Gas exchange rates and sucrose concentrations affect plant growth and production of flavonoids in Vernonia condensata grown in vitro

Tissue culture enables the efficient clonal propagation of plants. This prevents the loss of genetic information in the natural environment and, in the case of medicinal plants, helps produce bioactive metabolites. Here, we used Vernonia condensata to understand how in vitro culture conditions impacted development, anatomy, physiological performance, and biosynthesis of flavonoids and phenolic compounds. The plants were grown in MS medium supplemented with 0, 15, or 30 g L −1 sucrose in flasks with lids without membrane (14 μL L −1 s −1 CO 2 exchange rate) or with two membranes (25 μL L −1 s −1 CO 2 exchange rate). Cultures were maintained for 35 days in a growth room under an irradiance of 50 μmol m −2 s −1 , 16-h photoperiod, and 25 ± 2 °C. Plants exhibited greater growth, more photosynthetic pigments, and better leaf histological differentiation at a higher gas exchange rate and with sucrose supplementation. Despite the reduced stomatal density, a higher gas exchange augmented the photosynthetic rate and, consequently, increased the concentration of hexoses and starch while lowering the content of amino acids. Under conditions of lower gas exchange rates, plants grown in a medium with a higher concentration of sucrose showed an increase in phenolic compounds. However, the highest levels of these metabolites were found in plants grown under higher gas exchange rates. Thus, our findings show that the increase in gas exchange rates and sucrose supplementation are efficient strategies for obtaining plants with greater biomass and production of flavonoids. Key message Vernonia condensata cultured in vitro under higher gas exchange and sucrose supplementation leads to more vigorous plants with increased production of bioactive compounds.