Effects of Growth Regulators and Glutamine on In Vitro Development of Zygotic Embryos of Taro (Colocasia esculenta var. antiquorum)

Abstract

Zygotic embryos of taro, Colocasia esculenta var. antiquorum cultured on Linsmaier-Skoog (LS) medium without the addition of hormones develop into mature plants only in the presence of endosperm tissue. Growth is usually evident within the first week of culture when embryos swell and become green. Embryos excised from endosperm and cultured on LS containing 0-01 mg 1−1 naphthaleneacetic acid (NAA), and 0–01 mg 1−1 6-dimethylaminopurine (6-DMAP) grow at a rate comparable with controls for the first week of culture. During the second week, growth rates are higher than controls primarily because embryos form elongated hypocotyl regions which often produce swollen tissues and/or callus. In the presence of 200 mg 1−1 glutamine and a range of concentrations of 6-dimethylaminopurine, benzyladenine, or NAA, elongation of the hypocotyl axis is inhibited, and a compact callus may develop. Embryos grown on LS containing 200 mg 1−1 glutamine and 2.0 mg 1−1 2, 4, 5-trichlorophenoxyacetic acid form friable callus which was used to generate short-lived suspension cultures.