Somatic embryogenesis and regeneration using Gracilaria edulis and Padina boergesenii seaweed liquid extracts and genetic fidelity in finger millet (Eleusine coracana)

The effect of seaweed liquid extracts (SLEs) from Gracilaria edulis and Padina boergesenii was studied on finger millet bioassays. Finger millet seeds were germinated on 0-100 % of SLEs. Genotype 'PR-202' showed superior response with higher frequency of germination (99.6 %), fresh weight (1.1 mg seedling(-1)), shoot length (13.4 cm), root number (4.8), and root length (8.6 cm) with 60 % of G. edulis extract. Influence of SLEs and various phytohormones on somatic embryogenesis and regeneration of finger millet was studied. Shoot apical meristem was inoculated on Murashige and Skoog (MS) medium containing 3-5 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D) or 2,4,5-trichlorophenoxyacetic acid individually or in combination of 0.1-1.0 mg L-1 kinetin or 10-40 % each SLEs of G. edulis or P. boergesenii was used for callus induction and somatic embryogenesis. SLEs of each species were used individually at 20-60 % and 25-75 % for somatic embryogenesis and regeneration, respectively. The optimum levels of either SLE were found to be 20, 40, and 50 % for callus induction, somatic embryogenesis, and regeneration from somatic embryos, respectively. The MS medium containing 4.0 mg L-1 2,4-D and 0.5 mg L-1 kinetin produced 53.2 % somatic embryogenesis in genotype 'PR-202' where G. edulis extract improved the somatic embryogenesis to 66.6 %. Further, 40 % of SLEs emerged somatic embryogenesis 89.8 %, regeneration of embryogenic callus 96.3 %, and rooting of elongated shoots 97.4 %, respectively. Well-grown plantlets were acclimatized in the greenhouse with 94 % survival rate. RAPD profiles of in vitro regenerated and mother plants were similar and no somoclonal variation was detected. The current study confirmed that SLEs can be used for somatic embryogenesis and plant regeneration.