Temperature and GA₃ on ROS and cytogenetic stability during in vitro cultivation of strelitzia zygotic embryos

Temperatura e GA₃ na ERO’s e estabilidade citogenética durante o cultivo in vitro de embriões zigóticos de estrelitzia

ABSTRACT

Tropical species may require higher temperatures as well as higher growth regulator concentrations for in vitro development. Since these conditions may affect plant metabolism, the objective of this study was to identify how different temperatures and gibberellin concentrations may affect the in vitro development of strelitzia embryos, analyzing the effect on ROS and cytogenetic stability. Zygotic embryos were cultivated on MS medium supplemented with 5, 10 and 20 µM GA₃ under temperatures of 25 °C, 30/25 °C and 30 °C. After 60 days, higher embryonic germination rate (72%) and shoot length of plantlets (3.14 cm) were observed on medium containing 20 µM gibberellic acid (GA₃). At this concentration, there was an increase in nitrate reductase activity with no change in the cytogenetic stability. The temperature influenced only shoot and root lengths, which were highest at 25 °C. At 30 °C, superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities increased compared with those at 25 °C. Thus, the addition of 20 µM GA₃ to the culture medium and a temperature of 25 °C in the growth room should be used for zygotic embryo culture of strelitzia.

Index terms:
Antioxidant; embryo culture; gibberellin; nitrate reductase.