In vitro Multiple Shoots Formation in Wild Lettuce (Launaea taraxacifolia) (Willd.) Amin ex C. Jeffrey

Abstract

Background: Launaea taraxacifolia (Willd) Amin Ex.C Jeffrey is an undervalued traditional leafy vegetable, which is economically important as food and medicine. It also has several therapeutic and nutritive values. The cultivation is hampered by low seed viability, seed dormancy and poor vegetative propagation. Aim: The study aimed to develop an efficient protocol for micropropagation of L. taraxacifolia. Place and Duration of Study: The study was conducted at the tissue culture laboratory of National Centre for Genetic Resources and Biotechnology, Moor Plantation, Ibadan. Nigeria. Methodology: One centimetre (1.00 cm) double-sterilized single-node explants of L. taraxacifolia cultured on Murashige & Skoog (MS) medium amended with a constant concentration (0.5 mg/l) of 1-Naphthaleneacetic acid (NAA) in combination with varying concentration (0.5 mg/l, 1.0 mg/l,   1.5 mg/l, 2.0 mg/l and 2.5 mg/l) of two cytokinins, 6-Benzylaminopurine (BAP) and kinetin were investigated for their effects on shoot proliferation, multiplication and rooting. Growth parameters were observed and recorded and the data subjected to statistical analysis. Results: Among the cytokinin treatments, significant increase in means was observed with increase in the concentration of BAP. There was no significant difference among the treatments with kinetin.  BAP treatments at 2.5 mg/l gave significantly highest number of shoots (3.33 and 4.67) and number of leaves (16.70 and 30.00) at 4 and 8 weeks of culture, respectively as compared to the control. Shoot length was highest in treatment with MS+2 mg/l BAP+0.5 mg/l NAA and MS+1 mg/l KIN+0.5 mg/l NAA (2.33 and 0.30) and these were higher than that of control at 4 weeks and equal at 8 weeks. Residual effect of the Plant growth regulators (PGRs) was observed in treatment with MS+0.5 mg/l KIN+0.5 mg/l NAA alone. Conclusion: The results from the study revealed that L. taraxacifolia nodal explants resulted in multiple shoots in BAP treatments than in kinetin treatments. Double disinfection with treatment with MS+2.5 mg/l BAP+0.5 mg/l NAA which produced the highest number of clean multiple shoots and leaves is thereby proposed as shoot multiplication medium for this species.