Micropropagation of Piper crassinervium: an improved protocol for faster growth and augmented production of phenolic compounds

Abstract

The medicinal plant Piper crassinervium is a source of bioactive compounds with potential use in agrochemical and pharmaceutical industries. However, its propagation is slow and influenced by the composition of the culture medium and growth conditions. In the genus Piper, tissue oxidation limits the biomass and recovery of bioactive compounds such as phenols. We evaluated the effect of medium formulations, sucrose, growth regulators, medium consistency, explant type, gas exchange and irradiance levels on growth and phenols and total flavonoids content in P. crassinervium in vitro plants. Murashige and Skoog (MS) and DKW/Juglans (DKW/J) media induced the highest production of chlorophyll and phenolic compounds; however, the regeneration rate of the explants in the DKW/J medium was the lowest (~75%) in comparison with the other media (90%). The maximum biomass production was achieved when half-strength MS (½MS) liquid medium was used; while the optimum sucrose level depended on the medium salt concentration used. Notably, the irradiance altered the accumulation of biomass and phenolic compounds. The presence of one remaining leaf in the nodal segments, used as explants, produced taller plants in ½MS liquid medium, combined or not with 2-iP. The optimal growth conditions for biomass and phenolic compound production in P. crassinervium in vitro plants established were: nodal explant with a preexisting leaf cultured on ½MS stationary liquid medium, 15 g L−1 sucrose, using lids with one PTFE 0.45-µm-pore size membrane and an irradiance of 100 µmol m−2 s−1. Medium formulation, sucrose concentration, irradiance levels, gas exchange and explants with preexisting leaf improved the in vitro propagation and phenolic compounds production in Piper crassinervium.