Shoot organogenesis from petiole explants in the aquatic plant Nymphoides indica

A protocol for rapid shoot organogenesis from petiole explants of the ornamental aquatic plant Nymphoides indica L. Thwaites O. Kuntze was developed for use in future mutation breeding and cultivar selection studies. Optimum culture conditions for shoot organogenesis were determined. Effects of factorial combinations of 2-iP, BA or kinetin (0-25 muM) in factorial combination with IAA or NAA (0-25 muM) were examined. On the basis of regeneration frequency (80%) and adventitious shoot number (11.5 shoots per explant), most efficient shoot organogenesis occurred on petiole explants cultured on a basal medium consisting of full-strength MS inorganic salts, 0.56 mM myo-inositol, 1.2 muM thiamine-HCl, 116.8 mM sucrose supplemented with 10 muM BA and 20 muM IAA and solidified with 0.8% TC agar. Formation of adventitious shoots by direct and indirect shoot organogenesis from the same explant was verified by histological sectioning. With the exception of variegated leaf production on a single adventitious shoot produced in the presence of 25 muM kinetin and 15 muM NAA, no visible phenotypic abnormalities were observed in vitro in any of the shoots generated. Solid achlorophyllous adventitious shoots were recovered following culture of this variegated leaf tissue. Plantlets were easily acclimatized to ex vitro conditions.