Estabelecimento in vitro de guavirobiera (Campomanesia adamantium (Cambess.) O. Berg)

Abstract

Campomanesia adamantium (Cambess.) O. Berg (‘Guavirobeira’) is a species native to the Brazilian Cerrado bioma. It shows great potential for sustainable exploration due to its nutritional quality, variation in fruit use and plant medicinal properties. ‘Guavirobeira’ is naturally propagated by seeds; however, there is some limitations related to recalcitrance and loss of viability (germinative capacity). As an alternative to sexual propagation, this experiment aimed to establish a protocol for asepsis and in vitro establishment of stem explants of ‘guavirobeira’. In order to achieve the results it was evaluated different antimicrobial agents through treatments and distinct experimental design. Experiment 1: Effect of chemical agents (sodium hypochlorite and calcium hypochlorite at 2.5%), at different exposition periods (5 to 10 minutes). Experiment 2: Pre-treatment of plant stems with ascorbic acid (100 mg L-1 ) followed by explant inoculation in culture medium containing different concentrations of rifampicin antibiotic (0-control, 10, 20, 30 and 40 µg mL-1 ). Experiment 3: Effect of the immersion treatment of the pre-established stem with the antimicrobials tetracycline (300 mg L-1 ), carbendazin (1.8 g L-1 ), tetracycline + carbendazin (same respective concentrations) and control (no antimicrobial agent). Asepsis of the explants with calcium hypochlorite for 5 minutes showed higher efficiency in controlling fungal and bacterial contamination whether comparing to sodium hypochlorite. It also reduced the oxidation percentage of the explants which resulted in higher percentage of established explants. The immersion of plant stems in ascorbic acid solution (100 mg L-1 ) for 18 hours was apparently inefficient in controlling explant oxidation. Concentrations above 30 µg mL-1 of rifampicin in the culture medium controlled efficiently the bacterial contamination; however it completely inhibited in vitro establishment of ‘guavirobeira’. Combining carbendazin (1.8 g L-1 ) plus tetracycline (300 mg L-1 ) seemed to diminish bacterial and fungal contamination comparing to control and didn’t cause explant contamination during in vitro establishment.