Chemically Induced Polyploidization In Chlorophytum Amaniense through Indirect Shoot Organogenesis

Chlorophytum amaniense, a member of the family Liliaceae, has only one cultivar known as Fire Flash.  Coral-colored petioles and midribs contrasting with dark green leaves make it a sought after specimen.  ‘Fire Flash’ is a diploid species with 2n = 14; and a large number of seeds are produced from panicle inflorescences.  After seeds set, however, the dried panicle significantly reduces its overall ornamental value.  Additionally, ’Fire Flash’ leaves are fragile and are broken easily.  Since plant polyploidization usually reduces seed setting and increases plant sturdiness, this study was conducted to chemically induce polyploidy in ‘Fire Flash’.  Seeds were sterilized in a 20% Clorox solution and cultured in sterile water for one week on a shaker until sprouting occurred.  Sprouted seeds were treated with colchicine at 0.05%, 0.1%, and 0.2%, oryzalin at 0.001%, 0.005%, and 0.01%, and trifluralin at 0.05%, 0.1%, and 0.15% for 24 h, 48 h, and 72 h, respectively, with shaking.  The seeds were then rinsed 5 times with sterile water and cultured on MS medium containing 4.0 mg/L TDZ and 0.2 mg/L NAA.  Seed survival rates were 98% for those treated with water but decreased to 38.6%, 16.5%, and 4.5% for those treated with colchicine, oryzalin, and triflualin at the maximum concentrations and durations, respectively.  Calluses were formed from those survived seeds that failed to germinate.  Differentiation of calluses resulted in the formation of shoots.  Characterization of morphologically different regenerated plants using DNA flow cytometry showed that polyploidization occurred among those plants.  Flowering characteristics and leaf robustness will be evaluated to determine if polyploidized ‘Fire Flash’ set fewer seeds and if leaf sturdiness is improved once the plants mature.