Cultivo in vitro de Clivia miniata (AMARYLLIDACEAE)

Abstract

The growing concern for reducing environmental damage and the pursuit of greater sustainability in agricultural production have placed pressure on producers who are simultaneously seeking new technologies to increase yield and product quality. Plant biotechnology emerges as a complementary tool to traditional large-scale agriculture, offering benefits such as massive clonal propagation, obtaining disease-free plants, somaclonal variation, ploidy management, germplasm conservation, and genetic transformation. Within this context, Clivia miniata, a perennial herbaceous plant, stands out as a species of interest due to its ornamental value and pharmacological potential, attributed to the production of alkaloids like licorine, which has antiviral, antidiabetic, and antimicrobial benefits. However, the commercial in vitro cultivation of this plant faces challenges such as the time required for propagation and relatively low multiplication rates. The study aims to overcome these barriers through the application of tissue culture and biotechnology techniques, focusing on optimizing callus induction in C. miniata through experiments using different growth regulators. In Chapter 2, the research examines the effects of sucrose concentration and fruit maturity on the in vitro germination of Clivia miniata seeds and subsequent callus induction. Viability testing revealed that up to 70% of the seeds were viable. Five sucrose concentrations (0, 10, 20, 30, and 40 g.L-1) were tested in the MS culture medium. During in vitro germination, sucrose concentration affected the germination speed, with lower concentrations resulting in higher germination for seeds from mature fruits. Callus induction from in vitro germinated seedlings yielded variable results, with high concentrations of growth regulators leading to significant explant mortality. However, specific combinations of growth regulators showed high survival rates and callus induction. The results indicate that the optimal sucrose concentration for in vitro germination is 5.1 g.L-1, and the appropriate choice of growth regulators, especially the cytokinin BAP, is crucial for effective callus induction. The third chapter of the thesis consisted of two experiments. In Experiment I, clivia seeds were tested for viability, and after disinfection, embryos were transferred to glass tubes containing MS culture medium and different growth regulators. The experiment lasted 120 days under specific temperature and light absence conditions. Explants were visually evaluated every 30 days, and callus regeneration was performed in medium supplemented with kinetin and naphthaleneacetic acid. Histological analysis of the callus revealed the absence of somatic embryogenesis. In Experiment II, callus was cultivated in temporary immersion bioreactors with different combinations of growth regulators, and the treatment with 4 BAP + 4 NAA stood out for higher fresh mass after 60 days. Callus induction analysis showed notable results, especially in the combination 4 BAP + 4 2,4-D, with a constant increase in the percentage of induced callus and explant survival above 75%. Treatments containing naphthaleneacetic acid resulted in higher fresh mass production. Cytokinin BAP is identified as essential for callogenesis, regardless of the auxin used. In summary, the study provides valuable insights to optimize callus induction conditions in Clivia miniata, contributing not only to the advancement of in vitro cultivation of this species but also to the exploration of its pharmaceutical potential.