CO2-enriched atmosphere and supporting material impact the growth, morphophysiology and ultrastructure of in vitro Brazilian-ginseng [Pfaffia glomerata (Spreng.) Pedersen] plantlets
2014
Saldanha, Cleber Witt | Otoni, Caio Gomide | Rocha, Diego Ismael | Cavatte, Paulo Cézar | Detmann, Kelly da Silva Coutinho | Tanaka, Francisco André Ossamu | Dias, Leonardo Lucas Carnevalli | DaMatta, Fábio Murilo | Otoni, Wagner Campos
This study aimed to evaluate under photoautotrophic conditions the effect of CO₂-enriched atmosphere (360 or 1,000 μmol CO₂mol⁻¹air) combined with two substrate types (agar or Florialite®) in vitro on plants of Pfaffia glomerata, an endangered medicinal species with promising applications in phytotherapy and phytomedicine. The effects of the treatments on the growth, stomatal density, Rubisco activity, carbon isotopic discrimination, metabolite accumulation, photosynthetic pigments and ultrastructural characteristics were investigated. After a 35-day cultivation period, the in vitro-growth of P. glomerata nodal segments under the different treatments resulted in plants with substantial differences in relation to their growth, photosynthetic pigments, stomatal density and leaf ultrastructural characteristics. The enrichment with CO₂coupled with a porous substrate increased the growth of P. glomerata. The stomatal density in the abaxial epidermis more than doubled in response to the high CO₂supply in both supporting types, whereas the Rubisco activity and activation state were both unresponsive to the treatments. Regardless of the CO₂supply, the plants grown in agar displayed higher carbon isotope discrimination than their counterparts grown in Florialite®. We propose that the long-term photosynthetic performance was improved using Florialite®as a growth support in combination with a high CO₂supply. No apparent signs of photosynthetic down-regulation could be found under elevated CO₂conditions. The enrichment of in vitro atmospheres with CO₂coupled with a porous substrate offers new possibilities for improving the growth and production on a commercial scale of high morphological and physiological quality Pfaffia plants.
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