Optimization of callus induction protocol from leaf explants of P<i>ortulaca oleracea</i> and assessment of fatty acid profiles

A protocol for optimization of callus culture establishment from leaf explants of Portulaca oleracea L. was developed. The effect of ethyl methanesulphonate (EMS) on callus induction and synthesis of fatty acids was evaluated. Callus culture was initiated from leaf explants on Murashige and Skoog’s medium supplemented with 2,4‑dichlorophenoxy acetic acid (2,4‑D), a combination of 2,4‑D + 6‑benzyl adenine (BA) or 2,4‑D + kinetin. The maximum callus biomass was obtained at 2.5 µM BA + 2.5 µM 2,4‑D (20.22 g leaf explant–1 fresh weight). The leaves treated with EMS (0.1 to 0.4% h–1) differentiated callus on this optimized medium combination. The gas chromatography-mass spectrometry analysis of fatty acids indicated that the leaves had a high linolenic acid content (17.72%). The callus cultures synthesized heptadecanoic, oleic, and tricosanoic acids, which were otherwise absent in the leaves. Eicosanoic and docosanoic acids in callus cultures were 2.78 and 3.18 times higher than their content in the leaves, respectively. The diversity of fatty acids in treated callus cultures decreased with increased EMS concentration, but the content of a few individual fatty acids was enhanced. Callus at the dose of 0.1% EMS synthesized linoleic acid, which was two times higher than in the untreated callus, while at 0.2% EMS stearic acid was synthesized, which was absent in the untreated callus. It was concluded that the callus of P. oleracea accumulated different fatty acids, and EMS treatment enhanced the content of a few fatty acids in the cultures.