Efficiency of the partial substitution of agar with potato starch on the growth and phytochemical parameters of lulo (Solanum quitoense) cultured in vitro

The demand for agar, thanks to its different uses, generates the need to look for alternative substances that replace it. This work studied the influence of four different additions of potato starch into agar media (T1 = 50%, T2 = 45%, T3 = 40% and T4 = 0%) on the growth and chemical composition of essential oils of lulo (Solanum quitoense) explants cultured in vitro. The lengths, fresh and dry biomass weights, and number of nodes of the lulo explants were selected as growth indices and compared against either viscosity of the modified media or extraction percentage and relative concentration of the main components in the essential oils. A higher statistic variability and amount, of the lengths, fresh biomass and number of nodes, were found for the explants cultured in modified agar media compared to those cultured in pure agar. In contrast, minimal variation in metabolite extractions and concentrations were obtained as a function of potato starch addition. Cyclotetradecane, neophytadiene, 1-hexadecene, phytol, oleamide and 3-octadecene were found as the main components of the essential oils by gas chromatography-mass spectrometry (GC-MS). It was found that T1 was the treatment that yielded the best results in the analyzed variables.   Key words: Solanum tuberosum starch, in vitro culture, micropropagation, partial substitution, Solanum quitoense in vitro essential oil, secondary metabolites.