Dynamics of the antioxidant system during bud and shoot development in Nidularium minutum Mez (Bromeliaceae) in vitro culture
摘要
Cell differentiation and shoot formation in micropropagated plants is influenced by various factors, including the presence of plant growth regulators (PGR). Considering that the activity of antioxidant enzymes can increase due to cell division, this study aimed to investigate the activity of the antioxidant system in Nidularium minutum during the induction of shoot formation in vitro by cytokinin and to identify the anatomical changes resulting from bud development. Seedlings of N. minutum germinated in vitro were grown on Murashige and Skoog (MS) medium with or without 1.0 mg L−1 of 6-benzylaminopurine (BAP). Shoot formation, lipid peroxidation (LPO), and antioxidant enzyme activity were analyzed in plants with shoots and compared with those without shoots. Anatomical assessments performed on plants incubated for 90 day (d), revealed that bud formation occurred asynchronously, continuously intensified by BAP. The swelling at the stem base of these plants resulted from the division of subepidermal parenchyma cells, which originated adventitious buds by direct organogenesis. The LPO levels decreased after 240 d of cultivation. The transition from bud to shoot development was accompanied by changes in the activities of SOD, APX, and GR, which increased in plants maintained on a medium with BAP during shoot organogenesis. Understanding the enzymes involved in micropropagation is essential to comprehend how antioxidant system adjustment occurs during shoot formation. This knowledge can help overcome the subjectivity of visual identification of in vitro morphogenesis and support the early identification of this process.