Development of an in vitro plant regeneration protocol for the spotted duckweed, Landoltia punctata.

Abstract Landoltia punctata is an aquatic, free-floating angiosperm plant with a very high multiplication rate and numerous commercial uses. In vitro plant regeneration protocols are necessary to exploit these plants as biomanufacturing platforms. It is frequently observed that the protocols established elsewhere are not effective when it was adopted by another group of researchers due to various reasons. In an attempt to develop transgenic plants in L. punctata., the present study developed a successful and reproducible plant regeneration protocol using fronds as explants. Gamborgs’s B% media and MS media were used in the protocol. Callus induction was obtained on Gamborg’s B5 media supplemented with BAP (1 µM), Dicamba (20 µM), and sucrose (2%). For callus growth MS medium with 2, 4-D (30 µM), TDZ (1 µM), and sorbitol (2%) were used. MS medium supplemented with TDZ (15 µM) and the carbon source combination of sorbitol and sucrose (2:1) gave efficient plant regeneration in L. punctata. Half-strength basal MS media was used for rooting and the in vitro regenerated plants were successfully transferred to the maintenance solution (half-strength Hutner’s media) within a span of one week. The established protocol will be used to develop transgenic L. punctata plants expressing recombinant proteins.