Indução de brotação e calogênese in vitro de Casaqueira [Campomanesia rufa (O. Berg.) Nied.]

Abstract

The Campomanesia rufa (C. rufa) is a fruitful species native to Brazil. Information about this species is scarce and in vitro studies are still incipient. Thus, the present study aimed at developing germination, multiplication and calogenesis protocols for this species. For in vitro germination, seeds were inoculated in MS medium supplemented with GA3 (0, 2, 8, 32 and 128 µM). For multiplication three different experiments were conducted in addition to the shoot elongation. In the first multiplication experiment, the culture media were supplemented with three different cytokinins (BA, BAP or TDZ) at 0, 2.25, 4.5 and 9.0 µM concentrations. In the second experiment, for light quality, shoots were inoculated into culture medium containing 1μM BA, BAP or TDZ. After inoculation, the explants were maintained under white fluorescent lamps and under light-emitting diodes. The third multiplication experiment was performed in different photoperiods (8, 12 and 16h). The explants were maintained in culture medium supplemented with 4.5 µM BAP under white fluorescent lamps. In order to improve the multiplication protocol, an experiment was performed to lengthen the shoots. To that end, different GA3 concentrations (0, 0.5, 1.0, 2.0, 4.0 and 8.0 µM) were applied. Finally, experiments for oxidation control and calogenesis in the species were performed. For oxidation control, the medium was supplemented with different concentrations of PVP (0, 100, 200, 400 and 800 µM) and for callus induction, the regulator 2,4-D (0; 0, 1, 1.0, 5.0 and 10.0 µM) was applied to the culture medium. The Campomanesia rufa presented low germination in the dark (14%). In the multiplication step, BAP at 5.62 µM induced a higher number of sprouts (4.3) and LED lamps as the light source combined with the culture medium with 1μM BAP induced a higher number of sprouts (4.9). The 8h and 12h photoperiods showed the best results regarding the number of sprouts (7.3) and (5.4), respectively, at 90 days. The highest average C. rufa length (32.3 mm) was obtained at a GA3 concentration of 8 µM. The use of PVP at a concentration of 584.3 uM controls up to 27.3% oxidation in young leaf explants. In callus induction, 2,4-D at the concentration of 10 µM leads to a higher callus formation (58, 3%). Therefore, we can conclude that the use of BAP is efficient in shoot induction, PVP controls oxidation leaf segments, and 2,4-D induces callus in C.rufa.