Pigmented Plant Tissues in Culture

Abstract

The auxins, I-naphthylacetic acid (NAA) and 2, 4-dichlorophenoxyacetic acid (2, 4-D) are shown to stimulate to varying extents the growth of chloro-phyllous tissues of several plant species cultivated in vitro. Concentrations of 0.1 mg/1 of 2, 4-D or 1.0 mg/1 of NAA are optimal for Haplopappus gracilis, and concentrations of 1.0 mg/1 of 2, 4-D or 10.0 mg/1 of NAA are optimal for Hypochaeris radicata, Oxalis dispar, and Acer pseudoplatanus. NAA or 2, 4-D in concentrations optimal for growth do not affect pigment production in Hypochaeris, but inhibit in Acer and Oxalis. Inhibition of chlorophyll formation by 2, 4-D is partial in Acer and complete in Oxalis, whereas inhibition by NAA is partial in both species. Inhibition of carotenoid pigments by NAA or 2, 4-D is partial in both these species. NAA stimulates pigment production in Haplopappus and 2, 4-D inhibits; the inhibition of carotenoids is again partial, whereas the inhibition of chlorophyll is complete. The data are discussed in relation to the development of chloroplasts in tissue cultures.