Figure 2.

The effects of blue light and fluridone on heterophyllous switch in M. quadrifolia. Plants were cultured aseptically in a basal medium (Laetsch, 1967) supplemented with 3% Suc and were kept at 25°C with 16-h photoperiod. A, Control plant grown under the stated conditions for 3 weeks. B, Plant cultured under control conditions for 7 d (as the shoot apex reached the position indicated by the arrowhead) and then transferred to blue light and grown for another 2 weeks. Note the production of aerial leaflet morphology, the elongation of petioles and roots, the formation of lateral roots, and the shortening of the internodes in the part of plant developed under blue light (to the right of the arrowhead). C, Plant grown under control conditions for 7 d (as in A and B) initially and then with the addition of 1 μm fluridone to the culture medium for 2 weeks. The part of the plant to the right of the arrowhead was produced in the presence of 1 μm fluridone. Note the reduction in the coloration of shoot tissues and in the size of the organs. D, Plant as in C except blue light was applied simultaneously with fluridone. Note the formation of aerial characteristics under blue light in the presence of 1 μm fluridone. E, Leaflet morphology of a submerged-type leaf produced in the presence of 1 μm fluridone as described in C. F, Leaflet morphology of an aerial leaf produced under blue light in the presence of 1 μm fluridone as described in D. Scale bars = 1 cm (A–D), 2 mm (E), and 4 mm (F).