Identity of normal and mutant flower-color pigments in four different Tradescantia clones confirmed by means of microspectrophotometry

As a step to investigate the genetic identity of normal blue and mutant pink flower-color pigments in four different Tradescantia clones (BNL 02, KU 27, KU 9 and KU 20), which are heterozygous for flower color (blue/pink), the light absorption spectra of the normal blue and mutant pink cells in their stamen hairs were measured microspectrophotometrically. It was found that the blue cells of all the four clones showed the maximum absorption peak at 574 nm, the second peak at 618 nm, and a shoulder at around 544 nm. It was also found that the pink cells of all these clones had two absorption peaks at 546 and 586 nm and a shoulder at around 512 nm. These findings prove that all the four clones examined produce the identical blue-color pigment normally, and also the identical pink-color pigment when the dominant gene for the blue color underwent mutation. One leaky mutant (intermediately colored) hair cell of clone BNL 02 was shown to be producing both the blue- and pink-color pigments.