Plant regeneration in stem, petiole and leaf explant cultures of Ipomoea triloba L.

Abstract

Plant regeneration in tissue cultures of Ipomoea triloba L., one of the related species of sweet potato, I. batatas (L.) LAM., was studied. Stem, petiole and leaf explants of I. triloba L. produced white friable calli on MURASHIGE and SKOOG (MS) medium supplemented with 0.5mg/l 2, 4-dichlorophenoxyacetic acid (2, 4-D), 1.0mg/l kinetin, 3.0% sucrose and 0.8% agar, pH5.8. The induction frequency of callus reached 100.0% on all media used. When transferred onto MS medium supplemented with 0-0.4mg/l 3-indoleacetic acid (IAA), 0-10.0mg/l 6-benzylaminopurine (BAP), 3.0% sucrose and 0.8% agar, pH5.8, 65.0-100.0% of the calli formed adventitious roots. Except 0 level of IAA and BAP, the concentrations of IAA and BAP did not significantly influence the forination of adventitious roots. All calli cultured on the adventitious root formation medium were transferred onto hormone-free MS medium containing 3.0% sucrose and 0.8% agar, pH5.8, and the shoots were directly regenerated from (the green areas formed on) the stem-, petiole- and leaf-derived calli at the high frequencies. The highest frequencies of stem-, petiole- and leaf-derived calli regener-ating shoots were 68.4%, 42.1%, and 55.0%, respectively. The concentrations of IAA and BAP added to the adventitious root formation medium significantly influenced the shoot regeneration. The optimal concentrations were 0.4mg/l IAA + 2.0mg/l BAP to stem-derived calli, 0.4mg/l IAA + 5.0mg/l BAP to petiole-derived calli and 0mg/l IAA + 1.0mg/l BAP to leaf-derived calli, respectively. Some adventitious roots also produced a small number of shoots on the hormone-free MS medium. The regenerated shoots developed into whole plantlets after they were transferred onto the fresh hormone-free MS medium. No morphological variations were observed in the regenerated plants.