In vitro high frequency regeneration through apical shoot proliferation of Hemianthus callitrichoides `Cuba' - a multipurpose ornamental aquatic plant


Abstract: Hemianthus callitrichoides 'Cuba' is an ornamental aquatic plant used in water gardens and phytoremediation. A protocol for its rapid and reproducible shoot organogenesis from apical shoot explants was developed. Optimum culture conditions for shoot proliferation were tested in MS media containing different concentrations of 6-($\gamma$,$\gamma$-dimethylallylamino)purine (2iP), 6-benzylaminopurine (BAP), 1-phenyl-3-1,2,3-thiadiazol-5-yl urea (TDZ), and gibberellic acid (GA3). Plant growth regulators significantly (P ≤ 0.001) affected the diameter, area, and fresh weight of shoot clumps. On the basis of plant growth, the maximum shoot diameter (3.06 cm), area (6.12 cm), and clump weight (2.85 g) of apical shoots were achieved on MS medium containing 0.50 mg L-1 BAP. Higher concentrations of sucrose (9%) showed visible phenotypic growth inhibition and abnormalities were observed in vitro. The regenerated shoots rooted efficiently on MS medium without growth regulators. The growth pattern of multiple shoots indicated their origin from an enlarged shoot base via the proliferation of apical shoots. All in vitro regenerated plantlets acclimatized in aquariums successfully. The simplicity of the protocol and the direct production of multiple shoots make it a potential system that is highly amenable to true-to-type plant regeneration with the ability to maintain genetic stability.

Keywords: Aquatic plant, apical shoot, Hemianthus callitrichoides, in vitro, regeneration, proliferation, plant growth regulators

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