roem. & Schult.: genetic and chemical diversity of accessions cultivated in vitro and their introduction into the native environment

Uncaria tomentosa Willd. ex Roem. & Schult., known as cat's claw, is a medicinal plant that is native to the Amazon and used to treat inflammatory diseases. Currently plants are harvested in a predatory manner leading potentially to extinction of the species. The aims of this study were to develop an efficient protocol for the micropropagation of the species, to evaluate the genetic and chemical diversity of genotypes cultivated in vitro , and to determine the survival rate of plants introduced into the native environment. The optimised micropropagation protocol employed medium-sized flasks containing 20 mL of woody plant medium (WPM) supplemented with 5.0 µM 6-benzylaminopurine (BAP), with four explants per flask maintained under a 16 h photoperiod provided by light emitting diodes. Under these conditions, explants produced an average of 2.13 shoots bearing a total of 8.13 buds per explant. Twenty accessions of U. tomentosa , each originating from seeds of individual plants collected in three states of the Brazilian Amazon, were maintained in vitro and analyzed by start codon targeted (ScoT) molecular markers and chemically by liquid chromatography. These genotypes showed genetic diversity in vitro that was comparable with natural populations, and the majority of accessions accumulated mitraphylline and isomitraphylline. Plantlets cultivated in vitro were acclimatized and introduced into the native environment with a survival rate of 46 ± 18% after eighteen months. It is concluded that in vitro propagation of U. tomentosa is efficient for the production of vigorous plants capable of surviving in the natural conditions of the Amazon rainforest.