Conservação in vitro de germoplasma de Petiveria alliacea L. utilizando cultura de tecidos e criopreservação

Abstract

The implementation of conservation strategies for medicinal species has great importance, both ecologically and economically. Petiveria alliacea L., family Phytolacaceae, known as guinea, garlic-herb, herb-tipi or amansa-senhor , can be found from Central America to South America. This species has wide medicinal use, due to the presence of several chemicals in its composition, as polysulfides, with antifungal, anticancer and immunomodulatory properties, among others. The objective of this work was the in vitro conservation of Petiveria alliacea germplasm obtained from different populations occurring in Rio de Janeiro, through methods based on tissue culture and cryopreservation. The plants derived from in vitro germination were used as donors for micropropagation through multiplication of pre-existing meristems on MS medium without growth regulators, and somatic embryos were obtained directly from the leaf explants from the studied strains, in the presence of PIC (20μM), after 60 days of culture. Shoot tips from micropropagated plants and somatic embryos were subjected to cryopreservation using vitrification, encapsulation-vitrification and encapsulation-dehydration techniques, with the evaluation of pre-culture and cryoprotectant solutions (PVS2 and PVS3) at different concentrations and exposure times. The results showed a frequency of 100% of propagation of plants derived from in vitro germination. The conditions for shoot tips pre-culture were optimized, although no positive results were obtained after thawing. On the other hand, embryos from AL line, maintained their multiplication capacity (100%) when submitted to dehydration in 0.5M sucrose and exposed to the vitrification solutions PVS2 and PVS3 for short periods (15 and 30 minutes). The different recovery media showed variable responses regarding the multiplication capacity of the embryos. The encapsulation / vitrification technique provided the embryos the higher freezing tolerance. Embryo recovery by multiplication after cryopreservation, opens a conservation perspective for genotypes with high polysulfide production, interesting for the pharmaceutical industry