Gibberellic acid influences growth indices and biochemical parameters in micropropagated Ocimum gratissimum L. explants

Abstract

Background: Ocimum gratissimum L. is a well-known tropical and subtropical plant widely utilised for both medicinal and nutritional purposes. However, its continuous existence is currently threatened because of excessive human exploitation and non-regulated collection.

Aim: This study aimed at mass-producing O. gratissimum through its explants cultured on Murashige and Skoog (MS) medium.

Settings: Sterile explants of O. gratissimum were used to generate whole plant through the process of somatic embryogenesis and under the influence of different plant growth regulators (PGRs).

Methods: The growth medium was supplemented with various concentrations (0.1 mg/L, 0.5 mg/L and 1.0 mg/L) of PGRs, namely, gibberellic acid (GA₃) and benzyl aminopurine (BAP) in combination with 0.2 mg/L indole acetic acid (IAA), which also served as the control.

Results: The results showed that germination response, shoot and root lengths were significantly enhanced in O. gratissimum explants raised in media containing the two PGRs in a concentration-dependent manner after four weeks of culture. Ocimum gratissimum explants treated with GA₃ and BAP also experienced reduced lipid peroxidation and ascorbic acid concentration, particularly at the highest tested concentration (1.0 mg/L) as evidenced by the significant drop in malondialdehyde (MDA) concentration. In response to this, the activities of superoxide dismutase (SOD) and catalase (CAT) were significantly increased in O. gratissimum explants raised in MS medium supplemented with PGRs.

Conclusion: These results generally suggest that GA₃ in combination with IAA is more favourable than BAP for the micropropagation of O. gratissimum explants. Thus, our study revealed that PGRs possess special attributes, which could be exploited in tissue culture for the micropropagation of O. gratissimum explants.