In vitro somatic embryogenesis and plantlet regeneration from immature male inflorescence of adult dura and tenera palms of Elaeis guineensis (Jacq.)

We report here a method for plant regeneration through somatic embryogenesis from explants collected from immature male inflorescence of adult oil palm cultivated in India. Callus induction was successful from tissues of immature male inflorescence collected from both dura and tenera varieties of oil palm. A modified Y3 (Eeuwens) media supplemented with several additives and activated charcoal (3%) were used for the experiments. Out of four different auxin treatments, 4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid (picloram) produced maximum callus induction (82%) and it was not significantly different from 2,4-dichlorophenoxyacetic acid (2,4-D) and a combination of 2,4-D + picloram. The callus induction obtained with auxin α-naphthalene acetic acid was only 54% and it was significantly low as compared to the other treatments. Highest embryogenesis was obtained with a combination of 2,4-D + picloram (4.9%) followed by picloram (3.4%). Genotypic variation in response to the same auxins was observed both for callus induction and embryogenesis. Callus induction and embryogenesis ranged from 42 to 72% and 6.8 to 9.35%, respectively in tenera. The formation of embryogenic calli was marked by the appearance of white to yellowish globular or nodular structures which subsequently formed clear somatic embryos. Somatic embryogenesis was asynchronous and at one time we could find different stages of embryogenesis like the globular, torpedo and the cotyledonary stages. The somatic embryos when exposed to light in the same basal media along with 6-benzyladenine (18 µM), abscisic acid (3.78 µM) and gibberellic acid (5.78 µM) regenerated into plantlets. To the best of our knowledge this is the first report o f callus induction and somatic embryogenesis from immature male inflorescence of oil palm.