Shoot organogenesis from petiole explants in the aquatic plant Nymphoides indica

A protocol for rapid shoot organogenesis from petiole explants of the ornam ental aquatic plant Nymphoides indica L. Thwaites O. Kuntze was developed f or use in future mutation breeding and cultivar selection studies. Optimum culture conditions for shoot organogenesis were determined. Effects of fact orial combinations of 2-iP, BA or kinetin (0-25 muM) in factorial combinati on with IAA or NAA (0-25 muM) were examined. On the basis of regeneration f requency (80%) and adventitious shoot number (11.5 shoots per explant), mos t efficient shoot organogenesis occurred on petiole explants cultured on a basal medium consisting of full-strength MS inorganic salts, 0.56 mM myo-in ositol, 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 m uM kinetin and 15 muM NAA, no visible phenotypic abnormalities were observe d in vitro in any of the shoots generated. Solid achlorophyllous adventitio us shoots were recovered following culture of this variegated leaf tissue. Plantlets were easily acclimatized to ex vitro conditions.