Plant regeneration through somatic embryogenesis and genome size analysis of Coriandrum sativum L.

In the present study, an improved plant regeneration protocol via primary and secondary somatic embryogenesis was established in two Co-1 and Rajendra Swathi (RS) varieties of Coriandrum sativum L. Callus was induced from root explants on 2, 4-D (0.5-2.0 mg/l) supplemented MS. The addition of BA (0.2 mg/l) improved callus induction and proliferation response significantly. The maximum callus induction frequency was on 1.0 mg/l 2, 4-D and 0.2 mg/l BA added MS medium (77.5 % in Co-1 and 72.3 % in RS). The callus transformed into embryogenic callus on 2, 4-D added MS with maximum embryogenic frequency was on 1.0 mg/l. The granular embryogenic callus differentiated into globular embryos on induction medium, which later progressed to heart-, torpedo- and cotyledonary embryos on medium amended with 0.5 mg/l NAA and 0.2 mg/l BA. On an average, 2-3 secondary somatic embryos (SEs) were developed on mature primary SEs, which increased the total embryo numbers in culture. Histology and scanning electron microscopy (SEM) studies are presented for the origin, development of primary and secondary embryos in coriander. Later, these induced embryos converted into plantlets on 1.0 mg/l BA and 0.2 mg/l NAA-amended medium. The regenerated plantlets were cultured on 0.5 mg/l IBA added ½ MS for promotion of roots. The well-rooted plantlets were acclimatized and transferred to soil. The genetic stability of embryo-regenerated plant was analyzed by flow cytometry with optimized Pongamia pinnata as standard. The 2C DNA content of RS coriander variety was estimated to 5.1 pg; the primary and secondary somatic embryo-derived plants had 5.26 and 5.44 pg 2C DNA content, respectively. The regenerated plants were genetically stable, genome size similar to seed-germinated coriander plants.